[Natalizumab can induce progressive multifocal leucoencephalopathy].

Area of Science:

• Neurology
• Immunology

Background:

• The patient was a 41-year-old woman diagnosed with relapsing-remitting multiple sclerosis.
• She had been undergoing treatment with natalizumab for four years.

Observation:

• She presented for a scheduled natalizumab infusion with disorientation and inadequate responses.
• An MRI revealed findings consistent with progressive multifocal leucoencephalopathy (PML).

Findings:

• The patient's condition rapidly progressed to PML, a serious opportunistic infection.
• Despite immediate initiation of plasmapheresis, the patient's outcome was fatal.

Implications:

• This case highlights the potential risk of PML in patients treated with natalizumab, particularly those with unknown John Cunningham virus (JCV) status.
• It underscores the importance of JCV screening prior to initiating or during natalizumab therapy.
• The rapid progression and fatal outcome emphasize the critical nature of PML and the need for prompt diagnosis and management.