• Cerebrovascular disease
• Tumour
• Demyelination - MS
• Degen - Alc, Hereditary, (spinocerebellar)
• Dev - Arnold-Chiari and Dandy-Walker malformations, Von-Hippel-Lindau disease
• Misc - Hypothyroid, rel to gynae malignancies

DIAG: BS to cerebellum

DIAG: BS structures

DIAG: Cerebellar infarction

• Represented by black area
• Infarction on right side -> right sided cerebellar signs
• Each side of cerebellar hemispheres has own BS, therefore infarction does not cross mid-line

DIAG: midline cerebellar tumour

• Vestibulocerebellum affected - truncal ataxia, nystagmus

DIAG: Cerebellar atrophy

• Affects both sides
• All aspects of cerebellar co-ordination affected

Disorder of coord and rhythm

• Cerebellum
• BS
• SC
• Peripheral n

DYSKINESIA

Disturbance of the extrapyrmaidal system comprising the BG

• -Chorea
• Hemiballismus
• Athetosis
• Dystonia
• Tremor
• Myoclonus
• Tics

COMMON DYSKINESIAS

• Chorea: Irregular, jerky, non-repetitive; Resembling fragments of purposive movts following one another in a disorderly fashion
• Hemiballismus: Violent form of unilateral chorea resulting in wide excursions of the affected limbs (affects proximal m's)
• Dystonia: Distorted postures of limbs and trunk resulting in XS m tone in antagonistic m groups (Eg. Axial dystonia (back, neck -> abn posture); Neck dystonia - SCM (torticollis); Torticollis and retrocollis; Writer's dystonia (cramp) - task-specific; Pianist/ typewriters dystonia)
• Athetosis: Slow coarse, writhing movements of extremities and neck m's
• Tremor: Rhythmic oscillating movt of a segment of limb or head
• Myoclonus: Sudden and brief shock-like m contraction; Jerky, but simple in nature (twitch predictable) - cf. Chorea (v complex, randomised, unpredictable)

DIAG: Tremor EMG

• Oscillatory rhythmic contraction
• When anterior tibial m contracts, gastroc relaxes (and vice versa)

DIAG: myoclonus

Tics

• Brief, rapid, co-ordinated
• Repeated (stereotypic) at irregular intervals head, UL, vocals
• Ability of voluntary suppression in the expense of building up of psychic tension

All other movt disorders cannot be suppressed voluntary

• Chorea: Involuntary movt orolingual m's; Feet: repetitive, random movt
• Hemiballismus: 'Sub-type of tics; Affects more prox m's
• Dystonia: Abn posturing; Static or dynamic
• Torticollis: Precipitated by chewing movt
• Athetosis: More twisting movt cf. dystonia
• Cerebellum tremor: Accentuated at end of range
• Tics: Co-ordinated movt; The same each time

PD

• A clinicopathology entity
• Due to degen and loss of pigmentation at SN pars compacta
• And presence of intraneuronal Lewy bodies
• "Idiopathic" PD

PARKINSONISM

• Clinical features seen in PD
• But not exclusive for PD
• Therefore, Parkinsonism does not equal PD

Parkinsonism (eg. Parkinsonian syndromes, parkinsonian tremor)

PARKINSONISM

1. Tremor

2. Bradykinesia

3. Rigidity

Tremor

• Coarse, resting, tremor (3-5 Hz, low-freq)
• "Pill-rolling"
• Decreased with action, increased with stress
• Faster, fine postural tremor at 6-10 Hz may be seen

Bradykinesia

• Slowness of movt
• Monotonous speech (slow without variation of tone)
• Difficulty initiating movt
• Poverty of movt (facial animia, impaired arm swing, decreased eye blinking)
• Facial bradykinesia: difficulty swallowing saliva - t/f often drooling
• Diminished repetitive alternating movt - dysdiadochokinesia (can occur in all neuro conditions where m performance is affected)
• Postural instability (difficulty performing postural reflexes)

Rigidity

• Increased in tone, resistance to passive movt
• Flexor tone > extensor -. Part flexed "simian" posture (stooped and flexed, like a monkey)
• "Lead pipe" (resistance constant throughout range of passive movt)
• "Cogwheel" (leadpipe + superimposed tremor)
• Fatigue, m ache

PARKINSONIAN SYNDROMES

• Idiopathic PD
• Parkinsons Plus syndromes (worse Px):

1. Multiple system atrophy
2. Progressive supranuclear palsy
3. Corticobasal degeneration
4. Lewy body dementia
5. Vascular pseudoparkinonism

• Secondary parkinsonism: Postencephalitis
• Drug-induced (esp. dopamine depleting drugs used to treat schizophrenics, anti-emetics)
• Toxins (Cu (Wilson's disease),CO, MPTP - by-product in heroin production)
• Trauma - eg. Mohammed Ali

PD

• Prevalence: 3/1,000 general pop
• Mostly affects elderly
• Mortality 2-5x of age-matched controls
• Marked reduction in life expectancy - average survival from onset 13y (other coexisting morbidity: eg. CVA, IHD)
• Clinical Dx: demonstrating parkinonism without other features seen in parkinsonian plus syndromes, natural progression
• In later stages have complications relating to falls eg. #
• In latest stages have probs rel to immobility: eg. Hypostatic, pneumonia

