Transcranial doppler findings in a case of rabies encephalitis

Rabies encephalitis is a uniformly fatal disease with several hypothesis proposed to explain pathogenesis and mortality. One such theory premises deficiency of neuronal nitric oxide synthetase deficiency causing selective cerebral vasospasm. We present transcranial Doppler findings in a case of rabies that did not show imaging evidence of vasospasm. Transcranial Doppler in two published cases have reported occurrence of global vasospasm. Our case showed no sonographic vasospasm in middle cerebral arteries but consistently increased distal resistance indices likely due to cerebral edema. While vasospasm may occur in rabies, cerebral edema secondary to disease or pharmacological interventions confounds transcranial Doppler readings. Cerebral angiogram and multimodality monitoring is encouraged.