Movement Disorders: Akinetic-Rigid Syndromes Flashcards
What is the definition of Parkinson’s disease?
Neurodegenerative disease of the dopaminergic neurones of the substantianigra, characterized by bradykinesia, rigidity, tremor and postural instability.
Describe the epidemiology of Parkinson’s disease?
Very common: 1–2% of >60-year-olds.
Annual incidence is 20 in 100000.
Slightly more common in males M:F = 1.5:1
Mean age of onset is 57 years
Describe the pathogenesis of Parkinson’s disease
Main pathological finding in Parkinson’s is degeneration of pigmented dopaminergic neurons that project from the substantia nigra in midbrain to the basal ganglia.
Approx 70% of these neurons are lost before Parkinson’s becomes clinically evident.
-@ postmortem surviving neurons are found to have characteristic abnormalities known as Lewy bodies.
Insufficient dopamine formation leads to symptoms of Parkinson’s disease.
What would a patient with Parkinson’s disease describe in their history?
- Insidious onset.
- Tremor at rest, usually noticed in hands.
- Stiffness and slowness of movements.
- Difficulty initiating movements (e.g. getting out of chair, rolling in bed).
- Frequent falls.
- Smaller hand writing (micrographia).
- Insomnia, mental slowness (bradyphenia)
What would be found on examination of a patient with Parkinson’s disease?
Tremor: Classically pill rolling rest tremor in the hands of about 4–6Hz frequency. Decreased on action or flexed posture. Usually asymmetrical.
Rigidity: Lead pipe rigidity of muscle tone, with superimposed tremor (cogwheel rigidity).
Rigidity can be enhanced by distraction (asking the patient to keep raising and lowering the other arm).
Gait: Stooped, simian, shuffling, small-stepped gait with reduced arm swing. Freezing (difficulty in initiation of walking).
Postural instability: Falls easily with little pressure from the back (propulsion) or the front (retropulsion).
Other features:
Frontalis overactivation (furrowing of the brow), expressionless face (hypomimia),
soft monotonous voice (hypophonia),
impaired olfaction on formal testing.
There may be mild impairment of up-gaze and tendency to drool (sialorrhoea).
Involuntary movements in one part of the face associated with voluntary movement in another part of the face (synkinesis)
Psychiatric: Depression is very common. Cognitive problems and dementia may occur in late disease
What investigations would you perform if you suspected your patient had parkinson’s disease?
DIAGNOISIS IS CRUCIAL.
Levodopa trial: Timed walking and clinical assessment after levodopa may be informative.
Antiemetic (domperidone) may be needed.
Blood: Serum ceruloplasmin (excludes Wilsons disease in young onset).
CT or MRI brain: Useful for excluding other causes of gait decline (e.g.hydrocephalus, vascular disease).
Dopamine transporter scintigraphy (DAT-scan): Reduction in striatum and putamen. May benecessary for distinguishing from essential tremor.
How would you manage a patient with Parkinson’s disease?
Underlying neurodegenerative process is still not treatable.
Medical: Symptomatic therapy by dopamine replacement..
-L-DOPA with peripheral DOPA decarboxylase inhibitor (carbidopa, benserazide); varying formulations.
Most effective treatment but long-term therapy has serious complications.
-Dopamine receptor agonists, oral agents (e.g. ropinirole, pramipexole) and parentalagents (apomorphine subcutaneous pump, patch).
-Anticholinergics (e.g. benzatropine, amantadine) have a modest effect on tremor.
-COMT inhibitor (e.g.entacapone) may reduce end-of-dose deterioration, especially when combined with levodopa.
-MAO-B inhibitor (e.g. selegiline).
-Rivastigmine (anticholinesterase) has been shown to be beneficial for Parkinsons Disease patients with dementia.
Surgery:
Stereotactic thalamotomy, pallidotomy and deep brain stimulation (subthalamic nucleus) can substantially reduce levodopa requirements (and thus levodopa-induced dyskinesias)
Other: Physiotherapy, occupational and speech therapy is vital in maintaining a reasonable quality of life
What complications are associated with Parkinson’s disease?
Depression, dementia, autonomic dysfunction (postural hypotension,constipation, urinary retention or overflow incontinence, erectile dysfunction), death (usually from pneumonia or pulmonary embolism).
Treatment complications (develops over months and years on chronic levodopa therapy):
- On–offmotor fluctuations.
- Peak dose dyskinesias (typically choreaform, dance-like).
- On–off dystonia (e.g. typically in feet).
- Impulse control disorders (e.g. pathological gambling, hypersexuality, punding behaviour)
What prognosis would you expect for a patient with Parkinson’s disease?
Progressive but variable in rate.
Optimal treatment can delay impact of disability by 5–10 years.
Other than Parkinson’s disease give examples of other akinetic-rigid syndromes.
Drug induced parkinsonism
Parkinson plus syndromes
Diffuse cerebrovascular disease
What is drug-induced parkinsonism?
Relatively common adverse affect of neuroleptic drugs used for schizophrenia and other psychotic disorders.
These drugs block dopamine receptors in the brain, result in clinical features resembling parkinson’s disease
Symptoms may improve if the drug is stopped/
What are Parkinson Plus syndromes?
Uncommon disorders resulting in features of parkinsonism and other progressive neurological deficits.
Eg Progressive supranuclear palsy and multiple system atrophy.
These syndromes respond poorly to levadopa therapy and have a worse prognosis than Parkinson’s disease.
How might diffuse cerebrovascular disease present with features similar to those of Parkinson’s disease?
Indiv present with physical and mental slowing and a shuffling gait.
In contrast to Parkinson’s features tend to be symmetrical and a resting tremor is unusual
Other features of cerebrovascular disease, eg brisk reflexes, extensor plantar responses and a history of vascular risk factors are often evident.
Vascualr parkinsonism responds poorly to levadopa.
