"Involuntary tremulous motion, with lessened muscular power, in parts not in action and even when supported; with a propensity to bend the trunk forward, and to pass from a walking to a running pace; the senses and intellects being uninjured."
Parkinson's Disease (PD) is a progressive neurological disease involving loss of neurons in a part of the brain called the substantia nigra. This results in a reduction in the amount of the chemical dopamine and when 80% is depleted, the symptoms of the disease develop. The main symptoms are tremor, slowness of movement, stiffness and impairment of balance. It is a highly treatable disease and the life span is not shortened.
Parkinson's Disease affects about 0.3% of general population but 3% or more of those older than 60. There are approximately 60,000 people diagnosed with the disease per year. The average age of onset of symptoms is 60 but 5-10% of patients have symptoms before the age of 40. The prevalence is expected to triple in the next 50 years.
Figure 1 - The dopamine containing neurons are in the substantia nigra and appear black in the picture. The upper picture is from a normal brain and the lower from someone with Parkinson's Disease. Note that there is loss of the dopamine neurons in the Parkinson's diseased brain as indicated by the less blackened areasThe loss of dopamine in an area of the brain called the striatum is the main chemical abnormality and there is a correlation between dopamine loss and the severity of symptoms. It is thought that exposure to some unidentified environmental toxin in a person who has a certain genetic predisposition causes the person to develop the disease. Inside of the dopamine neurons, there are structures called mitochondria which use oxygen to turn food into energy. These mitochondria may be damaged in people with Parkinson's Disease.
Persons are diagnosed based on the symptoms they have and the physical examination. There are no standard laboratory tests available although testing is often done to exclude other similar diseases. A significant improvement in symptoms related to taking the medication carbidopa/levodopa is helpful in making the diagnosis since all patients with Parkinson's Disease respond to this medication.
Tremor: The tremor in PD is a characteristic one in that it occurs at rest rather than when the limb is being used and it is fairly slow occurring at a rate of about 5 times per second. It usually begins in one arm but spreads to involve the other side, sometimes the legs and occasionally the jaw. The tremor is usually reduced or eliminated when the limb is being used in some purposeful way. For this reason the tremor is often not functionally limiting. This symptom responds fairly well to anti-Parkinson's medications. For some patients, however, medications are not effective in treating the tremors. In these individuals, deep brain stimulators implanted in the thalamus can achieve very satisfactory results (see below and link to it).
Slowness of movement (Bradykinesia): The slowness of movement may be very disabling and is one of the major symptoms for which treatment is sought. It may involve tasks involving the arms such as writing and buttoning as well as the legs as when walking. The handwriting is characteristically small (micrographia) and this may be one of the first signs noted by some patients. This symptom responds well to anti-Parkinson's medications.
Rigidity: The rigidity is felt as a stiffness or tightness in the arms, legs, neck or trunk. It is not uncommon for a patient to be evaluated and treated for arthritis in a shoulder prior to diagnosis of Parkinson's Disease. This symptom responds well to anti-Parkinson's medications.
Walking/balance problems: One of the first signs of the disease is often a decrease in the natural swing of one of the arms when walking. As the disease progresses this involves both sides and there may be a difficulty in taking large steps so that a shuffling gait develops. There may be a tendency to take rapid short steps and to even have trouble stopping. With advancing disease, there may be "freezing" episodes where the feet feel as if they are glued to the floor and taking any steps becomes very difficult. Also with advancing disease, there may be impairment of balance. This may be related to a diminished ability to make corrective adjustments in the posture to prevent falling. When these later symptoms develop, physical therapy and the use of assistive devices such as canes and walkers, is recommended. Unfortunately, the balance problems do not respond well to anti-Parkinson's medications. Because there is often a difficulty in taking the firs steps, rolling walkers are recommend over the standard walkers. This is because after each step with a standard walker, the walker has to be lifted up before taking the next step. In this way the patient is continually "taking the first steps." The new "rollator" type walkers allow for greater independence. They are more stable than the standard rolling walkers, they have braking systems, and baskets to carry items in. Finally there is an interesting attachment for canes which take advantage of the finding that visual stimuli often allow patients to overcome the freezing. It is called a "stepover wand" and is essentially a hinged orange wire attaching to the lower part of the cane.
