Carpal tunnel syndrome#Symptoms

File:Carpal Tunnel Syndrome.png{{Main|Carpal tunnel}}

The carpal tunnel is an anatomical compartment located at the base of the palm. Nine flexor tendons and the median nerve pass through the carpal tunnel that is surrounded on three sides by the carpal bones that form an arch. The median nerve provides feeling or sensation to the thumb, index finger, long finger, and half of the ring finger. At the level of the wrist, the median nerve supplies the muscles at the base of the thumb that allow it to abduct, move away from the other four fingers, as well as move out of the plane of the palm. The carpal tunnel is located at the middle third of the base of the palm, bounded by the bony prominence of the scaphoid tubercle and trapezium at the base of the thumb, and the hamate hook that can be palpated along the axis of the ring finger. From the anatomical position, the carpal tunnel is bordered on the anterior surface by the transverse carpal ligament, also known as the flexor retinaculum. The flexor retinaculum is a strong, fibrous band that attaches to the pisiform and the hamulus of the hamate. The proximal boundary is the distal wrist skin crease, and the distal boundary is approximated by a line known as Kaplan's cardinal line.{{cite journal | vauthors = Brooks JJ, Schiller JR, Allen SD, Akelman E | title = Biomechanical and anatomical consequences of carpal tunnel release | journal = Clinical Biomechanics | volume = 18 | issue = 8 | pages = 685–693 | date = October 2003 | pmid = 12957554 | doi = 10.1016/S0268-0033(03)00052-4 }} This line uses surface landmarks, and is drawn between the apex of the skin fold between the thumb and index finger to the palpated hamate hook.{{cite journal | vauthors = Vella JC, Hartigan BJ, Stern PJ | title = Kaplan's cardinal line | journal = The Journal of Hand Surgery | volume = 31 | issue = 6 | pages = 912–918 | date = Jul–Aug 2006 | pmid = 16843150 | doi = 10.1016/j.jhsa.2006.03.009 }}

File:Carpal-Tunnel.svg is colored yellow. The carpal tunnel consists of the bones and transverse carpal ligament.]]{{See also|Pathophysiology of nerve entrapment}}

The carpal tunnel is formed by the carpal bones and the transverse carpal ligament. The median nerve passes through this space along with the flexor tendons. Increased compartmental pressure for any reason can squeeze the median nerve.{{cite journal |vauthors=Joshi A, Patel K, Mohamed A, Oak S, Zhang MH, Hsiung H, Zhang A, Patel UK |date=July 2022 |title=Carpal Tunnel Syndrome: Pathophysiology and Comprehensive Guidelines for Clinical Evaluation and Treatment |url= |journal=Cureus |volume=14 |issue=7 |pages=e27053 |doi=10.7759/cureus.27053 |doi-access=free |pmc=9389835 |pmid=36000134}} Theoretically, increased pressure can interfere with normal intraneural blood flow, eventually causing a cascade of physiological changes in the nerve itself.{{cite journal |vauthors=Mackinnon SE |date=May 2002 |title=Pathophysiology of nerve compression |url= |journal=Hand Clin |volume=18 |issue=2 |pages=231–41 |doi=10.1016/s0749-0712(01)00012-9 |pmid=12371026}} There is a dose-respondent curve such that greater and longer periods of pressure are associated with greater nerve dysfunction. The symptoms and signs of carpal tunnel syndrome causes are hypertrophy of the synovial tissue surrounding the flexor tendons such as with rheumatoid arthritis.{{cite journal |vauthors=Aboonq MS |date=January 2015 |title=Pathophysiology of carpal tunnel syndrome |url= |journal=Neurosciences (Riyadh) |volume=20 |issue=1 |pages=4–9 |doi= |pmc=4727604 |pmid=25630774}}

Prolonged pressure can lead to a cascade of physiological changes in neural tissue. First, the blood-nerve barrier breaks down (increased permeability of perineureum and endothelial cells of endoneural blood vessels). If the pressure continues, the nerves will start the process of demyelination under the area of compression. This will result in abnormal nerve conduction even when the pressure is relieved leading to persistent sensory symptoms until remyelination can occur. If the compression continues and is severe enough, axons may be injured and Wallerian degeneration will occur.{{cite journal |vauthors=Lundborg G, Dahlin LB |date=May 1996 |title=Anatomy, function, and pathophysiology of peripheral nerves and nerve compression |url= |journal=Hand Clin |volume=12 |issue=2 |pages=185–93 |doi=10.1016/S0749-0712(21)00303-6 |pmid=8724572}} At this point there may be weakness and muscle atrophy, depending on the extent of axon damage.{{cite journal |vauthors=Menorca RM, Fussell TS, Elfar JC |date=August 2013 |title=Nerve physiology: mechanisms of injury and recovery |url= |journal=Hand Clin |volume=29 |issue=3 |pages=317–30 |doi=10.1016/j.hcl.2013.04.002 |pmc=4408553 |pmid=23895713}}

The critical pressure above which the microcirculatory environment of a nerve becomes compromised depends on diastolic/systolic blood pressure. Higher blood pressure will require higher external pressure on the nerve to disrupt its microvascular environment.{{cite journal |vauthors=Szabo RM, Gelberman RH, Williamson RV, Hargens AR |date=1983 |title=Effects of increased systemic blood pressure on the tissue fluid pressure threshold of peripheral nerve |url= |journal=J Orthop Res |volume=1 |issue=2 |pages=172–8 |doi=10.1002/jor.1100010208 |pmid=6679859|s2cid=367271 }} The critical pressure necessary to disrupt the blood supply of a nerve is approximately 30mm Hg below diastolic blood pressure or 45mm Hg below mean arterial pressure. For normohypertensive (normal blood pressure) adults, the average values for systolic blood pressure is 116mm Hg diastolic blood pressure is 69mm Hg.{{cite journal |vauthors=Wright JD, Hughes JP, Ostchega Y, Yoon SS, Nwankwo T |date=March 2011 |title=Mean systolic and diastolic blood pressure in adults aged 18 and over in the United States, 2001-2008 |url= |journal=Natl Health Stat Report |volume= |issue=35 |pages=1–22, 24 |doi= |pmid=21485611}} Using this data, the average person would become symptomatic with approximately 39mm Hg of pressure in the wrist (69 - 30 = 39 and 69 + (116 - 69)/3 - 45 ~ 40). Carpal tunnel syndrome patients tend to have elevated carpal tunnel pressures (12-31mm Hg) compared to controls (2.5 - 13mm Hg).{{cite journal |vauthors=Gelberman RH, Hergenroeder PT, Hargens AR, Lundborg GN, Akeson WH |date=March 1981 |title=The carpal tunnel syndrome. A study of carpal canal pressures |url= |journal=J Bone Joint Surg Am |volume=63 |issue=3 |pages=380–3 |doi= 10.2106/00004623-198163030-00009|pmid=7204435}}{{cite journal |vauthors=Rojviroj S, Sirichativapee W, Kowsuwon W, Wongwiwattananon J, Tamnanthong N, Jeeravipoolvarn P |date=May 1990 |title=Pressures in the carpal tunnel. A comparison between patients with carpal tunnel syndrome and normal subjects |url= |journal=J Bone Joint Surg Br |volume=72 |issue=3 |pages=516–8 |doi=10.1302/0301-620X.72B3.2187880 |pmid=2187880|doi-access=free }}{{cite journal |vauthors=Luchetti R, Schoenhuber R, De Cicco G, Alfarano M, Deluca S, Landi A |date=August 1989 |title=Carpal-tunnel pressure |url= |journal=Acta Orthop Scand |volume=60 |issue=4 |pages=397–9 |doi=10.3109/17453678909149305 |pmid=2816314}} Applying pressure to the carpal tunnel of normal subjects in a lab can produce mild neurophysiological changes at 30mm Hg with a rapid, complete sensory block at 60mm Hg.{{cite journal |vauthors=Lundborg G, Gelberman RH, Minteer-Convery M, Lee YF, Hargens AR |date=May 1982 |title=Median nerve compression in the carpal tunnel--functional response to experimentally induced controlled pressure |url= |journal=J Hand Surg Am |volume=7 |issue=3 |pages=252–9 |doi=10.1016/s0363-5023(82)80175-5 |pmid=7086092}} Carpal tunnel pressure may be affected by wrist movement/position, with flexion and extension capable of raising the tunnel pressure as high as 111mm Hg. Many of the activities associated with carpal tunnel symptoms such as driving, holding a phone, etc. involve flexing the wrist and it is likely due to an increase in carpal tunnel pressure during these activities.

Nerve compression can result in various stages of nerve injury. The majority of carpal tunnel syndrome patients have a degree I nerve injury (Sunderland classification), also called neuropraxia. This is characterized by a conduction block, segmental demyelination, and intact axons. With no further compression, the nerves will remyelinate and fully recover. Severe carpal tunnel syndrome patients may have degree II/III injuries (Sunderland classification), or axonotmesis, where the axon is injured partially or fully. With axon injury there would be muscle weakness or atrophy, and with no further compression the nerves may only partially recover.

