Congenital insensitivity to pain with anhidrosis

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| image = HSANIV (CIPA).jpg

| caption = Charcot joints are shown in this boy with CIPA.

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| causes = Genetic mutations

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Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disorder of the nervous system which prevents the feeling of pain or temperature and prevents a person from sweating. Cognitive disorders are commonly coincidental. CIPA is the fourth type of hereditary sensory and autonomic neuropathy (HSAN), and is also known as HSAN IV.

Signs and symptoms

Signs of CIPA are present from infancy. Infants may present with seizures related to an abnormally high body temperature. Since people with this condition are unable to sweat, they are unable to properly regulate their body temperature.{{Cite book |title=Fenichel's Clinical Pediatric Neurology |date=2013 |publisher=Elsevier |edition=6th |pages=207–214}} Those affected are unable to feel pain and temperature.{{Cite journal |last=Kim |first=J. S. |last2=Woo |first2=Y. J. |last3=Kim |first3=G. M. |last4=Kim |first4=C. J. |last5=Ma |first5=J. S. |last6=Hwang |first6=T. J. |last7=Lee |first7=M. C. |date=1999 |title=Congenital insensitivity to pain with anhidrosis: a case report |journal=Journal of Korean Medical Science |volume=14 |issue=4 |pages=460–464 |doi=10.3346/jkms.1999.14.4.460 |pmc=3054407 |pmid=10485630}}{{Cite journal |last=Indo |first=Yasuhiro |date=November 2010 |title=Nerve growth factor, pain, itch and inflammation: lessons from congenital insensitivity to pain with anhidrosis |url=http://www.tandfonline.com/doi/full/10.1586/ern.10.154 |journal=Expert Review of Neurotherapeutics |language=en |volume=10 |issue=11 |pages=1707–1724 |doi=10.1586/ern.10.154 |pmid=20977328 |via=Taylor & Francis |hdl-access=free |hdl=2298/23889}}

The absence of pain experienced by people with CIPA puts them at high risk for accidental self-injury. Corneal ulceration occurs due to a lack of protective impulses. Joint and bone problems are common due to repeated injuries, and wounds heal poorly.{{Cite book |title=Swaiman's Pediatric Neurology |date=2017 |publisher=Elsevier |edition=6th |pages=e2652–e2669}}

Delayed developmental milestones in early years may be observed.

Patients often have severe learning difficulties, irritability, hyperactivity, self-injurious behaviour, and cognitive impairment, but patients with normal intelligence have also been reported.

Cause

CIPA is caused by a genetic mutation that prevents the formation of nerve cells responsible for transmitting signals of pain, heat, and cold in the brain.

The disorder is inherited in an autosomal recessive fashion.

CIPA is caused by a mutation in NTRK1, a gene encoding the neurotrophic tyrosine kinase receptor.{{Cite journal |display-authors=etal |vauthors=Shatzky S, Moses S, Levy J |date=June 2000 |title=Congenital insensitivity to pain with anhidrosis (CIPA) in Israeli-Bedouins: genetic heterogeneity, novel mutations in the TRKA/NGF receptor gene, clinical findings, and results of nerve conduction studies |journal=Am. J. Med. Genet. |volume=92 |issue=5 |pages=353–60 |doi=10.1002/1096-8628(20000619)92:5<353::AID-AJMG12>3.0.CO;2-C |pmid=10861667}} NTRK1 is a receptor for nerve growth factor (NGF). This protein induces outgrowth of axons and dendrites and promotes the survival of embryonic sensory and sympathetic neurons. The mutation in NTRK1 does not allow NGF to bind properly, causing defects in the development and function of nociceptive reception.

Mitochondrial abnormalities in muscle cells have been found in people with CIPA. Skin biopsies show a lack of innervation of the eccrine glands and nerve biopsies show a lack of small myelinated and unmyelinated fibers.{{Cite book |title=Volpe's Neurology of the Newborn |date=2018 |publisher=Elsevier |edition=6 |pages=887–921}}

Diagnosis

Diagnosis is made based on clinical criteria, supported by nerve biopsy findings of reduced unmyelinated and small myelinated fibres, and can be confirmed with genetic testing.

= Differential diagnosis =

The absence of or significantly reduced sweating in CIPA patients can be used for a differential diagnosis.

Treatment

There is no treatment for CIPA. Attention to injuries to prevent infection and worsening is necessary.

= Anaesthetic management =

Some patients with CIPA have been operated on without anesthesia, but the patient's anxiety might still need to be alleviated in these cases.

Patients might have tactile hyperesthesia, in which case anesthesia is necessary.[https://www.cureus.com/articles/120499-a-boy-who-knows-no-pain-anaesthetic-management-of-congenital-insensitivity-to-pain-with-anhidrosis#!/ A Boy Who Knows No Pain: Anaesthetic Management of Congenital Insensitivity to Pain With Anhidrosis ]

Bradycardia, hypotension, and hyperthermia also require management/attention, before, during, and after surgery.

Epidemiology

Worldwide several hundred cases have been reported, but the exact prevalence is unknown.[https://www.orpha.net/en/disease/detail/642?name=Hereditary%20sensory%20and%20autonomic%20neuropathy%20type%20IV&mode=name orpha.net: Hereditary sensory and autonomic neuropathy type IV] According to a study, congenital insensitivity to pain with anhydrosis occurs in about 1 out of 125 million births[Daneshjou, K., Jafarieh, H., & Raaeskarami, S. R. (2012). Congenital Insensitivity to Pain and Anhydrosis (CIPA) Syndrome; A Report of 4 Cases. Iranian journal of pediatrics, 22(3), 412–416]

The condition is inherited and is most common among Negev Arabs aka Negev Bedouins.{{Cite book |title=Tachdjian's Pediatric Orthopaedics |date=2014 |publisher=Saunders Elsevier |edition=5th |pages=285–319}}

For Japan, the prevalence is estimated at 1/600,000–950,000.

Approximately 20% of people with CIPA die of hyperthermia by age 3.