Localising The Lesion ‘where in the CNS’

Lauren O’Flynn

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

Definitions

• CNS– Brain and spinal cord• Protected by bone

• PNS– Everything else• Sensory, motor, autonomic

Homunculus

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

Cerebral lobes

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

Circle of Willis

Circle of Willis

Blood supply to the Brain

Spinal Tracts

Anterior Spinothalamic

• Sensory– Carries crude touch and

pressure

• Decussates at level of Spinal Cord

Lateral Spinothalamic

• Sensory– Carries pain and

temperature

• Decussates at level of Spinal Cord

Dorsal Columns

• Sensory– Carries vibration,

proprioception, and fine touch

• Decussates at level of the Medulla

Corticospinal

• Motor• Decussates at the level

of the Medulla

Brown-Sequard

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

Stroke

• Aetiology– Thrombus in situ– Heart emboli– CNS bleed

• Risk factors– Hypertension– Smoking– DM– CVS disease– PVD– Past TIA– Hypercholesterolaemia

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

Stroke - Ix

• Bedside– BP– ECG (+/- 24hr)

• Bloods

• Imaging– CT head– Carotid doppler– Echo– ?MRI head

• Special test– Swallow assessment

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

Stroke - Management

• Longterm– Antiplatelets

• Aspirin 75mg OD + Dipyridamole 200mg BD• Clopidogrel 75mg OD

– ?anticoagulation• If AF – warfarin

– Neurorehabilitation• Physio• OT• SALT• Stroke outreach team

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

Multiple Sclerosis

• Aetiology– Autoimmune?

• Epidemiology– Women > men– Onset ~30’s– Cold climates

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

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

Multiple Sclerosis – clinical features

• Swallowing disorders• Balance problems• Constipation• Fatigue• Amnesia– Memory conversion

affected

• Erectile dysfunction• Cerebellar features– Ataxia– Nystagmus– Intention tremor– Monotonous speech

Multiple Sclerosis - Ix

• Bedside– Urine dip– LP

• Oligoclonal bands• Increased

– IgG– Protein– Lymphocytes

• Bloods

• Imaging– MRI head

• Plaques (periventricular)

• Special tests– Electrophysiology

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

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

Motor Neurone Disease

• Aetiology– Unknown

• Epidemiology– Men > women– Onset ~60yrs

• Pathology– Degenerative disease– Selective loss of neurons

in motor cortex

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

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

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

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

Questions?