Spontaneous intracranial hypotension: headache with a reversible Arnold-Chiari malformation.

Spontaneous intracranial hypotension is characterized by severe postural headache in the setting of low CSF pressure, usually attributed to a cryptic CSF leak. We report a patient whose prolonged refractory headache was characterized by the clinical symptoms of occipital neuralgia, but was also associated with the radiographic appearance of an Arnold-Chiari malformation, type I and low CSF pressure. After extensive diagnostic evaluation, CT cisternomyelography ultimately demonstrated a CSF leak at the C2 vertebral level. Symptomatic relief was sustained only with long-term theophylline administration. The apparent Arnold-Chiari malformation resolved with treatment of the low CSF pressure.