Case presentation

A 44-year-old woman had 5 months of progressively slurred speech, followed by intermittent curling of her left hand while walking. She had difficulty gripping objects in her left hand and reduced handwriting size with her right hand. Her husband felt she was moving generally more slowly. A recent proneness to motion sickness had improved with the antihistamine meclizine. Two years before, she had stumbled and fallen with subsequent lumbar and left leg tightness, though these symptoms had resolved before the current problem began.

She had normal cognition and mood, no change in sense of smell, normal sleep and no dream enactment, and normal bowel and bladder function. She had no history of autonomic dysfunction, muscle spasms or relevant family history.

Prior investigations included a normal MR scan of the brain and normal laboratory testing for heavy metals, serum copper, acetylcholine receptor antibodies and Lyme disease antibodies. An electromyogram 2 months before had found no acute denervation but an incidental right fibular head conduction block.

On examination, her cognition was normal. She had slow rate of speech, with only mild dysarthria and flattened volume fluctuations. Her optokinetic response was blunted vertically and horizontally. She showed mild hypomimia. Her arms were mildly rigid bilaterally and her left leg was noticeably more rigid. Rapid movements of her arms showed reduced finger tap amplitude on the right with good speed, while left-handed taps were slow without clear decrement. Her hand-grip manoeuvre was normal on the right but slowed on the left, though again without obvious decrement. Her leg movements were slowed bilaterally, more on the left, but without waning amplitude or hesitation, and so not consistent with bradykinesia. There was no tremor or ataxia. Her muscle strength was normal. Knee and ankle reflexes were 3+ bilaterally, and brisker on the left. Her plantar reflexes …