Week 7: Movement disorders Flashcards
What are movement disorders?
- Abnormality in form and velocity of movements
- associated with neuropsychological deficits
Movement disorders have become synonymous with…
Basal ganglia disease
- Not always the origin of causation
Why is it not surprising the movement disorders can have neuropsychological affects?
Because the basal ganglia has extensive connectivity
Movement control requires what two systems
musculoskeletal and nervous system
What are the 3 stages of movement?
Planning, initiation and execution
What areas are involved in the planning of movement?
Cerebellum and BG
What areas are involved in the initiation of movement?
Motor cortex
What areas are involved in the execution of movement?
Alpha motor neurons and the cerebellum for fine-tuning movements
Movement is part of a circuit - explain the highest level?
Memory, emotion and motivation - intent to move is formed (command neurons)
Movement is part of a circuit - explain the middle levels
Information from the higher level is relayed here
- postures and movements required determined
- feedback loops to modulate the activity
- receive input from receptors in muscles, joints, skin
Creates a motor program, defines what is available to perform the desired task
Movement is part of a circuit - explain the local levels
Receptors send messages to the brain stem and spinal cord - motor neurons then send back to muscle fibres
Akinetic-rigid disorders?
Akinesia, bradykinesia and hypokinesia
What is Akinesia?
Lack of movement
What is bradykinesia?
Slow movement - speed of initiation and execution of purposeful and automatic movements
What is hypokinesia?
Poverty of movement - small in amplitude
Hyperkinetic disorders?
Jerky and non-jerky syndromes
Recognition and diagnosis of these are difficult
What are some of the jerky hyperkinetic disorders?
Myoclonus: sudden brief, shock-like involuntary movements.
Chorea: Quick, irregular, semi purposive involuntary movements
Tics: abrupt, jerky, non-rhythmic movements of sounds that are temporarily suppressible by will power. Preceded by a feeling of discomfort or an urge that is relieved by the tic
What are some of the non-jerky hyperkinetic disorders?
Tremor: Involuntary, rhythmic muscle contractions and relaxations involving oscillations or twitching movements by 1 or more body parts
Dystonia: abnormal movement, uncontrollable muscle contractions. affected body part twists uncontrollably - repetitive movements or abnormal pressure
What is huntingtons disease?
A progressive disorder combining chorea with behavioural disturbances and dementia
Abnormally large repeats of CAG (neucletide sequence) on chromosome 4
Huntingtons is genetic. What is the inheritability rate?
50%
Does parkinsons incidence increase with age?
Yes
Are there any gender differences in parkinsons?
Yes. More common in men
How many parkinsons patients suffer from cognitive deficits?
1/3
What did James Parkinson describe parkinsons as?
Involuntary tremulous motion, with lessened muscular power. Propensity to bend the trunk forward and to pass from a walking to a running pace, the senses and intellects being uninjured
What is a limitation to the way james parkinson described parkinsons disease?
He did not account for or recognise any cognitive impairments
What is parkinsons?
A progressive, degenerative disorder of the central nervous system
Is there a cure for parkinsons?
No. There is no way to replace the neurons that die
What are the major symptoms of parkinsons?
Bradykinesia
With the presence of at least one of the following: Temor, impaired postural reflexes and rigidity
How do those with parkinsons walk?
Slowed gait, feet tend to shuffle along the floor as if weighted down
Gross and fine motor skills in parkinsons?
Both are slowed.
Handwriting becomes small and imprecise
Resting tremor is a symptom of parkinsons - what is it?
Shaking that occurs in relaxed muscles - typically outer extremities such as the hands or feet (e.g. fingers display a regular twitching motion while at rest - pill-rolling tremor)
Occurs from activation of opposing muscles that alternated between contraction and relaxation
Rigidity is a symptom of parkinsons - what is it?
Increased muscle tension that feels rachet-like when resistance is applied
Repeated movements of arm and leg joints result in muscular stiffness, and movements take on a jerky quality
What postural deformity is common in parkinsons?
A stooped posture with flexion of the trunk
Parkinsons patients have difficulty in swallowing foods and liquids. What is this called?
Dysphagia
Slowed or slurred speech is common in later parkinsons why?
Because of a weakness in the muscles used for speech. This is dysarthria
Dementia prevalence in parkinsons?
It is a common late feature of idiopathic Parkinsons affecting 70-80%
How long after the onset of parkinsons, does dementia occur?
