Physical examination maneuver

Physical Exam

Alternate Cover Test

also known as Cross-cover test, Test of skew
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How to Perform

Ask the patient to fixate on a target. Cover one eye, then move the hand across to the other eye, and repeat back and forth, pausing briefly on each eye; watch the just-uncovered eye for any movement to take up fixation. A refixation movement indicates an ocular deviation, and a vertical movement can indicate a skew deviation.

How to Interpret

Showing 3 of 5 findings

Skew Deviation

Upright-supine test positive
Rule in
Very helpfulDerived CI
Rule out
HelpfulDerived CI
Evidence:Moderate

Stroke

HINTS exam concerning (central pattern) in a patient with acute vestibular syndrome
Rule in
Helpful
Rule out
Very helpful
Evidence:Strong

Vestibular Dysfunction

HINTS exam reassuring (peripheral pattern) in a patient with acute vestibular syndrome
Rule in
Very helpfulDerived CI
Rule out
Very helpfulDerived CI
Evidence:Moderate

Related Bedside Tests

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Rule in:VHStroke, SHHyperthyroidism, SHMyasthenia Gravis +9 more
Rule out:HMyasthenia Gravis, SHHyperthyroidism, NHOrbital Fracture +9 more
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aka Head thrust test; Halmagyi test
Rule in:VHVestibular Dysfunction, HStroke
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Rule in:VHVestibular Dysfunction, HStroke
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Rule in:VHStroke, VHVestibular Dysfunction
Rule out:VHStroke, VHVestibular Dysfunction
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Related Systems / Regions

Head, Eyes, Ears, Nose, ThroatNeurological

Related Diagnoses

HeterophoriaSkew DeviationStrokeVestibular Dysfunction

Related Chief Complaints

Balance ProblemsConfusionDifficulty SpeakingDifficulty WalkingDizzinessDouble VisionFacial DroopHeadacheNausea and VomitingNumbness on One SideSlurred SpeechSpinning SensationSudden Vision LossUnsteady GaitVertigoVision ChangesWeakness on One Side

References

  • Newman-Toker DE, Kerber KA, Hsieh YH, Pula JH, Omron R, Saber Tehrani AS, et al. HINTS outperforms ABCD2 to screen for stroke in acute continuous vertigo and dizziness. Acad Emerg Med. 2013;20(10):986-996. doi:10.1111/acem.12223. PMID: 24127701.
  • Ooi S, Phillips G, Tang T, Chen L, Fok A, Ly J, Ma H, Phan TG. Meta-Analysis of the Use of Head Impulse Test and Head Impulse Test with Direction Changing Nystagmus and Test of Skew Deviation in the Diagnosis of Peripheral Vertigo and Stroke. Cerebrovasc Dis. 2023;52(2):184-193. doi:10.1159/000526331. PMID: 36088909.
  • Tao WD, Liu M, Fisher M, et al. Posterior versus anterior circulation infarction: how different are the neurological deficits? Stroke. 2012;43(8):2060-2065. PMID: 22678088.
  • Wong AMF, Colpa L, Chandrakumar M. Ability of an upright-supine test to differentiate skew deviation from other vertical strabismus causes. Arch Ophthalmol. 2011;129(12):1570-1575. PMID: 22159676.
  • Holmes JM, Chandler DL, Christiansen SP, Birch EE, Bothun E, Laby D, Melia BM, Repka MX, Silbert DI, Zeto VL. Interobserver reliability of the prism and alternate cover test in children with esotropia. Arch Ophthalmol. 2009;127(1):59-65. doi:10.1001/archophthalmol.2008.548. PMID: 19139339.
  • Gottlieb M, Peksa GD, Carlson JN. Head impulse, nystagmus, and test of skew examination for diagnosing central causes of acute vestibular syndrome. Cochrane Database Syst Rev. 2023 Nov 2;11(11):CD015089. doi:10.1002/14651858.CD015089.pub2. PMID 37916744. PMC10620998.
  • Tao WD, Liu M, Fisher M, et al. Posterior versus anterior circulation infarction: how different are the neurologic deficits? Stroke. 2012;43(8):2060-2065. PMID: 22678088.

Research last updated September 9, 2026.