At the heart of primary progressive multiple sclerosis: three cases with diffuse MRI abnormalities only

Area of Science:

• Neurology
• Neuroimmunology
• Radiology

Background:

• Primary progressive multiple sclerosis (PPMS) is a debilitating neurological disease characterized by gradual neurological decline.
• Current diagnostic criteria for PPMS typically rely on the presence of focal lesions detected via magnetic resonance imaging (MRI).

Observation:

• Three patients presented with clinical and cerebrospinal fluid (CSF) findings indicative of PPMS.
• Despite extensive and repeated MRI examinations, these patients exhibited only diffuse abnormalities in the brain and spinal cord, with a notable absence of focal lesions.

Findings:

• The observed cases suggest a potential variant of PPMS that lacks the characteristic focal lesions on MRI.
• These findings challenge the established diagnostic framework for PPMS, particularly the mandatory requirement for focal lesions.

Implications:

• The study proposes that these cases represent the purest form of PPMS, necessitating a re-evaluation of diagnostic criteria.
• Revised diagnostic guidelines may be required to accurately identify and manage PPMS cases that do not present with focal MRI lesions.