Background: Cluster headache is an invalidating form of headache. Although cluster headache can be managed pharmacologically, some patients require surgical treatment with varying results. Microvascular decompression of the pterygo-palatine ganglion could be an alternative to traditional surgical management in patients with cluster headache. Methods: Microvascular decompression of the pterygopalatine ganglion was performed in three patients with refractory cluster headache. The pterygopalatine artery was ligated and a temporal muscle graft was placed between the artery and the ganglion.
Results: No differences were found between the presurgical period and 1 week, 1 month, 3 months, and 6 months postoperatively with respect to attack duration and frequency, visual analogue scale score during attacks and in remission periods, duration of remissions, and quality of life.
Conclusion: These preliminary data suggest that microvascular decompression of the pterygopalatine ganglion does not provide pain reduction or improvement of quality of life in patients with refractory cluster headache.
Dr. Sewell’s comment:
Many cluster headache patients require surgery, because the medications just don’t work. But what kind of surgery? Occipital nerve stimulator implantation has become popular of late, and evidence shows that deep brain stimulation also works remarkably well, although the thought of having a hole drilled in their skull puts many people off. From the Netherlands comes this report on microvascular decompression of the pterygopalatine ganglion.
What is the pterygopalatine ganglion, you ask? Also known as the sphenopalatine ganglion, it’s a “way station” for nerves leading to the tear ducts and snot glands, and it is accessible by going up the nose. The ganglion lies right along the pterygopalatine artery, so the thinking is that if the artery throbs too much, it can irritate the entire ganglion and cause cluster attacks. While it sounds far-fetched, compression of nerves by blood vessels can cause plenty of other pain disorders such as trigeminal neuralgia (which is very similar to cluster headache), hemifacial spasm, and glossopharyngeal neuralgia (which also feels a lot like a cluster attack). What’s more, previous studies that use radiofrequency ablation on the pterygopalatine ganglion have shown success rates of about two-thirds, but often it’s only temporary and patients have to have the procedure done more than once. Microvascular decompression of the trigeminal nerve tends to work better than radiofrequency ablation of the trigeminal nerve. So Dr Oomen, who conducted the study, thought it was worthwhile to see if there was a better way of attacking the pterygopalatine ganglion and stopping cluster attacks. His plan (or her plan; Dr Oomen could be a she, it’s hard to tell) was to lift the pterygopalatine artery off the ganglion rather than whack away at the ganglion itself, with the thought that no irritation would mean no cluster attacks.
The initial plan was to perform surgery on six patients at the University Medical Center in Utrecht, all of whom had chronic cluster headache that has been refractory to a lot of medication. The first patient was a 57-year-old woman who had had eight three-hour attacks a day for the last five years; the second was a 50-year-old woman who had been having 10 one-hour attacks a day for the last 12 years, and the third was a 33-year-old man who was having two to five attacks a day lasting several hours; this guy had had radiofrequency ablation of his pterygopalatine ganglion a few years earlier and had two months of pain relief from it, so he wanted to try again. First Dr Oomen studied an MRI of each patient and memorized the anatomy, then went up their noses on the side of the cluster attacks, created a hatch where he knew the ganglion was located, and put a sliver of jaw muscle tissue between the ganglion and the artery to keep them separated. Once the patients recovered from general anaesthesia, he kept an eye on them to see what happened to their cluster attacks, specifically measuring attack duration, attack frequency, attack intensity, and remission period duration by means of a “pain diary” that patients were told to keep as soon as they woke up. He also measured quality of life using a scale designed for that purpose at one week, three months, and six months when they came in for follow-up.
The results were lousy. Nobody noticed any improvement on any measure at one week, three months, or six months, and the first patient had even more attacks for the first month than he had before, though luckily this improved over time. Although the original plan had been to enroll six patients in this pilot study, after the third failure Dr. Oomen became discouraged and threw in the towel. His conclusion was that microvascular decompression of the pterygopalatine ganglion does not provide pain reduction or improvement in quality of life in patients with refractory cluster headache.
Why didn’t it work? The simplest explanation is that cluster attacks aren’t caused by a blood vessel irritating the pterygopalatine ganglion; the hypothesis is wrong. But that would be jumping to conclusions—clearly this wasn’t the cause in these three patients, but three is not a lot, and it would not surprise me at all to find that there were plenty of refractory chronic cluster headache patients running around out there in whom this was indeed the cause, though I don’t have any evidence for this—cluster headaches can be caused by a lot of different things. The trick, of course, is figuring out who’s got the aberrant blood vessel, and until we can do that, this surgery isn’t likely to become a popular one.