A pacemaker for your brain
Posted on 9 Oct 2018
Deep brain stimulation surgery changes the lives of those who need it the most, says Mediclinic Constantiaberg neurosurgeon Dr Nico Enslin.
People with serious neurological conditions may find the help they need in the form of deep brain stimulation (DBS), says Dr Nico Enslin, who is one of only two neurosurgeons in the Western Cape who regularly performs the procedure.
“We use deep brain stimulation to help treat the symptoms of people with movement disorders, including essential tremors, epilepsy, Parkinson’s and dystonia,” he says. “These are diseases that affect how the brain controls your body’s movements.”
While medication remains the first-line treatment for these conditions, Dr Enslin says DBS may be a useful or effective option for those patients who find they are unresponsive to medication or have become resistant to medication.
One example is dystonia. Some forms of this disease which causes the muscles to contract uncontrollably, leading to involuntary twisting movements, do not respond to medication, he says. In that case, DBS surgery becomes an option.
“We begin by inserting two small electrodes deep within the brain,” says Dr Enslin. “These are the areas of your brain responsible for coordinating movement. These electrodes connect under the skin to a pulse generator that is implanted in the chest. This will deliver a constant electric current, and we can adjust the frequencies of that current to suit the relevant condition and the patient’s needs.”
In this way, DBS acts as a pacemaker for your brain, says Dr Enslin – although it is still not clinically clear how exactly these electric pulses help to correct abnormal or involuntary muscle contractions. “The theory is that the current interrupts an abnormal neural pathway,” he explains. “The electrodes are placed in nuclei inside the brain that we know play an important role within a network that controls movement.”
A disease like Parkinson’s dampens that control. “It’s almost like slowly pulling up a handbrake. People with Parkinson’s experience a slowing-down of movement, almost a numbing effect, and deep brain stimulation can reprogramme, or modulate, the cells so the normal neural pathways can form.”
DBS is effective at treating dystonia too, which affects the body in a very different way. “The main effect of dystonia is to cause exaggerated involuntary movements,” Dr Enslin says. We place the electrodes in more or less the same part of the brain – the basal ganglia and thalamus – as when we treat Parkinson’s, yet we see a very similar improvement response.”
Dystonia is a rare condition that suffers from a minimum of research in South Africa. Estimates from further afield show it may affect 30 in 100,000 Americans. In general, Dr Enslin says, medical management is not very effective in treating this condition. “In fact, we find that over half of dystonia patients will turn to DBS as a necessity. There are other factors at play here – we will look at whether a patient would qualify and benefit for this surgery, and whether it is a therapy that is indicated for a specific cause, before operating.”
Risk is another factor. Dr Enslin says doctors will need to select qualifying patients carefully, as transient bleeds can occur in about 1% of cases, although they generally do not cause lasting deficits. “But we are implanting something unnatural into the body, and that can lead to infection in a small number of cases. When that happens, we will need to surgically remove the apparatus, or we run the risk of abscesses forming in the brain.”
When DBS is the right option for the patient, it is life-changing. “This surgery can give someone back their quality of life,” Dr Enslin says. “A lot of people with movement disorders become reclusive. They don’t socialise, they don’t even leave their homes. They feel it is embarrassing to have these contractions, and simple things – like typing or writing – become impossible. And they escalate, too: in the long term, people with dystonia can lose their ability to walk. So deep brain stimulation can give them back their freedom to move with purpose and control.”
DBS is also in the process of being medical aid-approved for difficult-to-treat cases of epilepsy. “About a third of epilepsy cases are resistant to medication. In those cases, surgery to remove the problematic part of the brain is usually effective – but for a percentage of them, that is not enough to cure the condition, and that’s where deep brain stimulation might help reduce the severity of their seizures.”
Dr Enslin is one of a handful of doctors in SA who regularly performs deep brain stimulation on children. “In kids, the effects really can’t be underestimated,” he says. “They can play sport again, they can go back to school. They can move as their friends do.”