A0044 Encephalitis: An “Enigma”

Background: Encephalitis is an acute inflammation of the brain parenchyma with varied etiologies that are difficult to diagnose. In majority of the cases, acute encephalitis is infective in origin, and less commonly, it may be autoimmune. Here we report a perplexing case of acute encephalitis.

Case Description: A 55-year-old male entomologist presented in emergency department with chief complaints of pain in the right knee, urinary retention, and constipation. He had no other known comorbidities. Baseline vitals and routine laboratories were unremarkable. T2 screening of the brain was normal, and MRI spine showed no significant compressive/noncompressive myelopathy. On the day 4 of hospital admission, the patient became drowsy for which he was intubated and kept on mechanical ventilation. Serum electrolytes and liver functions were normal, but serum ammonia was marginally raised (49.1 µmol/L). Metabolic encephalopathy was suspected, and the patient was started on lactulose and rifaximin. CSF analysis showed raised proteins, pleocytosis, and predominant lymphocytes, indicating viral/tubercular meningoencephalitis. On this ground, intravenous methyl prednisolone and antitubercular (ATT) drugs were started. Patient remained deeply comatose with GCS of E1VTM1. Electroencephalogram (EEG) ruled out nonconvulsive status epilepticus. Various reports including CSF TB-PCR, vasculitis profile, HSV IgG/IgM, Japanese encephalitis, NMDA Ag, and VGKC Ag all were inconclusive. After these investigations, ATT was stopped.

Repeat brain MRI revealed T2 hyperintense signals with mild restricted diffusion in bilateral parahippocampal gyri, right insular cortex, left basal ganglia, and bilateral temporoparietal lobes in cortical, subcortical locations, bilateral cerebral peduncles, mid-brain, pons, medulla, and cervical cord. A differential diagnosis of acute disseminated encephalomyelitis was suspected. Patient received IV methyl prednisolone 1 g/day for 5 days and then tapered off. By day 10 in ICU, patient's GCS started improving and he was discharged from the ICU on the 30th ICU day with E4V5M6 status. His power in both upper limbs was 4/5, proximal weakness more than distal and in both lower limbs was 2/5.

Conclusions: There are various etiologies of encephalitis. Clinical presentation, course, and outcome may be quite perplexing in uncommon etiologies. Autoimmune encephalitis has been shown to have favorable outcome over viral etiology. As a diagnosis of exclusion and owing to its clinical course, we made a provisional diagnosis of autoimmune encephalitis.

 

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