Rightward Gaze Deviation in Cerebrovascular Accident
Rightward gaze deviation in CVA is caused by a lesion in the left frontal lobe, specifically involving the left frontal eye field (FEF) or its descending pathways, resulting in unopposed action of the intact right FEF that drives the eyes toward the side of the lesion (rightward). 1
Neuroanatomical Mechanism
The frontal eye fields, located in the posterior frontal cortex (Brodmann area 8), control voluntary conjugate eye movements to the contralateral side. 2
- Left FEF normally drives eyes rightward (contralateral direction)
- Right FEF normally drives eyes leftward (contralateral direction)
- When the left FEF is damaged by stroke, the unopposed right FEF causes the eyes to deviate toward the left hemisphere lesion (rightward gaze preference) 1
Clinical Presentation Pattern
The classic teaching is: "The eyes look toward the lesion and away from the hemiparesis." 1, 2
- Right gaze preference = Left hemisphere stroke (typically left frontal lobe)
- Associated left-sided motor weakness (right hemiparesis) is expected, as the patient's eyes look away from their paralyzed side 1, 2
- The gaze deviation occurs because the stroke damages the left frontal cortex controlling rightward eye movements, leaving the intact right hemisphere to drive eyes leftward unopposed 1
Specific Anatomical Localization
Anterior right frontal lobe ischemia would actually cause leftward gaze deviation (not rightward), as this represents right hemisphere damage. 2 Therefore:
- Rightward gaze = Left frontal/frontoparietal stroke 1, 2
- Leftward gaze = Right frontal/frontoparietal stroke 2
- The gaze preference is ipsilateral to the lesion and contralateral to the hemiparesis 1
Associated Clinical Features to Monitor
Patients with frontal lobe strokes causing gaze deviation should be monitored for: 1, 2
- Contralateral hemiparesis (left-sided weakness with rightward gaze)
- Altered level of consciousness (somnolence may indicate expanding lesion or edema)
- Seizure activity (occurs in approximately 10-20% of acute strokes)
- Cerebral edema development (can occur days after initial infarction)
Critical Pitfall to Avoid
Do not confuse gaze deviation with gaze palsy from brainstem lesions. 1 Cortical lesions cause gaze preference (eyes can be moved past midline with vestibulo-ocular reflex testing), while brainstem lesions cause true gaze palsy (eyes cannot cross midline even with vestibulo-ocular maneuvers). 1 This distinction is crucial for localization and prognosis.