Brainstem and Cranial Nerves Part 2 Flashcards
Which blood vessels supply the medulla?
Blood supply to brainstem – medulla
- Vertebral arteries
- Anterior spinal artery
- Posterior spinal artery
- Posterior inferior cerebellar artery
- Anterior inferior cerebella artery
- Basal artery
See diagrams on lecture notes
Which blood vessels supply the pons?
- Basilar artery
o Paramedian branches – pontine arteries
o Anterior inferior cerebellar artery
o Superior cerebellar artery
See diagrams on lecture notes
Which vessels supply the midbrain?
- Basilar artery
o Superior cerebellar artery
o Posterior cerebral artery - Choroidal artery
What is the rule of 4 in the vascular lesions of the brainstem?
- Rule of 4
o 4 structures in the midline beginning with M
Motor pathways (CST), medial lemniscus, MLF, motor nucleus and nerve
o 4 structures to the side (lateral) beginning with S
SCT, STT, sensory nucleus of CN V , sympathetic pathway
o 4 cranial nerves in medulla, 4 in the pons and 4 above the pons
o 4 motor nuclei that are in the midline
Divide equally into 12 (3, 4, 6 and 12)
(5, 7, 9 and 11 are in lateral brainstem) - Medulla CNs = 9-12
- Pons CNs = 5-8
- Above pons CNs 1-4
See diagram on lecture notes for rule of 4 with deficit symptoms
What can you work out using the rule of 4?
- With this lets try and work out:
- What CNS structures are affected?
- Explain symptoms with regards to structures affected?
- Where is the lesion?
- Always remember
o Pathways and tracts pass through the entire length of the brainstem and can be likened to “meridians of longitude” whereas cranial nerves can be regarded as “parallels of latitude”
o If you establish where meridians of longitude and parallels of latitude intersect then you establish the site of the lesion
Deficits in which 4 CN above pons cause which deficits?
See diagram in lecture notes
You are presented with:
- 58 year old recent onset left hemiparesis
- Left-sided loss of proprioception
- Right-sided tongue deviation
What CNS structures are affected?
Explain symptoms with regards to structures affected.
Where is the lesion?
- What CNS structures are affected? o CST right side, Medial o Medial lemniscus right side, Medial o CN 12 right side, Medulla - Explain symptoms with regards to structures affected? o Medial medullary syndrome Right side o Vertebral artery medullary branch Right side - Where is the lesion? o Right side medulla See diagram in lecture notes to explain
You are presented with:
- 58 year old woman
- Right sided miosis, anhydrosis, ptosis (Horner’s Syndrome)
- Right sided ataxia
- Uvula deviated to left
- Analgesia and thermoanalgesia right side of face
What CNS structures are affected?
Explain symptoms with regards to structures affected.
Where is the lesion?
- What CNS structures are affected? o Sympathetic tract right side, side o Spinocerebellar tract right side, side o CN 10, right side, medulla o Sensation from CN V - Explain symptoms with regards to structures affected? o Lateral medullary syndrome right side o Posterior inferior cerebellar artery right side - Where is the lesion? o Medulla
See diagram in lecture notes to explain
You are presented with:
- 14 year old with:
- Left sided weakness
- Motor (CST) right side
- Right eye deviates medially
- Right sided facial weakness
What CNS structures are affected?
Explain symptoms with regards to structures affected.
Where is the lesion/tumour?
- Motor (CST) right side = medial
- Right eye deviates medially
o Lateral rectus weakness = CN 6 right side = Pons - Right sided facial weakness
o CN 7 right side = Pons - Where is the lesion?
o Medial Pons
o Pons tumour (Millard Gubler syndrome)
See diagram in notes
You are presented with: - 70 year old male history of hypertension suddenly develops: - Left sided ipsilateral opthalmoplegia o CN 3 left side (Medial) - Loss of pupillary light reflex in left eye o CN 3 left side (Medial) - Paralysis of right arm and leg o Motor CST left side (Medial)
What CNS structures are affected?
Explain symptoms with regards to structures affected.
Where is the lesion/tumour?
- Explain symptoms with regards to structures affected?
o Midbrain, occlusion of branch of posterior cerebral artery (paramedian branches at bifurcation) - Where is the lesion?
o Medial midbrain (Weber’s syndrome, midbrain stroke)
See diagram in notes
What is located in the posterior cranial fossa? What happens if it gets too full?
- Brainstem
- Cerebellum
- Occipital lobe of cerebrum
- Tentorium cerebelli separates cerebrum from cerebellum
- Falx separates cerebral hemispheres
- (If any more is put in the brain, it is likely to get squashed – causes raised intracranial pressure)
What can cause raised intercranial pressure? What are its symptoms?
- Haemorrhage
- Tumour
- Swelling of brain
- Berry Aneurysm (many people have these but only dangerous if they become very big)
Symptoms: headache, nausea, vomiting, bouts of unconsciousness = pressure on the brainstem (can compress ventricular system or cause herniations)
See lecture notes for graph
What is a berry aneurysm?
- Berry aneurysm— most have no symptoms unless rupture– enlarging ones can raise ICP —haemorrhage in subarachnoid space and sometimes in brain parenchyma
- Most common subfalcine and descending transtentorial herniation
- Rare are the transdural, transcranial herniation
How is a herniation of the brainstem caused?
- Uncus of temporal lobe pushed medially, hippocampus follows
o Both uncus and hippocampus herniate inferiorly through tentorial incisure
o Midbrain pushed towards opposite side
o CN III compressed
o PCA occlusion
See lecture notes for useful diagram
How can you safely check for raised intracranial pressure? What would this raised pressure be called?
o Check the eyes and the exit of the optic nerve specifically using an ophthalmoscope
o Eyes are an outgrowth of the brain
o Papilledema = raised pressure
See lecture notes for diagram
