BRAINSTEM LESION UNDERSTANING - WEEK 2ish Flashcards
What are the nuclei of all twelve cranial nerves? What are the cranial nerves names? Where in the brain are the nuclei located?
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What are the two main groups of arteries that give blood supply to the brainstem? These are branches from the basilar and vertebral arteries
- Paramedian pontine arteries
- The trio of long circumfrential arteries:
- Superior cerebellar artery
- Anterior inferior cerebellar artery
- Posterior inferior cerebellar artery
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?
Middle brainstem syndromes - due to paramedian branch occlusions Lateral brainstem sydnromes - due to long circumfrential branch occlusions
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?
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
What would be the associated side effects of a midline lesion then? Talk about the motor nuclei on next flashcard
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
Say the lesions was in the left medial longitudinal fasciculus, what would happen?
The left eye would fail to adduct medially and the right eye would have nystagmus on abduction
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?
- 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
What are the four lateral structures of the brain? Side structures begin with S
Spinocerebellar tract Spinothalamic tract Sensory nucleus of cranial nerve 5 (also nuclei of cranial nerves, 7,8,9,10,11) Sympathetic pathway
What symptoms would a lateral brainstem lesion therefore elicit?
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)
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?
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If there are signs of both a lateral and a medial (paramedian) brainstem syndrome, then what artery needs to be considered for an occlusion?
The basilar artery
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?
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
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?
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
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- 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
Why is it when the trigeminal nerve sensory nucleus (the pontine nucleus) was involved that the lesion was not located in the pons?
The pontine trigeminal nucleus spans the pons to medulla and therefore depends where the lesion affects this
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?
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
What is the lesion likely to be at the lateral pons compressing both the CN VII and CN VIII?
Acoustic neuroma - most common tumour of the cerebellopontine angle
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?
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
What is the vascular supply to the brainstem again? What is the arteries of the circle of willis that these branches come form?
* 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
Which arteries supply the midbrain?
The posterior cerebral artery and the superior cerebellar artery Posterior cerebral is the main
Which arteries supply the pons and medulla?
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
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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
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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
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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
