Clinical Profile and Diffusion Tensor Imaging in Patients of Subacute Sclerosing Pan Encephalitis

Background: Subacute Sclerosing Pan Encephalitis (SSPE) may present with atypical clinical features and lead to diagnostic dilemma. Conventional magnetic resonance imaging (MRI) may be normal in early stage of SSPE. Objective: The aim of this work was to study the demography, clinical profile including atypical features of SSPE patients, and the utility of diffusion tensor imaging (DTI) as an adjunctive diagnostic tool to the anti-measles antibody and conventional MRI. Material and Methods: Consecutive 25 patients of SSPE were included. Clinical details were recorded at baseline and 6 months follow-up. Anti-measles antibody in serum and CSF, CSF/Serum Quotient reference (CSQ ref), and radiological details including comparison of DTI between SSPE patients and controls were also noted. Results: Of 25 patients, 17 (68%) were male. The most common presenting feature at onset was myoclonus with or without falls (13, 52%). Atypical features such as seizure, hemiparesis, and visual problems were present in 28% patients. At 6 months, 9 patients had progressive course (6 expired), 10 were static, and 6 lost to follow-up. MRI was normal in 8 (32%) patients (stage 2/3- 7/1). On comparison between SSPE patients (N = 10) and control (N = 10) groups, fractional anisotropy (FA), and apparent diffusion coefficient (ADC) values were reduced and elevated, respectively, at most of the regions of interest with significant difference at many sites. Conclusions: A significant number of patients (28%) had atypical features at onset. DTI is an adjunctive tool which supplements the conventional MRI and increase diagnostic yield. It may be a future option to assess disease progression and treatment response.