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A 62-year-old patient with newly diagnosed high grade diffuse large B-cell lymphoma presented with intermittent expressive dysphasia and ‘vague’ episodes, 2 weeks after commencing her first cycle of R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone). These episodes became more frequent over the next 24 h, and she developed catatonia, dysarthria, dysphagia, drooling, facial numbness and deafness.

A computed tomography (CT) scan of her head was unremarkable, but magnetic resonance imaging (MRI) showed central pontine myelinolysis [sagittal T2-weighted and axial Fluid Attenuated Inversion Recovery (FLAIR) both showing a high signal area in the pons (top left and top right respectively)]. Gadolinium-enhanced images did not suggest lymphomatous involvement. Cerebrospinal fluid and cytospin analysis were normal. Blood chemistry investigations were stable except for sodium levels, which fluctuated between 129 and 134 mmol/l without any intravenous fluid correction. Blood analysis showed pancytopenia: haemoglobin concentration 71 g/l, platelet count 3 × 109/l, white cell count 0·4 × 109/l, with undetectable neutrophils. The patient was transferred to the acute neurology department where she was treated empirically with pabrinex, aciclovir, meropenem and intravenous steroids. She recovered over the next 2 weeks. No further episodes were noted, even after the 2nd treatment cycle of R-CHOP. A subsequent MRI of the head 1 month later showed significant improvement and no new abnormalities were identified [sagittal T2-weighted and axial FLAIR showing less extensive high signal areas in pons (bottom left and bottom right respectively)].

Central pontine myelinolysis (CPM) is a demyelinating disorder occurring in the pons. It is commonly associated with the rapid correction of electrolyte imbalances, alcoholism and immunosuppression. Several reported cases have linked CPM to Hodgkin lymphoma but, as far as we are aware, not to non-Hodgkin lymphoma. Clinical presentation depends on the extent of pontine involvement. MRI is the most useful confirmatory investigation, due to its sensitivity in detection of demyelination. On recovery, improvements in MRI tend to lag behind clinical improvement.There is currently no specific treatment. Although our patient recovered fully, CPM is correlated to poor prognosis and may cause permanent cognitive impairment.