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[back] Misconceptions about Parkinson's Disease Dr Norlinah Mohamed Ibrahim - 21 May 2009

Misconceptions About Parkinson's Disease

By: Associate Prof. Dr Norlinah Mohamed Ibrahim
Consultant Neurologist (Movement Disorders) and Head,
Neurology Unit, Pusat Perubatan Universiti Kebangsaan Malaysia,
Medical Advisor, Persatuan Parkinson Malaysia

Parkinson'S Disease
Parkinson's disease is the second commonest late life neurodegenerative disease after Alzheimer's disease. It is prevalent throughout the world and predominantly affects patients above 60 years of age. It is caused by progressive degeneration of dopamine containing cells (neurons) within the deep structures of the brain called the basal ganglia and substantia nigra. Both motor and non-motor symptoms exist in PD, although the cardinal features and the diagnosis of PD is based purely on the presence of motor symptoms.
Diagnosis of PD
Diagnosis of PD is purely clinical and requires the presence of bradykinesia or slowness of movement and one or more of the clinical features listed below:
  1. Tremor
  2. Rigidity
  3. Postural imbalance
Bradykinesia is the hallmark feature of PD and correlates with the extent of dopaminergic cell loss in the brain. Neuroimaging such as CT and MRI brain scans are only performed to exclude other conditions that may mimic PD such as vascular parkinsonism or Parkinson's Plus syndromes.
Motor symptoms of PD
Symptoms in PD can be divided into motor and non-motor. Typical motor symptoms include tremor of the hands and/or legs and slowness of movement. Tremor in PD is also known as 'pill-rolling' tremor, as it has the characteristic appearance of someone rolling a pill in his hands. It usually occurs when the patient is resting and become more pronounced with mental tasks or anxiety. Bradykinesia may affect any parts of the body including the face, causing reduced facial movements (hypomimia) and eye blinking resulting in a 'mask-like' or expressionless appearance. Hand-writing may become progressively smaller (micrographia) and patient may lose dexterity in carrying out daily tasks. The gait may also be affected, resulting in smaller strides with lack of arm swing, giving a shuffling appearance when walking. As the disease progresses, patients may develop freezing of gait, which could result in falls. The voice may become low-pitched and monotonous, with excessive drooling of saliva. In the beginning, symptoms of PD may be restricted to one side of the body (unilateral). However, with disease progression, both sides of the body will be affected, causing significant disability to patients if left untreated.
Non-motor symptoms (NMS)
In addition to the motor symptoms, non-motor symptoms (NMS) such as constipation, sleep disturbances and depression also predominate in PD. Unlike the motor symptoms, NMS are usually poorly recognised and hence inadequately treated. Studies have shown that NMS are important determinant of quality of life, causing significant disability to patients if left untreated. Some of the NMS features such as depression and constipation may even predate the clinical diagnosis of PD by several years. The NMS complex of PD can be broadly categorised into the following groups.
  1. Neuropsychiatric disturbances
    Among the common neuropsychiatric disturbances of PD include depression, anxiety, and apathy. Depression affect up to 45% of patients with PD and is characterised by feeling of guilt, remorse, sadness and contributes to poorer quality of life. Patients may also exhibit obsessional traits, anhedonia (lack of pleasure), attention deficits, panic attacks, delirium, confusion, delusions, illusions and dementia. Dementia affects up to 30% of patients with PD and typically occurs as a late feature.

  2. Sleep disturbances
    Almost all patients with PD will have some degree of sleep disturbances. The common sleep complaints in PD are insomnia (difficulty initiating and maintaining sleep) and excessive daytime sleepiness. Excessive daytime sleepiness affects up to 50% of patients with PD and is believed to be due to a combination of medications such as dopamine agonists and the presence of nocturnal sleep disturbances. Patients may fall asleep unexpectedly at unusual times. With disease progression, the sleep pattern becomes fragmented, with frequent awakenings throughout the night.

    Sleep disordered breathing or sleep apnoea syndrome affects up to 30% of patients with PD. Patients with this disorder will have excessive snoring and episodes of apnoea (breathing arrest), followed by periods of excessive breathing (hyperapnoea). Patients may also experience REM sleep behaviour disorder (RBD); during which they are noted to have violent movements and vocalisations, as if they are 'acting-out' their vivid or unpleasant dreams. Interestingly, RBD can precede the onset of PD by several years in up to 40% of patients. Other sleep disturbances that may affect sleep quality are restless leg syndrome (RLS) and periodic limb movements of sleep (PLMS). Symptoms of RLS occur mainly in the evenings, when the patient is resting. Patients will complain of intense restlessness in their legs which disappears with movements such as walking or shaking their legs. In PLMS, patients will have periodic cycling-like movements of their legs during sleep. Patients with PLMS are more likely to have fragmented sleep as a result of frequent awakenings throughout the night.

  3. Autonomic disturbances
    Autonomic dysfunction such as constipation, dizziness, drooling of saliva and sexual dysfunction are also common in patients with PD. Constipation is probably the most frequent complaint and usually requires the use of regular laxatives. Patients may also complain of bladder symptoms such as urinary frequency and urgency. Sexual dysfunction includes both erectile impotence and hypersexuality; the latter is usually medication-related. Orthostatic hypotension or postural drop in blood pressure may cause dizziness and falls in some patients, if untreated.

  4. Gastrointestinal problems
    Patients may also complain of problems with the gastrointestinal tract such as nausea, difficulty swallowing, choking, and sensation of incomplete voiding of bowels, severe constipation and inability to taste. Inability to smell (anosmia) occurs early in the disease and is an important preclinical marker of the disease.

  5. Sensory symptoms
    Pain is a common symptom of PD, which is frequently overlooked. Pain can be either due untreated motor problems such as early morning dystonia and akinesia or alternatively part of musculoskeletal problems.
Treatment of PD
PD is a treatable disease. The motor symptoms of PD can be effectively treated with dopamine replacement therapies i.e. dopamine precursors (levodopa) or dopamine agonists (mimics the action of dopamine on the dopamine receptor). Other medical treatment available include monoamine-oxidase inhibitors (MAO-I), which aim to delay the breakdown of levodopa in the brain. Treatment of PD has to be individualised, taking into account the patient's age of onset, the disease severity, the presence of non-motor symptoms and the patients' expectations. Counselling is an important part of treatment, so that patients and carers are aware of the prognosis and the expectation of the disease.

In the beginning, symptoms of PD may be completely abolished by medications. However, with disease progression, patients may develop complications related to medications and other non-motor problems such as depression and dementia, which makes treatment extremely challenging. Appropriately selected patients with medication-related complications can further benefit from brain surgery such as deep brain stimulation or lesioning procedures.
Conclusion
PD is a complex disease with both motor and non-motor manifestations. All patients should be screened for non-motor complaints as it has been shown to contribute to an overall poorer quality of life and institutionalised. Treatment of PD should be individualised and if possible should be managed by a multidisciplinary team, with aim to address all aspects of the disease.