Neuroscience Week 5: Brainstem Flashcards
The Reticular Formation It consists of centers that
7 listed
- Integrate cranial nerve reflexes
- Help conduct and modulate SLOW pain
- Influence voluntary movements
- Regulate autonomic nuclei
- Associate with diffuse modulating systems
- Integrate sleep and respiration
- ACTIVATE the cerebral cortex
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Which sensory systems provide input to the reticular formation?
Almost all of them
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Reticular Formation inputs
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Ascending reticular activating system
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Locus Coeruleus
the major source of noradrenergic innervation to all cortical regions
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Raphe Nuclei
diffuse serotonergic innervation and involved in alertness and wakefulness
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Basal forebrain
- Cholinergic innervation, originate in the nucleus of Meynert of the basal forebrain
- thought to degenerate in Alzheimer’s Disease
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Ventral Tegumental Area
- Dopaminergic innervation of the cerebral cortex
- arises from Ventral tegmental area and projects to aspects of the limbic system
- such as the cingulate gyrus and prefrontal cortex
- awareness, alertness, motivation
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Widespread projection systems in the nervous system
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Orexin system
- many functions but promote wakefulness and reward pathways
- enhance dopamine signaling that can trigger incentive or reward
- can modulate ARAS and therefore modulate wakefulness and alertness
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Histaminergic Neurons
- The tubomammilary nucleus of the hypothalamus can also control cortical activity and promote alertness
- can remember by thinking of benadryl which makes you drowsy if you take it
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Recap of Aras
numerous roles
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Importance of ARAS
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Bilateral inactivation of the pontomesencephalic reticular formation, thalamus and the cerebral cortex results in?
Coma
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Brainstem Reticular Formation consists of centers that
7 Listed
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ARAS Originates
midbrain and upper pons
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ARAS is responsible for?
- arousal
- attention
If cortex presses down on the brainstem can cause
- Coma if ARAS is being pressed on
- Particularly with Uncal Herniation
Blood supply to the brainstem
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Identify region and blood supply
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Identify region and blood supply
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Identify region and blood supply
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Identify region and blood supply
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Identify blood supply
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Identify brainstem anatomy
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Identify region, contents, anatomy and blood supply
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Cervicomedullary junction
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Trigeminal spinal pathway
- 1st neuron trigeminal ganglion in upper pons
- 2nd order is trigeminal caudal nucleus in caudal medulla and spinal cord
- decussates
- ventroposteriolateral thalamus
- Sensory cortices
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Trigeminal Pathway
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Identify region, contents, anatomy and blood supply
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Caudal (lower) Medulla
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Identify region, anatomy, blood supply and describe medial medullary syndrome
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Identify region, contents, anatomy and blood supply
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Rostral (upper) Medulla
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Identify region, anatomy, blood supply and describe Lateral medullary syndrome
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Identify region, contents, anatomy and blood supply
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Caudal to mid Pons
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Identify region, anatomy, blood supply and describe medial pontine syndrome
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Identify region, anatomy, blood supply and describe Lateral pontine syndrome
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Identify region, contents, anatomy and blood supply
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Full Basilar Stroke AKA
Locked-in syndrome
Identify region, anatomy, blood supply and describe Locked-in Syndrome
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Identify region, contents, anatomy and blood supply
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Caudal midbrain
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Identify region, contents, anatomy and blood supply
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Rostral Midbrain
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Identify region, anatomy, blood supply and describe Weber’s Syndrome
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Identify Syndromes associated with various arteries
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Identify arteries associated with various syndromes
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Identify arteries and associated syndromes
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Map of cranial nerve nuclei
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Red nucleus lesion in the midbrain
Tremor and ataxia because you cannot finetune your movements
Cerebral peduncle lesion in the midbrain will cause
UMN lesion in the face and lower extremities
MLF lesion in the midbrain will cause
horizontal gaze palsy
Benedikt Syndrome identify where the lesion is and effects
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Benedikt Syndrome structures affected
Red nucleus
CN 3
Medial lemniscus
Weber Syndrome identify lesion location and effects
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Describe Pseudobulbar palsy
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Parinaud syndrome identify lesion location and effects
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Identify structures and which segment
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Pons vestibular nuclei lesion effects
4 listed
- nausea
- vomiting
- nystagmus
- vertigo
Pons CN VII Tract lesion
- facial droop
- loss of corneal reflex
Pons Medial Lemniscus Lesion
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- loss of proprioception
- loss of vibration
