Parkinson's Disease Flashcards
Definition
- Parkinsonism: clinical syndrome characterised by a disorder of movement consisting of tremor, rigidity, elements of bradykinesia, hypokinesia, akinesia and postural abnormalities
- Parkinson’s Disease: clinical syndrome of Parkinsonism associated with a distinctive pathology
- Typically a slowly progressive degenerative disease
- Primarily related to a lack of dopamine
- Most common disease affecting the basal ganglia
Epidemiology
• PD is the second most common neurological disease in Australia (following dementia)
• Affects an estimated 10 million individuals worldwide
• Affects an estimated 80 000 individuals in Australia
• 32 Australians are diagnosed with the disease every day
• 20% of sufferers are < 50 years old and 10% are diagnosed < 40
• The number of people with Parkinson’s has increased by 17% in the last six years with costs to the community increasing by over 48%
• Incidence ~ 1.5 times higher in males than females
Pathophysiology
• Reduction in dopamine
– Disturbance of the central dopaminergic pathway from the substantia nigra to the striatum
• Depigmentation and neuronal loss in the in the substantia nigra
• Presence of lewy bodies with consequent changes to neural conduction in the nigrostriatal pathway
– Basal ganglia, brainstem, spinal cord and cortex
Pathophysiology (cont.)
• Idiopathic
• A family history of PD 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
Pathophysiology
• Reduction in dopamine
– Disturbance of the central dopaminergic pathway from the substantia nigra to the striatum
• Depigmentation and neuronal loss in the in the substantia nigra
• Presence of lewy bodies with consequent changes to neural conduction in the nigrostriatal pathway
– Basal ganglia, brainstem, spinal cord and cortex
• Idiopathic
• A family history of PD 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
Dx
• Up to 35% patients 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 (symmetrical start of symptoms; falls within first year; no response to levodopa)
• Medical imaging may be supportive
• Post mortem autopsy
Clinical Manifestations (5)
Resting Tremor
Rigidity
Bradykinesia
Freezing
Postural Instability
Gait Disturbances
medical mgmt
Medication
• First choice in care
• Aims to correct the neurotransmitter imbalance within the basal ganglia circuitry
• PD frequently necessitates 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 disabling complications such as restless legs, sleep fragmentation, early morning akinesia
***Neurosurgery
• 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; stimulation can be adjusted postoperatively; reversible
Neurosurgery
• Deep Brain Stimulator (cont.)
– Subthalamic nucleus (bradykinesia and rigidity) – Thalamus (tremor)
– Globus Pallidus (dyskinesia)
Neurosurgery
• 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 but results inconclusive at this stage
– Experimental only
PD clinical manifestations resting tremor
• Tremor: 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
PD clinical manifestations rigidity
- Rigidity: characterised by increased stiffness throughout PROM at a joint.
- Same intensity in both flexors and extensors
- Cogwheel rigidity: result of rigidity super imposed on, or interrupted by, tremor
- Degree usually relatively independent of stretch speed
- Degree not necessarily constant
- Major cause in PD is hyperactivity in the long loop reflex pathways, probably in the cortex
- Not considered to contribute to reduced mobility and QOL to the same extent as bradykinesia
PD clinical manifestation 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 phonation
• Mechanisms 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
PD clinical manifestation - 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
PD clinical manifestations -postural instability
• Postural Instability: inability to make appropriate postural adjustments
• Considered a major contributor to the disability associated with PD
• PD patients lose their balance easily, have an increased incidence of falls and fear of falling
• Instability due both to abnormal coordination resulting from brain impairment and secondary adaptions (behavioural and soft tissue)
Postural Instability (cont.)
• Typical PD standing posture: slight flexion of all joints leading to a ‘simian posture’ with the knees and hips slightly flexed, shoulders rounded and head held forward
• Typical PD sitting posture: slumped position in the chair, often sliding sideways and the head held forward
• Mechanisms poorly understood
– Efferent deficit: reduced ability to make rapid, accurately coordinated postural responses due to bradykinesia and/ or akinesia
– Afferent deficit: reduced ability to process afferent inputs preventing flexible adaption in various environments
PD clinical manifestations gait disturbances
- Slowness of movement
- Difficulty in initiation
- Typical PD gait: short, shuffling steps, uneven step lengths, flexed posture, reduced arm swing, decreased angular displacement of the lower limb joints
- Freezing and festination
- Reduced stride length is the biggest contributor to reduced speed and inefficient turning
- Disturbances amplified walking backwards
- Significantly increased falls risk
Goals of physiotherapy
Physiotherapy aims to maximise quality of movement, functional independence and general fitness and minimise secondary complications whilst supporting self management and participation, optimising the safety of people with Parkinson’s Disease
five core areas of PT for PD
– Physical capacity – Transfers – Manual activities – Balance – Gait
PT mgmt - physical capacity
• Sufficient physical capacity is required for performing activities of daily life and participation in society
• Entails the capacity of the neuromuscular and cardiorespiratory systems
• Comprised of:
– Muscle strength
– Endurance
– Coordination
– Range of movement
• Individuals with PD are 1/3 less active than healthy counterparts
– Influenced by: disease severity, gait impairments, activity limitations, mental impairments, fatigue, personal factors
– Results in: reduced muscle strength, length and power, increased falls risk, reduced walking speed, increased risk of adverse health conditions
• Postural changessecondary weakness