A year or more after
What is it when dementia symptoms appear at the same time as motor symptoms?
Dementia with Lewy bodies
Does dementia always occur in parkinsons disease?
No.
Those with parkinsons dementia have additional struggles with…
Social and occupational functioning
What are the biological hallmarks of parkinsons dementia?
Similar to dementia with lewy bodies
- sticky clumps of protein found in neurons
What increases the risk of parkinsons dementia?
Increasing age Advanced disease stage Being male Having hallucinations Older age at onset of parkinsons Family history of dementia More severe motor symptoms
What are movement deficits primarily linked to?
Dopamine deficits
What percentage of patients with parkinsons have depressive symptoms?
30-40%
What percentage of patients with parkinsons have anxiety? and what kinds?
40%
GAD, anxiety attacks, social avoidance and even OCD
Psychotic symptoms in parkinsons?
May affect up to 50%
May include visual hallucinations and delusional behaviour
Explain the parkinsons iceberg
People see some symptoms at the tip of the iceberg - rigidity, tremor, bradykinesia and postural disturbance
But what they don’t see is what is under the water - speech, panic attacks, swallowing problems lack of facial expression, pain, depression, anxiety, hallucinations, sweating
What are the 2 different categories of parkinsons?
Degenerative & symptomatic/secondary
What is degenerative parkinsonism?
Sporadic and genetic degenerative diseases cause nigrostriatal neurodegeneration
What is symptomatic/secondary parkinsonism?
Caused by non-degenerative lesions of the same system or other sites of the striatopallidothalamic-cortical motor circuitry
E.g. infectious, toxic, drug-induced, brain tumours, metabollic
The cause of both neurodegenerative and symptomatic parkinsons is
disorders that affect the nigrostriatal dopamine transmission and or downstream signalling pathways
What is the basal ganglia?
Brain area comprised of a set of brain structures in the telencephalon, diencephalon and mesencephalon
What are the forebrain components of the basal ganglia?
Caudate nucleus, putamen, nucleus accumbens and the globus pallidus
Which two regions of the BG are considered the striatum?
The caudate nucleus and the putamen
What is the substantia nigra and how does it relate to parkinsons?
Part of the BG Contains dopamine neurons 2 parts: - pars compacta - dopaminergic pathway to the striatum - loss of neurons here is the cause of parkinsons - pars reticulata
What are the two pathways of the BG?
Direct excitatory pathway (dopamine D1): activation of the motor cortex. The accelerator as the direct pathway inhibits the basal ganglia - meaning it doesnt have as much control as it normally does
Indirect inhibitory pathway (dopamine D2): inhibition of the motor cortex. is the brakes! excites the basal ganglia and therefore it has its normal control, inhibiting output
Which BG pathway do we use?
Both at the same time - in balance
What is Levodopa (L-DOPA)?
Most effective symptomatic treatment of parkinsons
Problems with L-DOPA?
There are some resistant symptoms: postural abnormalities, freezing episodes and speech impairments (motor), mood and cog impairment (non-motor)
Drug related side effects: psychosis, motor fluctuations,
Plain L-DOPA produces… and we fix it by….
- Nausea
2. Combining with carbidopa to prevent nausea
What are dopamine agonists?
Stimulate dopamine receptors directly
COMT inhibitors?
Are used in combination with L-DOPA. They black the action of enzymes that break down the drug
What are MAO-B inhibitors?
They stop the breakdown of dopamine in the brain - the longer you can keep dopamine available in the brain, the better
What are anticholinergics?
Can be helpful for tremor and may ease dystonia associated with wearing-off or peak-dose effect of levodopa
What is amantadine?
Antiviral drug used for people who may have developed dyskinesias following long term Levodopa use
What surgical technique has been developed to treat severe cases of parkinsons?
Deep brain stimulation
How does deep brain stimulation work?
Very thin wire electrodes are inserted through the skull and brain into the subthalamic nucleus
A connected wire is inserted into the chest under the skin (pacemaker-like control device)
During times of extreme tremor the patient can activate the pacemaker which electrically stimulates the subthalamic nucleus - stops tremor activity
Limitations to symptom relief after deep brain stimulation?
while the tremors stop, bradykinesia and rigidity often persist
Dangers of deep brain stimulation?
Invasive - low but potentially serious risks of haemorrhaging and infection
What else can dep brain stimulation be used for?
MDD, OCD, AD, PD, pain and addiction
