Ulnar tunnel syndrome

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| caption = Depiction of classic ulnar sensory distribution, including ulnar-4th and 5th fingers. Note that this diagram does not portray hand muscles affected by ulnar neuropathy.

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Ulnar tunnel syndrome, also known as Guyon's canal syndrome or Handlebar palsy, is ulnar neuropathy at the wrist where it passes through the ulnar tunnel (Guyon's canal).{{Cite web|url = http://www.orthobullets.com/hand/6022/ulnar-tunnel-syndrome|title = Ulnar Tunnel Syndrome|access-date = Sep 7, 2014|website = Orthobullets|last = Hatch|first = Daniel|date = August 20, 2014}} The most common presentation is a palsy of the deep motor branch of the ulnar nerve causing weakness of the interosseous muscles. Ulnar tunnel syndrome is usually caused by a ganglion cyst pressing on the ulnar nerve, other causes include traumas to the wrist and repetitive movements, but often the cause is unknown (idiopathic).{{cite web |last1=Taylor |first1=Michele |title=What Is Ulnar Tunnel Syndrome? Causes, Symptoms, Treatment |url=https://www.webmd.com/pain-management/carpal-tunnel/ulnar-tunnel-syndrome |website=WebMD |access-date=15 June 2024 |language=en}} Long distance bicycle rides are associated with transient alterations in ulnar nerve function.{{cite journal | url=https://pubmed.ncbi.nlm.nih.gov/16000656/ | pmid=16000656 | year=2005 | last1=Akuthota | first1=V. | last2=Plastaras | first2=C. | last3=Lindberg | first3=K. | last4=Tobey | first4=J. | last5=Press | first5=J. | last6=Garvan | first6=C. |title=The effect of long-distance bicycling on ulnar and median nerves: an electrophysiologic evaluation of cyclist palsy | journal=The American Journal of Sports Medicine | volume=33 | issue=8 | pages=1224-30 | doi=10.1177/0363546505275131 }} Sensory loss in the ring and small fingers is usually due to ulnar nerve entrapment at the cubital tunnel near the elbow, which is known as cubital tunnel syndrome, although it can uncommonly be due to compression at the wrist.

Causes

Ulnar neuropathy at the wrist is often associated with a mass such as a ganglion cyst or thrombosis or an aneurysm of the ulnar artery.{{Cite journal|last=Depukat|first=Paweł|last2=Mizia|first2=Ewa|last3=Kuniewicz|first3=Marcin|last4=Bonczar|first4=Tomasz|last5=Mazur|first5=Małgorzata|last6=Pełka|first6=Piotr|last7=Mróz|first7=Izabela|last8=Lipski|first8=Marcin|last9=Tomaszewski|first9=Krzysztof|date=2015|title=Syndrome of canal of Guyon - definition, diagnosis, treatment and complication|journal=Folia Medica Cracoviensia|volume=55|issue=1|pages=17–23|issn=0015-5616|pmid=26774628}} The role of activities and exposure is less certain.

Diagnosis

= Classification =

File:Guyon canal syndrome zones.svg

Ulnar tunnel syndrome may be characterized by the location or zone within the Guyon's canal at which the ulnar nerve is compressed. The nerve divides into a superficial sensory branch and a deeper motor branch in this area. Thus, Guyon's canal can be separated into three zones based on which portion of the ulnar nerve are involved. The resulting syndrome results in either muscle weakness or impaired sensation in the ulnar distribution.

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| | Zone

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| Proximal (prior to ulnar nerve bifurcation)

| Mixed motor & sensory

| Ganglia & hook of hamate fractures

| Surrounding deep motor branch ulnar nerve

| Motor only

| Ganglia & hook of hamate fractures

| Surrounding superficial sensory branch of ulnar nerve

| Sensory only

| Ulnar artery pathology

Zone 2 type syndromes are most common, while Zone 3 are least common.

Treatment

The role of gloves which help protect the ulnar nerve from compression is unclear. Palsy of the ulnar motor nerve isolated to the wrist is treated with operative decompression, often with concomitant ganglion excision. The surgery is to divide the volar carpal ligament which forms the roof of Guyon's canal, thereby reducing compression on the ulnar nerve.{{cite journal |vauthors = Okutsu I, Hamanaka I, Yoshida A |title=Pre- and postoperative Guyon's canal pressure change in endoscopic carpal tunnel release: correlation with transient postoperative Guyon's canal syndrome |journal = J Hand Surg Eur Vol |volume = 34 |issue = 2 |pages = 208–11 |date = April 2009 |pmid = 19282410 |doi = 10.1177/1753193408100122 }}{{cite journal |vauthors = Assmus H, Antoniadis G, Bischoff C, Hoffmann R, Martini AK, Preissler P, Scheglmann K, Schwerdtfeger K, Wessels KD, Wüstner-Hofmann M |title = Cubital tunnel syndrome - a review and management guidelines |journal = Cent Eur Neurosurg |volume = 72 |issue = 2 |pages = 90–8 |date = May 2011 |pmid = 21547883 |doi = 10.1055/s-0031-1271800 }}

Ulnar tunnel syndrome

Causes

Diagnosis

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Treatment

See also

References

Further reading