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 J apanese encephalitis (JE). In this communication we report clinical, radiol ogical and single photon emission computed tomography findings in subacute and chronic JE patients. Material and methods - Eight JE patients whose age s ranged between 10 and 50 years underwent neurological evaluation. Varying degree of parkinsonian features were present in all, dystonia in 4 and abu lia 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 involv ement in addition to bilateral thalamic involvement in all. Results - SPECT results on visual analysis revealed thalamic hypoperfusion in all the pati ents, frontal hypoperfusion was present in 5 and lentiform hypoperfusion in 2 patients. Frontal or lentiform hypoperfusion was not associated with cor responding CT or MRI changes. On semiquantitative measurement, thalamic hyp operfusion 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 corte x and lentiform area is consistent with the crucial role of thalamus and it s connections in the genesis of movement disorders in JE.