PARKINSON'S DISEASE AND TREATMENT
DEEP BRAIN STIMULATION
Parkinson’s Disease is a disease of the brain that is caused by the failure of a specific area, the substatia nigra compacta, to produce an essential substance, dopamine. This results in a host of abnormalities in brain function. It is these abnormalities that produce the clinical picture we recognise as Parkinson’s Disease. Although the condition can usually be recognised by experienced clinicians, there are other illnesses that may mimic Parkinson’s Disease. Unfortunately, there are no easily assessible, inexpensive, laboratory test we can do to prove that the patient suffers from Parkinson’s Disease, or one of its mimics. The most prominent symptoms leading to a clinical diagnosis are the abnormalities of movement that are noticed.
Tremor: Most often this is first noted in one hand when the person is at rest or if for any reason the patient is stressed. The minute the patient uses the hand, the tremor may stop. Sometimes it is just the thumb and forefinger that rub together. In days gone by when they made pills by hand, it was called a “pill rolling “tremor, the term is still found in medical text books.
Bradykinesia (slowness of movement): The brain loses the ability to automatically plan, start, or carry out a movement properly. Patients move slowly and sometimes, in advanced cases, are hardly able to move at all. PD patients find that fine movements are affected early, such as doing up buttons, using eating utensils and dressing.
Rigidity (stiffness): Muscles are stiff and the patient’s joints may not be easily moved during an examination. This too affects the patient’s ability to move with ease.
Posture and Gait: Patients often have a typical slightly forward bent posture. As they walk they tend not to swing their arms, as we all do as we walk. The steps they take my be short and shuffling.
Facial Expression: A doctor who has seen many patients suffering from the condition might recognise the patient as having PD as he/she walks into a room because of the typical facial expression.
There are many other variations on the theme which can be confusing and lead to an alternative diagnosis.
The entire brain is affected by the lack of dopamine. It stands to reason therefore, that other aspects of brain function may become apparent. These may include psychological abnormalities in thought processes, mood, anxiety, depression, memory, and behaviour.
Sleep disorders, and abnormalities of bowel and bladder function may also occur.
Books have been written about the non-motor symptoms of Parkinson’s Disease and this is not the place for a comprehensive dissertation on the illness. It is however important to understand that the surgeon can only hope to alleviate some of the motor symptoms and not the non-motor symptoms. It is important to understand that Deep Brain Stimulation surgery can be of benefit to people suffering from Parkinson’s Disease, but not those mimics that could be confused as the condition.
Medical Treatment: There are many drugs available to neurologists who treat PD. Levodopa is the corner stone of medical treatment and has been in use for many years. All medications have their special advantages and disadvantages and need to be matched to the patient’s particular requirements. This is best carried out by a neurologist who has an interest in Parkinson’s Disease.
Surgical Treatment – Deep Brain Stimulation (DBS): When the medical treatment of Parkinson’s Disease does not provide adequate control of the patient’s motor symptoms, deep brain stimulation surgery may be an option to consider. It can significantly improve the patient’s quality of life in properly selected cases.
There are nerve circuits in the brain that cause us to have the free effortless movements we are all accustomed to. In Parkinson’s Disease these circuits are disturbed because of the lack of dopamine.
It is possible to place an electrode deep in the brain that delivers a tiny electrical current, the disturbed circuit is influenced by the electrical stimulation. This can result in an improvement in the abnormal movements experienced by the Parkinson’s Disease patient.
We are actually not absolutely sure why the stimulation works. We do know that there are a few places (targets) that the stimulating electrode can be placed, and we have a fair idea of which target is best for a particular patient. We do know that the positioning of the electrode in the particular target has to be very accurate; otherwise there would be no benefit to the patient, or worse, there may be troublesome and unacceptable side effects of the stimulation. At least the stimulation device can be turned off if there are side effects. Before the days of DBS, neurosurgeons could produce a very small injury, called a lesion, at the target area; this too was effective. However, there was no turning back after the injury had been produced if it caused bad side effects. Hence, the popularity of DBS.