The Role of the Occipital Nerve
Occipital nerve compression headache is characterized by daily or near-daily pain in the distribution of the occipital nerve. Patients describe the pain as a tight, imploding pressure that sometimes radiates to frontal areas and becomes a throbbing pain. This headache rarely has a neuropathic component.
Allodynia is “almost a requirement of this diagnosis,” said Dr. Blake. The allodynia symptom checklist, however, does not capture it well in these patients because it focuses on pain in the trigeminal nerve distribution. Patients report that the back of the head is tender to the touch and that it hurts to rest the head on a pillow.
The cervical muscles compress the nerve and contribute to the symptoms as well. Patients often report that moving the head or neck exacerbates the pain. The headache also may have migrainous features. It takes skill and expertise to elicit an adequate history from these patients, said Dr. Blake. “Careful questioning is helpful. I often find … that a second visit is more helpful to obtain this history after reviewing the anatomy with the patient, reviewing this pathophysiology, and sending them back out to keep a careful log for two weeks.”
Nerve Blocks and Nerve Decompression
Occipital nerve blocks provide relief for these patients, but they may not be easy to administer. A large dorsal occipital nerve may be mistaken for the greater occipital nerve, for example. Physiologic abnormalities in some patients also can complicate this treatment.
Another effective treatment is nerve decompression surgery. Dr. Blake and colleagues conducted a retrospective review of patients who had undergone decompression of the greater occipital nerves at the point where they traverse the musculature of the posterior neck. The intervention provided complete relief for three to six years in one patient with new daily persistent headache and two patients with chronic posttraumatic headache. Two patients with chronic headache or migraine had partial relief. Surgery provided no relief for two patients with episodic migraine, one patient with chronic migraine, and one patient with chronic tension-type headache.
“In our experience, … 75% to 80% of patients experience a greater than 50% reduction in their headaches, measured by headache frequency and intensity,” said Dr. Blake. She and her colleagues compared outcomes between 18 chronic migraineurs with predominantly occipital pain who underwent surgical decompression of the occipital nerve and 23 patients who were referred for surgery but unable to receive it. In the surgical group, the number of predominantly occipital chronic migraine days per month decreased from 28.9 at baseline to 7.28 at a mean of 46 months later. The outcome in the control group did not change.
Correct patient selection “is the first, most important step” toward treatment success, said Dr. Blake. This process includes a preoperative psychologic evaluation that screens surgical candidates for somatic symptom disorder, mood disorders, a history of trauma, and catastrophizing. If indicated, neurologists may begin providing cognitive behavioral therapy or supportive psychotherapy before surgery. “We have a comprehensive program with postoperative management, including physical therapy and gradual taper of medications,” said Dr. Blake. Central migraine processes may contribute to headache in some of these patients. “Menstrual migraines are not going to go away with nerve decompression. Chronic migraine sometimes does not go away. This is a complex group of patients who definitely require a lot of follow-up.”