Introduction:

Parkinson’s disease is a progressive disorder of the nervous system that affects body movements of the affected person. As per an estimate, India has 1 Million people suffering from Parkinson’s, while worldwide this figure is about 10 million.

But, the unfortunate part is that our knowledge about its cause is very little. It is very rare to inherit this disease through genes (only 10 to15%). Most of the cases come under sporadic category. Similarly, there is no cure for this disease, as of now, but there are some medications, therapies and surgeries which can help control the symptoms.

Early Stages of Parkinson’s Disease:

In early stages, it’s bit difficult to detect PD. Though, there are some early indicators like the handwriting becomes smaller over time or crowded and/or patient looses smell of foods like bananas, dill pickles and licorice.

After some time, the patient starts showing other symptoms like tremors, limb rigidity, slowness of movements, change in voice, loss of balance etc. The progression of the disease varies from person to person due to diversity of the disease. No two people have the same exact symptoms.

In addition to movement symptoms, most people with PD also develop non-movement symptoms that many consider more disabling. They can include:

  • Problems with attention, planning, language or memory
  • Mood disorders, such as depression, anxiety, apathy and irritability
  • Fatigue
  • Hallucinations and delusions
  • Light headedness (orthostatic hypotension)
  • Sexual problems, such as erectile dysfunction
  • Sleep disorders, such as insomnia

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What is Deep Brain Stimulation?

But, despite all these problems, people with Parkinson’s can have a good quality life. There is no one-size-fits-all treatment approach when it comes to PD. While medication is the most common treatment, surgical therapy and lifestyle modifications, like rest and exercise, help manage the disease.

One such therapy which has been found very effective in treating PD is Deep Brain Stimulation (DBS). This is a surgery to implant a device that sends electrical signals to brain areas responsible for body movement. DBS can help reduce the symptoms of tremor, slowness, stiffness, and walking problems caused by Parkinson’s disease, dystonia, or essential tremor. Successful DBS allows people to potentially reduce their medications and improve their quality of life.

How Deep Brain Stimulation Works

There are 3 areas in the brain that can be targets for deep brain stimulation. They are the subthalamic nucleus, the globus pallidus internus, and the ventral intermediate nucleus of the thalamus. Each of these areas plays a role in the brain’s circuitry that is responsible for the control of movement.

Experts believe that DBS regulates abnormal electrical signaling patterns in the brain. To control normal movement and other functions, brain cells communicate with each other using electrical signals. In Parkinson’s disease, these signals become irregular and uncoordinated, which leads to motor symptoms. DBS may interrupt the irregular signaling patterns so cells can communicate more smoothly and symptoms lessen.

The specific area in the brain to target in an individual depends on symptoms that need to be treated. For example, DBS of subthalamic nucleus is effective for all major movement symptoms, such as tremor, slowness of movement (bradykinesia), stiffness (rigidity), and problems with walking and balance. DBS of globus pallidus is another effective target for a wide range of Parkinson’s symptoms. The thalamic target is sometimes selected for patients with tremor symptoms. The recommended target for each patient is made collaboratively with the neurologist, neurosurgeon and other caregivers involved in the decision making process.

What is the Procedure?

This surgery involves implanting a thin wire with electrodes at the tip. The electrodes can be precisely controlled to target the affected tissues. Then, high frequency electrical stimulations are delivered through these electrodes. These stimulations alter the abnormal signals, thereby resulting in improvement in the symptoms.

Prior to the surgery, the patients are subjected to some tests to enhance the success rate of DBS. The tests include brain MRI scan, neuropsychological testing, videotaped evaluation of movement both on and off medication, and others if required.</p/>

The MRI Scan and the intra-operative microelectrode mapping helps in precise placement of the electrodes. Then, the wire is connected to the neuro-stimulator power supply (a battery-operated generator), which is placed under the skin near the collarbone.

Once the electrodes start stimulating the high-frequency impulses, they start blocking the faulty signals in the brain, which are responsible for causing tremors and other movement symptoms. In simple words, they help normalize abnormal impulses. And, all this is done, without any damage to healthy tissues.

