A 29-year-old man comes to the emergency department due to lower extremity weakness. The patient has not been feeling well over the past several days and has had worsening back pain. When he woke up this morning, he noticed weakness in both legs and had to have a friend help him walk to the car. The patient has a history of HIV, which was acquired via shared needles, but does not take antiretroviral therapy consistently. The patient still uses injection drugs occasionally but no longer shares needles. Temperature is 38 C (100.4 F), blood pressure is 116/68 mm Hg, and pulse is 98/min. The lungs are clear on auscultation, and heart sounds are normal with no murmurs. Abdominal examination shows a distended bladder. The back is tender to palpation over the lower thoracic region. Neurological examination reveals 3/5 bilateral lower extremity muscle strength with upgoing bilateral plantar reflexes. Skin examination shows scattered folliculitis and no lower extremity edema. Which of the following is the most likely cause of this patient's weakness?

Question

A 29-year-old man comes to the emergency department due to lower extremity weakness.  The patient has not been feeling well over the past several days and has had worsening back pain.  When he woke up this morning, he noticed weakness in both legs and had to have a friend help him walk to the car.  The patient has a history of HIV, which was acquired via shared needles, but does not take antiretroviral therapy consistently.  The patient still uses injection drugs occasionally but no longer shares needles.  Temperature is 38 C (100.4 F), blood pressure is 116/68 mm Hg, and pulse is 98/min.  The lungs are clear on auscultation, and heart sounds are normal with no murmurs.  Abdominal examination shows a distended bladder.  The back is tender to palpation over the lower thoracic region.  Neurological examination reveals 3/5 bilateral lower extremity muscle strength with upgoing bilateral plantar reflexes.  Skin examination shows scattered folliculitis and no lower extremity edema.  Which of the following is the most likely cause of this patient's weakness?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d5a2_dd91_bc81_95d15645f458_MD0003_00 11ec25c8_d5a2_dd92_bc81_c9e15a44c675_MD0003_00 This patient's intravenous drug use, back pain, low-grade fever, and lower extremity neurologic symptoms raise strong suspicion for spinal cord compression due to spinal epidural abscess (SEA), a bacterial infection of the epidural space. SEA usually occurs in the setting of bacteremia due to intravenous drug use or a distant infection (eg, endocarditis); however, a minority of cases are caused by contiguous infection (eg, overlying cellulitis) or direct inoculation during an epidural or spinal procedure. Risk is greatest in those with compromised immunity due to HIV, diabetes mellitus, or alcoholism. Because the epidural space is a narrow, contiguous corridor within the spinal canal, bacterial invasion tends to affect multiple adjacent spinal levels and to eventually compress the spinal cord. Patients classically present with the triad of fever, spinal pain, and neurologic deficits, but all 3 findings are present in a minority of patients. Most individuals develop days/weeks of fever, malaise, and progressive neurologic deficits as follows: Worsening focal back pain → Radicular nerve pain (eg, shocklike) → Sensory/motor/reflex (eg, upgoing plantar reflex) deficits and bowel/bladder issues (eg, urinary retention) → Paralysis Suspected cases require urgent spinal MRI to confirm the diagnosis, followed by surgical decompression and antibiotics to prevent neurologic sequelae and death. (Choice B) Guillain-Barré syndrome is an immune-mediated polyneuritis. It can cause symmetric lower extremity weakness, but the weakness is usually ascending, progressive, and associated with loss of deep tendon reflexes. Fever is rare, and localized back pain would not be expected. (Choice C) Patients with HIV are at increased risk for transverse myelitis, which is associated with segmental spinal cord inflammation. Although motor weakness and acute urinary retention are common, patients generally have a sensory level (loss of sensation below a clearly defined dermatome), flaccid paralysis, and no fever. (Choice D) Spondylosis is a degenerative condition associated with vertebral body osteophyte formation and thickening of spinal ligaments. It typically causes chronic back/neck pain and impaired spinal mobility. Although cord compression occasionally occurs (from canal narrowing), it is most common in the cervical spine. Fever is uncommon. (Choice E) Polio and West Nile virus can cause acute flaccid paralysis due to viral infection of motor neurons. These diseases generally presents with rapid-onset asymmetric (not symmetric) proximal muscle weakness and loss of reflexes. Educational objective: Spinal epidural abscess, a bacterial infection of the epidural space, typically arises in the setting of bacteremia from intravenous drug use or distant infection. Manifestations include fever, malaise, focal back pain, and progressive neurologic findings (eg, sensory, motor, reflex deficits).

A 29-Year-Old Man Comes to the Emergency Department Due to Lower