Spectrum of Parkinson’s Disease
The main motor symptoms are collectively called parkinsonism, or a "parkinsonian syndrome".
Parksinson’s Disease is the most common of the parkinsonian syndrome. 85% of cases of parkinsonism have idiopathic PD, for which there is no known external identifiable cause. The diagnosis and management discussed in the rest of this resource refers to Idiopathic PD.
The remaining 15% of patients with parkinsonism have different rarer conditions and are briefly described below;
Vascular (arteriosclerotic) parkinsonism is a form of atypical parkinsonism where parkinsonian type symptoms are caused by multiple small strokes in the corpus striatum. CT findings often show small vessel disease in the basal ganglia and multiple cerebral infarcts. There is a preponderance to lower limb symptoms; e.g. shuffling short stepped gait, and falls. Tremor is usually absent.
Drug-induced, drugs used to treat schizophrenia, and other psychiatric conditions, i.e. neuroleptics such as haloperidol, or atypical anti-psychotics such as clozapine which are dopamine receptor blockers can induce parkinsonism. Commonly used antiemetics such as metoclopramide and prochlorperizine are also culprits.
Lewy Body Disease is the third commonest form of dementia, and the motor symptoms often overlap with Parkinson’s disease, the two conditions are often confused. Here Lewy bodies are widely present throughout the cortex and not predominantly in the substantia nigra as with idiopathic Parkinson’s. The dementia is characterised by non-threatening silent hallucinations, and motor symptoms are a late feature.
Parkinson plus syndromes; These 'atypical parkinsonism syndromes' are a rare group which look like PD but are much more severe, exhibiting red flags. Median survival is only seven years compared with the normal lifespan in PD. They include:
- Multiple system atrophy - initially appears as parkinsonism but there is early autonomic failure (incontinence and postural instability) and ataxia, cognition remains intact.
- Progressive supranuclear palsy - characterized by vertical gaze palsy, so struggle to look up and down. There is often chaotic falling (launching themselves into bed/ chair). There is loss of swallow and/or speech early and frontal lobe dementia.
Parkinson’s Disease affects 120,000 people in UK. The prevalence being 1 in 500. The mean age at presentation is 65 years. Incidence increases with age- 1% at age 60 to 4 % at age 80 There are slightly more males to females affected with a ratio of 1.8:1. Life expectancy is unaffected in Idiopathic PD, but 1/3 have associated depression and 1/3 have cognitive impairment. The annual cost to the NHS is £10,000 per year per patient. An increased risk of PD is associated with exposure to certain pesticides and there is a reduced risk in both tobacco smokers and those with increased caffeine consumption.