Arnold-Chiari malformation with syrinx presenting as carpal tunnel syndrome: a case report.

A 26-year-old administrative assistant presented with 3 years of left-hand dysesthesia involving primarily the first 3 digits. Her symptoms increased at night and with keyboard use. Through 12 visits to primary and specialty care physicians over 3 years, she experienced minimal improvement with splints and moderate improvement with gabapentin. On presentation, careful questioning revealed an abrupt onset of symptoms 3 years previously, related to a 2-week episode of gastritis associated with recurrent emesis. Examination revealed a negative Tinel sign over the median nerve at the wrist, decreased left biceps reflex, positive Spurling test, and decreased sensation over the palmar and dorsal surfaces of the left hand in the C5-6 distribution. The atypical onset of symptoms, poor response to therapy, and physical findings suggested the possibility of a radicular or central neurologic etiology for the patient's hand numbness. Magnetic resonance imaging demonstrated a Chiari I malformation with a syrinx extending from C2 to T10, with the greatest diameter at C4. Neurosurgical decompression led to a decrease in symptoms. A meticulous history and physical examination should be performed on patients with presumed carpal tunnel syndrome with an atypical onset of symptoms or response to therapy.