Skew Deviation: Case Report and Review of the Literature

To present a patient with a sudden onset ocular tilt reaction (OTR) and review recent knowledge and evolving insights of the underlying pathophysiological mechanisms of skew deviation and OTR.

A middle-aged hypertensive man who had previously suffered stroke with good recovery presented with sudden-onset double vision, slurred speech, ataxia, and a head tilt. Romberg test was positive. The patient denied having disturbances of visual acuity, eye pain, or recent trauma. The right eyeball was pushed upward. The patient complained of double vision in any gaze direction. Movements of the extraocular muscles (EOMs) in the horizontal plane were normal, whereas vertical version and convergence were not possible. We administered a Hess-Lancaster test, cover test, fundoscopic examination, Parks-Bielschowsky three-step test, upright-supine test, brain magnetic resonance imaging (MRI), transcranial doppler (TCD) ultrasonography, electrocardiogram (ECG), Holter monitor (24 h), and echocardiography.

The Hess-Lancaster test showed superior rectus muscle and inferior obliquus muscle palsy to the left and rectus inferior muscle and superior obliquus muscle palsy to the right. The right eyeball fell behind when looking downward and the left eyeball when looking upward. Cover alternating test was positive from vertical, R/L. Examination of the ocular fundus showed incyclotorsion of elevated right eye and excyclotorsion of depressed eye. The Parks-Bielschowsky three-step test was negative. A brain MRI with gadolinium revealed a small zone of diffusion restriction in the medial portion of the right cerebral peduncle and right thalamus. There was a gradual improvement in the patient's neurological status following treatment.

Skew deviation, a not uncommon clinical condition, should be promptly recognized when binocular vertical diplopia cannot be interpreted by trochlearis and oculomotor nerve lesion, myasthenia gravis, or orbital pathology. Maddox rod, cover test, Parks-Bielschowsky three-step, and other tests should help to establish the diagnosis. The prognosis depends on etiology, but it is commonly favorable; the majority of patients recover spontaneously after less than a year. More invasive management options should be discussed thereafter.