Acute demyelination following radiotherapy for glioma: a cautionary tale

Radiotherapy is the mainstay of treatment after surgery for high-grade gliomas and is usually well tolerated. Radiation toxicity in the brain is usually classified according to the timing of side effects in relation to treatment, as either acute (during radiotherapy), early delayed (within 12 weeks of radiotherapy) or late delayed (months to years after radiotherapy). We report two cases of young women who developed severe acute demyelination within 4 months of radiotherapy for glioma, one of whom had a previous history of transverse myelitis. Both improved with corticosteroids and remain in tumour remission. These cases emphasise the importance of careful discussion with patients before starting radiotherapy if there is a previous history of central nervous system demyelination or multiple white matter lesions on MRI.