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Pons Corticospinal tract Lesion
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contralateral Hemiparesis
Pons CN VI Tract Lesion
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problems with lateral gaze
Pons Spinothalamic Tract Lesion
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- loss of pain and temperature sensation
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Pons Trigeminothalamic tract Lesion
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- loss of pain of the face
- loss of temperature sensation of the face
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MLF Lesion in the pons
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- horizontal gaze palsy
- intranuclear opthalmoplegia
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Pons 4th ventricle Lesion
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noncommunicating hydrocephalus
Pons PPRF Lesion
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intranuclear opthalmoplegia
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Structures need to look laterally
3 listed
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- MLF
- PPRF
- Abducens nucleus
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Medial pontine syndrome location and effects
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Medial pontine syndrome structures damage
4 listed
- Corticospinal tract
- CN 6
- CN 7
- Lateral gaze structures MLF, CN 6 nucleus, PPRF
Medial pontine syndrome symptoms
4 listed
- Contralateral hemiparesis
- CN 6 palsy
- ipsilateral Facial weakness/droop
- ipsilateral Gaze palsy
Lateral pontine syndrome lesion location and effects
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Lateral pontine syndrome damaged structures
6 listed
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- Vestibular nuclei
- Spinothalamic tract
- CN V nucleus
- Sympathetic tract
- CN 7 nucleus
- Cochlear nucleus
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Lateral pontine syndrome Common cause
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AICA stroke
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horner’s syndrome symptoms and side affected in respect to the lesion
3 listed
Ipsilateral
- in a decreased pupil size
- a drooping eyelid
- decreased sweating
Lateral pontine syndrome symptoms associated with structures
6 listed
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- Vestibular nuclei: Nystagmus, vertigo, N/V
- Spinothalamic tract: Contralateral pain/temp
- V nucleus: Ipsilateral face pain/temp
- Sympathetic Tract Horner’s syndrome
- VII nucleus: Ipsilateral facial droop, loss of corneal reflex
- Cochlear nuclei: hearing loss
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Medulla Nucleus solitarius and dorsal motor nucleus of X function
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- where autonomic sensory information comes in from structures such as carotid sinus, aortic arch
- goes out to affect autonomic functions of the Vagus nerve
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Identify segment and structures
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medulla
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Medulla Nucleus Ambiguous
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Shared motor nucleus of IX, X, XI
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Medulla CN XII
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Medulla Medial Lemniscus
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Proprioception and vibration
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Medulla Pyramids
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is corticospinal tract
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pyramidal dysfunction AKA
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loss of corticospinal tract
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Medulla Inferior olivary nucleus
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involved with cerebellum
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Medulla Spinothalamic tract
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contralateral pain and temperature
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Medulla trigeminothalmic tract and nucleus
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facial pain andc temperature
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Medulla Hypothalamospinal tract
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- Sympathetic innervation from the thalamus
- damage will give Horner’s Syndrome
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Medulla Vestibular nuclei
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Medial Medullary Syndrome lesion location and effects
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Medial Medullary Syndrome structures damaged
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- Corticospinal tract
- medial lemniscus
- CN 12
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Medial Medullary Syndrome common causes
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ACA stroke
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Medial Medullary Syndrome Symptoms and associated structures
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- Corticospinal tract: Contralateral hemiparesis
- Medial lemniscus: contralateral loss of proprioception/vibration
- CN 12: Falccid paralysis of tongue (LMN) deviates to ipsilateral to lesion
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Lateral medullary syndrome AKA
Wallenberg Syndrome
Wallenberg Syndrome AKA
Lateral medullary syndrome
Lateral medullary syndrome damaged structures
5 listed
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- Vestibular nuclei
- Sympathetic tract
- spinothalamic tract
- Spinal V nucleus
- Nucleus ambiguous
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Lateral medullary syndrome Symptoms and associated structures
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- Vestibular nuclei: Nystagmus, vertigo, N/V
- Sympathetic tract: Horner’s Syndrome
- Spinothalamic tract: Contralateral pain/temp
- V nucleus: Ipsilateral face/pain
- Nucleus Ambiguous (IX, X): Hoarseness, dysphagia
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Lateral medullary syndrome common cause
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PICA stroke
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Lateral medullary syndrome looks a lot like?
How to distinguish them?
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- Lateral pontine syndrome
- distinguish by hoarseness and dysphagia in lateral medullary syndrome
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Rule of 4s
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4 CNs in
- Medulla
- Pons
- Above pons
4 CNs divide into 12
- 3, 4, 6, 12
- have midline motor nuclei
4 CNs do not divide into 12
5, 7, 9, 11
All are lateral
4 midline columns
- Motor nucleus
- Motor pathway
- MLF
- Medial lemniscus
- All start with M
4 Lateral (side) columns
- Sympathetic
- Spinothalamic
- Sensory
- Spinocerebellar
- All start with S
How to localize lesions using the rule of 4s?
