Idiopathic scoliosis as a presenting sign of familial neurologic abnormalities.

STUDY DESIGN: Familial cases of "idiopathic" scoliosis associated with neurologic abnormalities are reported with a review of the literature. OBJECTIVE: To investigate the prevalence of neurologic abnormalities such as syringomyelia, Chiari 1 malformation, and tonsillar ectopia in patients with genetically determined "idiopathic" scoliosis. SUMMARY OF BACKGROUND DATA: Idiopathic scoliosis is widely considered to be a genetic disorder of unknown etiology. Magnetic resonance imaging (MRI) studies have shown that several cases of "idiopathic" scoliosis show neurologic abnormalities including syringomyelia and Chiari 1 malformation. Recently, several familial cases of either syringomyelia or Chiari malformation were reported, and it is suspected that genetic factors may influence the development of the craniovertebral malformation. It was hypothesized that some cases of "idiopathic" scoliosis include a craniovertebral malformation that is genetically determined. METHODS: This study, using clinical examinations and MRI, investigated 71 patients with scoliosis and a family history of "idiopathic" scoliosis in third-degree relatives for the presence of neurologic abnormalities. If neurologic abnormalities were confirmed with MRI, the relatives affected with scoliosis were also examined. RESULTS: Nine (13%) patients showed neurologic abnormalities on MRI. Magnetic resonance imaging showed syringomyelia with Chiari 1 malformation in four patients, Chiari 1 malformation in three patients, and tonsillar ectopia in two patients. Among the relatives of these patients, 4 of 15 individuals affected with scoliosis also showed neurologic abnormalities on MRI. CONCLUSIONS: It is suggested that familial neurologic abnormalities may have a wide range of expression, and that some patients with "idiopathic" scoliosis present with genetically determined craniovertebral malformations such as syringomyelia, Chiari 1 malformation, and tonsillar ectopia.