A 67-year-old man comes to the emergency department with right arm and leg weakness that he first noticed approximately 2 hours ago when he could not grip a pen. He is now unable to shake hands and walks with a mild limp. The patient has also had a mild, constant headache the past several days that he attributes to stress from a new project at work. Medical history is significant for hypertension and hyperlipidemia, and the patient does not smoke or consume alcohol. Blood pressure is 180/100 mm Hg and pulse is 80/min. There is mild asymmetry of the lower face, decreased muscle strength in the right arm, and positive Babinski sign on the right side. Sensory examination is normal. Blood glucose is 210 mg/dL. ECG shows sinus rhythm with occasional premature ventricular complexes. Noncontrast CT scan of the head reveals no abnormalities. Which of the following is the most likely cause of this patient's symptoms?
Lacunar stroke | |
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Clinical |
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After several days of headache (likely due to hypertension), this patient developed acute pure motor hemiparesis impacting the leg, arm, and lower face, which localizes to the posterior limb (corticospinal tract) and genu (corticobulbar tract) of the internal capsule. Pure motor hemiparesis is the most common stroke syndrome caused by a lacunar stroke. The underlying pathology is a combination of microatheroma formation and lipohyalinosis that ultimately leads to thrombotic small-vessel occlusion.
The deep penetrating arteries are quite small and are therefore most susceptible to hypertension-related vascular disease, the most important risk factor for lacunar stroke. Lacunar strokes often result in classic stroke syndromes (eg, pure motor hemiparesis; pure sensory, ataxic hemiparesis; dysarthria–clumsy hand syndrome) referable to the impacted areas (eg, basal ganglia, internal capsule, corona radiata).
Mental status changes, seizures, cranial nerve deficits, and cortical signs are absent. Because they are small, lacunar strokes are often not appreciated on noncontrast CT scans obtained shortly after the event.
(Choice A) Carotid artery dissection (ie, intimal tear) usually results from trauma and may cause ischemic stroke due to thromboembolism or hypoperfusion. Patients typically experience neck pain followed by partial ipsilateral Horner syndrome (eg, ptosis and miosis without anhidrosis) due to damage of postganglionic sympathetic fibers.
(Choice B) Cerebral venous sinus thrombosis typically occurs in patients with hypercoagulable conditions (eg, pregnancy, malignancy) and presents with headache, increased intracranial pressure, altered mentation, and seizures. Accompanying neurologic deficits usually do not follow typical arterial patterns. CT scan often reveals focal or diffuse cerebral edema, venous infarction, or areas of hemorrhage.
(Choice C) Carotid artery occlusion typically leads to profound neurologic deficits (eg, contralateral homonymous hemianopia, hemiparesis, hemisensory loss) due to ischemic infarction of large portions of the cerebral hemisphere. Cortical signs and altered mental status are also usually present. Although embolism from an ulcerated plaque could cause a presentation similar to that of this patient's, large-artery occlusion would cause more severe symptoms.
(Choices D) Subarachnoid hemorrhage typically occurs due to a ruptured saccular aneurysm and presents with thunderclap headache associated with brief loss of consciousness and meningismus. Noncontrast CT scan of the head reveals acute hemorrhage between the arachnoid and pia mater in >90% of patients.
Educational objective:
Lacunar strokes occur due to microatheroma formation and lipohyalinosis in the small penetrating arteries of the brain. They often affect the internal capsule and result in pure motor hemiparesis. Hypertension is the most important risk factor.