Acute motor polyneuropathy as a rare neurological complication of mumps in a child: A case report

Abstract

Mumps is a self-limiting viral illness, but its neurological complications, although uncommon, can be serious. We report a 6-year-old developmentally normal male who presented with abdominal pain and rapidly progressive weakness of both lower limbs 10 days after a febrile illness with bilateral parotid swelling. Examination revealed lower-limb and truncal weakness with diminished deep tendon reflexes and mute plantar response, suggesting a lower motor neuron pattern. Cerebrospinal fluid analysis showed mildly elevated protein with normal cell count, and nerve conduction studies demonstrated bilateral ulnar, common peroneal and posterior tibial polyneuropathy. Serum mumps-specific IgM antibody was positive, supporting the diagnosis of post-mumps acute motor polyneuropathy. The child improved gradually with intravenous methylprednisolone pulse therapy and physiotherapy and achieved complete neurological recovery with full muscle power (5/5) in all limbs at 6-week follow-up. This case underscores the neurotropic potential of the mumps virus and supports the inclusion of the measles, mumps and rubella (MMR) vaccine in national immunisation programmes.