2nd September 2020

A 49-year-old man presents because he has noticed over the last 4 months that his left foot has been dropping

A 49-year-old man presents because he has noticed over the last 4 months that his left foot has been dropping. He has also had painful cramps within that foot. When you ask further questions, you get a story that over the last year he has noticed he is finding it harder to stand up from chairs and has been dropping things more frequently. 

On neurological examination you notice that there is bilateral weakness in the upper and lower extremities, but it is greater on the left lower extremity. There is associated muscle atrophy within the left foot. He has hyperreflexia within the lower limbs and a positive babinski sign on the left. Sensation seems to be intact throughout.

What is the most likely diagnosis?

Select the SINGLE most appropriate option from the list below. Select ONE option only.