Neurological Principles

NEUROLOGICAL

PRINCIPLES

Brain

Localisation

Dominant hemisphere

Almost all right handed have language function in

left hemisphere and prob about 70% left handed

Non-dominant hemisphere

In R hemisphere lesion (in L dominant) causes

abnormalities of perception eg. Losing way,

dressing apraxia or constructional apraxia

Examples of lesions in cortex (L hemisphere dominant)

Either frontal

Intellectual impairment, personality change

L temporoparietal

Acalculia, alexia, agraphia, Wernicke’s aphasia, field defects

R parietal

Dressing apraxia, neglect L limbs

Occipital

Visual field defects, disturbance of visual recognition

Spine

Neurological diagnosis

Anatomical

Where is the lesion?

Pathological

What disease?

History

History

Crucial

Allow patient to speak

Age

Occupation

Handedness

Timing of symptoms

Discriminant questions

Past medical history

Medication history

Family history

Social history

Examination

Level of consciousness

Cognitive function

Speech

Cranial nerves

Neck and trunk

Limbs – motor and sensory

Gait

Consciousness

Awareness of self and surroundings

Depends on:

Sensory input into brain

Intrinsic activity of reticular activating system in

brainstem

Intact cerebral hemispheres

Altered level of consciousness

Structural

Trauma, infarction, haemorrhage, tumour, demyelination of brainstem or cerebral hemispheres

Diffuse

Reduced availability of substances required for normal brain metabolism (oxygen, glucose)

Metabolic disorders (renal or liver failure, hypothermia, vitamin deficiencies)

Seizures

Inflammation of brain or meninges

Drugs and toxins (opiates, anti-depressants, hypnotics, alcohol)

Cognitive function

Higher brain function

Distributed functions

Require multiple parts of brain Attention and concentration

Memory

personality

Localised functions

Require part of one cerebral hemisphere language

Cranial nerves

I Olfactory nerve

II Optic nerve

III Oculomotor nerve

IV Trochlear nerve

V Trigeminal nerve

VI Abducens nerve

VII Facial nerve

VIII Vestibulocochlear nerve

IX Glossopharyngeal nerve

X Vagus nerve

XI Accessory nerve

XII Hypoglossal nerve

Motor function

Involves:

Higher centres

Upper motor neurone

Lower motor neurone

Neuromuscular junction

Muscle

Plus input from basal ganglia and cerebellum

Feedback from sensory pathways

Upper and lower motor neurones

Upper motor neurone

Cell body in motor cortex

Axon in corticospinal (pyramidal tracts)

Synapses with anterior horn cell

Lower motor neurone

Axon from anterior horn cell in spinal cord to

voluntary muscle

Upper and lower motor neurones

Examination

Wasting

Most prominent when muscle has been denervated from LMN lesion

Involuntary movements

fasciculations

Tone

Resistance detected on passive movement of patient’s joints

Power

Characteristic patterns of weakness eg. UMN ‘pyramidal distribution’ of weakness

Reflexes

Coordination

Ataxia - cerebellar disease.

Sensory ataxia due to loss of joint position sense

Sensation

Plantars

Neurological gait disorders

Spastic paraparesis scissoring

Spastic hemiparesis Rigid leg, circumducts

Bilateral foot drop steppage

Cerebellar lesion Wide-based gait, staggering, unable to walk heel-toe

Parkinsonism Rigid shuffling gait, ‘festinant’

Proximal myopathy waddling

Sensation

Joint position sense

Vibration sense

Touch and pressure

Pain and temperature

Sensation

Two main pathways

Joint position and vibration sense – posterior columns of spinal cord

Pain and temperature – spinothalamic tracts

Touch and pressure sensation – ascend by a number of routes

Sensory symptoms

Numbness

Inability to detect heat and cold

Paraesthesia – tingling, ‘pins and needles’

Dysaesthesia – distorted sensation from sensory stimuli

Sensory nerves

Dermatomes

Autonomic function

Sympathetic and parasympathetic

Involuntary control of viscera and glands

Involved in:

Pupil responses

Blood pressure and heart rate

Bladder, bowel, sexual function

Sweating, lacrimation, salivation