|Year : 2018 | Volume
| Issue : 1 | Page : 48-50
Congenital insensitivity to pain: Case report of a rare entity
Swati Dahiya, Kondajji Ramchandra Vijayalakshmi, Mubeen Khan
Department of Oral Medicine and Radiology, Government Dental College and Research Institute, Bengaluru, Karnataka, India
|Date of Web Publication||28-Dec-2017|
Department of Oral Medicine and Radiology, Government Dental College and Research Institute, Bengaluru - 560 002, Karnataka
Source of Support: None, Conflict of Interest: None
Hereditary sensory and autonomic neuropathies (HSANs) are a group of disorders characterized by insensitivity to noxious stimuli and autonomic dysfunction, associated with pathological abnormalities of the peripheral nerves. Five types of HSAN have been reported in literature, out of which Type V known as congenital insensitivity to pain (CIP) is a rare autosomal recessive condition. Self-mutilation is an invariable feature of this disorder, involving the teeth and orofacial structures. This case report describes a case of a 6-year-old girl with CIP brought by her parents for prostheses to replace her self-extracted primary teeth.
Keywords: Congenital, oral manifestations, pain
|How to cite this article:|
Dahiya S, Vijayalakshmi KR, Khan M. Congenital insensitivity to pain: Case report of a rare entity. Indian J Paediatr Dermatol 2018;19:48-50
|How to cite this URL:|
Dahiya S, Vijayalakshmi KR, Khan M. Congenital insensitivity to pain: Case report of a rare entity. Indian J Paediatr Dermatol [serial online] 2018 [cited 2020 Apr 5];19:48-50. Available from: http://www.ijpd.in/text.asp?2018/19/1/48/206071
| Introduction|| |
Hereditary sensory and autonomic neuropathies (HSANs) encompass a number of inherited disorders that are associated with sensory and varying degrees of autonomic dysfunction. Type V HSAN, also known as congenital insensitivity to pain (CIP), is a rare autosomal recessive condition caused by a mutation in the SCN9A gene, which codes for the sodium channel Nav 1.7 protein., It is often diagnosed in the late toddler age and is characterized by marked insensitivity to pain with tactile, vibratory, and thermal sensations usually intact. The oral manifestations in these patients are more pronounced, but owing to its rarity and noncharacteristic manifestations, it can often be missed, therefore the dental clinicians must be aware of this condition to reduce the frequency and severity of self-inflicted lesions and to prevent further complications.
| Case Report|| |
A 6-year-old girl accompanied by her mother reported with a chief complaint of missing lower teeth. According to the history revealed by her mother, the patient was born at full term through cesarean delivery and was younger of the two siblings from a second-degree consanguineous marriage. Both the parents and her elder sister were normal with no history of similar complaints.
Past medical history was suggestive of surgery of the right eye at the age of 2 years for congenital corneal anesthesia. The patient's mother gave a history of absence of response to any painful stimuli along with self-mutilating behavior, on account of which there was early exfoliation of primary mandibular teeth. However, the eruption of teeth was normal as reported by her mother. Any history of recurrent fever or absence of sweating was completely denied by her mother. Her existing previous medical records were suggestive of diffuse cerebral atrophy while the electroneuromyographic examination documented normal muscle strength with normal motor conduction of the right median, ulnar, common perineal, posterior tibial nerves and normal sensory conduction of the right median, ulnar, and sural nerves. Furthermore, assessment of autonomic function by heart rate variability parameters showed reduced power with maintained sympathovagal balance.
On examination, the child was conscious, hyperactive, and cooperative with suboptimal response to verbal commands. Her gait and posture were found to be normal; however, weight and height were below normal for her age along with poor speech. Neurological examination revealed normal tendon and plantar reflexes with decreased temperature and pressure sensation. Further, the motor milestones of the child were delayed by 3–6 months as confirmed by a pediatrician along with bilateral corneal opacity with absence of corneal reflex and lacrimation [Figure 1]a. Multiple scars and superficial erosions were present over the extremities with dystrophic nails of both hands and feet [Figure 2]a,[Figure 2]b,[Figure 2]c.
|Figure 1: (a) corneal opacity (b) fibrosed lower lip (c) bald tongue with ulcer on its dorsal surface|
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Intraoral examination revealed limited mouth opening (approximately 20 mm) due to fibrosis of the lower lip [Figure 3]a, [Figure 3]b and [Figure 1]b. The tongue was normal in size, pale pink with depapillation, and loss of tongue tip. However, movements of the tongue were normal. Ulcerated areas were noted on the dorsal surface of the tongue and on the right side of floor of the mouth [Figure 1]c. The lower arch was completely edentulous with irregular contour of the residual alveolar ridge [Figure 2]b. Orthopantomogram revealed complete anodontia with respect to lower arch except for the presence of developing crown in relation to 37, 47 [Figure 3]c. The lower alveolar ridge height was severely reduced and was thinnest in the symphysis region with irregular contour of the alveolar crest. Upper arch revealed the presence of multiple unerupted permanent teeth [Figure 3]a. The bone density of both the arches, however, appeared to be normal.