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CNs in the midbrain and lesion effects
CN 3 eye turned down and out
CN 4 Eye unable to look down when looking towards nose
CNs in the pons and deficits
- Trigeminal: Ipsilateral facial sensory loss
- Abducens: Ipsilateral abduction weakness
- Facial: Ipsilateral facial weakness/droop
- Auditory: Ipsilateral deafness
CNs in the medulla and associated deficits
- Glossopharyngeal: Ipsilateral sensory loss
- Vagus: ipsilateral palatal weakness uvula points away
- Spinal accessory: Ipsilateral shoulder weakness
- Hypoglossal: Ipsilateral weakness of tongue
Corticospinal tract sits _______ in brainstem
midline
Medial leminiscus sits _______ in brainstem
Midline
Medial longitudinal fasciculus sits _________ in brainstem
Midline
Motor Nucleus and nerves (3,4,6, and 12) sit __________ in brainstem
Midline
CN 3 motor nucleus and nerve sit ________ in brainstem
midline
CN 4 motor nucleus and nerve sit ________ in brainstem
midline
CN 6 motor nucleus and nerve sit ________ in brainstem
midline
CN 12 motor nucleus and nerve sit ________ in brainstem
midline
Corticospinal tract damage in the brainstem results in?
Contralateral weakness except below pyramidal decussation (cervicomedullary junction
Medial Lemniscus damage in the brainstem results in?
Contralateral loss of proprioception and vibration except below medullary decussation
Medial longitudinal fasciculus damage in the brainstem results in?
ipsilateral Intranuclear opthalmoplegia
CN 3 damage in the brainstem results in?
ipsilateral motor loss and corneal reflex?
CN 4 damage in the brainstem results in?
ipsilateral motor loss of the superior oblique, cant look down and in
CN 6 damage in the brainstem results in?
ipsilateral motor loss for eye abduction
CN 12 damage in the brainstem results in?
lick your wounds ipsilateral loss of tongue motor
Spinocerebellar pathway sits __________ in the brainstem?
Laterally/side
Spinothalamic tract sits __________ in the brainstem?
Laterally/side
Sensory nuclei of CN 5 sits __________ in the brainstem?
Laterally
Sympathetic pathway sits __________ in the brainstem?
Laterally/side
Spinocerebellar pathway damage in the brainstem results in?
Ipsilateral ataxia
Spinothalamic damage in the brainstem results in?
Contralateral loss of pain/temp
Sensory nucleus of CN 5 damage in the brainstem results in?
Ipsilateral pain/temp loss in face
Sympathetic pathway damage in the brainstem results in?
Ipsilateral Horner’s Syndrome
Trigeminal Nerve Caveats
- Lesion: loss of ipsilalteral pain/temp in the face
- Rule of 4 pons nucleu and side (lateral tract)
- Don’t localize to pons
- Use for lateral tract localization
Vestibulocochlear caveats
- Don’t use vestibular signs to localize to the pons
- Vestibular signs can be medulla/pons
- only use Lesion: hearing loss to localize CN 8 to the pons not the vestibular signs
Case 1
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- MCA or ACA - would give more arm than leg or vice-versa so this is a place where all motor fibers are together
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Blood vessel supply of the brainstem
5 listed
- PCA gives stroke syndrome of the midbrain
- Basilar artery gives a medial stroke syndrome in the pons
- AICA gives a lateral stroke syndrome in the pons
- PICA gives a lateral stroke syndrome in the medulla
- ASA gives a medial stroke syndrome in the medulla
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Case 2
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complete motor loss again so it cant be MCA or ACA
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Left medial midbrain lesion means
- Weber syndrome
- stroke of the branches of PCA
Case 3 which structures are affected
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Case 3 answer
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left face/pain and temp don’t use this as to localize to the pons but instead use it as evidence of sensory dysfunction in the CN 5 tract (S tract in rule of 4s)
Spinocerebellar
sensory of 5
Sympathetic
Spinothalamic
These are all Ss
CNs 9 and 10 localizes to medulla
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Left lateral medulla lesion is
Wallenberg syndrome
Left PICA stroke
Stroke of which artery produces Wallenberg syndrome?
Left PICA
Stroke of which artery produces Left lateral medulla lesion
Left PICA
Case 4 structures affected
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Case 4 answer
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Right lateral pontine syndrome
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Right lateral pontine syndrome usually caused by
often caused by tumors such as schwannomas
Cerebellopontine angle syndrome AKA
lateral pons often caused by tumors like schwannomas
How to best utilize the rule of 4s?
- first identify the involvement of the CNs 3, 4, 6 or 12 to indicate medial syndrome
- look for the involvement of S tracts to indicate a lateral problem
- Look for M tract involvement to indicate a medial problem
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Locked-in syndrome AKA
Full basilar stroke
Locked-in syndrome symptoms
4 listed
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