localising the lesion ‘where in the cns’ lauren o’flynn
TRANSCRIPT
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Localising The Lesion ‘where in the CNS’
Lauren O’Flynn
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Learning objectives
• Definition of CNS and PNS• Definition of UMN and LMN• Function of each of the cerebral lobes• The homunculus• Circle of willis and blood supply to the cerebral
hemispheres• Motor tracts – lateral corticospinal• Sensory tracts – lateral spinothalamic and dorsal
columns• Clinical case scenarios
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Definitions
• CNS– Brain and spinal cord• Protected by bone
• PNS– Everything else• Sensory, motor, autonomic
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Homunculus
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UMN vs LMN
• UMN– Entirely within CNS– symptoms
• Hyperreflexia• Spastic paralysis• Up-going plantar reflex
– Babinski’s sign
• LMN– Mostly outside of CNS– Symptoms
• Hyporeflexia• Flaccid paralysis• Muscle
wasting/fasiculations
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Cerebral lobes
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Cerebral function
• Frontal– Prefrontal cortex
• Personality• Reasoning/rationale• Cognition• Mood
– Motor area• Broca’s area
• Parietal– Sensory cortex– Visuospatial orientation
• Temporal– Auditory cortex
• Wernicke’s area
– Learning and memory– Emotional and affective
behaviour
• Occipital– Visual cortex– Meaning and
interpretation related to vision
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Circle of Willis
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Circle of Willis
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Blood supply to the Brain
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Spinal Tracts
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Anterior Spinothalamic
• Sensory– Carries crude touch and
pressure
• Decussates at level of Spinal Cord
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Lateral Spinothalamic
• Sensory– Carries pain and
temperature
• Decussates at level of Spinal Cord
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Dorsal Columns
• Sensory– Carries vibration,
proprioception, and fine touch
• Decussates at level of the Medulla
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Corticospinal
• Motor• Decussates at the level
of the Medulla
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Brown-Sequard
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Clinical scenario 1
• 75 year old • daughter noticed that he woke up with a left
facial droop and slurred speech• O/E– Left facial weakness– Unable to raise left arm– Upgoing left plantar
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Stroke
• Aetiology– Thrombus in situ– Heart emboli– CNS bleed
• Risk factors– Hypertension– Smoking– DM– CVS disease– PVD– Past TIA– Hypercholesterolaemia
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Stroke Syndromes
TACS – all 3 PACS – 2 of 3 LACS POCS
Hemiplegia/hemisensory loss
See left No visual field defect
Bilateral motor or sensory
Visual field disturbance
Pure motor Conjugate eye movement disturbance
Disturbance in higher function – e.g. dyphasia/dysphagia
Pure sensory Cerebellar dysfunction
Sensory-motor Hemiplegia or cortical blindness
Ataxia
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Stroke - Ix
• Bedside– BP– ECG (+/- 24hr)
• Bloods
• Imaging– CT head– Carotid doppler– Echo– ?MRI head
• Special test– Swallow assessment
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Stroke - Management
• Acute– A-E assessment– BP – only treat if >200– Throbolysis
• If <4.5 hrs after onset• Alteplase (tPA)
– NBM until swallow assessment– Fluid balance – beware cerebral oedema– Antiplatelets
• Aspirin 300mg OD for 2 wks
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Stroke - Management
• Longterm– Antiplatelets
• Aspirin 75mg OD + Dipyridamole 200mg BD• Clopidogrel 75mg OD
– ?anticoagulation• If AF – warfarin
– Neurorehabilitation• Physio• OT• SALT• Stroke outreach team
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Clinical scenario 2
• 26 year old female • 2 week history of bilateral leg weakness – started with pins and needles and numbness in
her hands and feet.• few days of urinary incontinence – resolved• Previous episodes?– episode of blurred vision and pain in the right eye
which lasted a month and fully resolved
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Multiple Sclerosis
• Aetiology– Autoimmune?
• Epidemiology– Women > men– Onset ~30’s– Cold climates
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Multiple Sclerosis
• Pathology– Chronic inflammatory condition of CNS
• CD4 mediated
– Characterised – multiple plaques of demyelination• Disseminated in TIME AND SPACE
• Types– Relapsing & remitting
• Demyelination heals incompletely
– Progressive• Prolonged demyelination and axonal damage
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Multiple Sclerosis – clinical features
• Eyes– Unilateral optic neuritis
• Pain on eye movement• Rapid loss of central vision
– Intranuclear ophthalmoplegia• Weak primary abduction of
ipsilateral eye and nystagmus of contralateral eye
– Interrupted visual pursuit
• Urinary symptoms– Retention– incontinence
• Sensory disturbance– Parasthesia– Numbness– L’hermitte’s sign
• Electrical like shocks on neck flexion
– Decreased vibration sensation
– Trigeminal neuralgia
• Motor disturbance– Leg weakness– UMN signs
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Multiple Sclerosis – clinical features
• Swallowing disorders• Balance problems• Constipation• Fatigue• Amnesia– Memory conversion
affected
• Erectile dysfunction• Cerebellar features– Ataxia– Nystagmus– Intention tremor– Monotonous speech
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Multiple Sclerosis - Ix
• Bedside– Urine dip– LP
• Oligoclonal bands• Increased
– IgG– Protein– Lymphocytes
• Bloods
• Imaging– MRI head
• Plaques (periventricular)
• Special tests– Electrophysiology
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Multiple Sclerosis
• Management– Acute
• Methylprednisolone– Decrease duration and severity of attacks
– Longterm• Biopsychosocial• B-interferon
– Relapsing and remitting
• Symptomatic
• Prognosis– Good features
• Female• Optic or sensory onset
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Clinical scenario 3
• 59 year old male• 6 month history of progressive weakness of
his right hand– Also had problems with swallowing and has
choked whilst eating on several occasions• o/e – wasting of his R arm and both lower limbs – some fasciculation's were noted – Sensation was normal
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Motor Neurone Disease
• Aetiology– Unknown
• Epidemiology– Men > women– Onset ~60yrs
• Pathology– Degenerative disease– Selective loss of neurons
in motor cortex
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Motor Neurone Disease - patterns
• Amytrophic lateral sclerosis – UMN & LMN
• Progressive muscular atrophy – LMN only
• Progressive bulbar atrophy– LMN of CN IX-XII only
• Primary lateral sclerosis– UMN only
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MND – clinical features
• Muscle weakness
• UMN signs (legs)– Beware if no UMN signs
above LMN signs
• LMN signs (arms)
• Bulbar palsy– Swallowing/speech
problems
• No Sensory disturbance
• No cognitive disturbance
• No eye or sphincter disturbance
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Motor Neurone Disease- Ix
• Bedside– LP
• Rule out inflam causes
• Bloods– CK
• >600 excludes MND• Anti-GAD Abs
• Imaging– MRI head & spine
• Special tests– neurophysiology
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Motor Neurone Disease
• Management– Anti-glutamate drugs
• Riluzole – Extends life by 3-5 months
– Symptomatic• Drooling – amytryptylline• Spasticity – baclofen• Pain – analgesia ladder• Resp failure – ventilation?• Surgical - gastrostomy
• Prognosis– Terminal– Usually die of resp failure rather than choking/aspiration
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Questions?