Figure 2 - Quad Cane |
Fugure 3 - Rollator-type walkers |
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The autonomic nervous system controls many of the automatic body functions such as with control of the heart rate and blood pressure, temperature control, sweating, and digestion. This system is often involved in Parkinson's Disease and results in several symptoms.
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Constipation: Constipation is a common complaint in many people and increases with age. Persons with PD are often more troubled with it because the transit of food through the gastrointestinal (GI) tract is slowed. Relative inactivity also slows down the GI tract. Natural methods such as ensuring regular activity, drinking plenty of fluids and eating more fiber can be helpful. Stool softeners such as Colace can be used and if needed laxatives. Failure of attending to the problem can lead to severe constipation with the possibility of developing obstructions
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Urinary Problems: Some patients can have difficulty with urination and this may include an urgency to urinate where there is little warning of the need to urinate. Because mobility may be impaired in these patients they may not be able to make it to the bathroom in time and incontinence may develop. There can also be the problem of inability to fully empty the bladder. If incontinence is present protective garments are often helpful. Depending upon the problem, medications can also be helpful.
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Orthostatic Hypotension: Both the disease process and the medications used to treat it can cause the blood pressure to fall when a person with Parkinson's Disease stands up. This can result in a feeling of lightheadedness and faintness and sometimes to the person actually passing out and falling. Especially in the morning after the patient has been laying flat for several hours it is important to get up slowly, perhaps sitting at the bed for a few minutes before arising. Because fluid can settle in the veins in the legs, the use of support stockings can sometimes be helpful. There are also several medications to treat this problem including Florinef (fludrocortisone), Midodrine (ProAmatine), and Yohimbine. Persons who have had hypertension are often able to come off medications previously being used to control hypertension, but this should be done according to the physicians orders.
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Sexual Problems: Sex can be more difficult in part because the person with PD has difficulty with mobility. The tremors in PD are often greatly increased with excitation and this can be an interference. Some men can have difficulty in achieving and maintaining an erection. The medication "Viagra" can be helpful in many of these cases.
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Pains: Pain is a common symptom in the general population. In PD, there can be back and neck pain due to the rigidity in the muscles and to the lessened mobility. Rare patients experience burning and cramping pains. Some of these pains respond to the usual Parkinson's medications but analgesicis (pain medications) are often used as well.
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Dysphagia [TBS]
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Excessive Salivation (Drooling) is probably a result of it not being as natural to swallow the saliva resulting in it accumulating in the mouth, rather than an over production of the saliva. Feedback therapies along with the speech therapy to encourage more frequent swallowing of the saliva is often helpful. If severe, drops of ophthalmic solutions of atropine under the tongue are helpful.
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Falls are a major source of injury in persons with PD. Each fall may lead to significant injury including hip fracture and head trauma. It is of great importance to identify the cause of the falls and to remedy the situation. Often the remedy is to have the person use an Assistive device such as a cane or a walker.
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Postural Instability (see walking/balance problems)
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Freezing Freezing is when persons are attempting to initiate walking and it feels as if the feet are glued to the floor. This can be an incapacitating problem and patients may become extremely frustrated. It also commonly results in falls. It can often be overcome with the use of visual stimuli such as another person placing their foot in front of the patient. Some people benefit from a pattern in tiles of the floor. There is also a special cane (stepover wand) which has an attachment providing a visual stimulus to step over.
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Orthostatic Hypotention: [TBS or duplicate?]
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Other neurological problems and Medical problems: We should understand that other medical conditions can contribute to falling. These include neurological problems such as with neuropathy (disease of the nerves) and strokes, as well as medical conditions such arthritis. Attention to diagnosing these other disorders and treating them if possible is important. Obesity may also contribute to postural instability because the added weight in the abdomen shifts the center of gravity in front of the feet.
