Congenital pain insensitivity is a rare genetic disorder characterized by the inability to perceive pain. Since affected individuals do not respond appropriately to painful situations, they engage in self-mutilating behavior such as biting of the oral mucosa and fingers and sustain injuries such as burns, fractures, and joint dislocations.
Congenital pain insensitivity (CPI) is an autosomal recessive disorder characterized by the inability to discern physical pain although the ability to feel a stimulus is intact . This rare ailment is considered to be a part of the hereditary sensory and autonomic neuropathies (HSAN) . CPI is a genetically heterogeneous disease caused by mutations in the SCN9A , NTRK1 , and NGFB genes . If left undetected and unaddressed, this condition can affect the patient's overall health and result in serious outcomes.
The clinical presentation reflects which gene is affected. Generally, the cases demonstrate a lack of pain perception with burns, bone fractures, joint dislocations, and other injuries . Moreover, they engage in self-mutilation by biting on their tongue, lips, and digits   resulting in laceration and ulceration of oral mucosa and scarring of the cheeks  . Additionally, affected individuals may exhibit mental retardation and developmental delays with varying degrees. Also common are behavioral issues and emotional lability. Furthermore, patients may be prone to developing neurotrophic keratitis, corneal ulcerations and scarring, and even infection.
Painless injuries induce severe consequences such as recurrent disease and repeated fractures. Specifically, sufferers are susceptible to developing osteomyelitis, acroosteolysis, and Charcot joints. Additionally, they may develop oral ulcers and other lesions, which further lead to infections, oral bleeding, and malnutrition . If not treated, poor outcomes such as failure to thrive are likely .
Jaw & Teeth
- Decreased Sweating
Over time, this lack of pain awareness can lead to an accumulation of injuries and health issues that may affect life expectancy. 0000970 Anosmia Lost smell 0000458 Autosomal recessive inheritance 0000007 Hypohidrosis Decreased ability to sweat Decreased [rarediseases.info.nih.gov]
HSAN type IV is characterized by anhidrosis, absent or markedly decreased sweating [ 1 – 3, 12, 13, 55 – 58 ]. [ojrd.biomedcentral.com]
- Neuropathic Arthropathy
Repeated trauma to joints results in progressive inflammation, damage, and deformity of the affected joints (Charcot joint or neuropathic arthropathy). The large, weight-bearing joints are especially prone to this complication. [rarediseases.org]
- Recurrent Fractures
Death from hyperpyrexia within the first three years of life may occur in 20% of these cases.  Insensitivity to pain is profound and results in deep ulceration on the knees and elbows, overuse of bones and joints leading to recurrent fractures, osteomyelitis [e-ijd.org]
- Indifference to Pain
[…] to pain congenital pain indifference indifference to pain, congenital, autosomal recessive pain insensitivity, congenital Dabby R. [ghr.nlm.nih.gov]
Other names for congenital insensitivity to pain include: asymbolia for pain channelopathy-associated insensitivity to pain CIP congenital analgesia congenital insensitivity to pain congenital pain indifference indifference to pain, congenital, autosomal [thinkgenetic.com]
A syndrome characterized by indifference to PAIN despite the ability to distinguish noxious from nonnoxious stimuli. Absent corneal reflexes and INTELLECTUAL DISABILITY may be associated. [connects.catalyst.harvard.edu]
There is indifference to pain, but this is usually far less of a problem than the autonomic dysfunction. Intelligence is usually normal, but emotions can be unstable. [contact.org.uk]
A twenty one year review of a case of congenital indifference to pain. J Bone Joint Surg Br 1975;57:241-3. [ PUBMED ] [ FULLTEXT ] 13. Abell JM, Hayes JT. Charcot knee due to congenital insensitivity to pain. [ijoonline.com]
- Poor Coordination
The NCS and nerve biopsy are normal. 1 Familial dysautonomia (HSAN-Type-III) also comprises of nystagmus, hypotonia, areflexia and poor coordination. 6 Asymbolia for pain usually has damaged insular cortex evident on magnetic resonance imaging of brain [apicareonline.com]
Type 3 (HSAN-III) features include, hypotonia, hypothermia, poor coordination and temperature regulation with indifference to pain. [neurosciencefundamentals.unsw.wikispaces.net]
Infants and young children with an impaired response to pain and repeated harmful behaviors should be evaluated for this medical entity. The workup will include the patient's history and presentation, a complete physical exam (including a focus on neurologic, oral, and eye tests), and specialized studies.
Biopsy of the skin and nerves can confirm the diagnosis by revealing distinctive findings . Specifically, microscopic analysis of the skin may show the abnormal functioning of nerves innervating eccrine sweat glands while examination of the nerve tissue may demonstrate a diminished quantity of unmyelinated small-diameter fibers. Another exam is characterized by applying pressure with a pen onto the patient's nail bed. Note that an absent withdrawal response is a result of the lack of pain perception . Clinicians may perform the axonal flare test, in which an intradermal histamine injection results in a characteristic skin response. An electromyogram (EMG) will typically yield normal results . Genetic testing is not routinely done since there are many mutations associated with CPI.
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- Genetics Home Reference (GHR). Congenital insensitivity to pain. http://ghr.nlm.nih.gov/condition/congenital-insensitivity-to-pain. Accessed May 22nd, 2017.
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