Fibromyalgia Treated with Occipital Nerve Stimulation
AANS 2015 MEETING HIGHLIGHT
The diagnosis, pathophysiology, and treatment of fibromyalgia were topics addressed by Jennifer Sweet, MD, Assistant Professor of Neurological Surgery, Case School of Medicine, University Hospitals Case Medical Center, Cleveland, Ohio, at the 83rd Annual Scientific Meeting of the American Association of Neurological Surgeons in Washington, DC. Particular attention was paid to neurosurgical techniques for treating fibromyalgia.
Definition, Epidemiology, and Predisposing Factors
Fibromyalgia is a clinical syndrome composed of chronic widespread pain and reduced pain thresholds, affecting up to 5% of the US adult population, with a significantly higher rate in females. The disorder involves a constellation of symptoms, including pain, psychological conditions such as depression, anxiety, and panic disorders, fatigue, and additional comorbidities. Predictors of fibromyalgia are obesity, limited physical activity, high workload, increased physical discomfort, and permanent local pain of over 6 years' duration.
The Pain of Fibromyalgia
The pain of fibromyalgia is characterized by chronic pain for at least 3 months in several regions of the body; neck, upper, mid, or low back, ribs, and at least one site on each limb; peripheral sensitization; diffuse muscle tenderness; and peripheral and central sensitization. Patients also complain of fatigue, characterized by difficulty sleeping through the night, mental and physical exhaustion, and altered non rapid eye movement sleep. Comorbidities of the cardiovascular, peripheral and central nervous, urinary, and gastrointestinal systems are also involved.
Fibromyalgia must not be mistaken for hypothyroidism, tendonitis, ankylosing spondylitis, lupus erythematosus, dermatomyositis, polymyositis, rheumatoid arthritis, or osteoarthritis, or other similar types of disorders.
- Peripheral and central sensitization: Fibromyalgia is characterized by an increased peripheral response to stimulation, increased excitability of dorsal horn neurons, wind-up (temporal summation), and temporal summation of second pain.
- Neurotransmitter release: In fibromyalgia, norepinephrine, dopamine, and serotonin (leading to depression and panic disorder) are reduced. Substance P, glutamate, and opioids can be increased. Altered connectivity and cerebral blood flow, and even anatomical changes such as cortical thickness, have been demonstrated on various functional magnetic resonance imaging studies.
Pharmacological treatments: Selective serotonin reuptake inhibitors, tricyclic antidepressants, gabapentin, pregabalin, opioids, ketamine, naltrexone, sodium oxybate, benzodiazepine, and hypnotics, or a combination.
- Selective serotonin reuptake inhibitors raise serotonin levels, which are reduced in fibromyalgia. Tricyclic antidepressants and dual reuptake inhibitors of serotonin and noradrenaline, such as venlafaxine, raise noradrenaline, which is reduced in fibromyalgia.
- Ketamine raises dopamine, which is reduced in fibromyalgia.
- Naltrexone reduces opioids, which are raised in fibromyalgia.
- Gabapentin and pregabalin lower glutamate and substance P, which are raised in fibromyalgia.
- Sodium oxypate, benzodiazepines, and hypnotics raise gamma-aminobutyric acid.
- Nonsteroidal anti-inflammatory drugs and corticosteroids have not been proven to be as effective.
Non-pharmacological treatments: Physical medical rehabilitation and regular exercise, cognitive behavioral therapy, meditation and yoga, hyperthermia and hydrotherapy have all been shown to be beneficial in the treatment of fibromyalgia. Additional studies suggest repetitive transcranial magnetic stimulation, transcranial direct current stimulation, xenon radiation of the stellate ganglion, and surgical interventions can also play a role in the management of these patients.
- Occipital nerve stimulation: Occipital nerve stimulation involves subcutaneous implantation of one or more electrodes over the sensory nerves of the second and third cervical segments of the spine, located over the occiput of the skull. The electrodes deliver electrical current to these superficial sensory nerves and are thought to influence pain processing and thus improve pain symptoms in patients with fibromyalgia. Stimulation is usually performed first as a short trial, during which an electrode is percutaneously placed with the use of fluoroscopy in an awake patient in a surgical suite. Over the course of several days, stimulation is delivered via an external battery source. If symptoms of fibromyalgia-related head and overall body pains improve, then surgery is scheduled to permanently implant the electrode and connect it to a battery source that is surgically implanted beneath the skin, similar to a pacemaker device.
- Studies investigating the effect of occipital nerve stimulation for fibromyalgia have shown significant decreases in pain visual analog scale scores as well as improvement in functional capacity during stimulation and at follow-up. One study also demonstrated significant improvements in fatigue per the modified fatigue and impact scale, number of trigger points, and overall morbidity per the fibromyalgia compact questionnaire. No serious adverse events were reported in these studies.
Fibromyalgia is a complex disease involving pain, psychological conditions, fatigue, and other comorbidities. Occipital nerve stimulation may be an effective option for fibromyalgia-related pain when pharmacological agents, physical therapy, and other conservative interventions have failed. “For fibromyalgia patients suffering from chronic, intractable, widespread pain, particularly of the head and back, and despite maximal conservative management,” Dr. Sweet said, “occipital nerve stimulation may be a treatment option. An occipital nerve stimulator trial is a relatively low-risk procedure, which may help to determine a patient’s eligibility for permanent implantation.”
The neurosurgeon and pain management physician can be of invaluable service to patients with fibromyalgia, which inflicts chronic pain, psychological symptoms, fatigue, and additional comorbidities on sufferers.
May 27, 2015