Transcranial Doppler Sonography in Acute Viral Encephalitis with Special Reference to Dengue Encephalitis

Introduction: Acute viral encephalitis syndrome including dengue encephalitis (DE) is an important tropical illness with a guarded prognosis. The cerebral blood flow may be affected in acute viral encephalitis. Transcranial Doppler (TCD) sonography can quantitatively determine intracranial vascular flow dynamics in acute viral encephalitis. Aim: We aimed to investigate the intracranial blood flow characteristics in patients with DE and compare with nondengue acute viral encephalitis patients. Materials and Methods: In this prospective study, all the cases of acute viral encephalitis including dengue were enrolled over 18 months and followed up at 3 months. TCD was performed to determine the mean velocity pulsatility index (PI) and resistive index (RI) across the middle cerebral artery, anterior cerebral artery, posterior cerebral artery (PCA), vertebral artery, and basilar artery and compared it among dengue versus nondengue group as well as outcome at 3 months. Results: Out of 39 patients, 19 were diagnosed with DE, whereas 20 patients suffered from the nondengue group. The elevated PI and RI in the left PCA were found to statistically significant (P = 0.001 and 0.008, respectively) in the DE group. There was no significant difference in any other TCD indices in any other vessel among both the groups. In addition, an initial low Glasgow Outcome Scale (GOS) and higher brain imaging abnormality were significantly associated with poor GOS of