HOW PARKINSON'S DISEASE OCCUR ?

Parkinson's disease is a slowly progressive neurodegenerative disease caused when a small group of brain cells that control body movements die. This disease was first described by James Parkinson in 1817. The disease occurs in about 1% of the people over the age of 65 years. The peak onset of the disease is in the sixth decade of the life. However young onset Parkinson's disease is not uncommon. Though we do not have a clear statistics for Indian population, we are aware that it is more common in Parsi community. According to one estimate it affects more than one million people in United States.


Symptoms


The four major symptoms of Parkinson's disease are:

* Rigidity - stiffness when the arm, leg, or neck are moved
* Resting tremor - tremor most prominent at rest, when sitting quietly
* Bradykinesia - slowness in initiating movement which may contribute to decreased facial expression, change in speech pattern, shuffling gait, smaller-lettered handwriting, trouble with fine finger movements
* Loss of postural reflexes - poor balance and coordination

Not every one with Parkinson's disease experiences the same symptoms. The speed at which symptoms appear in each individual also differs. Hence few people have an accelerated progress of the disease where as some people remains static and slowly progressive in their disease. The disease is never symmetrical on both the sides. It usually affects one side of the body first followed by the involvement of the other side of the body at the later stage.

About 60% of the people with Parkinson's disease experience resting tremor. Symptoms often begin with occasional trembling of one hand that gradually becomes constant. The tremor can progress to the other hand, to the legs and occasionally to the face. However in some patients first manifestation of the disease is bradykinesia i.e. slowness of body activities.

There are many other diseases that can present with parkinsonian symptoms. However they are different in their progress, response to treatment and outcome, than Parkinson's disease. This includes diseases like multi-system atrophy, progressive supranuclear palsy (PSP), cortico-basal ganglionic degeneration (CBGD), etc.

Although tremors would seem to be the biggest problem with the people suffering from Parkinson's disease, the most frustrating symptoms are the symptoms associated with slow movements and gait disturbances. As a result, people with this disease often have trouble dressing, handling utensils, eating, and with personal hygiene. They may also experience difficulty in rising from chair, turning in bed, or getting in and out of car. Without treatment, pronounced disability occurs in about 9 years. However current symptomatic medication may control progression and patients continue to do well longer.

There are no laboratory tests or radiological investigations to diagnose Parkinson's disease. The diagnosis of the disease still remains a clinical judgment. The Parkinson's disease disabilities can be assessed by Unified Parkinson's disease rating score (UPDRS), Schwab and England activities of daily living score and Hoehn and Yahr scoring.

What causes Parkinson's Disease?

Although no distinct cause has been determined, Parkinson's disease is due to gradual loss of cells in an area deep within the brain called substantia nigra, which normally produces a chemical called dopamine. Once produced, dopamine travels to other portions of the brain. One portion called the striatum is the coordination center for various brain circuits. As there is insufficient dopamine in the striatum, the chemical imbalance leads to the symptoms of Parkinson's disease. Later in the disease, cells in other portion of the brain and nervous system also degenerate.

No one knows why this dopamine producing cells die. Scientists are exploring several theories including chemical reactions within the body, exposure to toxic substances and certain genetic factors. A new gene in certain families suffering from Parkinson's disease known as Parkin gene has been identified to be the positive factor for Parkinson's disease. However this has been found to be positive in a small group of patients with young onset of Parkinson's disease. The research is still going on to find out the real cause for Parkinson's disease in large patient population.

Treatment, Medication and Surgery

Symptomatic treatment for Parkinson's disease is usually successful, especially in the early years, although it does not stop its progress to cure the disease. Experts believe that a comprehensive approach to treatment is most effective. This approach includes early diagnosis, exercise, good nutrition and medication that reduces the symptoms. Many people find that an important part of the care is the health, comfort, and information they get in participating the Parkinson's disease support group. These groups discuss such problems of daily living and are among the first to learn about research results and new treatments.

Medication can provide dramatic relief from the symptoms of Parkinson's disease. Neurologists prescribe treatment separately to each patient as disease of each patient is different from other. It may take time and patience to correctly titrate suitable medicine for every individual. The most effective medical treatment for parkinsonian symptoms has been a drug called Levodopa. This drug therapy replenishes the dopamine in the brain and hence is effective in reversing the symptoms of Parkinson's disease. Other drugs that mimic the effect of dopamine called dopamine agonist are also available. They may be prescribed alone in the early disease phase or in combination with Levodopa for later stages to reduce the side effect of Levodopa. Various group of dopamine agonist are available. Continuous research is going on to identify newer and more effective drugs to treat Parkinson's disease. Those who are interested in participating trial of new drugs can ask neurologists for information.

