The labeled obstruction is in the left middle cerebral artery (MCA), which would result in hemiparesis on the right side (contralateral), as well as aphasia that may be expressive or receptive depending on whether the frontal or superior temporal lobe is more affected.
Normally, the MCA supplies the lateral portion of the cerebral hemisphere, including frontal, parietal, and upper temporal regions. In addition to findings described above, MCA strokes may have contralateral sensation loss, hemianopsia, hyperreflexia, and Babinski sign. While left-sided strokes cause language deficits, right-sided MCA occlusions may produce visual hemianopsia with inattention to objects on the left side. Initial diagnosis of acute stroke in the emergency room requires non-contrast head CT to rule out hemorrhage; serum electrolytes, creatinine and glucose, CBC; PT/PTT; and EKG and troponins, although the last two tests should not delay administration of IV-tPA in ischemic stroke.
Yew and Chang review diagnosis of acute stroke and its imitators. They note that the most common presenting symptoms for stroke are hemiparesis and difficulty speaking. The two most common entities that mimic stroke are the postictal state and suffering from hypoglycemia. History is usually important in determining the cause of perceived deficits. Again, head CT is important to distinguish ischemic from hemorrhagic causes of brain injury.
Hand et al. examined a series of 350 cases of stroke-like presentations in a teaching hospital and performed a bedside exam. Experts then verified their diagnosis with a full complement of laboratory and radiologic tests. 241 of 250 (69%) patients examined were found to have had strokes. They concluded that the bedside clinical exam offered clues to the correct diagnosis of stroke, with the following signs suggesting stroke: exact time of onset, focal symptoms, neurologic signs that lateralized to a specific hemisphere. General cognitive impairment and abnormal findings in systems besides the neurologic system suggested a mimic of stroke.
Figure A is an image of blood flow in cerebral arteries taken with MRI angiography. Blood flow to the MCA is occluded at the point shown with the arrow by an embolus, thus the artery does not appear distal to this point.
Illustration A shows the different cerebrovascular territories.
Answer 2: Lacunar infarcts affecting blood flow to the pons result in clumsy hand-dysarthria syndrome.
Answer 3: Emboli in the vertebrobasilar circulation, from the posterior artery, that affect blood flow to the cerebellum would lead to vertigo, nystagmus, and cranial nerve palsy.
Answer 4: Weakness greatest in the legs is a feature of anterior cerebral artery stroke.
Answer 5: Lacunar infarcts affecting blood flow to the thalamus result in sensory-only deficits.
Yew KS, Cheng E. Acute stroke diagnosis. Am Fam Physician. 2009 Jul 1;80(1):33-40. Review. PubMed PMID: 19621844; PubMed Central PMCID: PMC2722757
PMID:19621844 (Link to Abstract)
Hand PJ, Kwan J, Lindley RI, Dennis MS, Wardlaw JM. Distinguishing between stroke and mimic at the bedside: the brain attack study. Stroke. 2006 Mar;37(3):769-75. Epub 2006 Feb 16. PubMed PMID: 16484610
PMID:16484610 (Link to Abstract)