The pathophysiology of the neurological deficits in hemiplegic migraine remains unclear. Both neurogenic and vascular etiologies have been proposed to explain this phenomenon. We present the case of a patient with hemiplegic migraine in whom there was no diffusion weighted magnetic resonance imaging evidence of cerebral ischemia, despite persistent left hemiplegia and diffuse vasospasm on cerebral angiography, there was no diffusion weighted magnetic resonance imaging evidence of cerebral ischemia. In addition, hypoperfusional changes were seen diffusely, more so on the less symptomatic hemisphere, whereas depression of cortical electrical activity was seen for several days on the right side. These findings support the notion that although both neurogenic and vascular changes occur in hemiplegic migraine, the former seems to be a more likely explanation for the neurological deficits.