neurologic disorders
Third Cranial (Oculomotor) Nerve Disorders
Symptoms and Signs of Third Cranial Nerve Disorders
Diplopia and ptosis (drooping of the upper eyelid) occur. The affected eye may deviate slightly out and down in straight-ahead gaze; adduction is slow and may not proceed past the midline. Upward gaze is impaired. When downward gaze is attempted, the superior oblique muscle causes the eye to adduct slightly and rotate. The pupil may be normal or dilated; its response to direct and to consensual light may be sluggish or absent (efferent defect). Mydriasis (pupil dilation) may be an early sign. Patients with oculomotor palsy with pupil dilation due to intracranial aneurysm or early transtentorial brain herniation can have severe headache, and mental status may deteriorate rapidly. 