Brainstem

Question 1

Medulla

Blood Supply

Answer 1

Medial region:

caudal ⟾ paramedial branches of anterior spinal artery

rostral ⟾ vertebral artery

Lateral region:

caudal ⟾ lateral branches of vertebral artery

rostral ⟾ posterior inferior cerebellar artery (PICA)

Question 2

Pons

Blood Supply

Answer 2

Medial region ⟾ paramedian branches of basilar artery

Lateral caudal region ⟾ anterior inferior cerebellar artery (AICA)

Lateral mid and rostral region ⟾ circumferential branches of basilar artery

Question 3

Midbrain

Blood Supply

Answer 3

Medial region ⟾ paramedian branches of basilar artery

Lateral region ⟾ posterior cerebral artery (PCA)

Dorsal midbrain and dorsal rostral pons ⟾ superior cerebellar artery (SCA)

Question 4

Cranial Nerve

Signs

Answer 4

Most ipsilateral to the lesion.

Good indication lesion location within brainstem.

Hypoglossal, vagus, or glossopharyngeal signs ⟾ medulla

Abducens, facial, or vestibulocochlear signs ⟾ caudal pons

Trigeminal nerve sign ⟾ mid-rostral pons

Trochlear or oculomotor signs ⟾ midbrain

Question 5

Long Tract Signs

Answer 5

Most contralateral to lesion.

Including medial lemniscus, STT, corticospinal tract, or corticobulbar tract.

Sx of lesion to descending sympathetic fibers are ipsilateral.

Provides little information about rostrocaudal level of the lesion.

Question 6

Medial Medullary Syndrome

(Dejerine’s)

Answer 6

Paramedian branches of anterior spinal artery caudally and vertebral arteries rostrally.

Long tract signs:

corticospinal tract and corticobulbar tract of pyramid ➡ contralateral spastic hemiparesis

medial lemniscus ➡ contralateral loss of fine touch and proprioception sensation from the body

Cranial nerve signs:

hypoglossal nerve/nucleus ➡ ipsilateral deviation of the tongue, dysarthria, fasciculations and atrophy

Question 7

Lateral Medullary Syndrome

(Wallenberg’s)

Answer 7

Posterior inferior cerebellar artery (PICA).

Long tract signs:

• anterolateral system ➡ contralateral loss of pain and temperature sensation from the body
• descending sympathetic fibers ➡ ipsilateral ptosis, miosis, anhidrosis (Horner’s syndrome)

Cranial nerve and other signs:

• cranial nerve IX and X, nucleus ambiguus ➡ dysphagia, hoarseness, and decreased gag reflex
• spinal nucleus and tract of V ➡ ipsilateral loss of pain from the face
• cochlear and vestibular nuclei ➡ vertigo, nystagmus, nausea, and ipsilateral sensoryneural loss of hearing
• solitari nucleus and tract ➡ ipsilateral loss of taste
• inferior cerebellar peduncle (ICP) ➡ ipsilateral ataxia

Question 8

Medial Pontine Syndrome

Basal Pons Infarc Only

Answer 8

Paramedian branches of basilar artery.

Long tract signs:

• corticospinal and corticobulbar tracts ➡ contralateral spastic hemiparesis

Cranial nerve and other signs:

• abducens nerve ➡ ipsilateral medial strabismus
• pontine nuclei and transverse pontine fibers ➡ contralateral ataxia

Question 9

Medial Pontine Syndrome

Basal Pons + Tegmentum Infarct

Answer 9

Paramedian branches of basilar artery.

Long tract signs:

• corticospinal and corticobulbar tracts ➡ contralateral spastic hemiparesis
• medial lemniscus ➡ contralateral loss of epicritic sensation

Cranial nerve and other signs:

• abducens nerve ➡ ipsilateral medial strabismus
• pontine nuclei and trasverse pontine fibers ➡ contralateral ataxia
• facial colliculus + facial motor fibers ➡ ipsilateral facial weakness and medial strabismus
• pontine nuclei and transverse pontine fibers ➡ contralateral ataxia
• paramedian pontine reticular formation (PPRF) and medial longitudinal fasciculus (MLF) ➡ ipsilateral horizontal gaze paralysis and internuclear ophthalmoplegia

Question 10

Lateral Caudal Pontine Syndrome

Answer 10

AICA or circumferential branches of the basilar artery.

Long tract signs:

• anterolateral system ➡ contralateral loss of pain/temp from body
• descending sympathetic fibers ➡ ipsilateral ptosis, miosis, and anhidrosis (Horner’s syndrome)

Cranial nerve and other signs:

• spinal nucleus and tract of V ➡ ipsilateral loss of pain and temp from face
• facial nerve/nucleus ➡ ipsilateral face weakness, dry eye, loss of taste in anterior 2/3 of tongue
• vestibulocochlear nerve/nuclei ➡ vertigo, nystagmus, and ipsilateral hearing loss
• middle cerebellar peduncle (MCP) ➡ ipsilateral ataxia

Question 11

Lateral Mid-Rostral Pontine

Syndrome

Answer 11

Circumferential branches of basilar artery.

Long tract signs:

• anterolateral system ➡ contralateral loss of pain and temperature sensation from body
• descending sympathetic fibers ➡ ipsilateral ptosis, miosis, anhidrosis (Horner’s syndrome)

Cranial nerve and other signs:

• trigeminal nerve/nuclei ➡
  
  • ipsilateral face hemianesthesia
  • weakness in muscles of mastication
  • jaw deviation towards lesion
  • diminished jaw reflex
  • loss of blink reflex
• middle cerebellar peduncle (MCP) ➡ ataxia

Question 12

Basal Midbrain Syndrome

(Weber’s)

Answer 12

Paramedian branches of basilar artery and posterior cerebral artery (PCA).

Long tract signs:

• corticospinal tract ➡ contralateral spastic hemiparesis
• corticobulbar tract ➡ contralateral lower face weakness​
  
  • drooping of the corner of the mouth

Cranial nerve and other signs:

• oculomotor nerve:
  
  • somatic and parasympathetic motor fibers ➡ 3rd nerve palsy
    
    • ipsilateral lateral strabismus
    • ptosis
    • dilated pupil
    • ophthalmoplegia
    • loss of accomodation
    • loss of pupillary reflex

Question 13

Tegmentum + Basal Midbrain Syndrome

(Benedikt’s)

Answer 13

Lateral paramedian branches of basilar artery and posterior cerebral arteries.

Long tract signs:

• corticospinal tract ➡ contralateral spastic hemiparesis
• corticobulbar tract ➡ contralateral lower face weakness, drooping of corner of the mouth
• superior cerebellar peduncle SCP and red nucleus ➡ contralateral ataxia, intention tremor, dysmetria
• medial lemniscus ➡ contralateral loss of fine touch and proprioception sensation from the body

Cranial nerve and other signs:

• oculomotor nerve/nucleus ➡ ipsilateral 3rd nerve palsy
  
  • ophthalmoplegia
  • lateral strabismus
  • ptosis
  • dilated pupil
  • loss of accomodation
  • loss of pupillary light reflex
• substantia nigra and basal ganglia ➡ involuntary movement