[Hereditary sensory and autonomic neuropathy type IV: a report on two cases].

Hereditary sensory and autonomic neuropathy type IV (HSAN IV) is a very rare autosomal recessive disorder characterized by recurrent episodes of unexplained fever, extensive anhidrosis, total insensitivity to pain, hypotonia, and mental retardation. The absence of urticarial reaction to intradermal injection of histamine is a sign of great diagnostic value, but this is common to all types of HSAN. The most frequent complications of this disease are corneal scarring, multiple fractures, joint deformities, osteomyelitis, and disabling self-mutilations. Malignant hyperthermia and sepsis are major causes of mortality. We relate the first observations of two Tunisian children with genetically confirmed HSAN IV. Our goal is to review the clinical aspects of this mysterious neuropathy and to emphasize the peculiarities of its management. These two patients are brothers from 1st-degree consanguineous parents (cousins) with no particular medical history. The 1st patient, the family's 1st child, presented in the 1st h of life with hypotonia and persistent fever, which was refractory to antipyretics. At the age of 8 months, the patient presented recurrent febrile seizures and developed significant self-mutilations of the fingers and tongue. He died 3 months later in a context of multivisceral failure from sepsis and malignant hyperthermia. The 2nd patient, currently aged 4 years, was born after a normal sister. He consulted in the neonatal period for a high fever. The diagnosis of HSAN IV was rapidly suspected and genetically confirmed. In fact, this patient is homozygous for the NTRK1 gene, whereas his sister and both parents are heterozygous. Special predispositions have been taken to improve the course of the disease such as air conditioning to control hyperthermia, a dental tray to reduce the injuries resulting from self-mutilation, regular moistening of the eyes to avoid corneal drying, and chlorpromazine to control hyperactivity and reduce injuries. The good progression with all these predispositions and others underlines the importance of appropriate multidisciplinary management and close monitoring of patients suffering from HSAN IV, especially during the first 3 years of life. Indeed, mortality, behavioral disorders, and mental retardation significantly decrease after this age. New curative treatments are expected in the next decade.