Tiny pellet to banish chronic back pain
A Tiny pellet no bigger than a grain of rice could banish the agony of sciatica — a major cause of back pain. implanted in the spine, it gradually releases painkilling medicine. made from biodegradable plastic, the miniature pellet slowly breaks down, releasing a constant supply of the drug into the affected area. it provides relief for up to a year before it needs replacing.
crucially, it contains a new type of painkiller, clonidine, which does not have the same addictive properties as potent opioid drugs often used to treat severe pain.
A major trial is under way at West Virginia University in the U. S. in around 200 patients with sciatica to see if the pellet could give them long-term pain relief and avoid the need for surgery.
Sciatica affects around one person in 20 at some point.
it is caused by irritation or compression of the sciatic nerve, which runs from the bottom of the spine to the knee. it can be triggered by bending awkwardly, lifting heavy items, sitting for long periods and being overweight, but is most often due to ageing.
The spine is made up of 24 bones called vertebrae, each stacked on top of one another. in between each bone and the next is a circular pad of tissue, or disc. These discs have a tough outer case which surrounds a gel-like substance called nucleus pulposus, and water to keep it moist and flexible.
Problems arise when the outer casing gets damaged as the soft gel and water inside leak and put pressure on the sciatic nerve, which causes pain.
TREATMENT involves a combination of physiotherapy — to mobilise the spine and ease pressure on nerves — and painkillers.
Steroid jabs are often used to dampen inflammation, but the effects can wear off.
in many instances, a slipped disc will eventually shrink back away from the nerve as the water naturally dries up. But in severe cases, surgery is needed to release the compressed nerve and remove part of the disc.
The new pellet could transform the lives of those who might otherwise need surgery.
clonidine’s powerful painkilling effect is due to the novel way it works. it stimulates the production of proteins called alpha-2 adrenergic receptors, which help process pain signals in the spine. The higher the levels of these proteins, the fewer pain signals reach the brain.
Some spinal surgeons already inject the drug during sciatica surgery as this can reduce the need for painkillers afterwards. The pellet is inserted under local anaesthetic through a long hollow needle into the damaged area in the spine. it is placed next to the damaged disc, and the procedure takes under an hour.
Studies show injecting clonidine into the area around a disc in patients with sciatic pain for at least three months significantly reduced pain scores within two weeks, and the effects lasted more than a month.
The pellet is expected to do the same but for much longer.
Patients in the trial will either be injected with a pellet or will have a sham injection. They will then be asked to rate pain levels every few months. The results are due later this year.
colin natali, a consultant spinal surgeon at The Lister Hospital in London, said: ‘We already inject clonidine during sciatica surgery because it significantly reduces the painkillers needed afterwards. Turning it into a pellet that is implanted in the spine is the next step and could reduce the need for surgery.’