Unilateral Pontine Syndrome

    • Reduced ipsilateral gaze and other neurologic deficits caused by a unilateral pontine lesion
    • Common causes: pontine stroke, hemorrhage, demyelination, cavernous malformation (“cavernoma”)
    • Uncommon causes: pontine tumor, osmotic demyelination (“myelinolysis”)
    • Core neuro-ophthalmic features
      • Slow or absent ipsilateral horizontal gaze
      • Doll’s eye maneuver does not elicit greater gaze amplitude than do saccades and pursuit
      • Trap: a gaze paresis may not be evident with pursuit, so you must test saccades
      • Intact vertical gaze and pupil constriction
      • Sixth nerve palsy
      • Internuclear ophthalmoplegia
    • Possible accompanying neuro-ophthalmic features
      • Lower motor neuron seventh nerve palsy
      • Exotropia (“pontine exotropia”)
      • Esotropia (from sixth nerve palsy)
      • Skew deviation
      • Gaze-evoked horizontal or upbeat nystagmus
      • Saccadic pursuit
      • Contralateral gaze deviation
      • Tip: various deficits may be seen in combination:
        • Unilateral gaze palsy + ipsilateral internuclear ophthalmoplegia (“1.5 syndrome”)
        • Unilateral gaze palsy + ipsilateral sixth palsy, creating esotropia in primary gaze position
        • Unilateral gaze palsy + ipsilateral internuclear ophthalmoplegia + ipsilateral lower motor facial palsy (“8.5 syndrome”)
        • Unilateral gaze palsy + ipsilateral internuclear ophthalmoplegia + skew deviation, creating hypotropia in primary gaze position
    • Possible accompanying neurologic features
      • Ataxia
      • Contralateral hemiparesis
    • MRI often shows the lesion
    • Myasthenia gravis
    • Fisher variant of Guillain-Barré syndrome
    • Wernicke encephalopathy
    • Frontoparietal stroke or hemorrhage
    • Localize the lesion to the pons by noting that the Doll’s eye maneuver does not overcome a volitional gaze paresis
    • Exclude myasthenia gravis, Fisher variant of Guillain-Barré syndrome, Wernicke encephalopathy, frontoparietal stroke/hemorrhage (frontoparietal stroke/hemorrhage causes contralateral neglect and contralateral hemiparesis)
    • Order brain MRI
    • Trap: MRI may not reveal the lesion, especially in acute demyelination
    • Depends on the cause
    • Ocular motor manifestations may improve
    • Other neurologic deficits tend to endure

    Brainstem Ocular Motor Disorders

    Internuclear Ophthalmoplegia Skew Deviation Dorsal Midbrain Syndrome Thalamic or Tegmental Midbrain Syndrome Unilateral Pontine Syndrome Bilateral Pontine Syndrome Dorsolateral Medullary (Wallenberg) Syndrome Ototoxic Vestibulo-ocular Dysfunction Syndrome Acute Upgaze Deviation Acute Downgaze Deviation Acute Comitant Esotropia Omnidirectional Slow Saccades Omnidirectional Saccadic Pursuit