While there is evidence that chronic compression is a major cause of carpal tunnel syndrome, it may not be the only cause. Several alternative, potentially speculative, theories exist which describe alternative forms of nerve entrapment. One is the theory of nerve scarring (specifically adherence between the mesoneurium and epineureum) preventing the nerve from gliding during wrist/finger movements, causing repetitive traction injuries.{{cite journal |vauthors=Armstrong TJ, Chaffin DB |date=July 1979 |title=Carpal tunnel syndrome and selected personal attributes |url= |journal=J Occup Med |volume=21 |issue=7 |pages=481–6 |doi= |pmid=469613}} Another is the double crush syndrome, where compression may interfere with axonal transport, and two separate points of compression (e.g. neck and wrist), neither enough to cause local demyelination, may together impair normal nerve function.

Carpal tunnel syndrome is estimated to affect one out of ten people during their lifetime and is the most common nerve compression syndrome. There is notable variation in such estimates based on how one defines the problem, in particular whether one studies people presenting with symptoms vs. measurable median neuropathy whether or not people are seeking care. Idiopathic neuropathy accounts for about 90% of all nerve compression syndromes.{{cite journal | vauthors = Ibrahim I, Khan WS, Goddard N, Smitham P | title = Carpal tunnel syndrome: a review of the recent literature | journal = The Open Orthopaedics Journal | volume = 6 | pages = 69–76 | year = 2012 | pmid = 22470412 | pmc = 3314870 | doi = 10.2174/1874325001206010069 |doi-access=free}} The best data regarding CTS comes from population-based studies, which demonstrate no relationship to gender, and increasing prevalence (accumulation) with age.

The characteristic symptom of CTS is numbness, tingling, or burning sensations in the thumb, index, middle, and radial half of the ring finger. These areas process sensation through the median nerve.{{cite journal | vauthors = Aroori S, Spence RA | title = Carpal tunnel syndrome | journal = The Ulster Medical Journal | volume = 77 | issue = 1 | pages = 6–17 | date = January 2008 | pmid = 18269111 | pmc = 2397020 }} Numbness or tingling is usually worse with sleep. People tend to sleep with their wrists flexed, which increases pressure on the nerve. Ache and discomfort may be reported in the forearm or even the upper arm.{{Cite web|url=http://www.nhs.uk/Conditions/Carpal-tunnel-syndrome/Pages/Symptoms.aspx|title=Carpal tunnel syndrome – Symptoms|website=NHS Choices | access-date=2016-05-21|url-status=live|archive-url=https://web.archive.org/web/20160524081418/http://www.nhs.uk/Conditions/Carpal-tunnel-syndrome/Pages/Symptoms.aspx|archive-date=2016-05-24}} Page last reviewed: 18/09/2014 Symptoms that are not characteristic of CTS include pain in the wrists or hands, loss of grip strength,{{cite journal | vauthors = Atroshi I, Gummesson C, Johnsson R, Ornstein E, Ranstam J, Rosén I | title = Prevalence of carpal tunnel syndrome in a general population | journal = JAMA | volume = 282 | issue = 2 | pages = 153–158 | date = July 1999 | pmid = 10411196 | doi = 10.1001/jama.282.2.153 | doi-access = free }} minor loss of sleep,{{Cite web| vauthors = Boyko T |date=January 24, 2022|title=Carpal Tunnel Syndrome|url=https://txosa.com/carpal-tunnel-syndrome/|url-status=live|website=TXOSA|archive-url=https://web.archive.org/web/20220124185447/https://txosa.com/carpal-tunnel-syndrome/ |archive-date=2022-01-24 }} and loss of manual dexterity.{{Cite web |title=Carpal Tunnel Syndrome Information Page |date=December 28, 2010 |publisher=National Institute of Neurological Disorders and Stroke | url=http://www.ninds.nih.gov/disorders/carpal_tunnel/carpal_tunnel.htm |url-status=live |archive-url=https://web.archive.org/web/20101222221850/http://www.ninds.nih.gov/disorders/carpal_tunnel/carpal_tunnel.htm |archive-date=December 22, 2010 }}

As the median neuropathy gets worse, there is loss of sensibility in the thumb, index, middle, and thumb side of the ring finger. As the neuropathy progresses, there may be first weakness, then to atrophy of the muscles of thenar eminence (the flexor pollicis brevis, opponens pollicis, and abductor pollicis brevis). The sensibility of the palm remains normal because the superficial sensory branch of the median nerve branches proximal to the transverse carpal ligament (TCL) and travels superficial to it.{{Cite web |date=September 10, 2009 |title=Carpal Tunnel Syndrome |url=http://emedicine.medscape.com/article/822792-overview |url-status=live |archive-url=https://web.archive.org/web/20100803005746/http://emedicine.medscape.com/article/822792-overview |archive-date=August 3, 2010 |publisher=eMedicine |vauthors=Norvell JG, Steele M}}

Median nerve symptoms may arise from nerve compression at the level of the thoracic outlet or the area where the median nerve passes between the two heads of the pronator teres in the forearm,{{Cite book| vauthors = Netter F |title=Atlas of Human Anatomy|year=2011|publisher=Saunders Elsevier|location=Philadelphia, PA|isbn=978-0-8089-2423-4|pages=412, 417, 435|edition=5th}} although this is debated.

Severe CTS is associated with measurable loss of sensibility. Diminished threshold sensibility (the ability to distinguish different amounts of pressure) can be measured using Semmes-Weinstein monofilament testing.{{cite journal | vauthors = Szabo RM, Gelberman RH, Dimick MP | title = Sensibility testing in patients with carpal tunnel syndrome | journal = The Journal of Bone and Joint Surgery. American Volume | volume = 66 | issue = 1 | pages = 60–64 | date = January 1984 | pmid = 6690444 | doi = 10.2106/00004623-198466010-00009 }} Diminished discriminant sensibility can be measured by testing two-point discrimination: the number of millimeters two points of contact need to be separated before you can distinguish them.{{cite journal | vauthors = Elfar JC, Yaseen Z, Stern PJ, Kiefhaber TR | title = Individual finger sensibility in carpal tunnel syndrome | journal = The Journal of Hand Surgery | volume = 35 | issue = 11 | pages = 1807–1812 | date = November 2010 | pmid = 21050964 | pmc = 4410266 | doi = 10.1016/j.jhsa.2010.08.013 }}

A person with idiopathic carpal tunnel syndrome will not have any sensory loss over the thenar eminence (bulge of muscles in the palm of hand and at the base of the thumb). This is because the palmar branch of the median nerve, which innervates that area of the palm, separates from the median nerve and passes over the carpal tunnel.{{Cite book | vauthors = Netter F |title=Atlas of Human Anatomy |publisher=Saunders Elsevier |year=2011 |isbn=978-0-8089-2423-4 |edition=5th |location=Philadelphia, PA |page=447}}

Severe CTS is also associated with weakness and atrophy of the muscles at the base of the thumb. The ability to palmarly abduct the thumb may be lost. CTS can be detected on examination using one of several maneuvers to provoke paresthesia (a sensation of tingling or "pins and needles" in the median nerve distribution). These so-called provocative signs include:

• Phalen's maneuver. Performed by fully flexing the wrist, then holding this position and awaiting symptoms.{{Cite book |title=Harrison's Principles of Internal Medicine |vauthors=Cush JJ, Lipsky PE |publisher=McGraw-Hill Professional |year=2004 |isbn=978-0-07-140235-4 |edition=16th |page=2035 |chapter=Approach to articular and musculoskeletal disorders}} A positive test is one that results in paresthesia in the median nerve distribution within sixty seconds.
• Tinel's sign is performed by lightly tapping the median nerve just proximal to flexor retinaculum to elicit paresthesia.
• Durkan's test, carpal compression test, or applying firm pressure to the palm over the nerve for up to 30 seconds to elicit paresthesia.{{cite journal | vauthors = González del Pino J, Delgado-Martínez AD, González González I, Lovic A | title = Value of the carpal compression test in the diagnosis of carpal tunnel syndrome | journal = Journal of Hand Surgery | volume = 22 | issue = 1 | pages = 38–41 | date = February 1997 | pmid = 9061521 | doi = 10.1016/S0266-7681(97)80012-5 | s2cid = 25924364 }}{{cite journal | vauthors = Durkan JA | title = A new diagnostic test for carpal tunnel syndrome | journal = The Journal of Bone and Joint Surgery. American Volume | volume = 73 | issue = 4 | pages = 535–538 | date = April 1991 | pmid = 1796937 | doi = 10.2106/00004623-199173040-00009 | s2cid = 11545887 }}
• Hand elevation test The hand elevation test is performed by lifting both hands above the head. Paresthesia in the median nerve distribution within 2 minutes is considered positive.

