MRCP2-3039

A 32-year-old male of Mediterranean descent presents to the Emergency department with complaints of progressive unsteadiness and double vision. He has also experienced weakness in his left arm and leg, accompanied by a throbbing headache. The patient has a history of joint pains and oral ulcers, and recently visited his GP for a rash on his shins. On examination, he appears unsteady and has herpetiform oral ulcers and bilateral red eye. There is evidence of right facial weakness and restricted abduction of the right eye. The upper limb shows increased tone on the left with mild pyramidal weakness of 4/5 and hyperreflexia. The lower limb has nodular lesions over both legs, with slightly increased tone on the left and some pyramidal weakness of 4/5 with a left extensor plantar. Sensory examination is normal, but the patient exhibits a broad-based ataxic gait. An MRI scan of the brain shows inflammatory white and grey matter lesions within the fronto-parietal lobes and a single lesion within the pons. The CSF opening pressure is 140 mmH2O, and the CSF protein is 1.2 g/L with a white cell count of 120 (80% lymphocytes). Blood tests show elevated C reactive protein and erythrocyte sedimentation rate. What is the likely diagnosis for this patient?