Brainstem Flashcards
Medulla
Blood Supply
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)
Pons
Blood Supply
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
Midbrain
Blood Supply
Medial region ⟾ paramedian branches of basilar artery
Lateral region ⟾ posterior cerebral artery (PCA)
Dorsal midbrain and dorsal rostral pons ⟾ superior cerebellar artery (SCA)
Cranial Nerve
Signs
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
Long Tract Signs
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.
Medial Medullary Syndrome
(Dejerine’s)
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
Lateral Medullary Syndrome
(Wallenberg’s)
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
Medial Pontine Syndrome
Basal Pons Infarc Only
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
Medial Pontine Syndrome
Basal Pons + Tegmentum Infarct
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
Lateral Caudal Pontine Syndrome
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
Lateral Mid-Rostral Pontine
Syndrome
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
Basal Midbrain Syndrome
(Weber’s)
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
- somatic and parasympathetic motor fibers ➡ 3rd nerve palsy
Tegmentum + Basal Midbrain Syndrome
(Benedikt’s)
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
