Parkinsons Flashcards
Classic triad of Parkinsons?
Bradykinesia
Rigidity
Resting Tremor
Presentation of Parkinsons?
Typically 70 year old man
Unilateral tremor
4-6 Hz (occurs 4-6 times a second)
“pill rolling tremor” because it looks like they are rolling a pill between their fingertips and thumb.
More pronounced when resting and improves on voluntary movement.
The tremor is worsened if the patient is distracted.
Asking them to do a task with the other hand, such as miming the motion of painting a fence, can exaggerate the tremor.
“Cogwheel” Rigidity
Rigidity is a resistance to passive movement of a joint. If you take their hand and passively flex and extend their arm at the elbow, you will feel a tension in their arm that gives way to movement in small increments (like little jerks). This is what leads to the cogwheel description.
Bradykinesia
Bradykinesia describes how their movements get slower and smaller. This presents in a number of ways:
Their handwriting gets smaller and smaller (this is a classic presenting complaint in exams)
They can only take small steps when walking (“shuffling gait”)
They have difficulty initiating movement (e.g. from standing still to walking)
They have difficulty in turning around when standing, having to take lots of little steps
They have reduced facial movements and facial expressions (hypomimia)
Other features of Parkinsons
There are a number of other features that often affect patients with Parkinson’s disease:
Depression
Sleep disturbance and insomnia
Loss of the sense of smell (anosmia)
Postural instability
Cognitive impairment and memory problems
Parkinsons vs Resting Tremor
Parkinsons Plus syndrome
Multiple System Atrophy
This is a rare condition where the neurones of multiple systems in the brain degenerate. It affects the basal ganglia as well as multiple other areas. The degeneration of the basal ganglia lead to a Parkinson’s presentation. The degeneration in other areas lead to autonomic dysfunction (causing postural hypotension, constipation, abnormal sweating and sexual dysfunction) and cerebellar dysfunction (causing ataxia).
Dementia with Lewy Bodies
This is a type of dementia associated with features of Parkinsonism. It causes a progressive cognitive decline. There are associated symptoms of visual hallucinations, delusions, disorders of REM sleep and fluctuating consciousness.
Others
Two other Parkinson’s-plus syndromes exist that involves a number of complex progressive neurological features:
Progressive Supranuclear Palsy
Corticobasal Degeneration
Diagnosis of Parkinsons
Parkinson’s disease is diagnosed clinically based on symptoms and examination. The diagnosis should be made by a specialist with experience in diagnosing Parkinson’s. NICE recommend using the UK Parkinson’s Disease Society Brain Bank Clinical Diagnostic Criteria.
Management of Parkinsons
Treatment is initiated and guided by a specialist, and is tailored to each individual patient and their response to different medications. There is no cure, so treatment is focused on controlling symptoms and minimising side effects.
Patients describe themselves as “on” when the medications are acting and they are moving freely, and “off” when the medications wear out, they have significant symptoms and their next dose is due.
Levodopa
COMT inhibitor
Dopamine agonists
Monoamine Oxidase-B Inhibitors
Levodopa
This is synthetic dopamine given orally to boost their own dopamine levels. It is usually combined with a drug that stops levodopa being broken down in the body before it gets the chance to enter the brain. These are peripheral decarboxylase inhibitors. Examples are carbidopa and benserazide.
Combination drugs are:
Co-benyldopa (levodopa and benserazide)
Co-careldopa (levodopa and carbidopa)
Levodopa is the most effective treatment for symptoms but becomes less effective over time. It is often reserved for when other treatments are not managing to control symptoms.
The main side effect of dopamine is when the dose is too high patients develop dyskinesias. Theses are abnormal movements associated with excessive motor activity. Examples are:
Dystonia: This is where excessive muscle contraction leads to abnormal postures or exaggerated movements.
Chorea: These are abnormal involuntary movements that can be jerking and random.
Athetosis: These are involuntary twisting or writhing movements usually in the fingers, hands or feet.
COMT inhibitor
The main example of this is entacapone. These are inhibitors of catechol-o-methyltransferase (COMT). The COMT enzyme metabolises levodopa in both the body and brain. Entacapone is taken with levodopa (and a decarboxylase inhibitor) to slow breakdown of the levodopa in the brain. It extends the effective duration of the levodopa.
Dopamine Agonsits
These mimic dopamine in the basal ganglia and stimulate the dopamine receptors. They are less effective than levodopa in reducing symptoms. They are usually used to delay the use of levodopa and are then used in combination with levodopa to reduce the dose of levodopa that is required to control symptoms. One notable side effect with prolonged use is pulmonary fibrosis. Examples are:
Bromocryptine
Pergolide
Carbergoline
Monoamine Oxidase-B Inhibitors
Monoamine oxidase enzymes break down neurotransmitters such as dopamine, serotonin and adrenaline. The monoamine oxidase-B enzyme is more specific to dopamine and does not act on serotonin or adrenalin. These medications block this enzyme and therefore help increase the circulating dopamine. Similarly to dopamine agonists, they are usually used to delay the use of levodopa and then in combination with levodopa to reduce the required dose. Examples are:
Selegiline
Rasagiline
