Congenital Insensitivity to Pain with Multiple Fractures: A Case Report and Literature Review

Congenital insensitivity to pain (CIP) is a rare autosomal recessive genetic disease, the main clinical manifestations are loss of pain or dullness, accompanied by a series of complications. We followed up a patient with CIP for 9 years, and a total of 4 fractures in 6 parts of the lower limbs were found. The patient presented with typical pain retardation, accompanied by osteomyelitis, multiple fractures, self-harm behavior (biting the tip of the tongue and fingers), and not being afraid of heat. A mutation was found on the sodium channel type IX a subunit (SCN9A) gene (chr2: 167056320 (EX27E), NM_002977. 3: c. 4796G>T (p. Arg1599Leu)). There is currently no effective treatment for this disease. We have adopted a combination of conservative and surgical treatment for this child's orthopedic disease (osteomyelitis and fracture). During the 4th fracture hospitalization, with the informed consent of the family, we used zoledronic acid to prevent fractures caused by low energy. Follow-up for 3 years found that zoledronic acid not only promoted fracture healing, but also avoided new fracture formation. Through reviewing the literature, we observe that this is the first report of using zoledronic acid to successfully avert new fractures in this type of patient. Now we summarize the treatment experience and review the literature in order to provide reference for the clinical treatment of this disease and enrich the SCN9A gene mutation spectrum.