A 34-year-old man comes to the emergency department due to progressive leg weakness for the past several days. He also reports a tingling sensation in the toes and mild low back pain. Three weeks ago, the patient was evaluated for flulike illness, oral ulcer, and lymphadenopathy and was diagnosed with HIV infection. He has not started antiretroviral therapy yet while waiting for drug resistance testing results. Temperature is 37 C (98.6 F), blood pressure is 120/70 mm Hg, and pulse is 72/min. Lower extremity examination shows marked muscle weakness and loss of deep tendon reflexes bilaterally. Touch, pain, and vibration sensations are intact. Upper extremity examination shows no abnormality. There is no focal back tenderness and no signs of meningeal irritation are present. Which of the following would be most helpful in revealing the cause of this patient's weakness?

Question

A 34-year-old man comes to the emergency department due to progressive leg weakness for the past several days.  He also reports a tingling sensation in the toes and mild low back pain.  Three weeks ago, the patient was evaluated for flulike illness, oral ulcer, and lymphadenopathy and was diagnosed with HIV infection.  He has not started antiretroviral therapy yet while waiting for drug resistance testing results.  Temperature is 37 C (98.6 F), blood pressure is 120/70 mm Hg, and pulse is 72/min.  Lower extremity examination shows marked muscle weakness and loss of deep tendon reflexes bilaterally.  Touch, pain, and vibration sensations are intact.  Upper extremity examination shows no abnormality.  There is no focal back tenderness and no signs of meningeal irritation are present.  Which of the following would be most helpful in revealing the cause of this patient's weakness?

Quizplus · Accepted Answer

11ec25c8_d5a7_7178_bc81_ef9f419163f1_MD0003_00 This patient with recently diagnosed acute HIV infection (eg, flulike symptoms, lymphadenopathy, oral ulcers) now has progressive lower extremity weakness with absent deep tendon reflexes. This is consistent with Guillain-Barré syndrome (GBS). GBS is often preceded by an acute infection. It may be caused by an immune response that cross-reacts (ie, molecular mimicry) with peripheral nerve components (eg, myelin). Although gastrointestinal and respiratory infections are most commonly implicated, acute HIV infection can also trigger GBS. In patients with HIV, GBS most commonly occurs prior to the onset of AIDS (ie, while there is still a robust immune response) and can be the initial HIV presentation. The clinical presentation of HIV-associated GBS is indistinguishable from non-HIV-associated GBS. Patients have ascending motor deficits, hyporeflexia, and back pain; sensation is classically unaffected (although paresthesias are common). Diagnosis is based on clinical findings, cerebrospinal fluid analysis, and nerve conduction studies, which reveal evidence of demyelination (eg, decreased motor nerve conduction velocity). HIV testing should also be performed. (Choice A) Although cerebrospinal fluid cell count and protein could be helpful to diagnose GBS (albuminocytologic dissociation), CSF PCR is used to detect viral CNS pathogens (eg, aseptic meningitis), which are not implicated in the pathogenesis of GBS. Viral meningitis classically presents with fever, headache, vomiting, and nuchal rigidity. (Choice B) A CT scan of the head can detect mass lesions in the brain, which may occur in immunosuppressed patients due to opportunistic infections and/or AIDS-associated tumors. However, cerebral masses are unlikely to cause back pain or motor deficits affecting the same area on both feet (because of the distribution of the homunculus). In addition, hyperreflexia (ie, upper motor neuron sign), rather than absent reflexes, would be expected. (Choice D) Toxoplasmic encephalitis, which can occur with a CD4 count <100/mm³ and no prophylaxis, can cause focal neurologic deficits but typically also presents with fever, headache, confusion, and seizures. (Choice E) HIV increases risk of tuberculosis, including CNS forms (eg, tuberculous meningitis, tuberculoma). However, tuberculous meningitis presents subacutely with fever, headache, and nuchal rigidity; a CNS tuberculoma would be unlikely to cause hyporeflexia or motor deficits affecting the same area on both feet. Educational objective: Guillain-Barré syndrome (GBS), an immune-mediated polyneuropathy, can be associated with early HIV infection. The clinical presentation and diagnostic workup of HIV-associated GBS is the same as non-HIV-associated GBS; nerve conduction studies (eg, showing demyelination) can help confirm the diagnosis.

A 34-Year-Old Man Comes to the Emergency Department Due to Progressive