Background: Cluster headache is a primary headache involving repeated attacks of excruciatingly severe headache usually occurring several times a day. Most patients with chronic cluster head- ache (CCH) have an unremitting illness requiring daily preventive therapy for years.
Objective: To describe the clinical outcome of occipital nerve stimulation (ONS) for 14 patients with intractable CCH.
Methods: Fourteen patients with medically intractable CCH were implanted with bilateral elec- trodes in the suboccipital region for ONS and a retrospective assessment of their clinical outcome obtained.
Results: At a median follow-up of 17.5 months (range 4–35 months), 10 of 14 patients reported improvement and 9 of these recommend ONS. Three patients noticed a marked improvement of 90% or better (90%, 90%, and 95%), 3 a moderate improvement of 40% or better (40%, 50%, and 60%), and 4 a mild improvement of 20 –30% (20%, 20%, 25%, and 30%). Improvement occurred within days to weeks for those who responded most and patients consistently reported their attacks returned within hours to days when the device was off. One patient found that ONS helped abort acute attacks. Adverse events of concern were lead migrations and battery depletion.
Conclusion: Intractable chronic cluster headache (CCH) is a devastating, disabling condition that has traditionally been treated with cranially invasive or neurally destructive procedures. ONS offers a safe, effective option for some patients with CCH. More work is required to evaluate and understand this novel therapy.
Dr. Sewell’s comment:
Occipital nerve stimulation appears to be the latest “hot treatment” in cluster headache therapy. The greater and lesser occipital nerves are in the neck, or more specifically, they emerge from between the first and second cervical vertebrae, and travel up to carry sensation from the back of the head (see diagram).
Occipital nerve block is a procedure where anesthetic agents (lidocaine and bupivacaine) are injected near the occipital nerve on the back of the head near the base of the skull on the side of the headache. A steroid is often added for anti-inflammatory effects. An occipital nerve block may provide permanent relief or provide a period of pain relief for several months while the cause of the pain is healing. It was first tried for “back-of-the-head” headaches such as migraine and tension headaches and found to be effective. It was first reported to be effective for cluster headache as well as far back as 1985 by Dr. Anthony. The downside, of course, is that once the injection wears off, the cluster attacks return—it’s not a permanent solution—and repeated steroid injections aren’t good for the joints.
Occipital nerve stimulation (ONS) is a little different. This involves implanting a neurostimulator under the skin at the base of the head that delivers electrical impulses near the occipital nerves through insulated lead wires tunneled under the skin. The first two chronic cluster headache patients were successfully treated with ONS in 2003, and a couple of larger case series followed in 2007. The question Burns tried to answer in this study was whether the effect of ONS persists or whether it wears off like occipital nerve block does. He implanted an ONS in 14 patients with medically intractable chronic cluster headache and followed them for times ranging from four to 35 months, and found that 10 improved. Four were practically cured, three were about 50% better, and the last three of the ten noticed a mild improvement.
There are a couple of catches to using an ONS. For one thing, the back of your head goes numb. For another, it can actually take weeks to months to reach maximal effect. Sometimes the battery can run out, or leads can shift and need to be surgically replaced. Nevertheless, only one of the 14 patients in the trial would recommend against ONS, and it these inconveniences seem minor when weighed against the pain of chronic cluster headache.
Why does it work? After all, cluster headache is a problem with the trigeminal nerve, which carries sensation from the front of the head, not the greater or lesser occipital nerves, which come from the back of the head, and the two nerves don’t cross or even come close to each other. I posed this question to Dr. Goadsby, the last author (and thus the supervisor) on this study at the 2008 meeting of the American Headache Society. I can’t remember exactly what he said, but I remember leaving feeling that he didn’t really know why any more than I did. Which just goes to show you, there is much about this disease that we still have yet to understand. But hey, if ONS works, then it works!