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Medical Conditions: [TBS]
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Environmental: For persons with PD who have some degree of loss of mobility and imbalance, the home environment should be looked at carefully to be sure that there is no extra clutter. Throw rugs, end tables and other articles on the floor should be removed from heavily trafficked areas.
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As the disease advances, the response to the medications used to treat it can become less reliable.
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Wearing Off: The first motor complication to develop is usually that the levodopa or dopamine agonist does not effectively treat the symptoms through to the next scheduled dose. This can usually be helped by decreasing the time between doses, adding a dopamine agonist to the medical regimen of persons on levodopa, or adding Comtan (which extends the effectiveness of levodopa).
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Dyskinesias: Dyskinesias are involuntary irregular, twisting or writhing movements occurring when a dose of levodopa is at its highest levels in the brain in patients with relatively advanced disease. These begin to occur in 50% of patients 5 years after they begin levodopa but in an even higher percentage of patients who begin treatment at a young age. They can often be alleviated by reducing the dose of medication of Sinemet or the dopamine agonist. Amantadine is a medication that has been used to treat the symptoms of PD for many years. More recently it has been shown to have a modest effect in reducing dyskinesias. If the dyskinesias are incapacitating and cannot be treated but adjustments in medications, Deep Brain Stimulation is an option.
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No Response (Dose Failure): Occasionally, a dose of medication may seem to fail to have any effect on the symptoms. This may be due to a failure to have the medication absorbed. High protein meals can compete with the levodopa getting into the brain. Under these circumstances some patients can overcome the problem by delaying the major protein consumption to the evening hours. For isolated "failed" doses, an extra dose can be taken and chewing a portion of the levodopa tablet can enable quicker absorption and action.
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Unpredictable On/Of: [TBS]
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Dystonia is a symptom of sustained muscle contractions causing twisting movements and abnormal postures. It may involved the head, neck and the limbs. It can be present as part of Parkinson's Disease and involvement of the foot may often precede other symptoms of Parkinson's Disease especially in young patients. It can also come about as a side effect of medications such as Sinemet and dopamine agonists.
Cognitive Impairment:
Cognitive impairment may occur in about 25% of patients as the disease advances. It may also be caused by other treatable conditions such as hypothyroidism and vitamin B12 deficiency. These other causes should be fully investigated. In addition, many medications used to treat Parkinson's Disease can cause or exacerbate cognitive impairment and this is particularly true about the anticholinergic medications (eg Artane) and the dopamine agonists. Of the medications used to treat Parkinson's Disease, levodopa is the least likely to cause cognitive problems.
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Hallucinations / Delusions:
Visual hallucinations are when people see things that are not really there. This may include objects and people. They may be "benign" in that the person has insight that they are not real and that they are not disturbing. Other times, the hallucinations are frightening and cause great disability. Delusions are thoughts or ideas which are false. These include feelings that persons are trying to steal from or harm the patient or feelings that a spouse is having an affair. Hallucinations and delusions usually occur in persons with advanced disease who are on multiple medications. The medications used to treat Parkinson's Disease which are most likely to cause them are the anticholinergic medications (Artane, Cogentin), Eldepryl (Selegiline), and the dopamine agonists such as Permax (Pergolide), Pramapexole (Mirapex), and Ropinirole (Requip). If reduction in medications are not possible or sufficient to stop the hallucinations or delusions, there are also medications available to treat them.
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Delusions/Paranoia: [TBS or part of previous section?]
Depression:
Depression is a very common symptom in people with Parkinson's Disease occurring in approximately 30% of people. It can often be the first symptom appearing, even before any movement problems develop but it may in part reflect the person's reaction to the disease symptoms as well. Because the motor symptoms may limit work and recreational activities the person was previously able to do, a loss is experienced along with some change in life style. Strong social supports are helpful and counseling by social workers or psychologists are often helpful. Antidepressant medications are effective as well and should be used when appropriate.