Diagnostic performance characteristics such as sensitivity and specificity are reported, but difficult to interpret because of the lack of a consensus reference standard for CTS.

Most presentations of CTS have no known disease cause (idiopathic).

The association of other factors with CTS is a source of notable debate. It is important to distinguish factors that provoke symptoms, and factors that are associated with seeking care, from factors that make the neuropathy worse.

Genetic factors are believed to be the most-important determinants of who develops carpal tunnel syndrome. In other words, one's wrist structure seems programmed at birth to develop CTS later in life. A genome-wide association study (GWAS) of carpal tunnel syndrome identified 50 genomic loci significantly associated with the disease, including several loci previously known to be associated with human height.{{cite journal | vauthors = Skuladottir AT, Bjornsdottir G, Ferkingstad E, Einarsson G, Stefansdottir L, Nawaz MS, Oddsson A, Olafsdottir TA, Saevarsdottir S, Walters GB, Magnusson SH, Bjornsdottir A, Sveinsson OA, Vikingsson A, Hansen TF, Jacobsen RL, Erikstrup C, Schwinn M, Brunak S, Banasik K, Ostrowski SR, Troelsen A, Henkel C, Pedersen OB, Jonsdottir I, Gudbjartsson DF, Sulem P, Thorgeirsson TE, Stefansson H, Stefansson K| title = A genome-wide meta-analysis identifies 50 genetic loci associated with carpal tunnel syndrome | journal = Nature Communications | volume = 13 | issue = 1 | pages = 1598 | date = March 2022 | pmid = 35332129 | pmc = 8948232 | doi = 10.1038/s41467-022-29133-7 |bibcode = 2022NatCo..13.1598S }}

Some other factors that contribute to carpal tunnel syndrome are conditions such as diabetes, alcoholism, vitamin deficiency or toxicity as well as exposure to toxins. Conditions such as these don't necessarily increase the interstitial pressure of the carpal tunnel.{{Cite journal |last1=Genova |first1=Alessia |last2=Dix |first2=Olivia |last3=Saefan |first3=Asem |last4=Thakur |first4=Mala |last5=Hassan |first5=Abbas |date=2020-03-19 |title=Carpal Tunnel Syndrome: A Review of Literature |journal=Cureus |volume=12 |issue=3 |pages=e7333 |doi=10.7759/cureus.7333 |doi-access=free |issn=2168-8184 |pmc=7164699 |pmid=32313774}} One case-control study noted that individuals classified as obese (BMI >29) are 2.5 times more likely than slender individuals (BMI <20) to be diagnosed with CTS.{{cite journal | vauthors = Werner RA, Albers JW, Franzblau A, Armstrong TJ | title = The relationship between body mass index and the diagnosis of carpal tunnel syndrome | journal = Muscle & Nerve | volume = 17 | issue = 6 | pages = 632–636 | date = June 1994 | pmid = 8196706 | doi = 10.1002/mus.880170610 | hdl-access = free | s2cid = 16722546 | hdl = 2027.42/50161 }} It is not clear whether this association is due to an alteration of pathophysiology, a variation in symptoms, or a variation in care-seeking.{{cite journal | vauthors = Padua L, Coraci D, Erra C, Pazzaglia C, Paolasso I, Loreti C, Caliandro P, Hobson-Webb LD | title = Carpal tunnel syndrome: clinical features, diagnosis, and management | journal = The Lancet. Neurology | volume = 15 | issue = 12 | pages = 1273–1284 | date = November 2016 | pmid = 27751557 | doi = 10.1016/S1474-4422(16)30231-9 | s2cid = 9991471 }}

Hereditary neuropathy with susceptibility to pressure palsies is a genetic condition that appears to increase the probability of developing CTS. Heterozygous mutations in the gene SH3TC2, associated with Charcot-Marie-Tooth, may confer susceptibility to neuropathy, including CTS.{{cite journal | vauthors = Lupski JR, Reid JG, Gonzaga-Jauregui C, Rio Deiros D, Chen DC, Nazareth L, Bainbridge M, Dinh H, Jing C, Wheeler DA, McGuire AL, Zhang F, Stankiewicz P, Halperin JJ, Yang C, Gehman C, Guo D, Irikat RK, Tom W, Fantin NJ, Muzny DM, Gibbs RA | title = Whole-genome sequencing in a patient with Charcot-Marie-Tooth neuropathy | journal = The New England Journal of Medicine | volume = 362 | issue = 13 | pages = 1181–1191 | date = April 2010 | pmid = 20220177 | pmc = 4036802 | doi = 10.1056/NEJMoa0908094 }}

Association between common benign tumors such as lipomas, ganglion, and vascular malformation should be handled with care. Such tumors are very common and are more likely to cause pressure on the median nerve.{{cite journal | vauthors = Kellett J, McKeown P, Deane B | title = Differences between self-referred and physician-referred hospital admissions | journal = Irish Journal of Medical Science | volume = 174 | issue = 3 | pages = 70–78 | year = 2005 | pmid = 16285343 | doi = 10.1007/BF03170208 | s2cid = 71606479 }} Similarly, the association between transthyretin amyloidosis-associated polyneuropathy and carpal tunnel syndrome is under investigation. Prior carpal tunnel release is often noted in individuals who later present with transthyretin amyloid-associated cardiomyopathy.{{cite journal | vauthors = Conceição I, González-Duarte A, Obici L, Schmidt HH, Simoneau D, Ong ML, Amass L | title = "Red-flag" symptom clusters in transthyretin familial amyloid polyneuropathy | journal = Journal of the Peripheral Nervous System | volume = 21 | issue = 1 | pages = 5–9 | date = March 2016 | pmid = 26663427 | pmc = 4788142 | doi = 10.1111/jns.12153 }} There is consideration that bilateral carpal tunnel syndrome could be a reason to consider amyloidosis, timely diagnosis of which could improve heart health.{{cite journal | vauthors = Donnelly JP, Hanna M, Sperry BW, Seitz WH | title = Carpal Tunnel Syndrome: A Potential Early, Red-Flag Sign of Amyloidosis | journal = The Journal of Hand Surgery | volume = 44 | issue = 10 | pages = 868–876 | date = October 2019 | pmid = 31400950 | doi = 10.1016/j.jhsa.2019.06.016 | s2cid = 199540407 | doi-access = free }} Amyloidosis is rare, even among people with carpal tunnel syndrome (0.55% incidence within 10 years of carpal tunnel release).{{cite journal | vauthors = Sood RF, Kamenko S, McCreary E, Sather BK, Schmitt M, Peterson SL, Lipira AB | title = Diagnosing Systemic Amyloidosis Presenting as Carpal Tunnel Syndrome: A Risk Nomogram to Guide Biopsy at Time of Carpal Tunnel Release | journal = The Journal of Bone and Joint Surgery. American Volume | volume = 103 | issue = 14 | pages = 1284–1294 | date = July 2021 | pmid = 34097669 | doi = 10.2106/JBJS.20.02093 | s2cid = 235370526 }} In the absence of other factors associated with a notable probability of amyloidosis, it is not clear that biopsy at the time of carpal tunnel release has a suitable balance between potential harms and potential benefits.

Other specific pathophysiologies that can cause CTS via pressure include:

• Rheumatoid arthritis and other diseases that cause inflammation of the flexor tendons.
• With severe untreated hypothyroidism, generalized myxedema causes deposition of mucopolysaccharides within both the perineurium of the median nerve, as well as the tendons passing through the carpal tunnel. Association of CTS with lesser degrees of hypothyroidism is questioned.
• Pregnancy may bring out symptoms in genetically predisposed individuals, which may be caused by the temporary changes in hormones and fluid increase pressure in the carpal tunnel. High progesterone levels and water retention may increase the size of the synovium.
• Bleeding and swelling from a fracture or dislocation. This is referred to as acute carpal tunnel syndrome.{{cite journal | vauthors = Dyer G, Lozano-Calderon S, Gannon C, Baratz M, Ring D | title = Predictors of acute carpal tunnel syndrome associated with fracture of the distal radius | journal = The Journal of Hand Surgery | volume = 33 | issue = 8 | pages = 1309–1313 | date = October 2008 | pmid = 18929193 | doi = 10.1016/j.jhsa.2008.04.012 }}
• Acromegaly causes excessive secretion of growth hormones. This causes the soft tissues and bones around the carpal tunnel to grow and compress the median nerve.{{Cite web|title=Carpel Tunnel Syndrome in Acromegaly|url=http://www.treatmentandsymptoms.com/endocrine/acromegaly/|url-status=dead|archive-url=https://web.archive.org/web/20160126014823/http://www.treatmentandsymptoms.com/endocrine/acromegaly/|archive-date=2016-01-26|access-date=2011-10-05|publisher=Treatmentandsymptoms.com}}

