Surgical therapy

OverviewDeep Brain StimulationLesioning Surgery

Surgery for Parkinson’s has come a long way since it was introduced in the 1960s. Surgery can offer benefits to some people by improving certain symptoms and sometimes reducing the need for medications. Currently, surgery is not known to provide a cure for Parkinson’s, although it can offer better control of Parkinson’s symptoms. However, even following a successful surgery, a person with Parkinson’s is still required to take continuous medication.

People with Parkinson’s who are likely to benefit from surgery are those who have previously had a good response to their Parkinson’s medication (particularly levodopa).

Generally surgery is advised for those in whom this response has become unpredictable and/or short lived motor fluctuations or who are troubled by dyskinesias Surgery has not been shown to improve symptoms that do not respond to dopamine medication. However, tremor which can be resistant to Parkinson’s medication generally responds well to surgery.

Surgery is advised by doctors only after due consideration and thorough and detailed assessments.

Types of Surgery
There are two main forms of surgery used currently in PD
Deep Brain Stimulation (DBS)
Lesioning

Developed in the 1990s, DBS is a surgical procedure which is a treatment option for advanced Parkinson’s. It is mainly used to treat disabling symptoms of Parkinson’s such as tremor, freezing of gait (hyperlink to symptoms) and rigidity.

Note – It is also used to treat essential tremor, which is another movement disorder.

What is DBS?
In DBS, the neurosurgeon implants a medical device called neuro-stimulator, similar to a cardiac pacemaker, to deliver electrical stimulation to precisely targeted areas on each side of the brain. Stimulation of these areas appears to block the signals that cause the disabling motor symptoms of Parkinson’s disease. As a result, many patients achieve greater control over their body movements.

A DBS system includes three components, which are implanted completely inside the body.

  • Neuro-stimulator – A pacemaker-like device that is the power source for the system. It contains a small battery and computer chip programmed to send electrical pulses to control Parkinson’s disease symptoms. A controller is given to the patient which allows them to turn the device on or off. The battery for the neuro-stimulator can last up-to 3-5 years (may vary) and can be replaced later.
  • Lead – An insulated wire with four electrodes. This is implanted in the brain with the help of MRI scans (to ensure correct placement), with its tip positioned within the targeted brain area.
  • Extension – An insulated wire placed under the scalp that connects to the lead and runs behind the ear, down the neck, and into the chest below the collar-bone where it connects to the neuro-stimulator.

How does it work?
Once the system is in place, electrical impulses are sent from the neuro-stimulator up along the extension wire and the lead into the targeted brain area. These impulses interfere with and block the electrical signals that cause Parkinson’s symptoms. Stimulation from the neuro-stimulator is adjustable; without further surgery if the patient’s condition changes. Such stimulator adjustments are called as “programming.”

Areas stimulated with DBS

There are two brain targets that are FDA approved for use in Parkinson’s.

  • subthalamic nucleus (STN) or
  • internal globus pallidus (GPi)

These structures are deep within the brain and involved in controlling movement and muscle function. A neurosurgeon determines which structure will be stimulated depending on each individual’s symptoms.

Am I suitable for DBS?

  • DBS is used for Parkinson’s patients who are “levodopa responsive.” This means the primary symptoms that respond to the drug levodopa.
  • DBS is known to be effective for individuals who experience wear offs, motor fluctuations, disabling tremor and dopa induced dyskinesias.
  • A person’s age or pre-existing medical condition does not necessarily exclude him or her from becoming a candidate for DBS.
  • A doctor considers all factors before determining if a patient is a good candidate, and recommends the surgery accordingly.

Caution – Like all brain surgeries, DBS has a small risk of infection, bleeding, stroke or other anaesthesia associated complications. It is best to discuss the risks with a doctor before exploring DBS as a potential surgical option.

While DBS can relieve some of the patient’s symptoms considerably it should be noted that it can target only some specific symptoms.

DBS does not eliminate the use of drugs/medication nor does it result in the reversal of the PD symptoms.

This involves destroying/eliminating the specific part of the brain that is causing PD symptoms. The operation is named after the part of the brain that is destroyed.

Thalamotomy

It is a type of brain surgery where a part of the brain i.e. the thalamus is operated upon. Thalamotomy is generally used for individuals presenting with severe tremor that does not respond to medications.

Pallidotomy
In Parkinson’s, a small part of the brain called globus pallidus is affected which is responsible for disabling tremor and rigidity (stiffness). In pallidotomy, the surgeon destroys a tiny part of the globus pallidus which help in relieving movement related symptoms.

Subthalamotomy
This is a type of brain surgery in which the subthalamus; a tiny area in the brain is destroyed.

However it may be noted that lesioning surgery is rarely performed nowadays.