A 64-year-old woman is brought to the office by her spouse due to cognitive impairment. The patient has been mildly forgetful over the past 2 years, with further significant decline in the last 3 months. She performs most daily activities independently but must be reminded frequently to perform basic self-care. The patient has also become unsteady, and she has had 2 near falls in the last 3 months. She still enjoys spending time with family and friends. The patient has a 6-year history of HIV infection and takes antiretroviral therapy. Her most recent CD4 cell count was 600/mm³ 3 months ago. Other medical history includes hypertension, hyperlipidemia, and type 2 diabetes mellitus. Temperature is 37.1 C (98.8 F), blood pressure is 140/82 mm Hg, and pulse is 80/min. On physical examination, the patient is oriented to time, place, and person, but there is short-term memory impairment. Mild weakness of the left-sided extremities and a pronator drift of the left arm are present. She is unsteady in the Romberg position with her eyes closed. Which of the following is the most likely cause of this patient's cognitive impairment?

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Explanation: 11ec25c8_d299_4723_bc81_f9d667e6c557_MD0003_00 This patient's relatively abrupt cognitive decline over the past 3 months, combined with focal neurologic findings suggestive of prior unrecognized stroke (eg, left-sided hemiparesis and pronator drift, Romberg sign), is strongly suggestive of vascular dementia (VaD). VaD is the second most common form of dementia after Alzheimer disease and is characterized by prominent executive dysfunction (ie, impaired ability to plan, solve problems, and think abstractly). Major risk factors include history of stroke, hypertension, hyperlipidemia, and diabetes (as seen in this patient) as well as smoking history, coronary artery disease, and atrial fibrillation. VaD can result from large artery cerebral infarctions (cortical or subcortical), small artery infarctions in subcortical areas (lacunae), or chronic subcortical ischemia. Patients who develop dementia following a recently diagnosed stroke typically have sudden or stepwise decline in cognitive function. Other patients without a history of a recent symptomatic stroke may have either progressive or stepwise decline and clinically unrecognized cerebrovascular disease detected only on imaging studies. (Choices A and E) Cerebral toxoplasmosis and progressive multifocal leukoencephalopathy (caused by JC virus infection) are typically complications of HIV infection that can present with focal neurologic deficits. However, these opportunistic CNS infections usually occur in severely immunocompromised patients who have a CD4 cell count <200/mm³ and who are not receiving antiretroviral therapy. ³ (Choice B) Lewy body dementia is differentiated from other forms of dementia by cognitive fluctuations, visual hallucinations, and parkinsonism (eg, rigidity, bradykinesia, gait disturbance), none of which are present in this patient. (Choice C) Although long-standing HIV infection can lead to dementia and myelopathy (which causes spastic paraparesis and urinary incontinence), HIV-associated dementia occurs almost exclusively in untreated HIV-infected patients with advanced disease (eg, CD4+ <200) and is characterized by apathy, attention impairment, and subcortical motor symptoms (eg, impaired psychomotor speed). (Choice D) Although normal pressure hydrocephalus can present with dementia and falls (due to ataxia), this patient's abrupt, stepwise decline and focal neurologic findings are more characteristic of VaD. Educational objective: Vascular dementia following stroke presents as sudden or stepwise decline in executive function that interferes with activities of daily living. Patients often have focal neurologic findings on examination (eg, hemiparesis, pronator drift, Romberg sign) due to prior (potentially unrecognized) strokes. References: The pathology and pathophysiology of vascular dementia. (http://www.ncbi.nlm.nih.gov/pubmed/29273521) Clinical presentations and epidemiology of vascular dementia. (http://www.ncbi.nlm.nih.gov/pubmed/28515342) Lewy body dementias: Dementia with lewy bodies and Parkinson disease dementia. (http://www.ncbi.nlm.nih.gov/pubmed/27042903) The neuropsychological profile of vascular cognitive impairment in stroke and TIA patients. (http://www.ncbi.nlm.nih.gov/pubmed/15037692)

A 64-Year-Old Woman Is Brought to the Office by Her