• Double crush syndrome is a debated hypothesis that nerve compression or irritation of nerve branches contributing to the median nerve in the neck, or anywhere above the wrist, increases sensitivity of the nerve to compression in the wrist. There is little evidence to support this theory and some concern that it may be used to justify more surgery.{{cite journal | vauthors = Molinari WJ, Elfar JC | title = The double crush syndrome | journal = The Journal of Hand Surgery | volume = 38 | issue = 4 | pages = 799–801; quiz 801 | date = April 2013 | pmid = 23466128 | pmc = 5823245 | doi = 10.1016/j.jhsa.2012.12.038 }}{{cite journal | vauthors = Kane PM, Daniels AH, Akelman E | title = Double Crush Syndrome | journal = The Journal of the American Academy of Orthopaedic Surgeons | volume = 23 | issue = 9 | pages = 558–562 | date = September 2015 | pmid = 26306807 | doi = 10.5435/JAAOS-D-14-00176 | s2cid = 207531472 | doi-access = free }}

Work-related factors that increase risk of CTS include vibration (5.4 odds ratio), hand force (4.2), and repetition (2.3).{{cite journal | vauthors = Newington L, Harris EC, Walker-Bone K | title = Carpal tunnel syndrome and work | journal = Best Practice & Research. Clinical Rheumatology | volume = 29 | issue = 3 | pages = 440–453 | date = June 2015 | pmid = 26612240 | pmc = 4759938 | doi = 10.1016/j.berh.2015.04.026 }} Exposure to wrist extension or flexion at work increases the risk of CTS by 2.0 times. {{As of|2023}}, a systematic review of studies looking at the relationship between CTS and computer use has found current studies to be inconclusive and contradictory, due to poor study methods and confounding variables not being accounted for.{{Cite journal |last1=Lisica Mandek |first1=Denis |last2=Brborović |first2=Hana |date=2023-07-03 |title=Computer use at work and carpal tunnel syndrome: overview of systematic reviews |journal=Sigurnost: časopis za sigurnost u radnoj i životnoj okolini |language=en |volume=65 |issue=2 |pages=163–177 |doi=10.31306/s.65.2.3 |issn=0350-6886|doi-access=free }}

The international debate regarding the relationship between CTS and repetitive hand use (at work in particular) is ongoing. The Occupational Safety and Health Administration (OSHA) has adopted rules and regulations regarding so-called "cumulative trauma disorders" based concerns regarding potential harm from exposure to repetitive tasks, force, posture, and vibration.{{cite journal | vauthors = Derebery J | title = Work-related carpal tunnel syndrome: the facts and the myths | journal = Clinics in Occupational and Environmental Medicine | volume = 5 | issue = 2 | pages = 353–67, viii | year = 2006 | pmid = 16647653 | doi = 10.1016/j.coem.2005.11.014 | doi-access = free }}{{Cite web |author=Office of Communications and Public Liaison |title=National Institute of Neurological Disorders and Stroke |date=December 18, 2009 |url=http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm |url-status=live |archive-url=https://web.archive.org/web/20160303181005/http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm |archive-date=March 3, 2016 }}

A review of available scientific data by the National Institute for Occupational Safety and Health (NIOSH) indicated that job tasks that involve highly repetitive manual acts or specific wrist postures were associated with symptoms of CTS, but there was not a clear distinction of paresthesia (appropriate) from pain (inappropriate) and causation was not established. The distinction from work-related arm pains that are not carpal tunnel syndrome was unclear. It is proposed that repetitive use of the arm can affect the biomechanics of the upper limb or cause damage to tissues. It is proposed that postural and spinal assessment along with ergonomic assessments should be considered, based on observation that addressing these factors has been found to improve comfort in some studies although experimental data are lacking and the perceived benefits may not be specific to those interventions.{{cite journal | vauthors = Cole DC, Hogg-Johnson S, Manno M, Ibrahim S, Wells RP, Ferrier SE | title = Reducing musculoskeletal burden through ergonomic program implementation in a large newspaper | journal = International Archives of Occupational and Environmental Health | volume = 80 | issue = 2 | pages = 98–108 | date = November 2006 | pmid = 16736193 | doi = 10.1007/s00420-006-0107-6 | bibcode = 2006IAOEH..80...98C | s2cid = 21845851 | collaboration = Worksite Upper Extremity Research Group }}{{cite journal | vauthors = O'Connor D, Page MJ, Marshall SC, Massy-Westropp N | title = Ergonomic positioning or equipment for treating carpal tunnel syndrome | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD009600 | date = January 2012 | pmid = 22259003 | pmc = 6486220 | doi = 10.1002/14651858.CD009600 }} A 2010 survey by NIOSH showed that two-thirds of the 5{{nbsp}}million carpal tunnel diagnosed in the US that year were related to work.{{Cite web |url = http://blogs.cdc.gov/niosh-science-blog/2013/06/24/nhis/ |title = How Does Work Affect the Health of the U.S. Population? Free Data from the 2010 NHIS-OHS Provides the Answers |date = 24 June 2013 | vauthors = Luckhaupt SE, Burris DL |publisher = National Institute for Occupational Safety and Health |access-date = 18 January 2015 |url-status = live |archive-url = https://web.archive.org/web/20150118192906/http://blogs.cdc.gov/niosh-science-blog/2013/06/24/nhis/ |archive-date = 18 January 2015 }} Women are more likely to be diagnosed with work-related carpal tunnel syndrome than men.{{Cite web |url = http://blogs.cdc.gov/niosh-science-blog/2013/05/13/womens-health-at-work/ |title = Women's Health at Work |publisher = National Institute for Occupational Safety and Health |access-date = 21 January 2015 |date = 13 May 2013 | vauthors = Swanson N, Tisdale-Pardi J, MacDonald L, Tiesman HM |url-status = live |archive-url = https://web.archive.org/web/20150118223513/http://blogs.cdc.gov/niosh-science-blog/2013/05/13/womens-health-at-work/ |archive-date = 18 January 2015 }} Many if not most patients described in published series of carpal tunnel release are older and often not working.{{cite journal | vauthors = Gelfman R, Melton LJ, Yawn BP, Wollan PC, Amadio PC, Stevens JC | title = Long-term trends in carpal tunnel syndrome | journal = Neurology | volume = 72 | issue = 1 | pages = 33–41 | date = January 2009 | pmid = 19122028 | pmc = 2633642 | doi = 10.1212/01.wnl.0000338533.88960.b9 }}

Normal pressure of the carpal tunnel has been defined as a range of {{cvt|2–10|mm}}.{{cite journal | vauthors = Zamborsky R, Kokavec M, Simko L, Bohac M | title = Carpal Tunnel Syndrome: Symptoms, Causes and Treatment Options. Literature Reviev | journal = Ortopedia, Traumatologia, Rehabilitacja | volume = 19 | issue = 1 | pages = 1–8 | date = January 2017 | pmid = 28436376 | doi = 10.5604/15093492.1232629 | doi-broken-date = 1 November 2024 }} Wrist flexion increases the pressure eight-fold and extension increases it ten-fold.{{cite journal | vauthors = Ibrahim I, Khan WS, Goddard N, Smitham P | title = Carpal tunnel syndrome: a review of the recent literature | journal = The Open Orthopaedics Journal | volume = 6 | issue = 1 | pages = 69–76 | date = 2012-02-23 | pmid = 22470412 | pmc = 3314870 | doi = 10.2174/1874325001206010069 |doi-access=free}} There is speculation that repetitive flexion and extension in the wrist can cause thickening of the synovial tissue that lines the tendons within the carpal tunnel.{{cite journal | vauthors = Lluch AL | title = Thickening of the synovium of the digital flexor tendons: cause or consequence of the carpal tunnel syndrome? | journal = Journal of Hand Surgery | volume = 17 | issue = 2 | pages = 209–212 | date = April 1992 | pmid = 1588206 | doi = 10.1016/0266-7681(92)90091-F | s2cid = 39895571 }}

A variety of patient factors can lead to CTS, including heredity, size of the carpal tunnel, associated local and systematic diseases, and certain habits.{{Cite web | vauthors = Scott KR, Kothari MJ |date=October 5, 2009 |title=Treatment of carpal tunnel syndrome |publisher=UpToDate | url=https://www.uptodate.com/contents/carpal-tunnel-syndrome-treatment-and-prognosis}} Non-traumatic causes generally happen over a period of time, and are not triggered by one certain event. Many of these factors are manifestations of physiologic aging.{{cite journal | vauthors = Stevens JC, Beard CM, O'Fallon WM, Kurland LT | title = Conditions associated with carpal tunnel syndrome | journal = Mayo Clinic Proceedings | volume = 67 | issue = 6 | pages = 541–548 | date = June 1992 | pmid = 1434881 | doi = 10.1016/S0025-6196(12)60461-3 }}

There is no consensus reference standard for the diagnosis of carpal tunnel syndrome. A combination of characteristic symptoms (how it feels) and signs (what the clinician finds on exam) are associated with a high probability of CTS without electrophysiological testing.