The 3 Components of DBS are:

  1. The lead (also called an electrode) is a thin, insulated wire inserted through a small opening in the skull and implanted in the brain. The tip of the electrode is positioned within the targeted brain area.
  2. The extension is an insulated wire passed under the skin of the head, neck and shoulder, connecting the lead to the neurostimulator.
  3. The neurostimulator (the battery pack”) is the third component and is usually implanted under the skin near the collarbone. In some cases it may be implanted lower in the chest or under the skin over the abdomen.

What Are the Facts?

Deep Brain Stimulation (DBS) surgery was first approved in 1997 to treat Parkinson’s disease (PD) tremor, then in 2002 for the treatment of advanced Parkinson’s symptoms. More recently, in 2016, DBS surgery has been approved for the earlier stages of PD — for people who have had PD for at least four years and have motor symptoms not adequately controlled with medication.

DBS is certainly the most important therapeutic advancement since the development of levodopa. Some of the facts associated with DBS are as follows:

  • DBS is a surgical procedure for treating a variety of disabling neurological symptoms, like symptoms of Parkinson’s, such as tremor, rigidity, stiffness, slowed movement and slowed walking.
  • It is also used to treat essential tremor, a common neurological movement disorder.
  • DBS does not damage healthy brain tissue or destroy nerve cells. It only interrupts the problematic electrical signals from targeted areas in the brain.
  • At present, this procedure is used only for patients whose symptoms cannot be adequately controlled with medications.
  • DBS uses a surgically implanted, battery-operated medical device called a neurostimulator — similar to a heart pacemaker and approximately the size of a stopwatch — to deliver electrical stimulation to targeted areas in the brain that control movement, blocking the abnormal nerve signals that cause tremor and PD symptoms.
  • Before the procedure, a neurosurgeon uses MRI or CT scanning to identify and locate the exact target within the brain where electrical nerve signals generate the PD symptoms.
  • During surgery, some surgeons use microelectrode recording — which involves a small wire that monitors the activity of nerve cells in the target area — to more specifically identify the precise brain target that will be stimulated.
  • Generally, these targets are the thalamus, sub-thalamic nucleus (STN) and a portion of the globus pallidus.
  • Once the system is in place, electrical impulses are sent from the neurostimulator up along the extension wire and the active contacts of the lead in the brain. These impulses interfere with and block the electrical signals that cause PD symptoms.

Am I a Good Candidate for DBS?

Are you not getting desired benefits from medication? Are you finding it increasingly difficult to do routine work? If your answer to these questions is “YES”, then you are a good candidate for DBS. You should immediately consult a doctor to see if DBS is the right treatment for you.

Specifically speaking, you are a good candidate for DBS, if:

  • You have had PD symptoms for at least five years.
  • You have “on/off” fluctuations despite consistent and regular medication dosing.
  • You have dyskinesias.
  • You are unable to tolerate anti-parkinson’s medications due to side effects.
  • You have tremor that is not well controlled with medication (even with medical management by a movement disorders specialist).
  • You continue to have a good response to PD medications, especially carbidopa/levodopa, although the duration of response may be insufficient.
  • You have tried different combinations of anti-Parkinson’s medications under the supervision of a movement disorders neurologist.
  • You have PD symptoms that interfere with daily activities.

Levodopa Response Test

One more test that doctors use to identify which patients are likely to benefit from DBS is called Levodopa response test. In this test, patients stop taking levodopa for 8 to 12 hours and then receive a single dose. If the patients show a clear positive response after this single dose, then they are likely to benefit from DBS.

Conclusion:

Deep brain stimulation (DBS) is the most commonly performed surgical treatment for Parkinson’s. Under this surgery, the surgeon places thin metal wires in the brain; these wires send electrical pulses to the brain to help control some motor symptoms.

While transformative for some, DBS works best for people who have had Parkinson’s disease for at least four years and who get a benefit from medication but have motor complications, and have significant “off” periods (when symptoms return because medication isn’t working well)

It typically works best to lessen motor symptoms of stiffness, slowness and tremor. Scientists are testing DBS in different parts of the brain to address other symptoms, such as balance problems and freezing.