Brainstem Leisions | Anatomy2Medicine
brainstem lesions

Brainstem Leisions

Lesions of the Brainstem

    • most frequently syndromes of arterial occlusion or circulatory insufficiency that involve the vertebrobasilar system.

 

  • Vascular Lesions of the Medulla

 

      • result from occlusion of the vertebral artery or its branches

 

  • anterior and posterior spinal arteries
  • posterior inferior cerebellar artery [PICA]).
  • Medial medullary syndrome

 

      • results from occlusion of the anterior spinal artery.
      • affected structures and resultant deficits

 

  • Corticospinal tract

 

          • contralateral hemiparesis of the trunk and extremities

 

  • Medial lemniscus

 

          • contralateral loss of proprioception, discriminative tactile sensation, and vibration sensation from the trunk and extremities

 

  • Hypoglossal nerve roots (intra-axial fibers)

 

          • ipsilateral flaccid paralysis of the tongue

 

  • Lateral medullary syndrome (PICA syndrome)

 

      • is also called Wallenberg syndrome.

 

  • results from occlusion of the vertebral artery or one of its medullary branches (e.g., PICA).

 

      • affected structures and resultant deficits:

 

  • Vestibular nuclei (medial and inferior)

 

          • nystagmus, nausea, vomiting, and vertigo

 

  • Inferior cerebellar peduncle

 

          • ipsilateral cerebellar signs (dystaxia, dysmetria, dysdiadochokinesia)

 

  • Nucleus ambiguus of cranial nerve (CN) IX, CN X, and CN XI (somatic visceral efferent [SVE])

 

          • ipsilateral laryngeal, pharyngeal, and palatal paralysis (loss of the gag reflex [efferent
          • limb], dysarthria, dysphagia, and dysphonia [hoarseness])

 

  • Glossopharyngeal nerve roots (intra-axial fibers)
  • loss of the gag reflex (afferent limb)
  • Vagal nerve roots (intra-axial fibers)

 

          • neurologic deficits same as those seen in lesion of the nucleus ambiguus

 

  • Spinothalamic tracts

 

          • contralateral loss of pain and temperature sensation from the trunk and extremities

 

  • Spinal trigeminal nucleus and tract

 

          • ipsilateral loss of pain and temperature sensation from the face

 

  • Descending sympathetic tract

 

          • ipsilateral Horner syndrome (ptosis, miosis, hemianhidrosis, vasodilation, and apparent enophthalmos)

 

  • Vascular Lesions of the Pons
  • result from occlusion of the basilar artery or its branches
  • anterior inferior cerebellar artery [AICA]
  • transverse pontine arteries
  • superior cerebellar artery
  • Medial inferior pontine syndrome
  • results from occlusion of the paramedian branches of the basilar artery.

 

      • affected structures and resultant deficits:

 

  • Abducent nerve roots (intra-axial fibers)

 

          • ipsilateral lateral rectus paralysis

 

  • Corticobulbar tracts

 

          • contralateral weakness of the lower face

 

  • Corticospinal tracts

 

          • contralateral hemiparesis of the trunk and extremities

 

  • Base of the pons (middle cerebellar peduncle)

 

          • ipsilateral limb and gait ataxia

 

  • Medial lemniscus

 

          • contralateral loss of proprioception, discriminative tactile sensation, and vibration sensation from the trunk and extremities
    • Lateral inferior pontine syndrome (AICA syndrome)
      • results from occlusion of a long circumferential branch of the basilar artery, AICA.
      • affected structures and resultant deficits

 

  • Facial nucleus and intra-axial nerve fibers

 

          • ipsilateral facial nerve paralysis

 

  • loss of taste from the anterior two-thirds of the tongue
  • loss of the corneal and stapedial reflexes
  • Cochlear nuclei and intra-axial nerve fibers

 

          • unilateral central nerve deafness

 

  • Vestibular nuclei and intra-axial nerve fibers
  • nystagmus, nausea, vomiting, and vertigo
  • Spinal trigeminal nucleus and tract

 

          • ipsilateral loss of pain and temperature sensation from the face

 

  • Middle and inferior cerebellar peduncles

 

          • ipsilateral limb and gait dystaxia

 

  • Spinothalamic tracts

 

          • contralateral loss of pain and temperature sensation from the trunk and extremities

 

  • Descending sympathetic tract

 

          • ipsilateral Horner syndrome (ptosis, miosis, hemianhidrosis, vasodilation, and apparent enophthalmos)

 

  • Lateral midpontine syndrome

 

      • results from occlusion of a short circumferential branch of the basilar artery.
      • affected structures and resultant deficits:

 

  • Trigeminal nuclei and nerve root (motor and principal sensory nuclei)

 

          • complete ipsilateral trigeminal paralysis, including:
          • Paralysis of the muscles of mastication

