Foramen magnum stenosis and bilateral benign subdural collections in achondroplasia: case report.

A case of achondroplasia is presented in which cervico-medullary junction compression by foramen magnum stenosis and generalized seizures by bilateral subdural effusions were relieved by suboccipital craniectomy with C1 laminectomy and drainage of the collections. The important role played by NMR in the diagnosis of foramen magnum stenosis is stressed; the possible causes of hydrocephalus and subdural collections in achondroplasic patients are discussed. According to the authors surgical drainage of benign subdural collections in these patients is indicated in case of intractable seizures.