Cognitive dysfunction is common in lacunar stroke patients

Image: CC/GGeek. Lacunar Infarct

Key study points:

1. Lacunar strokes are a common occurrence in patients with vascular risk factors and can lead to a wide range of cognitive and sensorimotor sequelae.
2. Cognitive deficits following lacunar strokes may be more prevalent than sensorimotor symptoms, and are characterized by impaired verbal fluency, executive dysfunction, and loss of motor dexterity.

Primer: Lacunar strokes, also termed small subcortical strokes, are ischemic events affecting the subcortical structures of the brain.  They most commonly affect, in order, the deep brain nuclei (thalamus, basal ganglia), pons, and white matter of the internal capsule.  A wide range of symptoms can result from these strokes, including impairment of speech, motor function, executive function, cognition, and sensation.  The five classic lacunar stroke syndromes are: 1) Pure motor: hemiparesis, dysarthria, and/or dysphagia; 2) Pure sensory: numbness or paresthesias; 3) Mixed sensorimotor: a combination of the symptoms described above; 4) Ataxic hemiparesis: hemiparesis and clumsiness affecting the leg more than the arm; and 5) Dysarthria/clumsy hand syndrome: dysarthria and ataxia of the hand, particularly when writing.

A syndrome of cognitive impairment due to lacunar strokes has also been recognized.  Termed subcortical vascular dementia (SVD), this syndrome shares features with other causes of dementia including Alzheimer’s Disease.  While MRI can easily identify lacunar strokes, SVD can coexist with other forms of dementia and these can be difficult to distinguish clinically.  For these reasons, the authors were interested in further characterizing cognitive deficits in lacunar stroke patients.

Background reading:

1. Frisoni GB, Galluzzi S, Bresciani L, et al. (2002) Mild cognitive impairment with subcortical vascular features: clinical characteristics and outcome. J Neurol 249(10):1423-32.
2. Gorelick PB, Scuteri A, Black SE, et al. (2011) Vascular contributions to cognitive impairment and dementia: a statement for healthcare professionals from the american heart association/american stroke association.  Stroke 42(9):2672-713.
3. Moorhouse P, Rockwood K. (2008) Vascular cognitive impairment: current concepts and clinical developments. Lancet Neurol 7(3):246-55.

This [cross-sectional cohort] study: The study examined participants from the Secondary Prevention of Small Subcortical Strokes (SPS3) trial, which was designed to investigate interventions for patients with first lacunar strokes in order to prevent recurrence of strokes and progression of cognitive sequelae.  As part of the analysis, patients were assessed with respect to neuropsychological status and independence in activities of daily living (ADLs).

A total of 1,636 patients were studied.  The domains of cognitive function most affected across all patients were verbal episodic memory, verbal fluency, clock drawing, and motor dexterity.  Forty-seven percent of the patients met criteria for mild cognitive impairment (MCI).  MCI was significantly more common in males, younger patients, and those with lower education levels.  Additionally, impaired ADLs were significantly associated with the presence of MCI.  The presence of MCI was more prevalent than physical disability, which was seen in only 33% of patients overall.  Of note, no significant association was found between vascular risk factors and presence of MCI.

In sum: This study examined neuropsychological testing in a large cohort of patients with recent first lacunar strokes.  Nearly half of the patients were found to have mild cognitive impairment, with the most commonly affected domains being verbal episodic memory and fluency, clock drawing (a measure of executive function), and motor dexterity.  While prior studies have indicated deficits in executive function and motor dexterity with lacunar strokes, there have not been many studies showing deficits in explicit memory, and this should be further examined. It is also important to note that mild cognitive impairment was more prevalent than motor deficits (47% vs. 33%) following lacunar stroke, which contrasts with the traditional understanding of lacunar stroke sequelae as primarily sensorimotor syndromes.

Limitations of this study include an inability to control for cognitive function prior to the stroke and the lack of comparison to age, sex, and education-corrective normative data.  However, the results emphasize the high prevalence of cognitive sequelae following lacunar strokes, along with the importance of neuropsychological testing and appropriate attention to cognitive deficits in these patients.

Click here to read the study in Annals of Neurology

By [JD] and [RR]

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