2nd September 2020

A 70-year-old male presents with a mixed upper and lower motor neurone disorder

A 70-year-old male presents with a mixed upper and lower motor neurone disorder, along with progressive dyspnoea on exertion and noticeable emotional lability. Motor neurone disease is suspected among the differential diagnoses. Which of the following investigations is most likely to be abnormal in a patient with motor neurone disease? 

Select ONE option only.