Surgery Pallidotomy, Thalamotomy and Deep Brain Stimulation are the commonly performed surgeries for Parkinson's disease.The surgery is usually offered when medicines fail to give adequate relief from the symptoms. Surgical treatment has been relatively safe and their results are long lasting.

FAQ'S

When should one think about surgery?

Surgery is helpful for relieving tremors, drug induced side effect leading to involuntary movements called dyskinesia, frequent on-off fluctuations, prolonged off periods, pain, dystonia (curling of fingers and toes), postural imbalance, severe rigidity, hallucinations, etc. In short any patient:

Who is not satisfied with his/her level of control of Parkinson's disease. Exhibits Parkinson's disease symptoms causing a decline in the quality of life Has had an adequate and reasonable trial of medications is a candidate for surgery.


Is there any age limit for Parkinson's disease surgery?

Though there are no specific age restrictions for this surgery, it can be said that the patient who is "young" enough to think about surgery can be offered surgery. Common age group of patients undergoing this surgery is between 40 to 75 years. The average age of our patient is around 53 years.


Does any intercurrent disease restrict surgical option?

Diseases like diabetes, hypertension or cardiac problems are not a contraindication for surgery. However active infection or blood clotting disorders are contraindications for surgery.

What is Thalamotomy?

Thalamotomy is an operation by which the tremor generating cells located within the thalamic nuclei of brain are selectively destroyed to control tremors.

What is Pallidotomy?

Pallidotomy is an operation in which an area in the brain called Globus pallidus internus is selectively destroyed to control symptoms of advanced Parkinson's disease like dyskinesias, dystonia, rigidity etc


What is Deep Brain Stimulation Surgery for Parkinson's Disease?

Deep brain stimulation (DBS) involves implantation of electrode deep within the brain. In recent times, Subthalamic Nucleus stimulation has emerged as the favoured site for DBS. This electrode is permanently left in place and connected to a small implantable pulse generator (IPG) (Fig. 3). This remotely programmed pacemaker emits minute pulses of energy through the electrode to block the abnormal activity in the brain that cause the symptoms of Parkinson's disease. Precise targeting improves effectiveness and reduces complications. Additional advantages are that these newer techniques do not require purposeful destruction of the brain. In addition, the stimulation is adjustable and can be tailored to the individual patient. Subthalamic DBS is the most effective in terms of the range of symptoms that respond and the ability of patients to reduce medications. It is better for gait and balance problems than most any other form of treatment.


What is a typical Parkinson's disease surgery like?

Parkinson's disease surgeries are done without general anaesthesia, with patient fully awake. It involves fixation of stereotactic frame to the patient's head under local anesthesia (Fig. 4). This frame is used to locate the brain targets with the help of CT and MRI scans. The coordinates (reference points) that are obtained from this scans are then transferred to the theater computers and final read outs are obtained. These points are then set on the stereotactic arc system and a fine electrode is introduced into the brain, through a small hole drilled into the skull. Electric current is passed through the electrode to check its position in relation to the vital structures surrounding the target area. Neurologist present in the operation theater constantly assesses the clinical improvement in the symptoms
like tremor and rigidity vis a vis side effects. Once it is confirmed that the electrode is in the right place, either destruction of small group of cells is done or a permanent electrode is implanted.


How long does the surgery take?

The actual operation takes approximately three to four hours, but the entire procedure including the CT and MRI scan takes five to six hours.

If the patient is awake, does it not cause any discomfort or pain?

No, the entire procedure is completely painless and without any discomfort. However, we do have an anesthetist and physiotherapist to look after the patient during surgery.


When does the patient realize the benefit of surgery?

The improvement is seen immediately on the operation table. The tremors disappear with similar improvement in stiffness, bradykinesia and pain.

What are the risks of surgery?

The surgery is very safe. There is negligible risk of weakness or visual disturbance. In our series (which is the largest no. of surgeries for Parkinson's disease performed in India) we have less than 2% risk of serious complications.


Who performs this procedure?

The procedure should be performed only at a center that has made the investment and commitment in obtaining state-of-the-art equipment and forming a multi-disciplinary, experienced team consisting of neurosurgeons, neurologists, and neurophysiologists. Wockhardt Brain & Spine Care at Mumbai, India, is one such place where there are dedicated Functional Neurosurgery and Movement Disorder departments having the necessary expertise to perform such complex surgeries.

What are the advantages of surgery?

The advantages of surgery are related to the improvement in disabilities that the patient suffers from Parkinson's disease. The activities of daily living improve, patient can resume his/her work and patients who are severely dependent on others become independent. It improves most of the symptoms of Parkinson's disease patient. Younger patients can even go back to work.