Electrodiagnostic testing including electromyography, and nerve conduction studies can objectively measure and verify median neuropathy.{{Citation | vauthors = Rosario NB, De Jesus O |title=Electrodiagnostic Evaluation Of Carpal Tunnel Syndrome |date=2022 |url=http://www.ncbi.nlm.nih.gov/books/NBK562235/ |work=StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32965906 |access-date=2022-07-28 }}

Ultrasound can image and measure the cross sectional diameter of the median nerve, which has some correlation with CTS. The role of ultrasound in diagnosis—just as for electrodiagnostic testing—is a matter of debate. EDX cannot fully exclude the diagnosis of CTS due to the lack of sensitivity.{{citation needed|date=July 2024}}

The role of confirmatory electrodiagnostic testing is debated. The goal of electrodiagnostic testing is to compare the speed of conduction in the median nerve with conduction in other nerves supplying the hand. When the median nerve is compressed, it will conduct more slowly than normal and more slowly than other nerves. Nerve compression results in damage to the myelin sheath and manifests as delayed latencies and slowed conduction velocities. Electrodiagnosis rests upon demonstrating impaired median nerve conduction across the carpal tunnel in context of normal conduction elsewhere.

It is often stated that normal electrodiagnostic studies do not preclude the diagnosis of carpal tunnel syndrome. The rationale for this is that a threshold of neuropathy must be reached before study results become abnormal and also that threshold values for abnormality vary.{{cite journal | vauthors = Graham B, Regehr G, Naglie G, Wright JG | title = Development and validation of diagnostic criteria for carpal tunnel syndrome | journal = The Journal of Hand Surgery | volume = 31 | issue = 6 | pages = 919–924 | year = 2006 | doi = 10.1016/j.jhsa.2006.03.005 | pmid = 16886290 }} Others contend that idiopathic median neuropathy at the carpal tunnel with normal electrodiagnostic tests would represent very, very mild neuropathy that would be best managed as a normal median nerve. Even more important, notable symptoms with mild disease is strongly associated with unhelpful thoughts and symptoms of worry and despair. Notable CTS should remind clinicians to always consider the whole person, including their mindset and circumstances, in strategies to help people get and stay healthy.{{cite journal | doi=10.1001/jama.2017.4545 | title=Changing Mindsets to Enhance Treatment Effectiveness | date=2017 | last1=Crum | first1=Alia | last2=Zuckerman | first2=Barry | journal=JAMA | volume=317 | issue=20 | pages=2063–2064 | pmid=28418538 | pmc=7608684 }}

A joint report published by the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM), the American Academy of Physical Medicine and Rehabilitation (AAPM&R), and the American Academy of Neurology defines practice parameters, standards, and guidelines for EDX studies of CTS based on an extensive critical literature review. This joint review concluded median and sensory nerve conduction studies are valid and reproducible in a clinical laboratory setting and a clinical diagnosis of CTS can be made with a sensitivity greater than 85% and specificity greater than 95%. The AANEM has issued evidence-based practice guidelines for the diagnosis of carpal tunnel syndrome, both by electrodiagnostic studies and by neuromuscular ultrasound.{{cite web |url=https://www.aanem.org/docs/default-source/documents/nmus-for-dx-of-cts_reaffirmed.pdf |title=Evidence-Based Guideline [reaffirmed]: Neuromuscular Ultrasound for the Diagnosis of Carpal Tunnel Syndrome |vauthors=Cartwright M, et al |publisher=American Association of Neuromuscular and Electrodiagnostic Medicine |date=September 2017}}

The role of MRI or ultrasound imaging in the diagnosis of CTS is unclear.{{cite journal | vauthors = Wilder-Smith EP, Seet RC, Lim EC | title = Diagnosing carpal tunnel syndrome--clinical criteria and ancillary tests | journal = Nature Clinical Practice. Neurology | volume = 2 | issue = 7 | pages = 366–374 | date = July 2006 | pmid = 16932587 | doi = 10.1038/ncpneuro0216 | s2cid = 22566215 }}{{cite journal | vauthors = Bland JD | title = Carpal tunnel syndrome | journal = Current Opinion in Neurology | volume = 18 | issue = 5 | pages = 581–585 | date = October 2005 | pmid = 16155444 | doi = 10.1097/01.wco.0000173142.58068.5a | s2cid = 945614 }}{{cite journal | vauthors = Jarvik JG, Yuen E, Kliot M | title = Diagnosis of carpal tunnel syndrome: electrodiagnostic and MR imaging evaluation | journal = Neuroimaging Clinics of North America | volume = 14 | issue = 1 | pages = 93–102, viii | date = February 2004 | pmid = 15177259 | doi = 10.1016/j.nic.2004.02.002 }} Their routine use is not recommended. Morphological MRI has high sensitivity but low specificity for CTS. High signal intensity may suggest accumulation of axonal transportation, myelin sheath degeneration or oedema. However, more recent quantitative MRI techniques which derive repeatable, reliable and objective biomarkers from nerves and skeletal muscle may have utility, including diffusion-weighted (typically diffusion tensor) MRI which has demonstrable normal values and aberrations in carpal tunnel syndrome.{{cite journal | vauthors = Rojoa D, Raheman F, Rassam J, Wade RG | title = Meta-analysis of the normal diffusion tensor imaging values of the median nerve and how they change in carpal tunnel syndrome | journal = Scientific Reports | volume = 11 | issue = 1 | pages = 20935 | date = October 2021 | pmid = 34686721 | pmc = 8536657 | doi = 10.1038/s41598-021-00353-z | bibcode = 2021NatSR..1120935R }}

Cervical radiculopathy can also cause paresthesia abnormal sensibility in the hands and wrist. The distribution usually follows the nerve root, and the paresthesia may be provoked by neck movement. Electromyography and imaging of the cervical spine can help to differentiate cervical radiculopathy from carpal tunnel syndrome if the diagnosis is unclear. Carpal tunnel syndrome is sometimes applied as a label to anyone with pain, numbness, swelling, or burning in the radial side of the hands or wrists. When pain is the primary symptom, carpal tunnel syndrome is unlikely to be the source of the symptoms.{{cite journal | vauthors = Graham B | title = The value added by electrodiagnostic testing in the diagnosis of carpal tunnel syndrome | journal = The Journal of Bone and Joint Surgery. American Volume | volume = 90 | issue = 12 | pages = 2587–2593 | date = December 2008 | pmid = 19047703 | doi = 10.2106/JBJS.G.01362 }}

When the symptoms and signs point to atrophy and muscle weakness more than numbness, consider neurodegenerative disorders such as Amyotrophic Lateral Sclerosis or Charcot-Marie Tooth.{{cite journal | vauthors = Genova A, Dix O, Saefan A, Thakur M, Hassan A | title = Carpal Tunnel Syndrome: A Review of Literature | journal = Cureus | volume = 12 | issue = 3 | pages = e7333 | date = March 2020 | pmid = 32313774 | pmc = 7164699 | doi = 10.7759/cureus.7333 | doi-access = free }}{{cite journal | vauthors = Masrori P, Van Damme P | title = Amyotrophic lateral sclerosis: a clinical review | journal = European Journal of Neurology | volume = 27 | issue = 10 | pages = 1918–1929 | date = October 2020 | pmid = 32526057 | pmc = 7540334 | doi = 10.1111/ene.14393 }}{{cite book | vauthors = Nagappa M, Sharma S, Taly AB | chapter = Charcot Marie Tooth |date=2022 | chapter-url=http://www.ncbi.nlm.nih.gov/books/NBK562163/ | title = StatPearls |place=Treasure Island (FL) |publisher=StatPearls Publishing |pmid=32965834 |access-date=2022-09-06 }}

There is little or no data to support the concept that activity adjustment prevents carpal tunnel syndrome.{{cite journal |vauthors=Lozano-Calderón S, Anthony S, Ring D |date=April 2008 |title=The quality and strength of evidence for etiology: example of carpal tunnel syndrome |journal=The Journal of Hand Surgery |volume=33 |issue=4 |pages=525–538 |doi=10.1016/j.jhsa.2008.01.004 |pmid=18406957}} The evidence for using a wrist rest at a computer keyboard is debated.{{Cite web|url=https://www.ccohs.ca/oshanswers/ergonomics/office/wrist.html|title=Wrist Rests: OSH Answers|website=Canadian Centre for Occupational Health and Safety | access-date=2017-04-14|url-status=live|archive-url=https://web.archive.org/web/20170415012243/https://www.ccohs.ca/oshanswers/ergonomics/office/wrist.html|archive-date=2017-04-15}} There is also little research supporting that ergonomics is related to carpal tunnel syndrome.{{Cite book| vauthors = Goodman G |title=Ergonomic interventions for computer users with cumulative trauma disorders|publisher=International handbook of occupational therapy interventions. 2nd ed.|isbn=978-3-319-08140-3|pages=205–17|date=2014-12-08}}

Given that biological factors such as genetic predisposition and anthropometric features are more strongly associated with carpal tunnel syndrome than occupational/environmental factors such as hand use, CTS might not be prevented by activity modifications.

