Clinical reasoning: a 47-year-old man with progressive gait disturbance and stiffness in his legs.

SECTION 1 A 47-year-old man presented with a 5-year history of slowly progressive gait disorder with clumsiness and unsteadiness during walking, as well as stiffness and cramping pain in his legs. He also had erectile dysfunction and nocturia. He denied sensory deficits and other focal neurologic or systemic symptoms. He had a medical history of hypogonadism, diagnosed 1 year before the onset of the gait disorder, attributed to a bilateral orchiectomy due to a testicular tumor, performed elsewhere when he was 37. He was receiving IM testosterone injections every 3 weeks. His family medical history included pes cavus in his mother and siblings, otherwise unremarkable. Neurologic examination revealed a wide-based spastic gait with positive Romberg sign. Cognition and cranial nerve examination were normal. Strength was 4/5 in both iliopsoas, and 41/5 in the remaining muscles of the lower limbs, with increased muscle tone. Deep tendon reflexes (DTR) were very brisk, with bilateral Achilles clonus, and bilateral Babinski signs. Vibration sensation was decreased in lower limbs, and joint position sense was lost in the toes. The rest of the examination was normal.