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Insomnia
Sleep problems are present in most patients with Parkinson's Disease. 1) Problems with sleep initiation. In persons with severe tremors, there may be an exacerbation of the tremors when laying down in bed resulting in problems falling asleep. Anxiety disorders and depression may cause a delay in falling asleep as it does in persons without Parkinson's Disease. These should be treated with antianxiety or antidepressant medications. Avoidance of beverages containing caffeine, regular afternoon exercise, and avoiding watching television or reading in bed are recommended. 2) Problems in maintaining sleep. There are often problems in staying asleep in part because involuntary movements during sleep awaken the patient. Periodic Movements of Sleep may be effectively treated with a bed time dose of levodopa or a dopamine agonist. Early morning awakenings can be a sign of depression and this should be considered. Sedating antidepressants are often helpful.
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Excessive Daytime Sleepiness
Excessive Daytime Sleepiness can result from poor sleep but also can be a side effect of the medications used to treat Parkinson's Disease. It is important to distinguish between these two possibilities. If the sleep quality is not the problem and adjustments in medications do not improve the sleepiness, the medication Provigil may be helpful, although it is not approved by the FDA for use in Parkinson's Disease.
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Speech Problems: The speech problems include a soft voice which may sound monotonous and sometimes hoarse. There is less animation to the voice. At times the speech may become very rapid with little separation between words. With advanced disease communication may become more difficult and this is first noticed over the phone. The speech problems do no respond well to anti-Parkinson's medications but to respond well to speech therapy. There is a specific speech therapy called the Lee Silverman Voice Treatment (LSVT) which is intense and uses feedback methods to encourage patients to increase, for example, their volume.
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Restless Legs and Periodic Movements of Sleep: [TBS]
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Multiple System Atrophies
Progressive Supranuclear Palsy
Cortico-basal-ganglionic degeneration
Striaonigral degeneration
Shy-Drager syndrome
Olivopontocerebellar degeneration
Drug-Induced
Toxins: Manganese, carbon monoxide, cyanide, methanol
Other
Normal Pressure Hydrocephalus
Stroke or trauma
Tumor
Each patient with Parkinson's disease has varying combinations of symptoms of the disease and therefore, therapy must be tailored to each individual. Patients should recognize that all medications have potential side effects so that they should be used only when the benefit of the medications is greater than the side effects. Early in the disease symptoms may not be so bothersome so it may not be necessary to be treated. Most neurologists would agree that therapy should be initiated when the patient begins to experience functional impairment in carrying out desired or necessary activities. In making the decision to treat it should be considered whether the dominant or non-dominant side is involved, whether the patient is employed and whether the symptoms involve bradykinesia or tremor.
Levodopa: This is the most potent medication used in treating Parkinson's Disease and virtually all patients respond to it. Since levodopa has been available, the lifespan of patients with Parkinson's Disease has become equal to the general population. It is supplied in combination with carbidopa. The levodopa (or l-dopa) is absorbed through the gut and enters the brain. Once there it is converted to dopamine by an enzyme in the brain. The dopamine results in alleviation of the main symptoms of Parkinson's disease (tremor, rigidity, bradykinesia).The carbidopa blocks the conversion of levodopa to dopamine when it is in the bloodstream. In this way more levodopa enters the brain to be useful there and less is converted to dopamine in the bloodstream. Because the "vomiting" center of the brain is a unique area of the brain in that it is exposed to chemicals from the blood stream, the carbidopa is effective in reducing nausea that would otherwise be a major problem. Although there are theoretical reasons to consider that levodopa may be toxic to the brain, there is no solid evidence in people that this is actually the case.
Sinemet 25/100 |
Sinemet 25/250 |
Dopamine Agonists: The dopamine agonists represent a class of medications which also alleviate the symptoms of Parkinson's Disease. Although they are not dopamine, they look like it to the brain and essentially "fool" the brain into thinking that they are dopamine. They are not quite as effective as levodopa especially in patients with severe disease. Side effects are more common and these include nausea, low blood pressure, confusion and hallucinations.
