An unusual case of quadriparesis

A 48 year old man presented with a four day history of lethargy, dizziness, and an unsteady gait with recurrent falls, on a background of chronic alcohol misuse. The patient was taking desmopressin for nocturnal enuresis and bendroflumethiazide for hypertension, which were both stopped on admission. On physical examination he appeared clinically euvolaemic and he had no focal neurological deficit. Vital signs were within normal limits. Serum biochemistry showed sodium of 110 mmol/L (normal range 137-145; 1 mmol/L=1mEq/L) and potassium of 2.6 mmol/L (normal range 3.5-5.5 mmol/L). A computed tomogram of the brain that was performed to rule out traumatic brain injury was unremarkable. Fluids were subsequently restricted and he was started on parenteral thiamine, oral chlordiazepoxide, and intravenous 0.9% sodium chloride with potassium supplementation. Twenty four hours later, serum sodium was 119 mmol/L and serum potassium was 3.3 mmol/L. Serum sodium eventually reached 130 mmol/L on day 4. Seven days after admission he developed delirium and on examination had bilateral pyramidal weakness, more pronounced on the right. Reflexes were generally brisk, with bilateral extensor plantar responses. He also developed mild dysarthria but there was no dysphagia. A repeat computed tomogram of the brain was normal. Magnetic resonance imaging of the brain was subsequently performed to obtain better images of the brainstem and posterior fossa (fig 1⇓). Fig 1 Axial T2 weighted magnetic resonance imaging of the head ### 1 What does the magnetic resonance imaging scan show and what is the most likely diagnosis? #### Short answer A hyperintense triangular lesion in the central pons with peripheral sparing. In the clinical context of spastic quadriparesis, this is consistent with central pontine …