Dorsolateral Medullary (Wallenberg) Syndrome

    • Constellation of neuro-ophthalmic and neurologic manifestations caused by a unilateral lesion of the dorsolateral medulla
    • Common cause: thrombosis or dissection of the ipsilateral vertebral artery with secondary occlusion of the ipsilateral posterior inferior cerebellar artery
    • Core neuro-ophthalmic features
      • Vertical misalignment of the eyes (skew deviation) with the lower eye ipsilateral to the lesion
      • Ipsilateral ptosis and miosis (Horner syndrome)
      • Torsional nystagmus
      • When the lids are closed, the eyes deviate toward the side of the lesion (“lateropulsion”)
    • Possible accompanying neurologic features
      • Ipsilateral extremity and gait ataxia
      • Nausea and vomiting
      • Hoarseness, swallowing difficulty, intractable hiccups
      • Ipsilateral facial numbness (trigeminal hypesthesia)
      • Contralateral extremity numbness (spinothalamic hypesthesia)
      • Ataxia
    • Imaging features
      • Restricted diffusion in the dorsolateral medulla
        and/or inferolateral cerebellar hemisphere
      • Blood in the wall of the vertebral artery
      • Narrowing or occlusion of the ipsilateral vertebral artery
    • If other neurologic deficits are present, diagnose a cerebellar or more rostral brainstem lesion, or multiple lesions
    • Look for the following combination of signs as unique to Wallenberg syndrome
      • Skew deviation
      • Horner syndrome
      • Nystagmus
      • Ataxia
      • Difficulty swallowing
      • Intractable hiccups (singultus)
      • Numbness (hypesthesia) on the ipsilateral face and contralateral extremities
    • Tip: order immediate brain CT/CTA (and MRI/MRA if CT/CTA is unrevealing) to rule out vertebral artery dissection, cerebellar infarction, or cerebellar hemorrhage, because cerebellar swelling could threaten medullary function, warranting emergency neurosurgical decompression to prevent death
    • Monitor intensively for the first 48 hours for declining brainstem function
    • Tip: anticoagulation has not been shown to be superior to aspirin in preventing further stroke
    • Consider these other interventions
      • Prism or ocular occlusion for palliation of diplopia
      • Medicinal palliation of vertigo, intractable nausea and vomiting, hiccups
      • Nasogastric intubation for swallowing difficulty and to prevent aspiration
      • Physical therapy for ataxia
    • Substantial recovery usually occurs, but may be delayed for months
    • Tip: marked clinical manifestations and cerebellar involvement on MRI are associated with early clinical decline and a longer duration of deficits
    • Nausea, vertigo, hiccups may be severe for weeks
    • Diplopia, Horner syndrome, and ataxia often endure indefinitely

    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