Spasmodic dysphonia (SD) is a low-incidence voice disorder of unknown origin. A subgroup of seven patients with SD from our larger pool of 70 report vocal symptoms subsequent to head injury. This article is a case report of the neurodiagnostic findings, including computed tomography, magnetic resonance imaging, auditory brain-stem response, brain electrical activity mapping, and single photon emission computed tomography for three such patients. For each patient, two or more tests revealed positive neurologic findings. Each test, except computed tomography, demonstrated abnormalities in one or more patients. Two principles of clinical management are derived: (1) information regarding head trauma sustained before SD symptom onset is significant; (2) the absence of neuropathology on a single measure of central nervous system function should not be considered conclusive evidence that no neurologic lesions exist.