20th June 2023

A 63-year-old man with a new diagnosis of small cell lung cancer attends Oncology Clinic with a several week history of unsteadiness,

A 63-year-old man with a new diagnosis of small cell lung cancer attends Oncology Clinic with a several week history of unsteadiness, global weakness affecting both lower limbs, and difficulty walking. On examination, he has globally reduced power and reduced tendon reflexes throughout the lower limbs bilaterally, worse in the proximal muscle groups, with normal sensation and tone. Neurological examination elsewhere, including cranial nerves, is normal. An MRI whole spine is performed and is unremarkable. Routine bloods, including a serum creatine kinase and urinary myoglobin, are all normal.

Which of the following is being affected by this disorder?

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