The onset of a stroke is typically sudden, although the precise onset may not be recognized in some individuals. Twenty-five percent of patients wake up with stroke symptoms (Chaturvedi et al 1999). Ischemic stroke is frequently dichotomized into cortical and subcortical presentations and anterior and posterior circulation distributions.
Both cortical and subcortical strokes may manifest with focal weakness, sensory loss, and dysarthria. Therefore, these findings do not help distinguish location. Aphasia (most often a left hemisphere event) and neglect (most often a right hemisphere event) occur most frequently with cortical strokes. Gaze deviation away from the side of weakness, suggests a cortical stroke ipsilateral to the side of gaze deviation. Gaze deviation toward the side of weakness suggests a subcortical event, typically in the pons contralateral to the side of gaze deviation. Occasionally, medial thalamic and supratentorial lesions produce ipsilateral version of the eyes toward the hemiparesis, known as “wrong-way deviation.” Epilepsy may also produce gaze deviation towards hemiparetic limbs but subtle nystagmoid jerks of the eyes may help distinguish this condition from stroke.
Distinguishing anterior (or carotid territory) from posterior (or vertebrobasilar territory) circulation strokes is important when deciding on the necessity and relevance of diagnostic testing (eg, carotid imaging). Approximately 80% of ischemic strokes involve the anterior circulation, and 20% involve the posterior circulation. Clinical features suggestive of ischemia in the anterior circulation are monocular visual loss, aphasia, and neglect. Posterior circulation infarction is suggested by diplopia, binocular visual loss, vertigo, hearing loss, lower motor neuron facial weakness, bilateral or alternating weakness, delirium or severely altered level of consciousness, and visual hallucinations. Focal weakness, focal sensory disturbance, dysarthria, and dysphagia are not helpful per se in distinguishing between anterior and posterior circulation ischemia. Headache occurs in approximately one third of patients and is less frequent in those with pure motor or sensory disturbance. The combination of headache and vomiting is more likely to be associated with intracerebral hemorrhage, especially when accompanied by rapidly progressing neurologic deficits.