Injections & Implantable Devices to Manage Pain
Spinal Injections | Implantable Pain Devices
Gordon Irving, M.D.
There are many parts of the back and neck that can cause pain. These include ligaments, muscles, joints, nerves, bones, and discs. Most back pain comes from more than one of these parts.
A bulging disc or disc degeneration, where the pads between the bones in your spine wear down, is normal as you age and usually does not cause pain. Pain going down the leg or arm does not mean there is a "pinched nerve" either. A pinched or inflamed nerve will usually cause sudden, short, shooting pains in the hand or foot. The most common cause of back pain for people 20-50 years old are the pads between your spinal bones (the intervertebral disc); after 65, it is arthritis of the spinal joints. The majority of back pain does not need injections and certainly not surgery.
Having an MRI or CT scan of the spine will not usually show the cause of the pain unless there is a pinched nerve. Even X-rays cannot show what is causing pain and they are usually not needed. Spinal injections may be used for diagnosis and sometimes treatment.
Types of Injection
- Trigger-point injections: Injections into a tight band in a muscle with a local anesthetic (numbing medicine). The tight band causes or triggers off pain in an area away from the muscle, hence the term trigger point. These injections can decrease pain, loosen tight muscles and allow you to stretch and stop the trigger point reforming. Trigger points are often over acupuncture points.
- Acupuncture: Thin acupuncture needles can be used in classic acupuncture points, just under the surface of the skin, for electrical acupuncture, or for "pecking" treatments. to treat a trigger point or generally to treat pain or headaches
- Ligaments: If numbing injections help decrease pain, prolotherapy injections may be used. For these injections, a mixture of local anesthetic dextrose (sugar) and sometimes other substances are injected to cause collagen (scar tissue) to strengthen the ligament and kill small pain nerve endings.
- Spinal joint injections (facet joint injections): These joints help the spine bend from the tailbone to the skull. Like any joint, they can be sprained or get arthritis. The injections are usually done with X-ray, but ultrasound can be used. Numbing medicine and steroids are injected into the joint, or onto the nerves in the joint. If two injections and physical therapy or exercise do not help, a radiofrequency neurotomy procedure (RF) may help (see below).
- Radiofrequency neurotomy procedure: A special needle is placed near the nerves in the painful joints. A microwave current in the needle kills the small nerve, so you can’t feel pain. These nerves regrow, and if the joint problem does not go away, the RF procedure may have to be repeated.
- Epidural injections: The space around the nerves in the spine is called the epidural space. The nerve exits out of the spinal bones via tunnels called foramen. Epidural injections can be done into the middle of the space (interlaminar) or into the tunnel from the side (transforaminal). The transforaminal route is used if there is a herniated disc hurting a nerve in that area. Epidural steroids are injected to decrease inflammation in the epidural space, because of a disc herniation or narrowing (spinal stenosis).
- Selective nerve blocks: Blocking nerves with local anesthetic where they come out of the spine helps doctors figure out which nerve is causing pain.
- Disc injections (discogram): Although these injections are sometimes used to diagnose if a disc (pad between the spinal bones) is the cause of pain, it carries significant risk with often not much long term benefit. Blood does not flow to the disc so it can get infected after an injection into it. More than one disc is usually injected, which can be extremely painful if they are a cause of pain. Often more than one disc causes the pain, and there are not good treatments for more than one painful disc. There may be advertisements for "minimally invasive disc surgeries", unfortunately the majority carry significant risk and have not been shown in careful clinical trials to help in the long term.
- If the first injection does not help, more injections in the same place will not help.
- A positive result indicating that an area is causing the pain is when a local anesthetic numbs the pain for two or more hours. Unfortunately even if one injection helped, a second injection may not work.
- Epidural injections will not help pain in the middle of the back that has been present for more than a year, unless it is due to spinal stenosis.
- Injections only help a few patients. Weight loss, stopping smoking and exercise have all been shown to decrease pain in the long term more successfully than injections
Problems with Spinal Injections
There are risks will all injections, especially with disc injections and some neck injections. Bruising and discomfort, infection, and reactions to the medications are possible, but rare. Epidural and transforaminal injections into the neck, however, have many more risks and have caused death, stroke and paralysis.
Implantable Pain Devices
Gordon Irving, M.D.
Spinal Cord Stimulators (SCS)
These are wires that send a small current to the spine that changes the pain signals going to the brain. They are usually used for patients whose usual therapy has not worked.
SCS have been used for many painful nerve conditions, including failed back surgery syndrome, severe back and leg pain, and complex regional pain syndrome (CRPS) types I and II (RSD and causalgia). They are used in Europe for problems like severe angina (chest pain because of poor circulation to the heart) and leg pain from poor circulation.
Before implantation, the wires are placed in the back and connected to an external generator that the patient can carry around. The patient goes home and has a normal routine for the next week to see if this helps the pain. This is inexpensive and reversible and shows if SCS will work over time. The permanent generators are placed in the body and can be recharged at home. The patient has a hand-held device to increase or decrease the stimulation.
These pumps are implanted under the skin and hold liquid medications. They pump the medication through a tube to the fluid around the nerves in the back (cerebrospinal fluid). This fluid bathes the spinal cord and the brain, so it gets the drug to where pain is felt more directly. Before the pump is placed, there is usually a three-day trial in the hospital.
The medication used is usually an opioid (morphine, hydromorphone or fentanyl), baclofen for spasticity, or ziconotide for neuropathic pain. There are other medications that may be used, including clonidine and bupivacaine. Several others are being tested.
- The pump could stop or the tube could dislodge.
- Scar tissue could form at the tip of the tube, which can press on the spinal cord and cause severe problems including paralysis if not caught in time.
- The pump has to be refilled every 2 to 3 months.