0.05 |
0.25 |
1.0 |
0.125 |
0.25 |
0.50 |
1.0 |
1.5 |
0.25 |
0.50 |
1.0 |
2.0 mg |
4.0 mg |
5.0 mg |
All of the dopamine agonists are effective in treating the symptoms of Parkinson's disease. For the two newer medications, Pramipexole and Ropinirole, there have been well-controlled double-blinded studies demonstrating benefit to patients with relatively early disease. The graphs below show that there is significant improvement in a measure of motor performance (The "Motor section" of the Unified Parkinson's Disease Rating Scale) for both of the dopamine agonists in patients with early disease. In fact the improvement is similar to that seen with levodopa.
There is some evidence that there may be a lower risk of developing dyskinesias (link to it above) in patients started on dopamine agonists compared to those started on Sinemet. More recently, PET and SPECT scans (which show the amount of dopamine in the brain) have indicated that the loss of dopamine is greater in patients started on levodopa compared to the dopamine agonists Ropinirole (Requip) and Pramepixole (Mirapex). This suggests that perhaps levodopa is relatively more toxic to the brain compared to the dopamine agonists. Although these studies compared the effects of levodopa to either Requip or Mirapex in a double-blinded fashion (neither patients or physicians knew which drug the patient was on), the patients on levodopa ended up more adequately treated compared to the dopamine agonist groups. This makes interpretation of the results more difficult.
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COMT inhibitors These medications slow down the break down of l-dopa and therefore prolong the action of l-dopa. This can lead to a longer duration of action of Sinemet so that it does not have to be taken as frequently. They are generally helpful when Sinemet has to be taken 4 or more times a day. They have no effect if taken by themselves, that is, they are only useful for people who are taking l-dopa. There are two such medications available: Entacapone (Comtan) and Tolcapone (Tasmar).
Anticholinergic medications The anticholingergic medications (eg. Artane) have been used for many years to treat some of the symptoms of Parkinson's Disease such as the tremors. They do have some effectiveness but their use is limited by significant side effects including dry mouth, dry eyes, sedation, confusion, and hallucinations. They are probably best used in younger patients.
Deep brain stimulators are devices implanted into certain areas of the brain which stimulate those areas and can alleviate many of the symptoms of Parkinson's disease. There are two types of patients with Parkinson's Disease who may benefit from deep brain stimulators:
- Patients with uncontrollable tremor for which medications have not been effective.
- Patients with symptoms which are well treated with medications but who experience severe motor fluctuations including wearing off and dyskinesias despite attempts at controlling the fluctuations by changes in medications.
Preoperative Assessment at Johns Hopkins All patients considering DBS to treat their symptoms are evaluated by a Movement Disorders Specialist. This is done to be certain that the patient suffers from PD rather than one of the less common similar disorders (Can we link to the list above?). The patient is evaluated to be certain that there is at least a small amount of time that the PD medications are effective. A judgment is made as to whether the medications the patient is taking are appropriate and optimal. Cognitive evaluation is also done because it is important that the patient be able to accurately and actively participate during the surgical implantation of the stimulator and also subsequent to the implantation when the brain stimulator is programmed. Medical clearance is obtained through the patient's internist. The neurosurgeon evaluates for the appropriateness of the surgery and assesses the risks of the surgery in comparison to the benefits of it. It is also important at this stage to clarify the expectations of the surgery. In treating tremor we should be clear that there is no guarantee that the tremor will be completely relieved. In patients who have motor fluctuations, it should be clear that the expectation is that they will have more of their best "on" time.
The Implanted System The system consists of the electrode that goes into the brain, a connecting cable, and the "neurostimulator" which contains electronic circuitry and battery.
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Programming of the Deep Brain Stimulator: Immediately following the surgery, there may be some benefit without the stimulator even being turned on. This is thought to be due to swelling around the tip of the implanted electrode. This effect often diminishes over the following weeks to months. Usually, initial programming is done 3-4 weeks after the surgery. During the first session which lasts a few hours, the implanted device is checked to see that it is functioning correctly and various parameters of stimulation (voltage, frequency of stimulator and which electrodes are used (there are four), are programmed. This requires continuous feedback from the patient to ascertain if there are any side effects and also benefit. Patients typically return several times of the next months until the stimulator is programmed optimally. This can be a frustrating time since there is some trial and error. It is also a time when patients realize that not all of their symptoms may be treated as much as they would like. However, most patients show very significant benefit as long as the expectations when going into the surgery were appropriate (see above).
