Overview of Occipital Nerve Stimulation
Occipital nerve stimulation (ONS) is a medical procedure that helps with different types of nerve pain, commonly known as neuralgia. This treatment is minimal and can be adjusted or reversed if needed. It involves an implanted device that consists of an under-the-skin electrode and a device that generates electrical pulses. The method was firstly introduced by Picaza and others in 1977, and was later performed on 13 patients by Weiner and Reed in 1999. Their aim was to manage a severe type of nerve pain commonly known as “occipital neuralgia”.
After this initial use, the potential scenarios where ONS can be used increased to various primary and secondary headache disorders that were not responsive to other treatments. These include medications for nerve pain, injections like corticosteroids, a treatment called radiofrequency rhizolysis which is a kind of nerve treatment, acupuncture, psychological strategies (approaches related to our behaviour and thoughts for managing pain), and various other strategies involving multiple healthcare disciplines.
Anatomy and Physiology of Occipital Nerve Stimulation
The back of your head, or the occipital area, is served by several nerves. These include the greater, lesser, and least occipital nerves. They all originate from certain parts of your spinal cord, specifically the second and third sections, known as C2 and C3.
The greater occipital nerve is the largest sensory nerve, meaning it mainly gives us our ability to feel. It’s responsible for the sense of touch in the back of your head and part of the side. This nerve is found near the occipital artery, which is a blood vessel in the same area.
The lesser occipital nerve supplies feeling to the skin around the top and back of your ear. The least occipital nerve is found towards the middle of the back of your head and helps in sending sensations from the joints between your second and third spinal sections. It also serves some muscles in your neck and a small area beneath the back of your head.
Neuroscientists are still not certain about how occipital nerve stimulation (ONS) works, which is a type of treatment involving these nerves. However, one theory suggests that constant stimulation of the occipital nerves could lead to various changes in several areas of the brain, including regions known as the pons, midbrain, and periaqueductal gray.
Why do People Need Occipital Nerve Stimulation
Occipital nerve stimulation (ONS) is a medical procedure that can help relieve some types of persistent headaches. These headaches can either be primary, meaning they exist on their own without a known cause, or secondary, meaning they are caused by something else such as neck injuries, infections, or severe high blood pressure. The latter type of headache can be harder to treat, especially when common medications fail to relieve pain, cause unbearable side effects, or can’t be used due to other medical reasons.
So, who might undergo ONS? The examples are listed below:
1. People with occipital neuralgia: This condition is characterized by sharp, intense pain in the back of the head or upper neck region. The pain is often described as electrical shocks, caused by long-term compacting of the C2 nerve. Occipital neuralgia follows migraines and tension headaches as the third most common type of headache.
2. Chronic migraine sufferers: Chronic migraines are extremely common globally, affecting nearly a billion people. These recurrent headaches significantly affect the person’s quality of life.
3. Cluster headache patients: These headaches are intensely painful, limited to one side of the head, and usually felt around the eye.
4. Those with cervicogenic headaches: These are chronic headaches that originate from the neck joints at the base of the skull and top of the spine.
5. Patients with hemicrania continua: This condition is a type of primary headache, meaning there are no other underlying medical conditions causing it. It occurs every day and is usually felt on one side of the head.
In a recent case, ONS has also shown promise in treating headaches triggered by chemotherapy treatments. However, each patient’s case is different, so it’s vital to discuss potential treatments with your healthcare provider.
When a Person Should Avoid Occipital Nerve Stimulation
There are a few reasons why a person might not be able to have ONS (Occipital Nerve Stimulation), a treatment used for certain types of nerve pain:
1. The procedure may not be advised if there is no improvement in the person’s quality of life after a trial period.
2. If there is a concern about misuse of strong painkillers (opioids), the person may not be able to get this treatment, even if they have had improvement with a trial block (a test to see if the procedure could help).
3. If a person has a local infection (an infection in a certain area of their body), they may not be able to have this procedure.
4. If a person has bleeding abnormalities (problems with their blood that makes clotting difficult), this procedure may be too risky.
5. Arnold-Chiari malformation (a condition where the lower part of the brain extends into the spinal canal) can make this procedure too risky.
6. If a person has an implanted electrical device like a pacemaker (a device to help control heartbeat) or a spinal cord stimulator (a device to manage pain), it might interfere with this therapy.
7. Pregnancy may be a reason to avoid this procedure.
Equipment used for Occipital Nerve Stimulation
Oscillatory Nerve Stimulation, or ONS, requires some specific tools and materials.
The first set of equipment needed are electrodes and leads. Leads are kind of like wires that send electrical signals from a power source to a target location. There are two types of leads. The first is a percutaneous lead, which is thin and cylindrical and can be inserted using a needle. The electric field around this type of lead goes in all directions. The second is a surgical or paddle lead, which is broader and flatter and requires surgery to implant. The electric field around the paddle lead is directed towards one side, which allows for stimulation even at low electric power, thereby helping to prolong the life of the device’s battery.
Next, we have anchors. Anchors work to secure the leads and extensions to the connective tissue in your body. Think of them as clips or fasteners that keep everything in place inside your body.
Then, there are the extensions. These are cable-like structures of varying lengths that link the leads to the source of power.
Finally, we have the power source for the device, which is usually a battery or an Internal Pulse Generator (IPG). This is typically planted in a pocket under the skin, away from where the lead is located. Just like your phone battery, the lifespan of the device’s battery varies – it depends on the strength of the electrical signals it sends and how long the device is used each day. Generally speaking, a lithium battery will last about 3 to 5 years, while rechargeable batteries will need to be replaced after around 7 to 9 years.
