Madam Chu Sai Leong, 51, had lived with chronic pain in her legs and back for more than eight years. So, she was naturally sceptical when her doctor told her about a procedure to implant a spinal cord stimulator – which acts like a pacemaker in the spine – to reduce the pain.

She had already had three operations to treat her spinal cord injury, but they had done nothing to relieve the pain. The first operation had also left her paralysed and wheelchair-bound with stabbing pains in her legs and back all day long, every day.

The pain was so severe that she had difficulty sleeping. When it got so bad that she could not even get out of bed – which was every two or three weeks – she had to be hospitalised. Sleeping pills and pain relief medication did nothing for her. Mdm Chu was also unable to work as the pain kept her a virtual prisoner at home.

Spinal cord stimulator to the rescue of chronic pain sufferers

Two years ago, she decided to have the spinal cord stimulator implanted. She did not see much change immediately after the operation, but a few months later, she realised that the pain which had plagued her for years was no longer bothering her.

Now Mdm Chu does not even think about it, as she no longer feels the pain. “I still stay at home watching TV most of the time, but now I can go out without having to worry about the pain.”

Most days, she can be found travelling to places in her neighbourhood in her motorised wheelchair, and occasionally, on weekends, enjoying the outdoors at East Coast Park. Now, she even dreams about eventually returning to work.

Associate Professor Ng Wai Hoe, Senior Consultant and Head, Department of Neurosurgery, National Neuroscience Institute (NNI) said that Mdm Chu had one of the most severe levels of pain among his patients, but she has had the best results. “Her condition has improved by about 90 per cent,” said Prof Ng. “She used to spend six months a year in hospital. I’m delighted that she is able to enjoy life now. It was a pleasant surprise to discover that her healthy tan now is the result of many hours spent at the beach at East Coast Park.”

How neuromodulation tricks the brain

Mdm Chu is among six patients who have undergone NNI’s Surgical Neuromodulation Pain Programme, which is an extension of the pain relief services provided at the Singapore General Hospital and Tan Tock Seng Hospital. The programme offers three types of surgeries: spinal cord stimulation, motor cortex stimulation and deep brain stimulation.

All six had their pain reduced greatly after spinal cord stimulation. The procedure involves placing a stimulating electrode in the spine and connecting it to a battery-operated pulse generator, which acts like a pacemaker, implanted in the lower abdominal or loin region. The pacemaker creates electrical signals which are delivered by a lead (thin wire) to nerves in the spine, stimulating it for the brain to alleviate the experience of chronic pain.

“In a way, the electrical signals trick the normal nervous circuitry (that perceives nerve damage as pain) and the brain into perceiving a more pleasant sensation. It converts a pain sensation into something that is more acceptable,” explained Prof Ng.

While it is not a cure for chronic pain, the procedure provides pain relief and helps patients lead a normal lifestyle and not be crippled by it. Research shows that approximately half of all patients will get about 50 per cent pain relief.

Before the operation, patients undergo trial stimulation for three to five days either as inpatients or outpatients. “For the trial, the electrode is placed on the surface of the spinal cord and the wire is connected to an external pacemaker. Over the next few days, the medical team will set different parameters and change the amount and frequency of the current that is running to determine the optimal setting,” said Prof Ng.

Who is neuromodulation meant for?

Those who will benefit most from spinal cord stimulation are those who have had many back surgeries and are still in a lot of pain, as well as those who have exhausted all the usual modes of pain management and treatment.

The procedure, while not new, uses the latest technology. It can also be used to treat arm pain due to nerve damage, although it does not work well for pain at the central neck area. “But researchers are now developing new electrodes that may help in this respect in the future,” said Prof Ng.

“The pain we can alleviate the most using this procedure is actually leg pain rather than back pain. Back pain is caused by many factors but leg pain is usually caused by nerve damage (at the back) and this kind of pain is very responsive to the procedure,” said Prof Ng.

He said some patients who have had many surgeries without positive results can become sceptical about the spinal cord stimulation procedure. “Sometimes they don’t want to try this, even though we believe it may help them a lot. It’s rather sad because it can give them a one-in-two chance of pain relief which is a fairly good chance of being pain-free.”

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