For patients undergoing bilateral (both sides) subthalamic stimulator implantation, the great majority show a reduction in the time that they were "off" and an increase in the good quality "on" time (see below graphs from New England Journal of Medicine, 2001, vol 345, p 956).
American Parkinson Disease Association
1250 Hylan Blvd. - Suite 4B
Staten Island, NY 10305
Toll Free: 800.223.2732
Phone: 718.981.8001
Email: info@apdaparkinson.com
National Parkinson Foundation, Inc.
1501 NW 9th Ave
Bob Hope Road
Miami, FL 33136-1494
Toll Free: 1.800.327.4545
Fax: 1.305.548.4403
Email: mailbox@npf.med.miami.edu
The organization supports research; conducts clinical trials; and provides physical, occupational, speech and neuropsychological therapies. Learn about Parkinson's disease-related news and events. The online library also holds publications and articles.
Parkinson's Disease Foundation
710 West 168th Street
New York, NY 10032-9982
Toll Free: 800.457.6676
Phone: 212.923.4700
Email: info@pdf.org
Educational Office (312)733-1893
The Foundation provides information about Parkinson's disease itself as well as related organizations, research centers and events. You can also read the latest Parkinson's news or join the online email list.
Parkinson's Action Network
840 Third Street
Santa Rosa, CA 95404
Toll Free: 800.850.4726
Phone: 707.544.1994
Fax: 707.544.2363
Email: info@parkinsonsaction.org
The Parkinson's Action Network was founded in 1991 with a mission to provide a voice for the Parkinson's community. Since that time, the Network's central objective continues to be to promote a level of research support sufficient to produce effective treatments and a cure.
Essential tremor (ET), the most common movement disorder, is an insidiously progressive often inheritable disorder usually beginning before the age of 50. It is characterized by involuntary tremors when the arms are held out in front and when they are being used. The tremors may also affect the head, voice, tongue and legs. The tremor is invariably worsened with stress, fatigue, and stimulant medications and is significantly improved by small amounts of alcohol. Although many features of ET differ from those of Parkinson's Disease, the two are often confused.
ET is thought to be due to oscillations of neuronal activity involving a part of the brain called the inferior olive.
Patients with significant functional impairment often opt for treatment. For some patients, the tremor may not be functionally disabling but instead may be a source of severe embarrassment causing social isolation, so that they also opt for treatment. The decision to treat with medications is made when the degree of impairment or discomfort outweighs treatment side effects.
Nonmedical therapy
In some patients, the tremors can be dampened by weighting the limb (usually by applying wrist weights). In a small proportion of patients, this can dampen the tremor effectively enough to improve functioning.
Since anxiety/stress classically make the tremor worse, non-medical relaxation techniques and biofeedback can be effective in selected individuals. Likewise, medications known to make tremors worse should be eliminated or minimized if possible. These include lithium, many antipsychotics, valproic acid, corticosteroids, tricyclic antidepressants and a class of drugs called adrenergic agonists. Patients should be evaluated for hyperthyroidism since this state can induce tremors.
Alcohol can be extremely effective in reducing tremor. Although there is a minor concern about alcohol addiction, small amounts of alcohol can be used prior to social events to reduce tremor. In fact, many patients have already discovered this on their own before coming to medical attention.
Medication therapy
Medication therapies have largely been discovered by chance when patients with ET have been treated for other medical conditions. The mainstay medications include beta adrenergic blockers, such as Propranolol (Inderal), and primidone (Mysoline).
