A 58-year-old man comes to the emergency department due to sudden right-sided weakness. He has no sensory loss, problems speaking/swallowing, or difficulty with balance. The patient was previously told that he has elevated blood pressure, but he does not routinely follow up with his physician. He takes no medications. Examination shows intact cranial nerves and sensory function. The patient has 3/5 muscle strength on the right side. Initial CT scan without contrast reveals no abnormalities. Four weeks later, repeat brain imaging shows a 9-mm, fluid-filled cavitary lesion in the left internal capsule. This patient's condition is most likely caused by which of the following?

Question

A 58-year-old man comes to the emergency department due to sudden right-sided weakness.  He has no sensory loss, problems speaking/swallowing, or difficulty with balance.  The patient was previously told that he has elevated blood pressure, but he does not routinely follow up with his physician.  He takes no medications.  Examination shows intact cranial nerves and sensory function.  The patient has 3/5 muscle strength on the right side.  Initial CT scan without contrast reveals no abnormalities.  Four weeks later, repeat brain imaging shows a 9-mm, fluid-filled cavitary lesion in the left internal capsule.  This patient's condition is most likely caused by which of the following?

Quizplus · Accepted Answer

This patient has pure motor hemiparesis and a small cavitary lesion in the internal capsule, characteristic of a lacunar infarct. This type of stroke affects the small penetrating arterioles that supply the deep brain structures (eg, basal ganglia, pons) and subcortical white matter (eg, internal capsule, corona radiata). Lacunar infarcts are primarily associated with chronic hypertension, which promotes lipohyalinosis, microatheroma formation, and hardening/thickening of the vessel wall (hypertensive arteriolar sclerosis). This leads to progressive narrowing of the arteriolar lumen and predisposes to thrombotic vessel occlusion, which causes characteristic clinical syndromes, depending on the portion of the brain affected: Posterior limb of the internal capsule and/or basal pons - pure motor hemiparesis or ataxia-hemiplegia syndrome (ie, ipsilateral limb ataxia out of proportion to motor deficit) Genu/anterior limb of the internal capsule and/or basal pons - dysarthria-clumsy hand syndrome (ie, dysarthria and dysphagia with clumsiness of one hand) Ventroposterolateral or ventroposteromedial thalamus - pure sensory stroke In the acute setting, CT imaging may not reveal the expected hypodensity of ischemic stroke due to the small infarct size (usually <15 mm). After several weeks, these necrotic lesions turn into cavitary spaces filled with cerebrospinal fluid and surrounded by scar tissue called lacunas. (Choices A and B) Cardiac embolism and carotid artery atherosclerosis usually result in occlusion of medium to large cerebral vessels (eg, middle cerebral artery), causing large-territory ischemic infarctions of the cerebral cortex evident on CT scan as large areas of hypodensity. (Choice D) Hypertensive encephalopathy is characterized by progressive headache and nausea/vomiting followed by nonlocalizing neurologic symptoms (eg, confusion). Cerebral imaging may be normal or show parietooccipital white matter edema. (Choice E) Hypoxic encephalopathy occurs from global interruption of the cerebral blood supply (eg, due to cardiac arrest). It commonly presents with decreased consciousness (eg, coma, vegetative state) as opposed to focal neurologic deficits. Cerebral imaging may show watershed infarcts at the border of perfusion zones between the major cerebral arteries. (Choice F) Saccular aneurysm rupture is associated with subarachnoid hemorrhage. Patients usually have abrupt onset of severe headache, and CT will show hyperattenuation (hemorrhage) in the sulci and basal cisterns. Focal neurologic deficits are uncommon. Educational objective: Lacunar infarcts are small, ischemic infarcts (usually <15 mm) involving the deep brain structures (eg, basal ganglia, pons) and subcortical white matter (eg, internal capsule, corona radiata). They most often occur due to hypertension, which causes hardening/thickening of the vessel wall (hypertensive arteriolar sclerosis), predisposing patients with this condition to thrombotic vessel occlusion. __________ References: Lacunar infarction and small vessel disease: pathology and pathophysiology. (http://www.ncbi.nlm.nih.gov/pubmed/25692102)

A 58-Year-Old Man Comes to the Emergency Department Due to Sudden