A case of enterovirus rhombencephalitis associated with ocrelizumab therapy used to treat multiple sclerosis

Background:

Ocrelizumab is a B-cell–depleting monoclonal antibody used in the treatment of relapsing–remitting multiple sclerosis (RRMS). It binds to the CD20 antigen expressed on B cells, leading to their depletion and a reduction in immune-mediated damage to the central nervous system. This immunosuppressive effect can impair humoral immunity and increase susceptibility to opportunistic infections (1), including rare but potentially severe complications such as enterovirus rhombencephalitis (EV-RE).

Methods:

We report the case of a woman in her 40s receiving regular ocrelizumab infusions for her RRMS who presented with vertigo, dysarthria, and muscular rigidity. Initial diagnostic investigations were inconclusive, and the patient was started on empirical antibiotics following the development of pyrexia. She deteriorated with progressive bulbar failure, necessitating intubation and a transfer to a specialist neurological hospital.  Five days after admission, EV-RE was diagnosed based on characteristic MRI findings and a positive enterovirus polymerase chain reaction result from cerebrospinal fluid analysis.

Results:

A few months into her admission, she developed a rhythmic tremor that was confirmed as post-encephalitic parkinsonian syndrome by electromyography and dopamine active transporter (DaT) imaging. After several months of antivirals, intravenous immunoglobulin, and steroids, the patient demonstrated symptomatic improvement, albeit below her pre-admission baseline.

Conclusions:

This case underscores the importance to consider opportunistic infections in patients receiving B-cell depleting therapies, specifically EV-RE with ocrelizumab use. Early recognition and timely involvement of specialist centres are essential to prevent further neurological deterioration and improve clinical outcomes.

Dr Annabelle Prosser graduated from Newcastle University Medical School in 2024, achieving a merit in her 2^nd year for academic excellence. She completed an 8-week elective in Bach Mai Hospital in Hanoi, Vietnam and Ramathibodi Hospital in Bangkok, Thailand during her studies. At the age of 24, she is now working as a rotational resident doctor at Royal Surrey County Hospital, just outside of London. She has published an article on the UK Foundation Programme website that has recently been created into an E-book.