SPECT studies of regional cerebral blood flow in 8 patients with Japanese encephalitis in subacute and chronic stage

Objective - There is a paucity of regional cerebral blood flow studies in Japanese encephalitis (JE). In this communication we report clinical, radiological and single photon emission computed tomography findings in subacute and chronic JE patients. Material and methods - Eight JE patients whose ages ranged between 10 and 50 years underwent neurological evaluation. Varying degree of parkinsonian features were present in all, dystonia in 4 and abulia in 5 patients. They were subjected to cranial CT, MRI and SPECT studies. CT scan revealed low density area in 7 patients and midbrain involvement in 1. MRI was carried out in 3 patients and revealed medial temporal involvement in addition to bilateral thalamic involvement in all. Results - SPECT results on visual analysis revealed thalamic hypoperfusion in all the patients, frontal hypoperfusion was present in 5 and lentiform hypoperfusion in 2 patients. Frontal or lentiform hypoperfusion was not associated with corresponding CT or MRI changes. On semiquantitative measurement, thalamic hypoperfusion was present in 7, frontal hypoperfusion in 3, occipital in 2 and lentiform in 1 patient. Conclusion - These results confirm high frequency of thalamic involvement in JE. The hypoperfusion in thalamus, frontal cortex and lentiform area is consistent with the crucial role of thalamus and its connections in the genesis of movement disorders in JE.