Peripheral Nerve Stimulation
Peripheral nerve stimulation is an alternative or next-line treatment for patients with severe or chronic headache pain. This treatment is recommended for cases in which conventional medications, such as oral analgesics, have not produced the expected effect. Peripheral nerve stimulation is a drug-free form of therapy in which devices that emit mild electrical impulses that correct high or abnormal level of pain signals are placed in the body near peripheral nerves that carry these signals. This type of technique is known as neuromodulation, which employs minimally-invasive surgery to provide medium- to long-term relief from pain.
Patients who experience treatment-resistant pain on a regular or constant basis, or who do not wish to rely on drugs to address this pain, may be candidates for peripheral nerve stimulation. The techniques involved in peripheral nerve stimulation are safe and have been shown to be effective in many conditions in which chronic pain is a factor. This may include consistent pain in the limbs or other tissues and pain felt in the skull or face (i.e. headaches).
Headache pain, and its various subtypes, is one of the most prevalent forms of pain as estimated by research from the United States and Europe. This research suggests that approximately 2% of the population suffer from chronic headache. This is typically defined as head pain that persists for three months or more. Many forms of headache may be experienced at regular, predictable intervals, with a frequency of up to once a day. For example, migraines, a common headache type, may occur in regular episodes or become chronic over time. Up to 50% of patients with chronic migraine report a lack of satisfaction with the treatment currently received.
Potential candidates for peripheral nerve stimulation may undergo screening to determine their suitability for the procedure. This may involve verifying their prior history of severe debilitating pain and that a course of conventional treatment (lasting three months or more) has failed. Candidates for this procedure may also undergo psychological screening. If the treatment is deemed appropriate, this may also help the physician or pain specialist choose optimal targets for the implanted devices.
Implantation is typically completed in two stages. The first stage may take the form of the implantation of a device on a temporary basis to test the effects on the patient in question. If this generates a positive response (typically the perception of an approximate 50% reduction in pain), the procedure to implant a more permanent device may go ahead. If the patient does not report the expected effect, alternative treatment options may be offered instead.
Peripheral nerve stimulation requires the patient to be conscious during the procedure, so they can report on the immediate effects of device activation. These devices tend to be very small electrodes that deliver relatively tiny electric pulses to modulate nerve signals. A local anesthetic is administered at the start of the procedure, so that the patient does not experience pain when these electrodes are placed. Device placement is aided by imaging technology such as fluoroscopy, so that the specialist or physician accurately places the electrodes in line with the targets identified previously.
When correct placement is achieved, the device is activated to test it. This should not cause pain, but may result in a sensation of tingling. The modulation is successful when activation results in pain relief, indicating that the signals of the peripheral nerve in question are being corrected. The device is often connected to leads, which travel into a battery pack which is also implanted under the skin. Peripheral nerve stimulators are nearly always contained in the body, and the vast majority of the apparatus cannot be seen.
Peripheral nerve stimulation is reported to have a rate of success of approximately 90%. Some studies indicate that the patients who receive this treatment are able to reduce their intake of pain-killing medication and return to normal daily activities unaffected by their headache condition.
Peripheral nerve stimulation may be used in a variety of conditions in which peripheral nerves may send disproportionate pain signals to the brain due to damage or disease. These may include:
Complex regional pain syndrome
Diabetic peripheral neuropathy
Occipital neuralgia, a type of headache that may be related to head trauma or certain conditions
Patients who wish to reduce their dependence (or expense) on conventional treatments, or find that these options are ineffective in their case, may consider peripheral nerve stimulation. Some reports indicate that up to 30% of patients are able to discontinue their medication regimens as a result of undergoing a procedure to implant a peripheral nerve stimulation device. This treatment may be applicable to other conditions in which the resultant pain is mediated by peripheral nerves.
The main risks of peripheral nerve stimulation include infection in the skin or tissues through which a device has been implanted. These may be managed with antibiotics in most cases. More serious complications are rare. Other adverse effects of peripheral nerve stimulation include implant failure, lead migration, or loss of power.
Peripheral nerve stimulation is an option for patients with treatment-resistant headache, neuropathy, or pain syndromes that are resistant to other conventional therapies. It is a form of neuromodulation in which peripheral nerves associated with pain signals are targeted with mild electrical impulses generated by a small implantable device. Research has demonstrated the efficacy and benefits of peripheral nerve stimulation in many conditions, including many types of severe chronic headache.