A patient with established primary progressive multiple sclerosis transitions to 'secondary' relapsing-remitting...

Area of Science:

• Neuroimmunology
• Central nervous system inflammatory disorders
• Demyelinating diseases

Background:

• Primary progressive multiple sclerosis (PPMS), relapsing-remitting MS (RRMS), and acute disseminated encephalomyelitis (ADEM) represent distinct inflammatory demyelinating disorders.
• Secondary progressive MS (SPMS) is a recognized progression following RRMS.
• Understanding the immunopathogenesis and clinical trajectories of these conditions is crucial for effective management.

Observation:

• A patient with established PPMS experienced a fulminant, ADEM-like demyelinating episode.
• Despite prior immunosuppressive treatment, the patient transitioned to clinically and radiologically active RRMS post-episode.
• Accelerated brain atrophy was observed following the onset of the RRMS course.

Findings:

• This case demonstrates an unusual transition from PPMS to active RRMS.
• The transition occurred subsequent to an ADEM-like event, challenging typical disease progression models.
• Immunosuppressive therapy did not prevent the shift in disease phenotype.

Implications:

• This unique disease course highlights the potential for phenotypic switching in inflammatory demyelinating disorders.
• It underscores the dissociation between the biological activity of relapses and their impact on long-term disability and progression.
• Further research is needed to understand the mechanisms driving such transitions and their prognostic significance.