MRCP2-3097
A 25-year-old woman presents to her GP with progressive unsteadiness, numbness, and weakness in her lower legs, as well as slurred speech. She reports a history of being clumsy as a child and follows a vegan diet. On examination, she has dysarthria, bilateral optic atrophy, and horizontal nystagmus. Her upper limb reflexes are depressed, and there is reduced vibration sense. In her lower limbs, she has bilateral pes cavus, distal muscle wasting, absent ankle and knee jerks, and a pyramidal distribution of weakness. Sensory examination reveals reduced vibration and joint position sense. Her gait is ataxic, and Romberg’s test is positive. Blood tests show elevated glucose levels, and a double apical impulse and ejection systolic murmur are noted on cardiovascular examination. CSF analysis reveals elevated protein levels but no oligoclonal bands. What is the likely diagnosis?