Week 9 : PD Flashcards
What is parkinsonism
clinical syndrome characterised by a disorder of movement consisting of tremor, rigidity, elements of bradykinesia, hypokinesia, akinesia and postural abnormalities
What is Parkinson’s disease
clinical syndrome of Parkinsonism associated with a distinctive pathology
Aetiology of parkinson’s
typically a slowly progressive degenerative disease
primarily related to a lack of dopamine
most common disease affecting the basal ganglia
epidemiology of parkinson’s disease
2nd most common neurological disease in Australia (following dementia)
M 1.5: 1 F
pathophysiology of parkinson’s disease
reduction in dopamine
- disturbance of the central dopaminergic pathway from the substantia nigra to the striatum
deep pigmentaton and neuronal loss in the substantia nigra
presence of lewy bodies with consequent changes to neural conduction in the nigrostriatal pathway
- BG, brainstem, spinal cord and cortex
pathophysiology of parkinson’s disease #2
idiopathic
a family hx is the strongest risk factor for the development of the disease
genetic mutations
rural residence is a significant risk factor for PD
positive association between PD and pesticides
negative association with cigarette smoking
genetic and environmental factors are now thought to interact and increase the risk of developing PD
diagnosis of PD
35% Misdiagnosed /mismanaged
primarily clinical diagnosis
- presence of bradykinesia and progressive reduction of speed amplitude of repetitive movements
- rigidity, resting tremor and/or postural instability
- absence of red flags
what are the four clinical subtypes of PD
earlier disease onset (<55 years)
tremor dominant
postural imbalances and gait disorder (PIGD)
disease progression, prognostic factors and mortality
high variability in impairments of functions, activity limitations and participation restriction
postural and axial symptoms evolve more rapidly than other motor features are appear to be the index of disease progression.
Hoehn and Yahr staging scale is used clinically to stage PD progression
it’s not linear
doesn’t include non-motor functioning
slide 11
MDT involved with PD
as many as 19 health professionals and institutions may be involved in one patient’s care
medication for PD
first choice in care
aims to correct the neurotransmitter imbalance within the basal ganglia circuity
PD frequently necessities multiple doses of multiple medications
current pharmacological management largely based on dopamine precursor levodopa and dopamine agonists
levodopa
gold standard : offers best symptomatic relief of rigidity, bradykinesia and tremor
dopamine agonists
often prescribed to alleviate other diabling complications such as restless legs, sleep fragmentation, early morning akinesia
Neurosurgery
thalamotomy
deep brain stimulator
thalamotomy
lesioning procedure, not widely used now
deep brain stimulator
high frequency electro-stimulation through permanent implanted electrodes in the brain
-battery implanted in chest wall below clavicle and connects to DBS by subcutaneous wire
Mimics lesioning procedure without destroying brain tissue; can be performed bilaterally; stimualation can be adjusted postoperatively; reversible
subthalamic nucleus (bradykinesia and rigidity) Globus pallidus (dyskinesia)
Transplant surgery
foetal nigral cells (dopamine- producing) are introduced into appropriate areas of the brain to replace degenerating substantia nigra
they may restore dopamine production by results inconclusive at this stage
experimental only
clinical manifestations of PD: Resting tremor
Temor: approximately rhythmic, involuntary and roughly sinusoidal movement of a body part
• Resting tremor is a cardinal sign of PD
– Often the first sign of PD
– Typically unilaterally
– More prominent distally
– Commonly observed in: hands, feet, lips, chin, jaw
– Usually supressed by voluntary activity, sleep and complete relaxation
– Results from oscillations in a hyperactive long loop reflex pathway triggered at the thalamic level and influenced by peripheral afferents
Clinical manifestations of PD : bradykinesia
Bradykinesia: umbrella term to describe slowness of or absence of movement
– Hypokinesia: reduced amplitude of movement
– Akinesia: reduced spontaneous movement (e.g. facial expression, arm swing during gait), slowness to initiate movement and freezing while moving
• Most disabling manifestation of PD
• Affects performance of all motor actions and associated postural adjustments and articulation and phonationMechanisms poorly understood
– Failure of basal ganglia to reinforce the cortical mechanisms that prepare and execute motor commands
– Cueing or directing attention towards the size and/or speed of the movement can normalise many movements
– Compensation not limitless
clinical manifestations : freezing
-Freezing: difficulty starting or continuing rhythmic repetitive movements (e.g. gait, handwriting, speech)
• Distinct clinical sign of PD
• Freezing of gait (FOG): episodic gait disturbance, typically experienced when walking through an enclosed space or turning
– Festination (progressive shortening of stride length and increasing cadence) often occurs prior to freezing
– Feet appear to stick to the floor while momentum carries the centre of body mass forward
– Occurs more frequently in cluttered environments, stressful circumstances or when patient is distracted
clinical manifestations : Postural instability
postural instability: inability to make appropriate postur
