When the English physician James Parkinson published his Essay on the Shaking Palsy, 190 years ago, he did not know that the disease he discovered would bear his name.
Today, the disease named after Parkinson is ranked among one of the most common neuro-degenerative diseases that affects about 30 per cent of people in their seventies.
Parkinsonism is, in actuality, a syndrome characterised by features of Parkinson's disease, in association with other neuromuscular manifestations. More of this later.
It ain't as simple, in reality, though - because many of the changes that occur with normal aging mimic Parkinsonism. It is, therefore, important to differentiate between them - if proper treatment is to be offered.
Our balance, posture and movements are controlled by a complex mechanism involving the cerebral cortex and brainstem — with dopamine being the essential neurotransmitter [chemical messenger] in the process. Progressive loss of nerve cells and depletion of dopamine, particularly in the substantia nigra, a part of the brain stem, results in Parkinson's disease.
Loss of dopamine simply affects balance, posture, movements, memory, and concentration.
It is not yet clear what causes dopamine loss. Experts believe that a combination of genetic and bio- logic factors, triggered by some environmental insult, may be responsible. It is estimated that, per decade of life, about 9-13 per cent of approximately 4,50,000 dopamine-producing neurons in the substantia nigra undergo age-related attrition and/or death.
With advanced age, about 70-80 per cent of such neurons may be lost when the disease first manifests itself.
A number of environmental neurotoxins, industrial chemicals, metals, pesticides and herbicides have, of course, been reported as possible causes for Parkinsonism. It is suggested that they may accelerate the process of nigral cell death.
Role of genes
In some individuals, a certain genetic susceptibility may play a role. Recently, defects in the genes coding for the proteins alpha-synuclein and parkin have been identified, particularly in young patients developing Parkinsonism.
Injury from oxygen free radicals, overexcited N-methyl-D-aspartate [NMDA] receptors, overactive immune response, heightened inflammation and infectious organisms have all been blamed as causative factors for Parkinsonism. This is not all. The substantia nigra and other parts of the brain may also characteristically show fibrous deposits in some individuals. This is called as Lewy Bodies — the hallmark of Parkinson's disease.
A resting tremor, rigidity of muscles, slowness of movements and postural instability are characteristic features of Parkinsonism. Rest tremor is an easily recognisable and specific sign of Parkinson's disease. It usually starts on one side of the body and may remain so for a long time. Classically appearing as pill-rolling movements with the thumb and fingers, it occurs when the arm is resting with support and disappears with action. Resting tremor is a reliable clue to the diagnosis of Parkinson's disease. Slowness of movements is another important feature that distinguishes Parkinson's disease — this is also the most disabling.
Lack of expression on the face with reduced blinking [mask face], abridged arm swinging while walking, difficulty in arising from the chair, or turning around, or rolling over in bed, are some of the manifestations of slow motor activity. Eventually, the person may develop a stooped posture and slow, shuffling walk.
Decreased motor activity can lead to many other problems. Difficulty in walking and unstable posture can increase the risk of falls and injury. Patients can also suffer from problems while swallowing with risk of aspiration pneumonia. Constipation and problems in passing urine can also occur. Also, as many as 70 per cent of individuals, affected by the disorder, may have difficulty in speaking.
It is common to find Parkinsonism individuals bogged down by depression, anxiety, or behavioural problems. Dementia, or memory loss, can occur in progressive forms of the disease.
In some, there may be dysfunction of the autonomic nervous system characterised by fall in blood pressure on standing, resulting in dizziness, or fainting. Early onset of dementia, falling and hallucinations and lack of tremors usually indicate Parkinsonism rather than Parkinson's disease.
Diagnosis of Parkinson's disease is primarily based on clinical findings, as imaging studies and other investigations are of limited value. Presence of any two - tremors, rigidity and slowness of movements - would strongly suggest the possibility of Parkinson's disease.
Cerebrovascular disease and multiple small strokes, Alzheimer's disease, dementia with Lewy bodies, encephalitis caused by influenza, progressive palsy and multiple system atrophy [wasting] can have symptoms similar to Parkinson's disease. Essential tremors and senile gait may also be confused with Parkinson's disease in the elderly.
It should also be kept in mind that certain drugs can cause symptoms of Parkinsonism, when elderly patients are on multiple medications.
Management or treatment of Parkinsonism includes drugs, physical therapy and, in certain cases, surgery. Treatment is targeted at improving the person's motor activity and providing relief from disconcerting tremors. Treatment is often individualised depending on the severity of the disease, and the needs of the patient. It is ideal for patients to work closely with their physicians/therapists to customise treatment plans. Medications and their dosage should not be changed, or stopped abruptly, without consulting your physician/therapist.
Treatment aimed at replenishing brain levels of dopamine and levodopa, or L-dopa, has remained the gold standard for years. They increase brain levels of dopamine.
Other drugs which are used in every phase of the disease, especially in the initial stages, mimic the action of dopamine [or, so-called dopa agonists]. These include bromocriptine, pramipexole and ropinirole. Selegiline and amantadine also offer benefit in some patients. Levodopa can be used alone, though it is often combined with carbidopa. This improves its availability in the brain and helps prolong its action. Experts suggest that it won't be long before newer drugs help slow down the progression of the disease.
When drugs fail, surgical treatment like deep brain stimulation and pallidotomy may help some patients. Deep brain stimulation, also called neurostimulation, makes use of an electric pulse generator that sends electrical pulses to specific regions of the brain to help control symptoms.
Stem cell transplants into the substantia nigra to improve dopamine production is now being actively studied. If successful, they hold promise for the future.
In addition to drugs, various exercise programmes and gait training may also help Parkinson's patients.
Important: although Parkinson's disease is not fatal, it can reduce longevity, and cause serious complications due to falls. In certain cases, it can also seriously impair the quality of life. In addition to this, as patients become increasingly dependent, physical and emotional impact on the family can be ever so demanding.
It is imperative that good understanding between patients, families, and the physician/therapist is nurtured for better treatment outcomes.
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