Primidone's effectiveness in treating ET was first noted in a patient being treated for epilepsy. Its mechanism of action is not well understood. It has been shown to be effective in several controlled trials. Its use is occasionally associated with transient, acute vertigo and feelings of unsteadiness and nausea when therapy is first initiated (the first dose phenomena). Sedation is also a common side effect. However, if patients are warned of the first dose phenomena and if treatment is initiated at small doses, most persons are able to tolerate it. In various studies, 60-100% of patients demonstrate response to primidone.
Propranolol was also discovered by chance to be effective for ET. _-adrenergic blocking agents are affective in 40-50% of patients. Like primidone, the effects are less in reducing head and voice tremor. They should not be used in patients with asthma, emphysema, congestive heart failure, heart block and used with caution in persons with diabetes on insulin. They may reduce exercise tolerance, exacerbate depression, and cause impotence. Other beta-blockers such as atenolol, nadolol, metoprolol, and timolol may also be effective and with less side effects.
If both primidone and propranolol are not effective alone, there may be a more significant effect in combination and this should be tried unless there are contraindications.
Miscellaneous medications: Benzodiazepines, especially clonazepam, have long been used in the treatment of ET. There is little direct effect on the tremor although relief of anxiety may indirectly lessen the tremor. Because of the sedative effects, these should only be used rarely in individuals with a significant anxiety problem exacerbating the tremor.
Botulinum Toxin Injections: Medications are effective treatments for the tremor of the arms but not as much for voice and head tremor. Although head tremor rarely leads to impairment of functional abilities, the social embarrassment may be extreme causing social isolation. Several studies have shown that botulinum toxin injections may significantly help the head tremor (as well as the voice tremor). Although the amplitude of hand tremors may be reduced with botulinum toxin, the injections are more difficult and there has not been shown to be clear functional improvement.
When patients do not achieve satisfactory control of their tremor with medical therapy, and there is significant functional impairment, surgical options should be considered. Placing a surgical lesion in an area of the brain called the thalamus has been used for decades and between 80-100 % of patients have sustained benefit. The procedure cannot be performed on both sides because slurred speech often develops. Deep brain stimulation (DBS) of the same brain region at high frequencies is effective in most patients and appears to be a safer option. Advantages include that it creates a reversible lesion, the stimulus parameters can be changed in response to waning efficacy, and it can be used safely for bilateral treatment.
Preoperative Assessment
All patients considering DBS to treat their symptoms are evaluated by a neurologist specializing in Movement Disorders. This is done to be certain that the patient suffers from essential tremor. A judgment is made as to whether the medications the patient is taking are appropriate and optimal. Cognitive evaluation is also done because it is important that the patient be able to accurately and actively participate during the surgical implantation of the stimulator and also subsequent to the implantation when the brain stimulator is programmed. Medical clearance is obtained through the patient's internist. The neurosurgeon evaluates for the appropriateness of the surgery and assesses the risks of the surgery in comparison to the benefits of it. It is also important at this stage to clarify the expectations of the surgery. In treating tremor we should be clear that there is no guarantee that the tremor will be completely relieved.
The Implanted System
The system consists of the electrode that goes into the brain, a connecting cable, and the "neurostimulator" which contains electronic circuitry and battery.
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Programming of the Deep Brain Stimulator:
Immediately following the surgery, there may be some benefit without the stimulator even being turned on. This is thought to be due to swelling around the tip of the implanted electrode. This effect often diminishes over the following weeks to months. Usually, initial programming is done 3-4 weeks after the surgery. During the first session which lasts a few hours, the implanted device is checked to see that it is functioning correctly and various parameters of stimulation (voltage, frequency of stimulator and which electrodes are used (there are four), are programmed. This requires continuous feedback from the patient to ascertain if there are any side effects and also benefit. Patients typically return several times of the next months until the stimulator is programmed optimally. This can be a frustrating time since there is some trial and error. However, most patients show very significant reduction in their tremor.
International Tremor Foundation
7046 W. 105th St
Overland Park, KS 66212-1803
Phone: 913.341.3880
Fax: 913.341.1296
Email: IntTremorFnd@worldnet.att.net