Preparing for Occipital Nerve Stimulation
Before having a permanent ONS (Occipital Nerve Stimulation) implant, you will first need to go through a trial. During this time, thin, flexible wires known as leads are put underneath your skin and connected to a battery that’s outside your body. These leads are then connected to a cable. A special tool that uses radio waves is used to send signals to various combinations of electrodes, allowing you to inform your doctor of the location, intensity, and feeling of the stimulation. This trial lasts about 4 to 7 days. During this trial, you’ll keep a diary of your headaches. If your pain improves by more than half, or if you have fewer days with headaches, or your quality of life improves, the trial is considered a success. If the trial is successful, you can then get a permanent implant. After the procedure, it takes about six weeks for your body to completely heal. It’s important to avoid intense physical activity during this time.
Your doctor can use local or general anesthesia for the procedure. Local anesthesia, used by doctors Weiner and Reed, is a type of pain blocker that numbs a small area of your body. One advantage of this is that it allows you to give your doctor feedback about where you’re feeling the effects of the electrodes, which can help to confirm they’re in the right place. Sometimes, doctors might also give you some medicine to help you relax during the procedure (a process known as procedural sedation). Staff could wake you up midway to check on how you’re feeling. Some doctors prefer to use general anesthesia, which makes you unconscious during the procedure. With this approach, you’ll lie face down which minimizes the risk of the leads moving around.
Depending on where the surgeon make the incision, the procedure can be done with you either lying on your side or on your stomach.
How is Occipital Nerve Stimulation performed
Occipital Nerve Stimulation (ONS) is a process where a device, referred to as a stimulator, is implanted in the body, typically near the back of the neck, to help manage nerve-associated pain. This process can be done on either or both sides of the body, depending on what’s suitable for you.
This stimulator works by sending out electric signals. They can adjust the exact strength, frequency, and duration of these signals to create a tingling sensation in the area the nerve affects. As a result, this can help ease the discomfort felt in that area. This procedure can be done in two ways: lateral and medial approaches.
In the lateral approach, which was first used by doctors named Weiner and Reed, the doctor makes a small cut in a bony part behind the ear (called the mastoid process). They then take a thin, long, flexible tube (catheter) and guide it under the skin towards the middle of the body. They do this with the help of a special imaging technique called fluoroscopy, which allows the doctor to see the catheter’s location inside the body.
In the medial approach, the doctor makes a small cut in the middle of the base of the neck. The leads, which are wires that carry electricity from the stimulator to the body, are then inserted from the cut and directed outwards. This method has a few advantages:
- There’s more fatty tissue in the middle of the body than on the sides. This allows for a bigger pocket to be created under the skin to hold the leads securely and reduce the risk of them moving out of place.
- This method is typically more comfortable for people who wear glasses, as the cut used for inserting the leads is positioned in a less sensitive area.
- The leads going to both sides of the body can be inserted through one cut, instead of needing two separate cuts.
Once the stimulator is inserted and the leads are placed, the stimulator’s position can vary. It can be implanted in the upper part of the buttock, abdomen, or below the shoulder blade or collarbone. For placement in the upper buttock, patients lie on their stomach; for the other sites, patients lie on their back or side. This procedure is done under general anesthesia, so you won’t feel any pain during the process.
After the procedure is completed, the device’s settings can be adjusted by specialized technicians from the company that made the device. Lastly, you will undergo a simple X-ray test to confirm the lead’s position in the body after this procedure, and this could also be helpful to assess any complications associated with future lead migration or fracture.
Possible Complications of Occipital Nerve Stimulation
There are two main types of complications that can occur with surgical procedures: those related to the equipment used (hardware) and those that are biological in nature.
The first type, hardware-related complications, most often involve something called lead migration. This is where a component of the surgical tools or devices moves from its original placed position. For example, in studies on headache treatments involving surgical procedures, lead migration was reported in as many as 60 to 100 percent of patients. It’s worth noting, however, that this complication can usually be reduced by limiting movement of the neck and is often associated with severe trauma like a car accident. Other steps that can be taken to prevent lead migration include using silicone glue or soft neck collars, and opting for a midline surgical approach. Other hardware complications can involve issues with the surgical leads, like breakages, malfunctions, and the need to reposition the device that powers the surgical equipment.
The second type of complications, biological complications, often involve pain in the area where the device is implanted. Reports include symptoms like burning pain or muscle spasms, wound openings (also known as wound dehiscence), infections (which can occur in up to 4% of patients), and skin erosion. These risks can be reduced by giving preventive antibiotics, keeping the surgical area very clean, and trimming hair around the surgical site. Other complications that have been reported with this kind of surgery include the surgical device not working properly, issues with patients following treatment instructions, ineffective electrical stimulation of nerves, and the device delivering a shock.
What Else Should I Know About Occipital Nerve Stimulation?
Chronic headaches are a common ailment, affecting 3 to 5% of people globally. This condition is a significant cause of disability, often leading to a loss in productivity and daily activities. Fortunately, recent developments in medical treatments have made it possible to effectively manage chronic headaches in most people.
However, there’s a small group of people whose headaches don’t improve with usual treatments. In such instances, a treatment method called Occipital Nerve Stimulation (ONS), could be a promising alternative. Despite this, evidence supporting its effectiveness is limited because only a small number of people have been involved in studies until now, and the studies lacked controls for comparison.
Moreover, we don’t know much about its long-term effectiveness. Currently, Nantes University Hospital is conducting a larger-scale, controlled study for a more straightforward comparison between ONS and traditional treatments. It’s a randomized trial (which means participants are randomly assigned to different treatments), intending to finalize by the end of 2022. The results from this study could help in understanding whether ONS is truly beneficial in managing chronic headaches.