Some claim that worksite modifications such as switching from a QWERTY computer keyboard layout to Dvorak is helpful, but meta-analyses of the available studies note limited supported evidence.{{cite journal | vauthors = Lincoln AE, Vernick JS, Ogaitis S, Smith GS, Mitchell CS, Agnew J | title = Interventions for the primary prevention of work-related carpal tunnel syndrome | journal = American Journal of Preventive Medicine | volume = 18 | issue = 4 Suppl | pages = 37–50 | date = May 2000 | pmid = 10793280 | doi = 10.1016/S0749-3797(00)00140-9 }}{{cite journal | vauthors = Verhagen AP, Bierma-Zeinstra SM, Burdorf A, Stynes SM, de Vet HC, Koes BW | title = Conservative interventions for treating work-related complaints of the arm, neck or shoulder in adults | journal = The Cochrane Database of Systematic Reviews | volume = 2013 | issue = 12 | pages = CD008742 | date = December 2013 | pmid = 24338903 | pmc = 6485977 | doi = 10.1002/14651858.CD008742.pub2 }}

{{Further|Carpal tunnel surgery}}

There are more than 50 types of treatments for CTS with varied levels of evidence and recommendation across healthcare guidelines, with evidence most strongly supporting surgery, steroids, splinting for wrist positioning, and physical or occupational therapy interventions.{{cite journal | vauthors = Baker NA, Dole J, Roll SC | title = Meta-synthesis of Carpal Tunnel Syndrome Treatment Options: Developing Consolidated Clinical Treatment Recommendations to Improve Practice | journal = Archives of Physical Medicine and Rehabilitation | volume = 102 | issue = 11 | pages = 2261–2268.e2 | date = November 2021 | pmid = 33932358 | doi = 10.1016/j.apmr.2021.03.034 | s2cid = 233477339 }} When selecting treatment, it is important to consider the severity and chronicity of the CTS pathophysiology and to distinguish treatments that can alter the natural history of the pathophysiology (disease-modifying treatments) and treatments that only alleviate symptoms (palliative treatments). The strongest evidence for disease-modifying treatment in chronic or severe CTS cases is carpal tunnel surgery to change the shape of the carpal tunnel.{{cite journal | vauthors = Hageman MG, Kinaci A, Ju K, Guitton TG, Mudgal CS, Ring D | title = Carpal tunnel syndrome: assessment of surgeon and patient preferences and priorities for decision-making | journal = The Journal of Hand Surgery | volume = 39 | issue = 9 | pages = 1799–1804.e1 | date = September 2014 | pmid = 25087865 | doi = 10.1016/j.jhsa.2014.05.035 }}{{cite journal | vauthors = Wood MR | title = Hydrocortisone injections for carpal tunnel syndrome | journal = The Hand | volume = 12 | issue = 1 | pages = 62–64 | date = February 1980 | pmid = 6154006 | doi = 10.1016/S0072-968X(80)80031-3 | s2cid = 43399056 }}

The American Academy of Orthopedic Surgeons recommends proceeding conservatively with a course of nonsurgical therapies tried before release surgery is considered.{{Cite book |date=September 2008 |title=Clinical Practice Guideline on the Treatment of Carpal Tunnel Syndrome |publisher=American Academy of Orthopaedic Surgeons | url=http://www.aaos.org/Research/guidelines/CTSTreatmentGuideline.pdf |url-status=dead |archive-url=https://web.archive.org/web/20091211112335/http://www.aaos.org/research/guidelines/CTSTreatmentGuideline.pdf |archive-date=2009-12-11 |access-date=2010-06-27 }}{{Page needed|date=January 2011}} A different treatment should be tried if the current treatment fails to resolve the symptoms within 2 to 7 weeks. Early surgery with carpal tunnel release is indicated where there is evidence of median nerve denervation or a person elects to proceed directly to surgical treatment. Recommendations may differ when carpal tunnel syndrome is found in association with the following conditions: diabetes mellitus, coexistent cervical radiculopathy, hypothyroidism, polyneuropathy, pregnancy, rheumatoid arthritis, and carpal tunnel syndrome in the workplace. CTS related to another pathophysiology is addressed by treating that pathology. For instance, disease-modifying medications for rheumatoid arthritis or surgery for traumatic acute carpal tunnel syndrome.{{cite journal | vauthors = Werthel JD, Zhao C, An KN, Amadio PC | title = Carpal tunnel syndrome pathophysiology: role of subsynovial connective tissue | journal = Journal of Wrist Surgery | volume = 3 | issue = 4 | pages = 220–226 | date = November 2014 | pmid = 25364632 | pmc = 4208960 | doi = 10.1055/s-0034-1394133 }}{{Cite journal | vauthors = Mahmoud W, El-Naby MM, Awad AA |date=2022-11-09 |title=Carpal tunnel syndrome in rheumatoid arthritis patients: the role of combined ultrasonographic and electrophysiological assessment |journal=Egyptian Rheumatology and Rehabilitation |volume=49 |issue=1 |pages=62 |doi=10.1186/s43166-022-00147-9 |s2cid=253400371 |issn=2090-3235 |doi-access=free }}{{cite journal | vauthors = Gillig JD, White SD, Rachel JN | title = Acute Carpal Tunnel Syndrome: A Review of Current Literature | journal = The Orthopedic Clinics of North America | volume = 47 | issue = 3 | pages = 599–607 | date = July 2016 | pmid = 27241382 | doi = 10.1016/j.ocl.2016.03.005 | series = Orthopedic Urgencies and Emergencies }}

There is insufficient evidence to recommend gabapentin, non-steroidal anti-inflammatories (NSAIDs), yoga, acupuncture, low level laser therapy, magnet therapy, vitamin B6 or other supplements.{{cite journal | vauthors = Piazzini DB, Aprile I, Ferrara PE, Bertolini C, Tonali P, Maggi L, Rabini A, Piantelli S, Padua L | title = A systematic review of conservative treatment of carpal tunnel syndrome | journal = Clinical Rehabilitation | volume = 21 | issue = 4 | pages = 299–314 | date = April 2007 | pmid = 17613571 | doi = 10.1177/0269215507077294 | s2cid = 39628211 }}

File:Carpal tunnel splint.jpg

File:Karpaltunnelsyndrom-Orthese aussen.JPG

Wrist braces (splints) alleviate symptoms by keeping the wrist straight, which avoids the increased pressure in the carpal tunnel associated with wrist flexion or extension. They are used primarily to help people sleep.{{cite journal | vauthors = Povlsen B, Bashir M, Wong F | title = Long-term result and patient reported outcome of wrist splint treatment for carpal tunnel syndrome | journal = Journal of Plastic Surgery and Hand Surgery | volume = 48 | issue = 3 | pages = 175–178 | date = June 2014 | pmid = 24032598 | doi = 10.3109/2000656X.2013.837392 | s2cid = 25257778 }}

Many health professionals suggest that, for the best results, one should wear braces at night. When possible, braces can be worn during the activity primarily causing stress on the wrists.{{cite journal | vauthors = Premoselli S, Sioli P, Grossi A, Cerri C | title = Neutral wrist splinting in carpal tunnel syndrome: a 3- and 6-months clinical and neurophysiologic follow-up evaluation of night-only splint therapy | journal = Europa Medicophysica | volume = 42 | issue = 2 | pages = 121–126 | date = June 2006 | pmid = 16767058 }}{{cite journal | vauthors = Michlovitz SL | title = Conservative interventions for carpal tunnel syndrome | journal = The Journal of Orthopaedic and Sports Physical Therapy | volume = 34 | issue = 10 | pages = 589–600 | date = October 2004 | pmid = 15552705 | doi = 10.2519/jospt.2004.34.10.589 }} The brace should not generally be used during the day as wrist activity is needed to keep the wrist from becoming stiff and to prevent muscles from weakening.{{Cite book|url=https://www.ncbi.nlm.nih.gov/books/NBK279596/|title=Carpal tunnel syndrome: Wrist splints and hand exercises|last=Institute for Quality and Efficiency in Health Care|date=November 16, 2017|publisher=Institute for Quality and Efficiency in Health Care (IQWiG)}}

Corticosteroid injections may provide temporary alleviation of symptoms although they are not clearly better than placebo.{{cite journal | vauthors = Marshall S, Tardif G, Ashworth N | title = Local corticosteroid injection for carpal tunnel syndrome | journal = The Cochrane Database of Systematic Reviews | issue = 2 | pages = CD001554 | date = April 2007 | pmid = 17443508 | doi = 10.1002/14651858.CD001554.pub2 | veditors = Marshall SC }} This form of treatment is thought to reduce discomfort in those with CTS due to its ability to decrease median nerve swelling. The use of ultrasound while performing the injection is more expensive but leads to faster resolution of CTS symptoms. The injections are done under local anesthesia.{{Cite web|url=http://emedicine.medscape.com/article/103333-overview#a4|website=Medscape|title=Carpal Tunnel Steroid Injection|access-date=July 9, 2015|url-status=live|archive-url=https://web.archive.org/web/20150729191652/http://emedicine.medscape.com/article/103333-overview#a4|archive-date=July 29, 2015}}{{Cite web|url=http://www.mountsinai.org/patient-care/health-library/treatments-and-procedures/carpal-tunnel-injection|title=Carpal Tunnel Injection Information|publisher=EBSCO|via=The Mount Sinai Hospital|url-status=live|archive-url=https://web.archive.org/web/20150710145752/http://www.mountsinai.org/patient-care/health-library/treatments-and-procedures/carpal-tunnel-injection|archive-date=2015-07-10}} This treatment is not appropriate for extended periods, however. In general, local steroid injections are only used until more definitive treatment options can be used. Corticosteroid injections do not appear to slow disease progression.

