This patient presents with a pure motor stroke, which is one of the stroke syndromes caused by lacunar infarcts. The most important predisposing risk factors for lacunar infarcts are diabetes and hypertension.
Lacunar strokes are small infarcts which occur due to the occlusion of small perforating branches arising from major intracerebral arteries. Lacunar infarcts affect the deep nuclei of the brain. Depending on which perforating artery is involved, a number of clinical syndromes can arise, including the pure motor stroke described in the question stem. The pathogenesis of lacunar strokes is different than that of the classic large vessel strokes; in particular, lacunar strokes involve lipohyalinosis of the perforating vessels.
Yew et al. discuss the diagnosis of stroke. The most reliable finding in diagnosing stroke is the abrupt onset of focal neurologic symptoms. Diagnosing lacunar stroke can sometimes be challenging, as a variety of syndromes can occur (including pure motor, pure sensory, etc.), and lesions may be small in size and thus difficult to see on imaging. Lacunar stroke is often ischemic without a hemorrhagic component and is more likely to be seen on MRI than CT.
Tuszynski et al. discuss the risk factors for lacunar strokes. Hypertension is the most common and most important risk factor. In their series, the authors found that nearly two-thirds of patients with lacunar stroke were hypertensive, even using a threshold of 160/95 mmHg as the cutoff for hypertension. Moreover, about one-third of patients with lacunar stroke were diabetic. Family history of stroke was more weakly associated with lacunar stroke.
Illustration A is a cartoon depicting the anatomy of the perforating arteries and their relationship to lacunar stroke.
Answer 2: Atrial fibrillation can predispose to an embolism originating from the left atrium and causing stroke. However, lacunar stroke is rarely embolic in nature.
Answer 3: Lacunar infarcts occur in subcortical areas, not in major vascular watershed areas of the brain.
Answer 4: IV thrombolysis can be used for ischemic lacunar infarction if the patient is otherwise a candidate for thrombolysis.
Answer 5: Race and sex are not known to be particularly important risk factors specifically for lacunar stroke.
Yew KS1, Cheng E. Acute stroke diagnosis. Am Fam Physician. 2009 Jul 1;80(1):33-40.
PMID:19621844 (Link to Abstract)
Tuszynski MH1, Petito CK, Levy DE. Risk factors and clinical manifestations of pathologically verified lacunar infarctions. Stroke. 1989 Aug;20(8):990-9.
PMID:2474207 (Link to Abstract)