6th February 2024

A 56-year-old male with small cell lung cancer has progressive weakness

A 56-year-old male with small cell lung cancer has progressive weakness. Initially, he could not stand from a chair, but this progressed to a generalised weakness and inability to mobilise upstairs. He has accompanying dry mouth and orthostatic hypotension. Examination showed absent reflexes without significant muscle wasting. Power was 3./5 throughout, increasing to 4-/5 with sustained contraction. EMG showed increased amplitude with high-frequency stimulation.

Given the likely diagnosis, which of the following structures has contributed to the condition’s pathophysiology?

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