|Figure 3: (a) Limited mouth opening (b) completely edentulous lower arch (c) orthopantomogram showing missing permanent mandibular teeth except for developing tooth bud in relation to second molars|
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Further, the patient was sent for investigations, which revealed 7.7 mg Hb% with microcytic hypochromic anemia. Uric acid levels were within normal limits. In addition, IQ assessment using Binet–Kamat test revealed average-level intellectual ability (IQ-88). Based on the history, clinical presentation, and the available pediatric and neurological records, a diagnosis of CIP was given.
| Discussion|| |
HSANs have been classified into five types:
- Type I - Hereditary sensory radicular neuropathy
- Type II - Congenital sensory neuropathy
- Type III - Familial dysautonomia or Riley–Day syndrome
- Type IV - CIP with anhidrosis
- Type V - CIP.
The most frequently affected areas are tongue and lips. Self-injury of the tongue starts when the primary incisors erupt and lead to ulcers on the ventral surface of the tongue, bifid tongue, or absent tip of the tongue. Although taste buds are normal, traumatic injuries of the tongue such as partial loss of papillae and scar formation may cause secondary hypogeusia or decreased taste sensation. Scarring or fibrosis of the lower lip with decreased mouth opening may also be seen in up to 50% of the patients. Early loss of primary dentition or premature loss of permanent tooth germ can lead to loss of arch length in both the jaws. Severe attrition with jaw fractures may also be present.
Orthopedic manifestations include multiple fractures, avascular necrosis, osteomyelitis, auto-amputation, leg length discrepancy, joint subluxation and dislocation, septic arthritis, progressive scoliosis, and Charcot arthropathy of the feet, ankles, knees, and hips.
Dermatological manifestations include ulcerated fingertips with bruises, cuts, burns, and multiple scars. Biting of fingertips can lead to digital shortening, nail deficiency, and phalangeal osteomyelitis.
Our case presents all the typical features of this disorder, which include auto-extraction of all primary mandibular teeth with fibrosis of the lower lip, presence of dystrophic nails, and multiple scars all over the extremities, which were suggestive of injury due to thermal burns and repeated falls. Further, bald tongue was suggestive of atrophy of filiform papillae, also reported in a case by Sasnur et al. 2011. The unique finding observed in our case was the absence of mandibular permanent tooth buds except for the presence of developing crown in relation to 37, 47. Ravichandra et al. in 2015 also reported similar finding, wherein lower arch was completely edentulous except for the presence of permanent first molars.
According to literature, the initial diagnosis of CIP is suspected based on clinical presentation along with the history of repeated traumatic injuries. Pharmacologic tests that evaluate autonomic function include mecholyl test that produces prompt pupillary miosis and absence of a flare in reaction to intradermal histamine injection. Sural nerve biopsy may reveal severe reduction of unmyelinated fibers with normal or moderate loss of thin myelinated fibers. Histopathologic evaluation reveals normal skin and appendageal structures, but there is absence of nonmyelinated, small-myelinated nerve fibers with normal sweat glands that lack innervation by small diameter neurons. Finally, molecular evaluation that reveals mutations of NTKR1 gene provides the definitive diagnosis.
CIP has to be differentiated from other hereditary sensory neuropathies. Type I (HSAN) is a relatively mild condition, manifesting in the second to fourth decade and mainly affecting the lower limbs. Type II (congenital sensory neuropathy) is also associated with loss of sweating, but temperature and control of blood pressure are normal. Type III (familial dysautonomia or Riley–Day syndrome) has a multisystem presentation including postural hypotension, ataxia, kyphoscoliosis, oropharyngeal dyscoordination, and abnormal gastro-esophageal motility resulting in feeding difficulties and recurrent aspiration pneumonia. Type V disease is similar to Type IV but is relatively mild without mental retardation and significant anhidrosis and it selectively affects nociception. Lesch–Nyhan syndrome resulting from hypoxanthine-guanine-phosphoribosyl transferase deficiency is characterized by hyperuricemia, self-induced trauma, mental retardation, chorea, and athetosis. Hereditary anhidrotic ectodermal dysplasia is characterized by typical facies, scarce body hair distribution, anhidrosis, and dental abnormalities.
At present, there is no specific treatment for HSANs. However, prevention of self-mutilation in patients is of prime importance. Several methods of prevention of injuries to oral tissues have been suggested which include elimination of sharp surfaces of the teeth by grinding (enameloplasty) with the help of mouthguards or tongueguards and other appliances to prevent injury to the tongue and extraction of offending teeth.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]