The eyes have it: conjugate eye deviation on CT scan aids in early detection of ischemic stroke =============================================================================================== * Jessica E. Simon * James Kennedy * J.H. Warwick Pexman * Alastair M. Buchan A 65-year-old right-handed man, who had moved to Canada from Pakistan a year earlier, presented to the emergency department with a 75-minute history of “speech problems.” The exact nature of his presenting complaint was difficult to assess because of a language barrier and the absence of a fluent translator. The man had a history of hypertension treated with atenolol and amplodipine and was taking ASA for a previous transient ischemic attack that had caused left-sided numbness. Clinically he was noted to have a mild expressive dysphasia and slurred speech, which suggested a left cortical stroke. No conjugate eye deviation was observed. The remainder of his examination was unremarkable except for hypertension (191/85 mm Hg). The patient was rated as mildly affected on the National Institutes of Health Stroke Scale in the language category (NIHSS score of 1).1 A non-contrast CT scan of his head performed 3 hours after symptom onset was described initially as showing no acute ischemic tissue (Figs. 1A and 1B; arrows demonstrate early ischemic changes that were appreciated later: loss of differentiation between grey and white matter and mildly effaced sulci in the right cortex and hypodensity of the right insula). The blood work and electrocardiogram yielded unremarkable findings. ![Figure1](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/168/11/1446/F1.medium.gif) [Figure1](http://www.cmaj.ca/content/168/11/1446/F1) Figure 1b. Photo: Images courtesy of Dr. Rob Sevick ![Figure2](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/168/11/1446/F2.medium.gif) [Figure2](http://www.cmaj.ca/content/168/11/1446/F2) Figure 1a. Photo: Images courtesy of Dr. Rob Sevick The patient was treated conservatively and admitted for further tests and observation. By the next morning he clearly had sensory and visual neglect for the left side of his body, a left facial droop and dysarthria (NIHSS score of 4). Again, no eye deviation was detected on clinical examination. On review of the initial CT scan, however, conjugate eye deviation to the right was noted, and the ischemic changes were then appreciated (Fig. 2). A CT scan performed 20 hours after symptom onset confirmed a right frontal infarct in the right middle cerebral artery territory (Figs. 3A and 3B). Subsequent CT angiography revealed complete occlusion of the right common carotid artery with reconstitution in the petrous segment of the right internal carotid artery. The patient responded to rehabilitation therapy and was discharged home with minimal deficits. ![Figure3](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/168/11/1446/F3.medium.gif) [Figure3](http://www.cmaj.ca/content/168/11/1446/F3) Figure 3b. Photo: Images courtesy of Dr. Rob Sevick ![Figure4](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/168/11/1446/F4.medium.gif) [Figure4](http://www.cmaj.ca/content/168/11/1446/F4) Figure 3a. Photo: Images courtesy of Dr. Rob Sevick ![Figure5](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/168/11/1446/F5.medium.gif) [Figure5](http://www.cmaj.ca/content/168/11/1446/F5) Figure 2. Photo: Images courtesy of Dr. Rob Sevick Conjugate eye deviation, a sustained shift in horizontal gaze toward the affected hemisphere, is a well-recognized finding in acute stroke. Several supranuclear lesions, such as in the cortical frontal eye fields or in the brainstem paramedian pontine reticular formation, can cause conjugate eye deviation.2 On CT scans, conjugate eye deviation or a lone abducting eye has been shown to reliably point toward the affected hemisphere in acute ischemic stroke.3 Eye deviation observed on CT scans appears to be more common than is apparent on clinical examination. This is probably because most patients close their eyes during CT scanning, which removes fixation. Recognizing our patient's eye deviation might have allowed earlier recognition of his subtle right hemispheric ischemic changes (Fig. 1B). When eye deviation is observed that does not agree with clinical information, the patient and CT scan should be examined carefully. In some cases eye deviation may be away from the side of the brain lesion and toward the symptomatic body side, such as in thalamic infarction and non-stroke diagnoses (e.g., seizure). Most stroke patients have readily identifiable and localized symptoms and clinical signs, but when there is limited history or findings on physical examination, as in our case, the detection of eye deviation on a CT scan can help to identify the affected hemisphere. **Jessica E. Simon** **James Kennedy** **J.H. Warwick Pexman** **Alastair M. Buchan** Calgary Stroke Programme Department of Clinical Neurosciences University of Calgary Calgary, Alta. ## References 1. 1. Lyden P, Brott T, Tilley B, Welch KM, Mascha EJ, Levine S, et al. Improved reliability of the NIH Stroke Scale using video training. NINDS TPA Stroke Study Group. Stroke 1994;25:2220-6. [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6OToic3Ryb2tlYWhhIjtzOjU6InJlc2lkIjtzOjEwOiIyNS8xMS8yMjIwIjtzOjQ6ImF0b20iO3M6MjI6Ii9jbWFqLzE2OC8xMS8xNDQ2LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 2. 2. Lavin PJM, Donahoe SP. Neuro-ophthalmology: occular motor system. In: Bradley WG, Daroff RB, Fenichel GM, Marsden CD, editors. *Neurology in clinical practice*. 3rd ed. Boston: Butterworth–Heinemann; 2000. p. 699-720. 3. 3. Simon JE, Morgan SC, Pexman JHW, Hill MD, Buchan AM. CT assessment of conjugate eye deviation in acute stroke. Neurology 2003;60:135-7. [Abstract/FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6OToibmV1cm9sb2d5IjtzOjU6InJlc2lkIjtzOjg6IjYwLzEvMTM1IjtzOjQ6ImF0b20iO3M6MjI6Ii9jbWFqLzE2OC8xMS8xNDQ2LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==)