Gold standard case presentation

Parkinson’s Disease

Parkinson’s Disease (PD) is a neurodegenerative disorder that often takes decades to diagnose and has unfortunately significant co-morbidities associated. The exact cause is unclear, with some genetic predisposition identified in some, but not others. The end result is breakdown of the dopaminergic pathways with Lewy bodies developing and spreading often diffusely, which leads to associated dementia.

The first step is diagnosis, and this requires specific criteria to be met in a specialist clinic. It is frequently suspected of course, but not diagnosed by a generalist or the primary care physician.

Diagnosis

PD should be suspected in people with tremor, slowness, stiffness, difficulty with balance and/or gait dysfunction. There is no specific test and PD is diagnosed based upon the history and clinical features.

The formal diagnosis requires the following: bradykinesia (progressive retardation of movements) must be present along with one, or more than one of the following symptoms:

• rigidity (‘lead pipe’ with ‘cogwheeling’, which is noticed especially in the upper limbs);
• tremor (at rest and on movement – low frequency and asymmetrical ‘pill rolling’);
• neck and trunk flexor dysfunction;
• difficulty in maintaining balance due to dysfunction reflexes;
• shuffling gait with festinate sites and frequent freezing, reduced arm swing and more frequent steps.

Continuing movements is not the issue, but initiating them is.

Additional clinical features which help confirm the diagnosis:

• onset was unilateral with potential persistent asymmetry;
• progression of symptoms;
• good response to levodopa (diagnosis with trial of treatment) which needs to be maintained for a minimum of 5-years;
• development of levodopa-induced chorea after 10 years (of treatment);
• symptoms and progression of over 10 years (in retrospect patients often report they experienced symptoms longer than initially thought at presentation);

Common clinical features:

• reduced gesturing of the arms;
• reduced facial expressions;
• reduced blinking;
• retardation of speech;
• fatiguability of recurrent movements.

Differential Diagnosis

It is important to exclude other causes of similar symptoms, or PD mimics, which can result in parkinsonism, but not Parkinson’s disease, which include:

• progressive cerebrovascular damage with stepwise deterioration;
• recurrent head injury (i.e. boxer);
• Use of anti-psychotic and domaine-depleting drugs;
• confirmed encephalitis;
• remission that is maintained;
• confirmed unilateral clinical features for a minimum of 3-years;
• other neurological features such as early-onset severe dementia;
• drugs that can induce symptoms such as metoclopramide or prochlorperazine;
• confirmed intracerebral tumour;
• Wilson’s disease;
• occurs with Alzheimer’s dementia, Lewy Body dementia and normal pressure hydrocephalus (with associated dementia and dyspraxic gait).

The average of diagnosis is in the early-to-mid 60’s and the life expectancy at diagnosis is on average 16-17 years.

Parkinson’s and Dementia

There is an overlap of around 90% of PD and cognitive impairment, with up to 40% of these patients displaying overt dementia.

The definition of dementia in the context of PD is the normal definition of dementia with the presence of PD motor symptoms that have been present for at least one year.

Most people with PD after 20-years will have dementia. There are Lewy bodies in PD dementia, but the difference between PD dementia and Lewy Body dementia is that the Lewy bodies in PD dementia develop sub cortically to cortically and in Lew Body dementia, they develop in the other direction, i.e. cortically to sub cortically, which then leads to symptoms of Parkinsonism.

Management

PD is very much a multi-disciplinary team condition, requiring specialists from many areas to coordinate and manage the symptoms and outcome of patients.

Medication:

• should be initiated by specialist only;
• after the initiation phase, at some point (around 5 years after commencement) medication enters the complex phase:
  • this indicates multiple drugs, over multiple doses with frequent changes and unfortunately often side effects;

Key drug: Levodopa

• primary treatment for disease management (but not cure);
• has no effect on progression of disease, but reduced symptoms;

Side effects:

• postural hypotension (which is also a complication of PD itself and hence can be difficult to determine if due to medication or the disease itself)
• cognitive decline
• dyskinesias
• fluctuations of disease that are sudden, such as freezing or bradykinesia
• treatment starts to wear off, on average after 5-years
• older patients are more susceptible to non-motor complications such as cognitive decline and less susceptible to dyskinesias
• to reduce tremors and rigidity, drugs to reduce cholinergic activity via anti-muscarinics are effective

Physiotherapy:

• gait disturbance;
• management of autonomic symptoms such as postural hypotension.

Dietician:

• with associated dementia, good dietetics is key

Speech and language:

• with retardation comes retardation of swallow and retention of secretions leading to increased dysphagia and infections;
• SLT assessments are useful to monitor and advise regarding the consistency of food items to reduce this.

Pharmacy:

• with other co-morbidities, reducing polypharmacy and drug interactions is essential

Drugs that can induce Parkinsonism

There are a number of drugs that can cause symptoms of Parkinsonism, such as the classic anti-psychotics (which inhibit dopamine D2 receptors).