Chiari I malformation in patients with FG syndrome

The FG syndrome (FGS) is a common, heterogeneous group of clinically indistinguishable X-linked disorders comprising congenital hypotonia, macrocephaly, psychomotor delay, abnormalities in sensory integration, agenesis of corpus callosum, an unusual personality with behavior abnormalities, and disturbances of gastrointestinal function. On magnetic resonance (MR) imaging, some patients have evidence of tonsillar ectopia. The authors describe the incidence of Chiari I malformation in patients with FGS and attempt to determine the optimal treatment of these patients.

The authors performed a retrospective chart and radiological review of 144 pediatric patients with FGS for evidence of tonsillar ectopia on brain MR imaging. Eleven (7.6%) of these 144 patients had tonsillar ectopia, and in eight patients (5.6%), the tonsils were located more than 5 mm below the foramen magnum. Four of these patients underwent posterior fossa decompression, and surgery was performed at a mean age of 3 years. Indications for surgery included significant headaches and behavioral problems in two patients and failure to thrive with severe breathing and feeding difficulties in two infants. All four improved after surgery. The other patients remained asymptomatic from their tonsillar ectopia, showed no clinical or radiological signs of progression, and did not require surgery.

Chiari I malformation is more common in individuals with FGS than in the general population. Some of these patients with FGS require decompression surgery, but the decision to operate can be difficult because of their developmental delay, difficulties with language skills, general fatigue, possibility of upper motor neuron dysfunction, behavioral problems, or failure to thrive, which may mask the symptoms of a Chiari I malformation.