Localising the lesion – where in the nervous system?

CRAIG HICKSON & HELGA MAGNUSSON

Aims and objectives

Definitions of the CNS & PNSTo learn the signs associated with LMN and UMNBrief recap on the functions associated with

different lobesCortical representation of body partsCircle of Willis and blood supply to each hemisphereMotor tracts – lateral corticospinalSensory – lateral spinothalamic & dorsal column

Clinic scenarios/Case vignettes

The central nervous system

‘The CNS consists of the ........ and the ....... .......

Some definitions include the ....... ....... and the retina

?

The peripheral nervous system

‘The PNS consists of the nerves and the ganglia outside of the brain and the spinal cord’

Includes autonomic NS and in most definitions the cranial nerves

Upper motor neuron signs

Spastic paralysisHypereflexiaHypertoniaNo muscle wasting – some wasting from lack of use eventually

Pyramidal weakness – flexion of upper limbs, extension of lower limbs

Positive Babinski – up-going plantar

?

Lower motor neuron signs

Flaccid paralysisHyporeflexiaHypotoniaMuscle wastingFasiculationsWeakness of muscle groups – mytomes

-ve Babinski?

Lobar function

Fontal – personality, executive function, cognition, & primary motor cortex. Left Frontal – Broca’s area

Parietal – primary sensory cortexOccipital – visionTemporal – hearing

Left Temporal – Wernicke’s area

Cerebellum – balance, co-ordinationBasal ganglia – initiation, inhibition of movement

Homonculus

Hands and face massively‘over represented’

More sensitive

Circle of Willis

Anterior cerebral artery

Middle cerebral artery

Posterior cerebral artery

Basilar artery

A = ?

B = ?

?Anterior spinal artery

Vertebral artery

Blood supply to the brain

The tracts

Dorsal column

Corticospinal

Spinothalamic

?

?

?

Spinothalamic

• Contra-lateral

• Cross at entry level pain and temp over 1 level touch over several

• Pain, Temperature, touch• ?

Dorsal Column

• Contra-lateral

• Cross at Medulla

• Vibration, propriaception Discriminative touch• ?

Corticospinal

• Motor tracts

• Contra-lateral

• Cross at Medulla

How to think

UMN or LMN signs?LMN: peripheral nerve/neuromuscular

junction/muscular.UMN: cerebral (?lobe), cerebellar, spinal cord

(?tract)Can the symptoms be explained by one

lesion?Differential diagnosis:

Immediate: vascular. Intermediate: inflammation/infection/malignancy. Long term: degenerative/malignancy.

Cases

• 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

What could have caused this picture?

Cases

• 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 propriaception with +ve romberg

What could have caused this picture?

Cases

• 35 year old lady who cant feel hot water when she puts her hand in the bath anymore

• ON Examination• Sensation – pain and temp reduced in upper

limbs• Light touch and propriaception retained

What could have caused this picture?

Cases

• 42 year old lady complaining of unsteadiness of balance and slurred speech, she has noticed weakness and loss of sensation in her left leg

• Leg symptoms have been present for two months• Unsteadiness and slurred speech came on over last 10

days• On examination:• CN intact• Weakness left lower limb 4/5• Hyper-reflexia – left leg only• Coordination impaired on left• Mental state NAD

What could have caused this picture?

Thankyou for listening and contributing

Stroke syndromes

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