Is surgery beneficial for people with Parkinson’s disease? Let’s look at the options and criteria.
Parkinson’s disease (PD) is one of the most common neurological disorders that cause progressive disability. Some of the debilitating symptoms may be slowed with treatment, but it cannot be halted and currently there is no cure. Signs and symptoms to look for in the early states are:
- Decreased arm swing on the first-involved side,
- Soft voice,
- Decreased facial expressions,
- Sleep disturbances
- Rapid eye movement behavior disorder (RBD),
- Decreased sense of smell,
- Symptoms of autonomic dysfunction (e.g. constipation, sweating abnormalities, sexual dysfunction, seborrheic dermatitis),
- A general feeling of weakness, malaise, or lassitude,
- Depression
- Anhedonia (inability to feel pleasure), and
- Slowness in thinking.
The onset of motor signs is typically asymmetric and the most common initial finding is a resting tremor in an upper extremity. Over time, patients experience progressive bradykinesia, rigidity, and gait difficulty, axial posture becomes progressively flexed and strides become shorter. Postural instability (balance impairment) is a late phenomenon.
Non-motor symptoms are common in early PD. Recognition of the combination of non-motor and motor symptoms can promote early diagnosis and thus early intervention, which often results in a better quality of life.
PD is a clinical diagnosis and requires the presence of two of three cardinal signs.
- Resting tremor,
- Rigidity, and
- Bradykinesia.
The goal of medical management of the disease is to provide control of signs and symptoms for as long as possible while minimizing the adverse effects. For mid to late state patients, there are surgeries available.
Up to fifty percent of patients on levodopa for a period of five years or more experience motor fluctuations and dyskinesia, especially in patients with an early onset of the disease. The symptoms are unique to levodopa and are not produced by the other antiparkinsonian drugs. As the disease advances, the effect of the drug begins to wear off a few hours after each dose. In the beginning, the dopamine nerve terminals store and release dopamine, but with more advanced stages, these terminals degenerate and levels fluctuate erratically and are unpredictable.
Brain surgery may be very beneficial for an appropriate subgroup of patients with this disease. Surgery has come a long way over the last 50 years for those suffering from PD. It is usually reserved for patients who have exhausted medical treatment of PD tremor or who suffer from profound motor fluctuations.
There are two main surgical approaches to the management of PD:
- brain lesioning surgery and
- deep brain stimulation, the newest approach.
Lesioning procedures destroy a small area of the brain that is involved in abnormal circuits causing symptoms of Parkinson's disease. Doctors learned in the early 1950s that lesioning or destroying specific areas of the brain could be helpful in treating certain movement disorders. This surgical process carefully injures a very specific part of the brain so that it will improve the patient’s function and quality of life. There are multiple ways to cause a lesion such as:
- using focused radiation or radiosurgery, or
- using a heating probe that is introduced very carefully into the brain.
The most recent method uses ultrasound therapy and is not yet approved by the FDA. This technique has largely been replaced by deep brain stimulation.
Deep brain stimulation involves the placement of an electrode using an MRI and neurophysiological mapping on one or both sides of the brain to provide electrical stimulation of specific areas that are impaired due to the disease.
It was developed in the 1990s and is now a standard treatment. About 30,000 people have had DBS surgery worldwide. It does not involve destruction of brain tissue and it is reversible.
The implanted device is an impulse generator or an IPG and is similar to a pacemaker that provides an electrical impulse to a part of the brain involving motor functions. The recipient uses a controller that allows them to check the on or off stage and the battery status. It can be adjusted as the disease progresses or adverse events occur.
Bilateral procedures can be performed without a significant increase in adverse events. Typically, an IPG battery lasts for about three to five years. The procedure to replace the battery requires local anesthesia.
DBS is not for everyone with Parkinson’s disease. It is most effective for individuals who experience disabling tremors, wearing off spells and medication induced dyskinesia. DBS is not a cure for the disease and it does not slow the progression.
RF lesions are produced by electrodes placed in the brain tissue. A RF current is an alternating current of very high frequency. The process during which the current passes through tissue produces heat that kills cells in the surrounding area. These lesions destroy everything in the nearby vicinity of the electrode tip.
Recently, lasers have been shown to be effective in ablation of both cerebral and cerebellar tissue. A laser technology called MRI-guided laser ablation allows great precision in location and size of the lesion and causes little to no thermal damage to adjacent tissue.
When lesioning surgery is chosen, it provides a reasonable alternative to DBS for patients who are averse to the cosmetic appearance of the implanted pulse generator or do not want to be burdened by repeated battery replacements.
Not every patient will benefit from the surgical treatment, and appropriate patient selection is a crucial step in the process. Best candidates for the surgery are patients who:
- developed disabling dyskinesia that cannot be managed optimally with medication changes;
- have pronounced fluctuations in response to the medication regimen; and
- have severe tremors that cannot be controlled with medications.
There is a small but real risk of complications associated with the surgeries. The most serious risk is a one to two percent incidence of stroke or hemorrhage during the mapping phase of the surgery. In addition, the optic tract may be damaged if the electrode is not targeted precisely. There is also the risk that the symptoms may not improve.
Patients with coexistent serious medical problems, dementia, psychiatric issues and advanced age in general are not good candidates for surgery. Therefore, each patient should be carefully evaluated for surgery, and those selected to be good candidates should be counseled about the risks and benefits of the surgery. For many people, it can greatly relieve some of the symptoms and improve their quality of life. It is very important to be well informed and ask questions about the procedures and have realistic expectations.