 

  • Jaw deviation to the paretic side (due to unopposed action of the intact lateral pterygoid muscle)

 

          • Facial hemianesthesia (pain, temperature, touch, and proprioception
          • Loss of the corneal reflex (afferent limb of CN V-1)
        • Middle cerebellar peduncle (base of the pons)
          • ipsilateral limb and gait dystaxia
    • Lateral superior pontine syndrome
      • results from occlusion of a long circumferential branch of the basilar artery, the superior cerebellar artery.
      • affected structures and resultant deficits:

 

  • Superior and middle cerebellar peduncles

 

          • ipsilateral limb and trunk dystaxia

 

  • Dentate nucleus
  • signs similar to those seen with damage to the superior cerebellar peduncle (dystaxia, dysmetria, and intention tremor)
  • Spinothalamic and trigeminothalamic tracts

 

          • contralateral loss of pain and temperature sensation from the trunk, extremities, and face

 

  • Descending sympathetic tract

 

          • ipsilateral Horner syndrome (ptosis, miosis, hemihidrosis, and apparent enophthalmos)

 

  • Medial lemniscus (lateral division [gracilis])

 

          • contralateral loss of proprioception, discriminative tactile sensation, and vibration sensation from the trunk and lower extremity
    • Locked-in syndrome (pseudocoma)
      • results from infarction of the base of the superior pons
      • infarcted structures include the corticobulbar and corticospinal tracts,
      • results in quadriplegia and paralysis of the lower cranial nerves.
      • also may result from central pontine myelinolysis.

 

  • Communication occurs only by blinking or moving the eyes vertically

 

 

 

  • Lesions of the Midbrain

 

      • result from
        • vascular occlusion of the mesencephalic branches of the posterior cerebral artery
        • aneurysms of the posterior circle of Willis.
        • tumors of the pineal region.

 

  • hydrocephalus.

 

    • Dorsal midbrain (Parinaud) syndrome
      • is frequently the result of a pinealoma or germinoma of the pineal region.
      • affected structures and resultant deficits:

 

  • Superior colliculus and pretectal area

 

          • paralysis of upward and downward gaze
          • pupillary disturbances
          • absence of convergence

 

  • Cerebral aqueduct

 

          • noncommunicating hydrocephalus
          • occur as a result of compression from a pineal tumor
    • Paramedian midbrain (Benedikt) syndrome

 

  • results from occlusion or hemorrhage of the paramedian midbrain branches of the posterior cerebral artery.

 

      • affected structures and resultant deficits:

 

  • Oculomotor nerve roots (intra-axial fibers)
  • complete ipsilateral oculomotor nerve paralysis
  • eye abduction and depression because of the unopposed action of the lateral rectus (CN VI) and the superior oblique (CN IV) muscles

 

          • severe ptosis (paralysis of the levator palpebrae muscle)
          • ipsilateral fixed and dilated pupil (complete internal ophthalmoplegia)

 

  • Red nucleus and dentatorubrothalamic tract

 

          • contralateral cerebellar dystaxia with intention tremor

 

  • Medial lemniscus

 

          • contralateral loss of proprioception, discriminative tactile sensation, and vibration sensation from trunk and extremities
    • Medial midbrain (Weber) syndrome
      • results from
        • occlusion of midbrain branches of the posterior cerebral artery
        • aneurysms of the circle of Willis.
      • Associated structures and resultant deficits:
        • Oculomotor nerve roots (intra-axial fibers)

 

  • Corticobulbar tracts

 

          • contralateral weakness of the lower face (CN VII), tongue (CN XII), and palate (CN Corticospinal tracts
          • contralateral hemiparesis of the trunk and extremities
    • Internuclear Ophthalmoplegia (INO)
      • is also known as medial longitudinal fasciculus (MLF) syndrome, which results from a lesion of the MLF.
      • Lesions occur in the dorsomedial pontine tegmentum
      • may affect one or both MLFs.

 

  • is a frequent sign of multiple sclerosis.

 

      • results in medial rectus palsy on attempted lateral gaze and monocular nystagmus in the abducting eye with normal convergence.

 

  • Jugular Foramen (Vernet) Syndrome

 

    • affects CN IX, CN X, and CN XI.
    • affected structures and resultant deficits:
      • Glossopharyngeal nerve (CN IX)
        • loss of the gag reflex (afferent limb)
        • loss of taste sensation in the posterior third of the tongue
        • unilateral loss of the carotid sinus reflex
      • Vagal nerve (CN X)
        • laryngeal paralysis with dysarthria, dysphagia, and dysphonia (hoarseness)
        • palatal paralysis with loss of the gag reflex (efferent limb)
      • Accessory nerve (CN XI)

 

  • weakness of the sternocleidomastoid and upper trapezius muscles (the shoulder droops)