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Brainstem Infarction

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This causes complex signs depending on the relationship of the infarct to cranial nerve nuclei, long tracts and brainstem connections.

  • The lateral medullary syndrome
  • The medial medullary syndrome
  • Pontine hemorrhage
  • Pseudobulbar palsy


Features of Brainstem Infarction

Clinical feature Structure involved
Hemiparesis or tetraparesis Corticospinal tracts
Sensory loss Medial lemniscus and spinothalamic tracts
Diplopia Oculomotor system
Facial numbness Vth nerve nuclei
Facial weakness VIIth nerve nucleus
Nystagmus,vertigo Vestibular connections
Dysphagia,Disarthria IXth and Xth nerve nuclei
Dysarthria, ataxia, hiccups, vomiting Brainstem and cerebellar connections
Horner’s syndrome Sympathetic fibres
Coma, altered consciousness Reticular formation


Lateral medullary syndrome

(posterior inferior cerebellar artery (PICA) thrombosis and Wallenberg’s syndrome) is a common example of brainstem infarction presenting as acute vertigo with cerebellar and  other signs ,It follows thromboembolism in the PICA or its branches, vertebral artery thromboembolism or dissection. Features depend on the precise structures damaged.


Clinical feature Affected site
Dysphagia Nucleus ambiguous
Vertigo, nystagmus Vestibular nuclei
Ipsilateral loss of pain and temperature sensation of face Trigeminal (V) spinal nucleus
Cerebellar signs Inferior cerebellar peduncle
Contralateral loss of pain and temperature sensation of the body Spinal lemniscus


Medial Medullary Syndrom

Occlusion of medullary branches of Vertebral Artery causes the signs and symptoms of medial medullary syndrome



Clinical feature Affected site
Contralateral hemiparesis Corticospinal tracts
Contralateral loss of discriminative touch, vibration sensation Medial leminiscus
Hypoglossal nerve palsy Hypoglossal nerve


Pseudobulbar palsy

Pseudobulbar palsy Describes bilateral supranuclear  (UMN)  lesions  of  lower cranial  nerves  producing  weakness  of  the  tongue  and  pharyngeal  muscles.  This  resembles,  superficially,  a  bulbar palsy,  hence  pseudobulbar.  Findings  are  a  stiff,  slow,  spastic tongue  (not  wasted),  dysarthria  and  dysphagia.  Gag  and palatal  reflexes  are  preserved  and  the  jaw  jerk is exaggerated. Emotional  lability  (inappropriate  laughing  or  crying)  often accompanies  pseudobulbar  palsy.

Principal  causes

  • Motor neuron disease  –  often  both  UMN  and  LMN lesions  (i.e.  elements  of  both  pseudobulbar  and  bulbar palsy)
  • Cerebrovascular disease, typically  following  multiple infarcts
  • Neurodegenerative disorders such  as  progressive supranuclear  palsy
  • Severe traumatic brain  injury
  • MS, mainly as  a  late  event

Difficulty  swallowing,  dysarthria  and  drooling  also  develop in  later  stages  of  Parkinson’s  disease.


Pontine hemorrhage


Clinical features:

  • Contralateral hemiplegia
  • Contralateral hemisensory loss
  • Loss of light touch sensation of face
  • Weakness of jaw muscles
  • Ipsilateral Lower motor neuron facial nerve palsy
  • Abducent nerve palsy
  • Hearing impairment, nystagmus
  • Pinpoint pupils

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Categorised in: Medicine, Neurology, Neurosurgery

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