Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterised by the loss of neuronal dopamine production in the brain. Parkinson's disease symptoms include muscle rigidity, tremors, and changes in speech and gait. After diagnosis, treatments can help relieve symptoms, but there is no cure.

“One per cent of the world population aged more than 60 years have PD and with an ageing population, the burden of PD continues to increase. The number of PD cases in individuals more than 50 years is predicted to reach between 8.7 to 9.3 million worldwide in the next 25 years,” explained Dr Ahmad Tauqeer, Specialist in Neurology & Consultant of Raffles Neuroscience Centre, Raffles Hospital.

Although there’s no cure for Parkinson’s disease, there are medications that can help patients better cope with the symptoms of the condition. If patients no longer find these medications helpful, they have the option of deep brain stimulation.

“Deep brain stimulation (DBS) has become an effective therapy option for several different neurologic and psychiatric conditions, including PD,” highlighted Dr Ahmad. DBS, a form of stereotactic surgery, has become the surgical procedure of choice for PD because it does not involve destruction of brain tissue; it is reversible; it can be adjusted as the disease progresses or adverse events occur; and bilateral procedures can be performed without a significant increase in adverse events.

Surgical procedure and complications

In DBS, surgeons implant electrodes into a specific part of your brain. The electrodes are connected to a generator implanted in your chest near your collarbone that sends electrical pulses to your brain and may reduce your Parkinson's disease symptoms. Some people experience problems with the DBS system or have complications due to stimulation, and doctors may need to adjust or replace some parts of the system.

He noted that complications of surgery may include bleeding in the brain, stroke, infection, breathing problems, nausea, heart problems and even seizures. A few weeks after the surgery, some possible side effects of stimulation may include numbness or tingling sensations, muscle tightness of the face or arm, speech problems, balance problems, lightheadedness and unwanted mood changes, such as mania and depression.

DBS is most often offered to people with advanced Parkinson's disease who have unstable medication (levodopa) responses. It can stabilise medication fluctuations, reduce or halt involuntary movements (dyskinesias), reduce tremor, reduce rigidity, and improve slowing of movement. DBS is effective in controlling erratic and fluctuating responses to levodopa or for controlling dyskinesia that don't improve with medication adjustments.

However, DBS isn't helpful for problems that don't respond to levodopa therapy apart from tremor. A tremor may be controlled by DBS even if the tremor isn't very responsive to levodopa. Although DBS may provide sustained benefit for Parkinson's symptoms, it doesn't keep PD from progressing.

Deep brain stimulation, a form of stereotactic surgery, has become the surgical procedure of choice for PD because it does not involve destruction of brain tissue.
Deep brain stimulation, a form of stereotactic surgery, has become the surgical procedure of choice for PD because it does not involve destruction of brain tissue.

The future for DBS

DBS has provided dramatic improvements in the quality of life for patients with PD, tremor, dystonia, and other movement and basal ganglia related brain disorders.  With a more refined technology, there is a need to improve our treatment of “motor (tremor, stiffness, slowness, balance, gait),” as well as “non-motor (mood, cognitive, and behavioral)” symptoms, in combination with other therapies. There will be rechargeable devices in the foreseeable future, as well as devices that will work on a closed-loop circuit, meaning they will automatically turn on when needed (like a cardiac defibrillator).

Finally, there is a need to adapt this technology to be used for other promising therapies such as viral vectors, gene therapies, stem cell therapies, and the instillation of other factors which may aid in the survival of brain cells. Since many of these diseases are neurodegenerative, and many have multiple motor and non-motor manifestations, DBS will be used in combination with other promising therapies and technologies. “While DBS is widely known as an accepted therapy, doctors need to proceed with caution, and realize that just like any choice in life, DBS is not for everyone,” he concluded. MIMS

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