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Medial Medullary Syndrome

Summary

fleuron

  • Medial medullary syndrome (Dejerine syndrome) is a rare brainstem stroke syndrome caused by occlusion of paramedian branches of the anterior spinal artery or vertebral artery
  • Presents with contralateral hemiparesis sparing the face, contralateral loss of proprioception/vibration, and ipsilateral tongue weakness
  • MRI demonstrates acute infarction in the medial medulla, typically appearing as a unilateral paramedian lesion on DWI

Pathophysiology

  • Vascular territory involved:
    • Paramedian branches of the anterior spinal artery
    • Direct paramedian perforators from the vertebral artery
    • Occasionally from the lower basilar artery
  • Affected anatomical structures:
    • Medial lemniscus (contralateral proprioception/vibration loss)
    • Corticospinal tract/pyramid (contralateral hemiparesis)
    • Hypoglossal nerve fibres (ipsilateral tongue weakness)
  • Mechanism:
    • Atherothrombotic disease (most common)
    • Cardioembolism
    • Vertebral artery dissection

Diagnosis

  • Clinical presentation (classic triad):
    • Contralateral hemiparesis (sparing face)
    • Contralateral loss of proprioception and vibration sense
    • Ipsilateral tongue deviation and atrophy
  • Additional features may include:
    • Nystagmus (if lesion extends laterally)
    • Vertigo
    • Contralateral hemisensory loss (if medial lemniscus involved)
  • Differential diagnosis:
    • Lateral medullary syndrome (Wallenberg)
    • Pontine infarction
    • High cervical cord lesion
    • Multiple sclerosis

Imaging

  • CT:

    • Low sensitivity as expected for small infarcts in the posterior fossa (therefore potentially normal in the acute phase)

  • MRI:

    • DWI: restricted diffusion (hyperintense) in medial medulla, "heart-shaped" or triangular configuration
    • ADC: corresponding hypointense signal confirming restricted diffusion
    • T2: hyperintense signal in medial medulla, typically unilateral paramedian location
    • FLAIR: hyperintense signal, may be subtle in hyperacute phase

  • CTA/MRA:

    • Vertebral artery stenosis or occlusion
    • May appear normal if small perforator involvement

panels-1

  • A 60-year-old patient presented with acute onset left-sided arm and leg weakness and sensory disturbance.
  • The tongue was also deviated to the right side.
  • Imaging showed an infarct along the right paramedian medulla secondary to thrombus (red arrow) in the right V4 vertebral artery that impaired flow in the right PICA.

Differential diagnosis

Differential diagnosis Differentiating feature
Lateral medullary syndrome (Wallenberg) Infarction in the lateral medullary region (inferior cerebellar peduncle, nucleus ambiguus) rather than the medial medulla; may involve PICA territory
Multiple sclerosis Medullary plaque typically ovoid with periventricular and juxtacortical lesions elsewhere; no restricted diffusion acutely
Brainstem tumour Expansile mass with T2 signal abnormality and mass effect on the brainstem; enhancement on contrast-enhanced MRI