Acute encephalitis with flaccid paralysis following an adenoviral infection presenting as a rare variant of Guillain Barre syndrome in a school-age child

Guillain-Barre syndrome (GBS), Miller-Fisher syndrome (MFS), and Bickerstaff’s brainstem encephalitis (BBE) are syndromes which represent a spectrum of post-infectious inflammatory immune-mediated diseases. They may share a common autoimmune pathogenetic mechanism presenting with progressive ascending weakness or flaccid paralysis affecting both pediatric as well as adult populations. MFS and BBE are rare variants of GBS that should be part of the differential diagnosis when relevant features are present. We present a case of a 6-year-old boy, presenting with a sore throat of one-day duration, associated with difficulty in swallowing, increased salivation and drooling, inability to speak or swallow following an adenoviral upper respiratory infection with exudative tonsillitis and diarrhea. Clinical evaluation showed weak gag reflex and cough reflex, hyperreflexia without clonus, upgoing Babinski reflexes, and hypotonia. A diagnosis of BBE was made based on specific neurological manifestations of hyperreflexia and drowsiness, serological studies, and MRI findings.