Congenital insensitivity to pain with anhidrosis.

Dear Sir,

Congenital insensitivity to pain with anhidrosis (CIPA) or hereditary sensory; Type IV autonomic neuropathy, is an extremely rare autosomal recessive disorder[1] characterized by congenital pain insensitivity, lack of thermal sensitivity, mental retardation of varying intensities, self-mutilation, little or no perspiration, failure to thrive, and recurrent episodes of fever secondary to anhidrosis.[2]

A 7-year-old female child was posted for closed reduction of recurrent hip dislocation. Only child born of a non-consanguineous marriage, with insignificant family and antenatal history, delivered at term through normal vaginal delivery. Dislocation of hip first occurred at the age of 2 years and has recurred ever since. She weighed 23 kg, unable to walk, conscious and oriented. She had titubation. Finger tips ulcerations were seen due to repeated episodes of finger chewing [Figure 1]. Thermal injuries were noted in the lower limbs [Figure 2]. The child's development was normal for age. On examination, there were signs of self-mutilation in the form of ulcerations of the lower lip, tongue, and oral mucosa [Figure 3]. Auto-amputations of the finger tips and toes were also noted. On neurological examination, cranial nerve, tone, power, reflexes, and the fundus examination were normal. Sensory examination revealed absent corneal reflex. Response to pinprick was severely limited and there was no response to temperature sensation. No hypopigmented patches or any thickened palpable nerves were seen. Nerve conduction study was normal. Sympathetic skin testing response was absent. Computed tomography (CT) scan was normal, no intracranial bleed. Hematological profile and serum uric acid level were normal. Closed reduction of hip dislocation and prosthodontic treatment were done with counseling of family members regarding risk in relation to the environment in absence of pain constraints and high incidence of self-abusive behavior.

Figure 1

Ulceration on the finger tip

Figure 2

Thermal injuries on lower limbs

Figure 3

Ulceration of lower lip, tongue, and mucosa

CIPA is secondary to a mutation in the neurotrophic tyrosine kinase receptor type I (NTRK1) gene.[34] Mutation of this gene inhibits the development of nerve growth factor (NGF), and dependent sensory and autonomic neurons during the embryonic period. There is absence of unmyelinated fibers in addition to the loss of small myelinated ones. This result in the absence of epidermal nerve fibers and fibers around the sweat glands and forms the morphological basis of analgesia and anhidrosis in CIPA. Sense of touch and pressure sensitivity are not impaired in these patients. Self-mutilating behavior due to a lack of pain perception is frequently seen in these patients using their teeth.[1]

No specific therapy is available. Treatment depends on the patient's age and intelligence, as well as the parent's attitude and cooperation. The use of a night-guard, grinding sharp edges of the teeth, the addition of a composite, routine dental work (root canal therapy), prosthodontic treatment (crowns), and/or orthodontic treatments can be considered.[5] Prevention of self-mutilation in CIPA patients should involve a team of multidisciplinary physicians as well as a dentist. Conventional radical full mouth teeth extraction should be avoided in CIPA patients and it should be the last alternative therapy.