Brainstem Syndromes

Brainstem Syndromes 2018-01-30T16:37:19+00:00

Brainstem Anatomy

  • The brainstem is divided transversely into the midbrain, pons and medulla
  • All the cranial nerve nuclei save I and II lie in the brainstem
  • Midbrain:
    • III (oculomotor)
    • Pre-tectal and Edinger-Westphal nucleus (consensual light reflex)
      • II → pre-tectal nucleus → projections to bilateral Edinger-Westphal nuclei (parasympathetic nuclei of III) → ciliary ganglion → pupil constriction
    • IV (trochlear), the only cranial nerve which decussates
  • Pons
    • V (trigeminal)
    • VI (abducens)
    • VII (facial)
    • VIII (vestibulocochlear)
  • Medulla
    • IX (glossopharyngeal)
    • X (vagus)
    • XI (spinal accessory)
    • XII (hypoglossal)
  • The midline structures of the brainstem are:
    • Motor (pure) nuclei: III, IV, VI and XII
    • Medial longitudinal fasciculus
    • Motor (corticospinal) tract, which decussates in the lower medulla
    • Medial lemniscus (proprioception and vibration), which decussates in the middle medulla
  • The lateral structures of the brainstem are:
    • Sensory nucleus of Vth nerve
    • Spinothalamic tract (pain and temperature, decussates immediately in lower cord)
    • Spinocerebellar tract (proprioception from limbs to cerebellum), ipsilateral (does not cross)
    • Sympathetic pathway, ipsilateral

Midbrain Syndromes

  • Weber’s syndrome
    • Ipsilateral third nerve palsy
    • Contralateral hemiparesis (involvement of cerebral peduncle containing corticospinal fibres which decussate in the medulla)
  • Benedikt’s syndrome (posterior cerebral artery)
    • Ipsilateral third nerve palsy
    • Contralateral chorea, athetosis, tremor or cerebellar ataxia (involvement of the red nucleus which receives projections from the contralateral hemisphere and projects to the ipsilateral cerebellum)
  • Claude’s syndrome (posterior cerebral artery)
    • Ipsilateral third nerve palsy
    • Contralateral ataxia (involvement of the superior cerebellar peduncle)
  • Parinaud’s syndrome
    • Typically caused by tumours of the pineal gland
    • Compress on the vertical gaze centre, resulting in vertical gaze palsy
    • Vertical Doll’s not affected as the lesion is supra-nuclear
    • Irregular pupils
    • Eyelid retraction
    • Convergence nystagmus on upward gaze
    • Loss of accommodation

Pontine Syndromes

  • Raymond’s syndrome
    • Ipsilateral sixth nerve palsy
    • Contralateral hemiparesis (corticospinal tract which decussates in medulla)
  • Millar-Gubler’s syndrome
    • Ipsilateral abducens nerve palsy
    • Ipsilateral facial nerve palsy with loss of corneal reflex
    • Contralateral hemiparesis
    • ± contralateral loss of vibration / proprioception
  • Lateral pontine syndrome (anterior inferior cerebellar artery)
    • Ipsilateral loss of pain and temperature from face (sensory trigeminal)
    • Loss of ipsilateral corneal reflex (sensory trigeminal)
    • Contralateral loss of pain and temperature from limbs (spinothalamic tract)
    • Ipsilateral lower motor neuron facial weakness (course of nerve)
    • Ipsilateral sensorineural hearing loss (vestibulocochlear nerve)
    • Ipsilateral Horner’s syndrome (descending sympathetic pathway)
  • One-and-a-half syndrome
    • Conjugate horizontal gaze palsy in one direction (involvement of ipsilateral abducens)
    • Internuclear ophthalmoplegia in the other eye
  • Bilateral lesion (locked-in syndrome)
    • Quadriplegia
    • Aphonia
    • Bilateral facial and abducens nerve palsy
    • Spares oculomotor and trochlear nerves (lesion below midbrain)

Medullary Syndromes

  • Medial medullary syndrome (Dejerine’s syndrome – distal vertebral artery / proximal anterior spinal artery)
    • Spares face
    • Ipsilateral tongue weakness (tongue deviates towards side of lesion)
    • Contralateral hemiparesis (may be variable depending on location of lesion in relation to decussating corticospinal tract fibres)
    • Contralateral loss of vibration / proprioception
    • Pain and temperature from limbs not affected
  • Lateral medullary syndrome (Wallenberg’s syndrome – vertebral artery / posterior inferior cerebellar artery)
    • Ipsilateral ataxia (spinocerebellar tract and inferior cerebellar peduncle)
    • Ipsilateral loss of pain and temperature sensation in face (spinothalamic tract of trigeminal nerve)
    • Contralateral loss of pain and temperature sensation from limbs (spinothalamic tract)
    • Ipsilateral Horner’s syndrome (sympathetic fibres)
    • Ipsilateral reduced gag reflex (vagus nerve)
    • Dysphagia, dysarthria (bulbar palsy)

Differential Diagnosis of Brainstem Syndromes

  • Vascular (ischaemic / haemorrhagic stroke)
  • Inflammatory (e.g. demyelination in multiple sclerosis, acute disseminated encephalomyelitis)
  • Brainstem encephalitis (Bickerstaff’s encephalitis)
  • Central pontine myelinolysis
  • Trauma
  • Neoplastic (brainstem gliomas / ependymomas)
  • Arnold-Chiari malformation
  • Syringobulbia

Brainstem Syndromes

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