File:Hess Chart.jpg

Clinical Case - This Hess chart presents the case of a 66-year-old male with a right fourth-nerve palsy after neurosurgery for pleomorphic pineocytoma, experiencing diplopia during left gaze and presenting with right hypertropia (right eye higher than the left). The chart demonstrates underaction of the right superior oblique muscle, which is responsible for intorsion (inward rotation) and depression (downward movement) of the right eye, particularly during left gaze. Additionally, the chart reveals all the muscle sequelae associated with this condition: overaction of the left inferior rectus (contralateral synergist - yoke muscle), overaction of the right inferior oblique (ipsilateral antagonist), and underaction of the left superior rectus (contralateral antagonist). The presence of all muscle sequelae suggests a long-standing palsy.