BRAINSTEM LESION UNDERSTANING - WEEK 2ish

Question 1

What are the nuclei of all twelve cranial nerves? What are the cranial nerves names? Where in the brain are the nuclei located?

Answer 1

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Question 2

What are the two main groups of arteries that give blood supply to the brainstem? These are branches from the basilar and vertebral arteries

Answer 2

• Paramedian pontine arteries
• The trio of long circumfrential arteries:
  
  • Superior cerebellar artery
  • Anterior inferior cerebellar artery
  • Posterior inferior cerebellar artery

Question 3

And occlusion of these two groups of vessels (paramedian and long circumfrential arteries) results in two distinct types of brainstem syndrome: Median or lateral brainstem sydnromes Occlusion in which group of arteries causes the middle cerebral syndromes and lateral?

Answer 3

Middle brainstem syndromes - due to paramedian branch occlusions Lateral brainstem sydnromes - due to long circumfrential branch occlusions

Question 4

in the rule of 4 there are 4 rules

• There are 4 structures in the ‘midline‘ beginning with M
• There are 4 structures to the ‘side‘(lateral) beginning with S
• There are 4 cranial nerves in the medulla, 4 in the pons and 4 above the pons (2 in the midbrain)
• The 4 motor nuclei that are in the midline are those that divide equally into 12 except for 1 and 2, that is 3, 4, 6 and 12 (5, 7, 9 and 11 are in the lateral brainstem)

What are the 4 midline structures beginning with M?

Answer 4

Motor pathway - corticospinal tract

Medial lemnsicus (DCML)

Medial longitudinal fasciculus

Motor nucleus and nerve 3,4,6,12 - obviously each cranial nerve nucleus is located at different aspects of the brainstem

Question 5

What would be the associated side effects of a midline lesion then? Talk about the motor nuclei on next flashcard

Answer 5

Motor tract - corticospinal tract - patient would have contralateral weakness in the arms and legs Medial lemniscus (DCML) - patient would have contralateral loss of fine touch, vibration and proprioception Medial longitudinal fasciculus - internuclear opthalmoplegia would occur - (failure of adduction of ipsilateral eye towards the nose and nystagmus on opposite eye as it looks laterally) Motor nucleus and nerve - CN 3,4,6,12 nuclei

Question 6

Say the lesions was in the left medial longitudinal fasciculus, what would happen?

Answer 6

The left eye would fail to adduct medially and the right eye would have nystagmus on abduction

Question 7

Where in the brainstem is the nuclei of CN 3,4,6 and 12 found? What are the nuclei known as? What defect would occur in a lesion affecting these cranial nerve?

Answer 7

• CNIII- midbrain - oculomotor nucleus (level of superior colliculus) - patient ipsilateral eye to look down and out - CNIV - midbrain - trochlear nucleus (level of inferior colliculus) - eye unable to perfom test looking down and in and a head tilt (bilateral IV would be chin depress) - CNVI - pons - abducent nuceus - ipsilateral eye unable to move laterally - CNXII - medulla - hypoglossal nucleus - ipsilateral weakness of tongue on protrusion

Question 8

What are the four lateral structures of the brain? Side structures begin with S

Answer 8

Spinocerebellar tract Spinothalamic tract Sensory nucleus of cranial nerve 5 (also nuclei of cranial nerves, 7,8,9,10,11) Sympathetic pathway

Question 9

What symptoms would a lateral brainstem lesion therefore elicit?

Answer 9

Spinocerbellar tract - ipsilateral ataxia of arm and leg Spinothalamic tract - contralateral loss of deep touch, pressure, pain and temperature Sensory nucleus of CN V - ipsilateral loss of pain and temperature and sensation in face Sympathetic pathway- ipsilateral Horner’s syndome- miosis (constricted pupil), ptosis (drooping eyelid), annhydrossi (lack of sweating)

Question 10

What are the cranial nerves in each region of the brainstem and what is they defect if a lesion effects one? What region of the space is spared in trigeminal nerve lesion?

Answer 10

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Question 11

If there are signs of both a lateral and a medial (paramedian) brainstem syndrome, then what artery needs to be considered for an occlusion?

Answer 11

The basilar artery

Question 12

Scenario 1 You are examining a patient with sudden onset left-sided weakness. These are your clinical examination findings: weakness of the left upper and lower limbs, with sparing of the face. tongue deviation to the right, with no ophthalmoplegia. loss of vibration and proprioception in the left upper and lower limbs. Explain as to where the lesion is located in brainstem?

Answer 12

Weakness of left upper and lower limbs - corticopsinal tract affect (motor tract) which is medial and should be contralteral so medial brainstem lesion here Tongue deviation to the right - hypoglossal nerve so medulla Loss of vibration and proprioception - Medial lemniscus (DCML) - medial brainstem again Lesion in the right medial medulla

Question 13

Scenario 2 You are examining a patient with sudden onset right-sided weakness. These are your clinical examination findings: weakness of the right face, upper and lower limbs. the left eye is turned “down and out” and the pupil is dilated. Explain as to where the lesion is located in the brainstem?