{{Main|Carpal tunnel surgery}}

File:Carpal Tunnel Syndrome, Operation.jpg

Release of the transverse carpal ligament is undertaken in carpal tunnel surgery. The purpose of cutting the transverse carpal ligament is to relieve pressure on the median nerve, and this is a type of nerve decompression surgery. It is recommended when there is constant (not just intermittent) numbness, muscle weakness, or atrophy, and when night-splinting or other palliative interventions no longer alleviate intermittent symptoms.{{cite journal | vauthors = Hui AC, Wong SM, Tang A, Mok V, Hung LK, Wong KS | title = Long-term outcome of carpal tunnel syndrome after conservative treatment | journal = International Journal of Clinical Practice | volume = 58 | issue = 4 | pages = 337–339 | date = April 2004 | pmid = 15161116 | doi = 10.1111/j.1368-5031.2004.00028.x | s2cid = 12545439 }} The surgery may be done with local{{Cite web|url=http://www.webmd.com/pain-management/carpal-tunnel/open-carpal-tunnel-surgery-for-carpal-tunnel-syndrome|website=WebMD | title=Open Carpal Tunnel Surgery for Carpal Tunnel Syndrome|access-date=July 9, 2015|url-status=live|archive-url=https://web.archive.org/web/20150707145827/http://www.webmd.com/pain-management/carpal-tunnel/open-carpal-tunnel-surgery-for-carpal-tunnel-syndrome|archive-date=July 7, 2015}}{{cite journal | vauthors = Al Youha S, Lalonde DH | title = Update/Review: changing of use of local anesthesia in the hand | journal = Plastic and Reconstructive Surgery. Global Open | volume = 2 | issue = 5 | pages = e150 | date = May 2014 | pmid = 25289343 | pmc = 4174079 | doi = 10.1097/GOX.0000000000000095 }}{{cite journal | vauthors = Nabhan A, Ishak B, Al-Khayat J, Steudel WI | title = Endoscopic Carpal Tunnel Release using a modified application technique of local anesthesia: safety and effectiveness | journal = Journal of Brachial Plexus and Peripheral Nerve Injury | volume = 3 | pages = e35–e38 | date = April 2008 | pmid = 18439257 | pmc = 2383895 | doi = 10.1186/1749-7221-3-11 | number = 11 | doi-access = free }} or regional anesthesia with{{cite journal | vauthors = Lee JJ, Hwang SM, Jang JS, Lim SY, Heo DH, Cho YJ | title = Remifentanil-propofol sedation as an ambulatory anesthesia for carpal tunnel release | journal = Journal of Korean Neurosurgical Society | volume = 48 | issue = 5 | pages = 429–433 | date = November 2010 | pmid = 21286480 | pmc = 3030083 | doi = 10.3340/jkns.2010.48.5.429 }} or without sedation, or under general anesthesia.{{Cite web|url=http://www5.aaos.org/icm/PrintModule.cfm?module=icm002|title=AAOS Informed Patient Tutorial – Carpal Tunnel Release Surgery|publisher=The American Academy of Orthopaedic Surgeons | access-date=July 9, 2015|url-status=dead|archive-url=https://web.archive.org/web/20150719060013/http://www5.aaos.org/icm/PrintModule.cfm?module=icm002|archive-date=July 19, 2015}} In general, milder cases can be controlled without surgery for months to years, but severe cases are unrelenting symptomatically and are likely to result in surgical treatment.{{cite journal | vauthors = Kouyoumdjian JA, Morita MP, Molina AF, Zanetta DM, Sato AK, Rocha CE, Fasanella CC | title = Long-term outcomes of symptomatic electrodiagnosed carpal tunnel syndrome | journal = Arquivos de Neuro-Psiquiatria | volume = 61 | issue = 2A | pages = 194–198 | date = June 2003 | pmid = 12806496 | doi = 10.1590/S0004-282X2003000200007 | doi-access = free }}

{{Main|Physical therapy in carpal tunnel syndrome}}

There are many different techniques used in manual therapy for patients with CTS. Some examples are manual and instrumental soft tissue mobilizations, massage therapy, bone mobilizations or manipulations, and neurodynamic techniques, focused on skeletal system or soft tissue.{{cite journal | vauthors = Bialosky JE, Bishop MD, Price DD, Robinson ME, George SZ | title = The mechanisms of manual therapy in the treatment of musculoskeletal pain: a comprehensive model | journal = Manual Therapy | volume = 14 | issue = 5 | pages = 531–538 | date = October 2009 | pmid = 19027342 | pmc = 2775050 | doi = 10.1016/j.math.2008.09.001 }}

In cases of epineural tethering in the upper extremity, manual therapy can reduce this dysfunction and can have a positive impact on the gliding of the nerves through the carpal tunnel while moving the elbow, fingers, or wrist. Manual therapy included the incorporation of specified neurodynamic techniques, functional massage, and carpal bone mobilizations. People who receive physical therapy not only report a decrease in symptoms of pain, but also have increased functional ability of their wrists and hands.{{cite journal|vauthors=Jiménez-Del-Barrio S, Cadellans-Arróniz A, Ceballos-Laita L, Estébanez-de-Miguel E, López-de-Celis C, Bueno-Gracia E, Pérez-Bellmunt A|title=The effectiveness of manual therapy on pain, physical function, and nerve conduction studies in carpal tunnel syndrome patients: a systematic review and meta-analysis|journal=International Orthopaedics|year=2022|volume=46|issue=2|pages=301–312|doi=10.1007/s00264-021-05272-2|pmid=34862562|pmc=8782801}}

Self-myofascial ligament stretching has been suggested as an effective technique, although a meta-analysis claimed this kind of therapy does not show significant improvement in symptoms or function. However, if stretching is received from a physical therapist, it can be more beneficial rather than if it is done by the patient themself. Tendon and nerve gliding exercises appear to be useful in carpal tunnel syndrome.{{cite journal |vauthors=Kim SD |date=August 2015 |title=Efficacy of tendon and nerve gliding exercises for carpal tunnel syndrome: a systematic review of randomized controlled trials |journal=Journal of Physical Therapy Science |volume=27 |issue=8 |pages=2645–2648 |doi=10.1589/jpts.27.2645 |pmc=4563334 |pmid=26357452}}

A 2018 Cochrane review on acupuncture and related interventions for the treatment of carpal tunnel syndrome concluded that, "Acupuncture and laser acupuncture may have little or no effect in the short term on symptoms of carpal tunnel syndrome (CTS) in comparison with placebo or sham acupuncture." It was also noted that all studies had an unclear or high overall risk of bias and that all evidence was of low or very low quality.{{cite journal | vauthors = Choi GH, Wieland LS, Lee H, Sim H, Lee MS, Shin BC | title = Acupuncture and related interventions for the treatment of symptoms associated with carpal tunnel syndrome | journal = The Cochrane Database of Systematic Reviews | volume = 12 | issue = 12 | pages = CD011215 | date = December 2018 | pmid = 30521680 | pmc = 6361189 | doi = 10.1002/14651858.CD011215.pub2 }}

File:Carpal tunnel scars.jpg

The natural history of untreated CTS seems to be gradual worsening of the neuropathy. It is difficult to prove that this is always the case, but the supportive evidence is compelling.

Atrophy of the thenar muscles, weakness of palmar abduction, and loss of sensibility (constant numbness as opposed to intermittent paresthesia) are signs of advanced neuropathy. Advanced neuropathy is often permanent. The nerve will try to recover after surgery for more than 2 years, but the recovery may be incomplete.{{cite journal | vauthors = Mondelli M, Reale F, Padua R, Aprile I, Padua L | title = Clinical and neurophysiological outcome of surgery in extreme carpal tunnel syndrome | journal = Clinical Neurophysiology | volume = 112 | issue = 7 | pages = 1237–1242 | date = July 2001 | pmid = 11516735 | doi = 10.1016/S1388-2457(01)00555-7 | s2cid = 43083160 }}

Paresthesia may increase after release of advanced carpal tunnel syndrome, and people may feel worse than they did prior to surgery for many months.

