Neurology · MU Sofia

31. Syndromes of the brainstem

Covers the anatomy of the brainstem and the crossed syndromes that follow a lesion there, with ipsilateral cranial nerve deficits and contralateral motor or sensory loss. It then goes through midbrain syndromes (Weber), pontine syndromes (Millard-Gubler and locked-in) and medullary syndromes (lateral and medial), listing the lesion site, cause and features of each. A closing section summarises cranial nerve, long tract and cerebellar signs.

Inside: 1 section · 15 flashcards · 2 min

Topic 31 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 1 section, about 268 words (2 min of reading), with 15 flashcards.

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  1. Syndromes of the brainstem

Syndromes of the brainstem

Anatomy

The brainstem consists of: Midbrain. Pons. Medulla oblongata

It contains: Cranial nerve nuclei (III–XII). Ascending sensory pathways. Descending motor pathways. Reticular formation

A brainstem lesion typically produces "crossed (alternating) syndromes":

  • Ipsilateral cranial nerve deficits
  • Contralateral motor and/or sensory deficits

Midbrain Syndromes

Weber Syndrome: rare midbrain stroke syndrome that causes paralysis on one side of the body (contralateral hemiplegia) and eye movement issues on the opposite side (ipsilateral third cranial nerve palsy).

Lesion: Oculomotor nerve (CN III). Cerebral peduncle

Features

  • Ipsilateral: CN III palsy (ptosis, mydriasis, eye down and out)
  • Contralateral: Hemiparesis/hemiplegia.

Pontine Syndromes

1.Millard-Gubler Syndrome: a rare crossed-brainstem disorder caused by a unilateral lesion in the basal portion of the lower pons

Lesion: CN VI. CN VII. Corticospinal tract

Features

  • Ipsilateral: Facial paralysis (CN VII). Lateral rectus palsy (CN VI)
  • Contralateral: Hemiparesis

2.Locked-in Syndrome is a rare neurological disorder where a patient is fully conscious, awake, and cognitively intact, but suffers complete paralysis of all voluntary muscles except for vertical eye movements and blinking

Cause: Bilateral lesion of ventral pons.

Features: Quadriplegia. Anarthria (cannot speak). Consciousness preserved. Vertical eye movements preserved

Medullary Syndromes

1.Lateral Medullary Syndrome (Wallenberg Syndrome):

Cause: Occlusion of the PICA (Posterior Inferior Cerebellar Artery)

Features

  • Ipsilateral: Facial pain and temperature loss. Ataxia. Horner syndrome. Dysphagia, dysarthria, hoarseness (CN IX, X)
  • Contralateral: Loss of pain and temperature sensation from body

2.Medial Medullary Syndrome:

Features

  • Contralateral: Hemiparesis. Loss of vibration/proprioception
  • Ipsilateral: Hypoglossal nerve palsy (tongue deviates toward lesion)

General Brainstem Findings

  • Cranial Nerve Signs: Diplopia. Facial weakness. Dysphagia. Dysarthria. Tongue weakness
  • Long Tract Signs: Contralateral hemiparesis. Sensory deficits. Hyperreflexia. Babinski sign
  • Cerebellar Signs: Ataxia. Nystagmus. Incoordination

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