An AIDS patient under treatment with a nucleoside analog and a protease inhibitor comes to
medical attention with complaints of leg weakness and incontinence. His vital signs are within
normal limits. Physical examination reveals reduced strength in the lower extremities with
accompanying mild spasticity. There is also diminished sensation in the feet and legs bilaterally.
Lumbar puncture shows:
Opening pressure…100 mm H20
Cell count…5 lymphocytes/mm3
Glucose…48 mg/dL
Proteins, total…33 mg/dL
Gamma globulin…8% total protein
Additional laboratory investigations show normal hematologic parameters, vitamin B12 within
normal values, and negative serology for syphilis. MRI of the head fails to reveal any focal
abnormality. Which of the following is the most likely diagnosis?
A. AIDS dementia complex
B. CMV polyradiculopathy
C. Cryptococcal meningoencephalitis
D. Vacuolar (HIV) myelopathy
E. Zidovudine-related toxicity
Explanation:
The correct answer is D. This is one of the most common neurologic complications of AIDS. Its
pathologic substrate is degeneration of the spinal tracts in the posterior and lateral columns,
which have a vacuolated microscopic appearance. Although the morphologic changes and
clinical manifestations are similar to those associated with vitamin B12 deficiency, the
pathogenetic mechanism is probably not related to dietary deficiencies. Since there is no specific
clinical or laboratory test available for the diagnosis of this syndrome, vacuolar myelopathy in
AIDS patients remains a diagnosis of exclusion. This implies that other HIV-related neurologic
complications must be ruled out (see below).
AIDS dementia complex (choice A) manifests with progressive memory loss, alterations in fine
motor control, urinary incontinence, and altered mental status.
CMV polyradiculopathy (choice B) may simulate HIV myelopathy and is a relatively frequent
complication of AIDS. It can be excluded by the results of CSF analysis. CMV infection leads to
neutrophilic pleocytosis in the CS
F.
Cryptococcal meningoencephalitis (choice C) would lead to signs and symptoms of meningitis.
The CSF would show the fungal organism, which can be detected by special stains and culture
studies.
Zidovudine-related toxicity (choice E) would lead to proximal muscle weakness and tenderness
due mainly to a myopathic process.