Question

A $68$-year-old man presents to the emergency department complaining of severe, progressively worsening mid-back pain over the past $2$ weeks. He has a history of advanced prostate cancer treated with androgen deprivation therapy. Over the past $24$ hours, he has developed difficulty walking and states his legs feel "heavy." He also reports an inability to urinate since early this morning. His temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $142/88\text{ mm Hg}$, and pulse is $88\text{/min}$. On physical examination, there is exquisite point tenderness to palpation over the T10 spinous process. Neurologic examination reveals $3/5$ motor strength in the lower extremities bilaterally. There is decreased sensation to pinprick and temperature below the umbilicus. Deep tendon reflexes are $3+$ at the patellae and ankles, with bilateral upgoing plantar responses. Post-void residual ultrasound shows $550\text{ mL}$ of urine in the bladder. Which of the following is the most appropriate initial step in the management of this patient?