A 26-year-old man was referred with facial weakness, dysarthria, dysphagia, ophthalmoparesis and severely weak and wasted legs. His symptoms had begun when aged 20 with electric shock pains and paraesthesia in both feet progressing over 6 months to the lower calves. He then developed buttock numbness and occasional faecal incontinence. By age 22, he had diffuse lower limb weakness and wasting, with difficulty standing from a seated position and frequent tripping. He became wheelchair-dependent within 3 years. Over the same time period, he developed progressive facial weakness, bilateral ptosis, slurred speech, difficulty chewing and swallowing and lost 10 kg of weight. He reported hearing difficulty, and an audiogram showed high-frequency hearing loss. Important negatives included absence of upper limb symptoms, autonomic, cardiac, respiratory or cognitive dysfunction. He was from a non-consanguineous, Lithuanian background and the eldest of three siblings. He was born following a normal pregnancy and delivery, and motor development was normal. He had sustained a left corneal abrasion with visual impairment following an accidental chemical injury aged 14. During the initial investigation of his symptoms (age 23), he was found to have a choroid plexus lesion in the fourth ventricle. It was completely resected and histology confirmed benign choroid plexus papilloma WHO grade I. Postoperative neuro-oncology discussion deemed the lesion cured. He had bilateral ptosis, bilateral facial wasting and could not close his mouth against gravity (figure 1A). Visual acuity was reduced to perception of light on the left, 6/9 on the right. There was almost complete, complex ophthalmoplegia (figure 1B) without fatiguability. Trigeminal sensation was reduced. He could not achieve eyelid closure; frontalis, buccinator and orbicularis oris were symmetrically weak. His speech was dysarthric and his tongue was weak. His uvula was central with symmetrical palatal movement, but the gag reflex was reduced. Figure 1 Clinical examination at age 26. …