Answer 13

Upper and lower limb weakness - corticospinal tract affected whcih is medial and contralteral Left eye is down and out - oculomotor nerve affected - this is medial and in the midbrain Pupil is dilated is another sign that the oculomtoor parasympathetics have also been affected - also ipsilateral Lesion in left medial midbrain

Question 14

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Answer 14

• Left sided limb ataxia - spinocerebellar tract - ipsilateral so left side and lateral in brain
• Pain and temperature - snesory trigeminal nucleus - ipsilateral - left side
• Left sided ipsilateral horners synddrome - left side
• Right side alterating of pain and temp in arms and legs - spinothalamic tract - contralteral - so left side and lateral
• Dysarthria and gag reflex - CN IX and CN X - so medulla

Lesion in the left lateral medulla

Question 15

Why is it when the trigeminal nerve sensory nucleus (the pontine nucleus) was involved that the lesion was not located in the pons?

Answer 15

The pontine trigeminal nucleus spans the pons to medulla and therefore depends where the lesion affects this

Question 16

Scenario 4 You are examining a patient with right-sided deafness, that was preceded by tinnitus. These are your clinical examination findings: right-sided limb ataxia (predominantly affecting the right upper limb). right-sided facial numbness with loss of the corneal reflex. right-sided hemi-facial spasms. Explain as to where the lesion is located in brainstem?

Answer 16

Right sided deafness - vestibulocochlear - right side and lateral and pons right sided limb ataxia - spinocerebellar tract - ipsilateral - right side and lateral loss of corneal reflex with facial numbness - trigeminal nerve is affected - lateral side of brainstem, and ipsilateral Facial spasms are due to CN VII being affected Lesions is located in the right lateral pons

Question 17

What is the lesion likely to be at the lateral pons compressing both the CN VII and CN VIII?

Answer 17

Acoustic neuroma - most common tumour of the cerebellopontine angle

Question 18

If the onset of symptoms is sudden is it likely to be a Vascular, infective, tumour or degenerative cause? If the onset is gradual ie weeks to months, what is likely cause? If the onset is gradual ie months to years, what is likely cause?

Answer 18

Sudden onset is likely to be vascular Weeks to months is likely to be due to a tumour Months to years is liekly to be degenerative

Question 19

What is the vascular supply to the brainstem again? What is the arteries of the circle of willis that these branches come form?

Answer 19

* The pontine (paramedial arteries) - supply medial brainstem The long circumfrential arteries: * Superior cerebellar * Anterior inferior cerebellar arteries * Posterior inferior cerebellar artereis These supply the lateral brainstem These all branch from the basilar artery

Question 20

Which arteries supply the midbrain?

Answer 20

The posterior cerebral artery and the superior cerebellar artery Posterior cerebral is the main

Question 21

Which arteries supply the pons and medulla?

Answer 21

Pons -basilar, anterior inferior cerbellar arteries (also paramedian arteries - these are main coming from basilar))

Medulla - anterior and posterior inferior cerebellar arteries And anterior spinal artery - this is the main

Question 22

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Answer 22

Dysarthria - vagus nerve affected Deviation of his tongue - hypoglossal nerve affected on the right side Left hemiplegia - corticospinal affected - contralateral and is medial Loss of proprioception to upper and lower limbs - DCML - contralateral and also medial Side affected - Right medial medulla Anterior/posterior inferioror cerebellar arteries and anterior spinal arteries

Question 23

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Answer 23

Tinnitus and gradual hearing loss right ear -vestibulocochlear - lateral pons, right side right sided facial parasthesis and loss of corneal reflex - facial nerve affected Side - right lateral pons Nystagmus due to cerebellum being involved Main source of lesion is tumour - acoustic neuroma

Question 24

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Answer 24

Imparied adduction in left eye with nystagmus on abduction of right - ipsilateral to left eye lesion in MLF tract Imparied adduction of right eye and nystagmus on abductionof left - ipislateral to right eye lesion in MLF tract Pain behind eye lasting 30s - optic neuritis Bilateral MS lesions in medial longitduinal fasciculus seen by internuclear opthalmoplegia and optic neuritis

Question 25

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Answer 25

Ptosis and miosis - Horner’s syndrome - lateral brainstem as sympathetics Loss of pain and temperature sensation on same side of face - trigeminothalamic tract - ipsilateral Lower limbs pain and temp loss - spinothalamic tract - lateral and isplateral - so right side lateral lesion Palate deviated to the left - vagus nerve so medulla (anterior spinal, posterior/anterior inferior cerebellar artery) Right lateral medulla