Unknown aetiology

• Degen of melanin-containing dopaminergic neurones of SN

1. Disruption of BG motor loop
2. Motor dysfunction - tremor, bradykinesia, rigidity

Time course

• Stage 1 ; unilateral disease - mean time from Dx 3y
• Stage 2 - bilateral mild - 6y
• Stage 3 - bilateral an postural 7y
• Stage 4 severe needing help etc

PRINCIPLES OF PD MEDIAL THERAPY

• Increased secretion of DA from depleted dopaminergic neurones
• Increase action of DA at DA-rec level (increased efficiency of depleted DA)
• But these are all palliative, not curing, just ameliorating symptoms (natural Hx: still progressive)

1. Levodopa - most effective converted to DA
2. Dopamine receptor agonist (upregulate DA level at rec level) to increase sensitivity of dopamine
3. MAOB inhibitor - block MAOB - decrease breakdown of DA at synapse
4. Levodopa to dopamine (dopadecarboxylase) in peripheral circulation. Therefore use dopa decarboxylase inhibitors to decrease break-down of DA (does not cross BBB)
5. COMT: Levodopa to 3-OMT therefore use COMT-inhibitor

• Motor cortex -> cortciostriatal neurones -> BG ->complex inhibitory and excitatory interaction -> supplementary motor area -> motor cortex -> initiate motor signal through corticospinal tract -> motor response
• SN: main role in direct excitatory pathway (dopaminergic)
• Upregulation of indirect (inhibitory) pathway - therefore decreased motor output from motor loop - decreased motor signal through corticospinal tract - hypokinetic movt like PD
• Disorder in inhibitory pathway (eg. Striatum) - resulting in chorea
• Subthalamic nucleus: disorder results in hemiballismus (also dyskinetic movt disorder

SURGICAL TREATMENT OF PD

• Upregulation of inhibitory targets (Globus pallidus, SN)
• Reduces this increased inhibitory tone - restore balance in motor loop

1. Destroy part of subthalamic nucleus or globus pallidus
2. Deep brain stimulation to switch off (electrolytes into subthalamic nucleus or GB, pacemaker to generate high-freq. signal to switch off inhibitory tone, each $60,000)
3. Drugs: inhibitory pathway uses GABA + Ach - therefore dev specific antagonists of these rec (not validated yet)

• AD (4p16.3)
• Chorea, dementia, behavioural probs
• Age of onset 30-50 (after child-bearing, can pass on disease to generations)
• Cortical atrophy, striatal neuronal loss
• Unknown pathogenesis
• No effective Tx
• Progression to death 10-12 years

Afferents

1. Proprioception

2. Vestibular

3. Visual

Execution

"Central processing"

1. Motor cortex

2. BG

Efferents

"Motor output"

1. Motor pathway and motor system

2. Cerebellar co-ordination

If one part is defected, the other part with compensate

Eg. Blind: no visual input, but can still walk with proprioceptive and vestibular input

Eg. Peripheral neuropathy: decreased proprioception - therefore increased vision and vestibular (therefore if close eye, not sufficient and pt has defective gait - sensory ataxia)

PROPRIOCEPTIVE DYSFUNCTION

• NM spindles
• GTO
• Free n endings at m and jt
• Mechanoreceptors at soles of foot
• Sensory n Ia, Ib, III, IV fibres

SENSORY ATAXIA

• Proprioceptive defect
• Open eyes: good stability
• Close eyes: unsteadiness
• Principles of Rhombergs test

CEREBELLAR ATAXIA

• Unsteady whether eyes open or close

WIDE-BASED GAIT ATAXIA

• Cerebellar ataxia: eyes open or closed
• Sensory ataxia: eyes closed

PARKSONIAN GAIT

• Flexed, stooping posture
• Due to bradykinesia
• Slow, small steps, shuffling
• Decreased arm swing
• Poor gait initiation
• Hurrying (festinating): catch up with COG
• Tendency of retropulsion (pull Pt backwards and they fall backwards)
• Freezing of gait (severe cases)

UMN DEFICITS

• Spastic hemiparesis
• Bilateral (eg. Cerebral palsy) - diplegic gait
• Arm adducted
• Internally rotated at shoulder
• Flexed at elbow
• Pronated at forearm
• Flexion of wrist and fingers
• Leg slightly flexed at hip
• Extended at knee
• Plantar flexion
• Inversion at foot
• Walk with circumduction gait

Due to release of primitive reflex

Eg. Monkey: primitive spastic reflex to reach for height

APRAXIC GAIT

• Apraxia
• Failure to carry out purposive. Skilled movt (walking) in absence of sig motor, coord, sensory of comprehensive movt

Ataxia gait

• Difficulty initiation
• "Walking through mud" - foot stuck to the ground
• Instability with tendency to fall
• Base slightly widened cf. PD

Diffused disorder of cerebellar cortex resulting in disturbed central organisation of walking

Eg. AD, ischaemic or HT encephalopathy, normal pressure hydrocephalus

Also

M disorder

Arthritis

Jt pain

MUSCLE DISORDER

• Tredelenburg sign
• Fix pelvis with gluteus medius (normally)
• But this weak in proximal myopathy, therefore pelvis tilted when walking
• Waddling gait

GAIT IN NORMAL AGEING

• "Cautious" gait
• Slightly widened base
• Shortened stride
• Slowness in walking
• Reduced synergistic arm and trunk movts
• Mild disequilibrium in response to a push
• Difficulty balancing on one foot
• Note: Normal rhythm and foot clearance (cf. PD and apraxia)

VIDEO: Parkinsonian gait