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Difficulty: MediumNeurocognitive Disorders

A 48-year-old man is brought to the clinic by his sister due to a 5-month history of progressive forgetfulness, social withdrawal, and difficulty concentrating. The sister reports that he takes an unusually long time to answer simple questions and that his walking has become slow and uncoordinated. His medical history is significant for HIV infection, diagnosed 12 years ago. He admits to poor adherence to his antiretroviral therapy over the past 18 months. His most recent CD4+ T-cell count was 145/mm³. Vital signs are within normal limits. Neurological examination reveals marked psychomotor slowing, saccadic pursuit eye movements, and brisk deep tendon reflexes in the bilateral lower extremities. His Montreal Cognitive Assessment score is 19/30. Magnetic resonance imaging of the brain demonstrates diffuse cortical atrophy and symmetric, bilateral periventricular white matter hyperintensities without contrast enhancement or mass effect. Which of the following is the most likely diagnosis?

  1. HIV-associated neurocognitive disorderAnswer
  2. B
    Progressive multifocal leukoencephalopathy
  3. C
    Toxoplasma encephalitis
  4. D
    Primary central nervous system lymphoma
  5. E
    Major depressive disorder

Answer

The correct diagnosis is HIV-associated neurocognitive disorder.
HIV-associated neurocognitive disorder (HAND) is a neurodegenerative condition resulting from HIV infection of the central nervous system, typically seen in patients with long-standing, poorly controlled disease and low CD4+ counts. It classically presents with a subcortical pattern of dementia characterized by a triad of cognitive impairment (memory loss, executive dysfunction), behavioral changes (apathy, social withdrawal), and motor abnormalities (psychomotor retardation, slow gait, hyperreflexia, saccadic eye movements). Magnetic resonance imaging characteristically demonstrates diffuse cortical atrophy and symmetric periventricular white matter hyperintensities. Importantly, there is no mass effect, edema, or contrast enhancement, which perfectly matches this patient's presentation.

Step-by-Step Solution

1
Identify the core clinical syndrome based on the history and physical exam.
The patient exhibits a triad of cognitive decline (forgetfulness, MoCA 19/30), behavioral changes (apathy, social withdrawal), and motor symptoms (psychomotor retardation, hyperreflexia).
Establishing the specific pattern of neurological deficits is essential for narrowing the differential diagnosis in an immunocompromised patient.
2
Analyze the neuroimaging findings in the context of the patient's immune status.
MRI shows diffuse cortical atrophy and symmetric periventricular white matter hyperintensities, with no mass effect, edema, or contrast enhancement.
Imaging differentiates neurodegenerative processes from focal opportunistic infections or malignancies.
3
Synthesize the clinical and imaging data to determine the most likely etiology.
The insidious onset, symmetric subcortical imaging findings, and lack of focal deficits in a poorly controlled HIV patient point directly to a primary viral neurodegenerative process rather than an opportunistic infection.
This confirms HIV-associated neurocognitive disorder and rules out conditions like PML or toxoplasmosis.

Key Concept

HIV-associated neurocognitive disorder (HAND) typically presents with subcortical cognitive decline, behavioral apathy, and motor symptoms (hyperreflexia, psychomotor slowing). MRI classically shows diffuse atrophy and symmetric white matter changes without enhancement or mass effect.
Estimated Time:1m 15s
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Topics

Neurocognitive Disorders

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