Localising the lesionEd Hutchison and Paul Swift

AimsApproachUMN vs. LMNSpinal tractsCerebellumCerebrumVisual lesionsCases

Approach to localising the lesion

Be systematic!

…A patient presents with arm weakness…

Muscle – e.g. diabetic myopathy

NMJ – e.g. myasthenia gravis

Peripheral nerve – e.g. GBS

Spinal cord – e.g. cord compression

Cerebrum – e.g. Stroke

Timeline

Immediate

Intermediate

Long-term

UMN vs. LMN???

UMN vs. LMNUMN LMNHyperreflexia HyporeflexiaHypertonia HypotoniaClonus Muscle wastingNo muscle wasting/fasciculation

Fasciculation

Plantars upgoing (lower limbs)

Plantars downgoing (lower limbs)

Pyramidal vs. Extrapyramidal

Pyramidal ExtrapyramidalWeakness TremorSpasticity ChoreaPronator drift HemiballismusLoss of skilled movement AthestosisHyperreflexia DystoniaChange in tone/tendon reflexesPlantars upgoingLoss of abdominal/cremasteric reflex

Clonushttp://www.youtube.com/watch?feature=player_detailpage&v=8GC8F2UMYbQ#t=42

Facial nerve palsiesBulbar vs. pseudobulbarPseudobulbar = UMN of CN IX-XII

Spastic tongueSparing of forehead

Bulbar = LMN of CN IX-XIITongue wasting/fasciculationAffects all facial muscles

The tracts

Dorsal column

Corticospinal

Spinothalamic

?

?

?

Lateral Spinothala

micPain and temperatureDecussates at the level of the spinal cord

Anterior Spinothala

micCrude touch and pressureDecussates at the level of the spinal cord

Dorsal columnsDiscrimination, proprioception, vibration.Crosses at the medulla.

Subacute combined degeneration of the cord,Tabes dorsalis,Spinal trauma.

Corticospinal Tracts

Descending motor tracts.Cross at the medulla.

Brown-Sequard

Brainstem

Symptoms/signs:• Dysarthria• Dysphagia/drooling• Tongue weakness• Absent palatial

movement

CN IX-XII

CerebellumCerebellospinal tractsIpsilateral – DO NOT CROSS

Blood Supply

Cerebellar Signs– dysdiadochokinesia – ataxia (truncal and limb)

– nystagmus

– intention tremor

– slurred speech

– hypotonia

DANISH

CausesAlcoholThiamine deficiencyCVAFriedreich’s ataxia

Etc etc…

The Homunculus

Cerebral Artery Territories

Circle of WillisAnterior cerebral artery

Middle cerebral artery

Posterior cerebral artery

Basilar artery

A = ?

B = ?

?Anterior spinal artery

Vertebral artery

Speech Centres

Tono manhttp://www.youtube.com/watch?v=6CJWo5TDHLE

Broca’s dysphasiahttp://www.youtube.com/watch?v=1aplTvEQ6ew

Stroke SyndromesTACS – all 3 PACS – 2 of 3 LACS POCSHemiplegia/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

Visual DefectsIpsilateral blindessBilateral hemianopia

Left homonymous hemianopia

Left superior quadrantanopia

Left homonymous hemianopia with macular sparing

Cases

Case 1• 57 year old man complaining of weakness and

altered sensation in upper limbs and lower limbs• Loss of sensation from shoulders and down,

urinary incontinence• On Examination:

• CN intact• Upper limbs weakness, hypotonia, reduced

reflexes• Lower limbs spasticity, hyper-reflexia and

Babinski +ve, reduced sensation from shoulders down

Case 2• 85 year old man with long standing (20yr)

history of balance problems worse in the dark.• Gait is high stepping• On Examination:

• CN intact• Motor intact• Loss of proprioception with +ve Romberg’s

test

Case 323, female presents to her GP with a 2 week history of bilateral leg weakness having started with pins and needles and numbness in her hands and feet. She has had a few days of urinary incontinence which has resolved. 2 years ago she had an episode of blurred vision and pain in the right eye which lasted a month and fully resolved

Case 456 male6 month history of progressive weakness of his right hand. Also had problems with swallowing and has choked whilst eating on several occasionso/e he has wasting of his upper and lower limbs and some fasciculation's were noted his right plantar was up going and his reflexes were generally brisk

Things we’ve not had time to cover

Peripheral neuropathiesMotor neuroneParkinson’sHuntington’sGBSMyasthenia gravis

Peripheral NeuropathiesA – alcoholB – B12 deficiencyC – CKDD – drugs/diabetesE – every vasculitis