Troublesome recovery seems related to symptoms of anxiety or depression, and unhelpful thoughts about symptoms (such as worst-case or catastrophic thinking) as well as advanced neuropathy with potentially permanent neuropathy.{{cite journal | vauthors = Lozano Calderón SA, Paiva A, Ring D | title = Patient satisfaction after open carpal tunnel release correlates with depression | journal = The Journal of Hand Surgery | volume = 33 | issue = 3 | pages = 303–307 | date = March 2008 | pmid = 18343281 | doi = 10.1016/j.jhsa.2007.11.025 }}

Recurrence of carpal tunnel syndrome after successful surgery is rare.{{cite journal | vauthors = Ruch DS, Seal CN, Bliss MS, Smith BP | title = Carpal tunnel release: efficacy and recurrence rate after a limited incision release | journal = Journal of the Southern Orthopaedic Association | volume = 11 | issue = 3 | pages = 144–147 | year = 2002 | pmid = 12539938 }}{{cite journal | vauthors = Karthik K, Nanda R, Stothard J | title = Recurrent carpal tunnel syndrome--analysis of the impact of patient personality in altering functional outcome following a vascularised hypothenar fat pad flap surgery | journal = Journal of Hand and Microsurgery | volume = 4 | issue = 1 | pages = 1–6 | date = June 2012 | pmid = 23730080 | pmc = 3371121 | doi = 10.1007/s12593-011-0051-x }} Caution is warranted in considering additional surgery for people dissatisfied with the result of carpal tunnel release as perceived recurrence may more often be due to renewed awareness of persistent symptoms rather than worsening pathology.{{cite journal | vauthors = Amadio PC | title = Interventions for recurrent/persistent carpal tunnel syndrome after carpal tunnel release | journal = The Journal of Hand Surgery | volume = 34 | issue = 7 | pages = 1320–1322 | date = September 2009 | pmid = 19576701 | doi = 10.1016/j.jhsa.2009.04.031 }}

CTS was first described around 1850, but infrequently diagnosed until findings publicized by neurologist W. Russell Brain in 1947. People were often diagnosed with acroparesthesia.{{cite journal | vauthors = Boskovski MT, Thomson JG | title = Acroparesthesia and carpal tunnel syndrome: a historical perspective | journal = The Journal of Hand Surgery | volume = 39 | issue = 9 | pages = 1813–1821.e1 | date = September 2014 | pmid = 25063390 | doi = 10.1016/j.jhsa.2014.05.024 }} Clinicians would often ascribe it to "poor circulation" and not pursue it further.{{cite journal | vauthors = Boskovski MT, Thomson JG | title = Carpal tunnel syndrome, syndrome of partial thenar atrophy, and W. Russell Brain: a historical perspective | journal = The Journal of Hand Surgery | volume = 39 | issue = 9 | pages = 1822–1829.e1 | date = September 2014 | pmid = 25063392 | doi = 10.1016/j.jhsa.2014.05.025 }}

Sir James Paget described median nerve compression at the carpal tunnel in two patients after trauma in 1854.Paget J (1854) Lectures on surgical pathology. Lindsay & Blakinston, Philadelphia{{Cite web | vauthors = Fuller DA |date=September 22, 2010 |title=Carpal Tunnel Syndrome |url=http://emedicine.medscape.com/article/1243192-overview |url-status=live |archive-url=https://web.archive.org/web/20100727165230/http://emedicine.medscape.com/article/1243192-overview |archive-date=July 27, 2010 |publisher=eMedicine}} The first was due to an injury where a cord had been wrapped around a man's wrist. The second was related to a distal radial fracture. For the first case Paget performed an amputation of the hand. For the second case Paget recommended a wrist splint.

The first to notice the association between the carpal ligament pathology and median nerve compression appear to have been Pierre Marie and Charles Foix in 1913.{{Cite journal |vauthors=Marie P, Foix C| year = 1913 | title = Atrophie isolée de l'éminence thenar d'origine névritique: role du ligament annulaire antérieur du carpe dans la pathogénie de la lésion | journal = Rev Neurol | volume = 26 | pages = 647–649 }} They described the results of a postmortem of an 80-year-old man with bilateral carpal tunnel syndrome. They suggested that division of the carpal ligament would be curative in such cases. Putman had previously described a series of 37 patients and suggested a vasomotor origin.{{Cite journal | vauthors = Putnam JJ | year = 1880 | title = A series of cases of paresthesia, mainly of the hand, or periodic recurrence, and possibly of vaso-motor origin | journal = Archives of Medicine | volume = 4 | pages = 147–162 }} The association between the thenar muscle atrophy and compression was noted in 1914.{{Cite journal | vauthors = Hunt JR | year = 1914 | title = The neural atrophy of the muscle of the hand, without sensory disturbances | journal = Rev Neurol Psych | volume = 12 | pages = 137–148 }} The name "carpal tunnel syndrome" appears to have been coined by Moersch in 1938.{{Cite journal | vauthors = Moersch FP | year = 1938 | title = Median thenar neuritis | journal = Proc Staff Meet Mayo Clin | volume = 13 | page = 220 }}

Physician George S. Phalen of the Cleveland Clinic drew attention to the pathology of compression as the reason for CTS after working with a group of patients in the 1950s and 1960s.{{cite journal | vauthors = Phalen GS, Gardner WJ, La Londe AA | title = Neuropathy of the median nerve due to compression beneath the transverse carpal ligament | journal = The Journal of Bone and Joint Surgery. American Volume | volume = 32A | issue = 1 | pages = 109–112 | date = January 1950 | pmid = 15401727 | doi = 10.2106/00004623-195032010-00011 }}{{cite journal | vauthors = Gilliatt RW, Wilson TG | title = A pneumatic-tourniquet test in the carpal-tunnel syndrome | journal = Lancet | volume = 265 | issue = 6786 | pages = 595–597 | date = September 1953 | pmid = 13098011 | doi = 10.1016/s0140-6736(53)90327-4 }}

In 1933 Sir James Learmonth outlined a method of nerve decompression of the nerve at the wrist.{{Cite journal | vauthors = Learmonth JR | year = 1933 | title = The principle of decompression in the treatment of certain diseases of peripheral nerves | journal = Surg Clin North Am | volume = 13 | pages = 905–913 }} This procedure appears to have been pioneered by the Canadian surgeons Herbert Galloway and Andrew MacKinnon in 1924 in Winnipeg but was not published.{{cite journal | vauthors = Amadio PC | title = The first carpal tunnel release? | journal = Journal of Hand Surgery | volume = 20 | issue = 1 | pages = 40–41 | date = February 1995 | pmid = 7759932 | doi = 10.1016/s0266-7681(05)80013-0 | s2cid = 534160 }} Endoscopic release was described in 1988.{{cite journal | vauthors = Chow JC | title = Endoscopic release of the carpal ligament for carpal tunnel syndrome: 22-month clinical result | journal = Arthroscopy | volume = 6 | issue = 4 | pages = 288–296 | year = 1989 | pmid = 2264896 | doi = 10.1016/0749-8063(90)90058-l }}

• Cheiralgia paresthetica
• Cubital tunnel syndrome
• Radial tunnel syndrome
• Tarsal tunnel syndrome
• Ulnar tunnel syndrome

{{Reflist}}

{{Medical resources

| DiseasesDB = 2156

| ICD10 = {{ICD10|G|56|0|g|50}}

| ICD9 = {{ICD9|354.0}}

| ICDO =

| OMIM = 115430

| MedlinePlus = 000433

| eMedicineSubj = orthoped

| eMedicineTopic = 455

| eMedicine_mult = {{eMedicine2|pmr|21}} {{eMedicine2|emerg|83}} {{eMedicine2|radio|135}}

| MeshID = D002349

}}

• [http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm Carpal Tunnel Syndrome Fact Sheet (National Institute of Neurological Disorders and Stroke)] {{Webarchive|url=https://web.archive.org/web/20160303181005/http://www.ninds.nih.gov/disorders/carpal_tunnel/detail_carpal_tunnel.htm |date=2016-03-03 }}
• [https://web.archive.org/web/20200524230750/http://www.carpal-tunnel.net/ NHS website carpal-tunnel.net provides a free to use, validated, online self diagnosis questionnaire for CTS]
• {{Cite web | url = https://medlineplus.gov/carpaltunnelsyndrome.html | publisher = U.S. National Library of Medicine | work = MedlinePlus | title = Carpal Tunnel Syndrome }}

{{Nervous system symptoms and signs}}

{{PNS diseases of the nervous system}}

{{Authority control}}

Category:Mononeuropathies of upper limb

Category:Physical ergonomics

Category:Syndromes affecting the nervous system

Category:Wikipedia medicine articles ready to translate

Category:Wikipedia emergency medicine articles ready to translate