Drilling holes in the skull and implanting slim electrodes in the brain may sound a little too similar to those infamous lobotomies of the 1940s. But neuroscience has come a long way since, and a neurosurgical procedure known as deep-brain stimulation (DBS) is increasingly being used by doctors today to treat a variety of movement disorders.
Movement disorders are neurological conditions that interfere with a person’s movements. They include Parkinson’s disease, essential tremors, dystonia as well as tic.
Dr Prakash Kumar, Consultant at the Department of Neurology, National Neuroscience Institute (Singapore General Hospital Campus), specialises in DBS. He explains: “DBS basically involves securing electrodes in the affected regions of the brain, such as the subthalamic nucleus in Parkinson’s patients. Wires connect these electrodes to the neurostimulator, which is a small battery pack in the chest.”
How DBS is performed
There are two stages of DBS surgery:
Stage 1: Placed under local anaesthesia, the patient’s head is secured in a rigid frame. One or two holes are then drilled in the skull and the electrode is placed in a particular part of the brain. As this is being done, tiny electrical impulses are sent over the electrodes while the patient is awake to ensure that they are properly connected.
Stage 2: During this stage, the patient is placed under general anaesthesia and is unconscious. An incision is made below the collarbone so that the neurostimulator can be implanted beneath the skin in the chest area. The neurostimulator is then connected to the brain electrode via a connecting wire that is passed under the skin of the head, neck, and shoulder.
Before DBS surgery can be performed, the patient has to undergo a physical examination, as well as a CT scan and MRI scan to identify and locate the exact target within the brain.
Dr Kumar adds: “The doctor will also remind the patient to share details about his or her health conditions (such as hypertension, diabetes and heart disease) and any current medication. In the days leading up to the surgery, certain medications should be stopped, while lifestyle habits like smoking and alcohol should be avoided.”
A pacemaker for the brain
In cases of Parkinson’s disease, a lack of dopamine (crucial for the proper transmission of nerve-cell signals) causes the transmission of nerve signals to go haywire.
Dr Kumar says: “When the DBS electrodes are switched on, they pump steady pulses of electricity to the brain, thereby blocking any abnormal firing of neurons.”
While DBS may not fully cure Parkinson’s disease, it can successfully decrease the severity of its symptoms like tremors, gait problems, stiffness, slowness and involuntary movements (known as dyskinesia). “This means Parkinson’s patients regain control of their movements, although non-motor symptoms like depression and balance problems still persist,” says Dr Kumar. “And as it is a chronic neurological disease, there will still be a need for patients to manage the condition long-term.”
Hope for the future?
When it comes to treating movement disorders, DBS is actually not an experimental procedure.
Since 1997, DBS has helped improve symptoms in more than 100,000 patients with Parkinson’s and other movement disorders worldwide, including Singapore.
Meanwhile, scientific researchers are studying the use of DBS for other medical conditions, such as:
- Bipolar disorder
- Treatment-resistant depression
- Post-traumatic stress disorder
- Alzheimer’s disease
- Tourette syndrome
- Urinary tract infections
- Traumatic brain injury
- Cluster headache
- Chronic pain
- Multiple sclerosis
Dr Kumar observes: “DBS is definitely a potential treatment option for any condition where brain regions are not functioning properly. But clinical trials for DBS to treat these medical conditions are still ongoing – it can be years before DBS can be employed in these ways here.”