Clinical and electrophysiologic recovery in Arnold-Chiari malformation.

The case of a 16-year-old boy with occipital headache, diplopia, ataxia, and weakness in the lower extremities of 1-month duration is reported. Slowness of mentation, speech, and motor action was also present. Massive chronic hydrocephalus was indicated by an enlarged head. The prominent clinical features suggested involvement of the brainstem, and contrast studies showed compression of the brainstem and a filling defect posteriorly at C1-2. Brainstem auditory evoked potential latency suggested bilateral lesions of the brainstem. Posterior fossa decompression confirmed the presence of an Arnold-Chiari malformation, with the cerebellar tonsils as low as C-3. The fourth ventricle was microdissected and opened. Remarkable clinical and evoked potential recovery ensued over several months. Clinical-anatomic and anatomic-physiologic correlations in Arnold-Chiari malformation are discussed.