Lateral medullary syndrome

Lateral medullary syndrome, also known as Wallenberg syndrome, is a clinical syndrome caused by an acute ischemic infarct of the lateral medulla oblongata. This is most commonly due to occlusion of the intracranial portion of the vertebral artery followed by PICA and its branches 1-3

20% of ischemic strokes occur in the posterior circulation 5. Lateral medullary syndrome is the most prevalent posterior ischemic stroke syndrome 5.

Hypertension is the commonest risk factor followed by smoking and diabetes mellitus 5.

This syndrome is characterized by:

  • vestibulocerebellar symptoms: vertigo, falling towards the side of lesion, diplopia, and multidirectional nystagmus (inferior cerebellar peduncle and vestibular nucleus1-3
  • autonomic dysfunction: ipsilateral Horner syndromehiccups 1-3
  • sensory symptoms: initially abnormal stabbing pain over the ipsilateral face then loss of pain and temperature sensation over the contralateral side of body (spinal trigeminal nucleus involvement) 1-3
  • ipsilateral bulbar muscle weakness: hoarseness, dysphonia, dysphagia, and dysarthria, decreased gag reflex (nucleus ambiguus1-3

Lateral medullary syndrome is caused most commonly by:

  • atherothrombotic occlusion of the vertebral artery, the posterior inferior cerebellar artery, or the medullary arteries
  • cerebral embolism
  • vertebral artery dissection, the commonest cause in young patients

MRI with DWI is the best diagnostic test to confirm the infarct in the lateral medulla 6. The infarcted area has high DWI signal and is low signal on ADC 6.

The syndrome was first described by Adolf Wallenberg (1862-1949), a German physician, in 1895 4.

Stroke and intracranial haemorrhage
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Article information

rID: 12193
Section: Syndromes
Synonyms or Alternate Spellings:
  • Wallenberg syndrome
  • Wallenberg's syndrome
  • Lateral medullary syndrome

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Cases and figures

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  • Case 4: on left with supratentorial tumor
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  • Case 6: on left
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  • Case 7: on right
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  • Case 8: on left with VA dissection
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  • Case 9: on right
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  • Case 10
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