New types of surgical treatment for cluster headache
Surgical treatment for cluster headache should only be considered after a patient has exhausted all medicinal options. In some instances the surgery can produce side effects that are worse than the cluster headaches themselves. Surgical treatments that have been utilized for the treatment of cluster headaches and have recently been reported in the headache literature include:
During the last several years cluster headache patients have been found to respond to suboccipital stimulation. This is a procedure in which a wire electrode is burrowed under the skin in the back of the neck region near the occipital nerve, and when electrical stimulation is provided, the cluster headaches can be turned off. This procedure seems to work best in patients who have had positive benefit from an occipital nerve block.
A newer form of neurostimulation for cluster headache is currently being tested. An electrode is inserted into the sphenopalatine ganglion region, which is above the upper gum line on each side of the face. An electrode is inserted under the gum line and tunneled upward. When the stimulation occurs by placing a battery operated transmitter over the face area, the stimulator appears to be able to reduce the frequency of headaches and the intensity. This procedure is not yet available in general practice.
Radiofrequency thermocoagulation is the most commonly used surgical technique for cluster and it provides the best option for pain relief. The results of radiofrequency rhizotomies in cluster are encouraging although there are only a handful of studies in the literature. Overall with radiofrequency about 50% of patients have done very well, 20% fair to good and about 30% fail the procedure. Adverse events with radiofrequency include moderate to severe facial dysesthesias, corneal sensory loss and anesthesia dolorosa. Other less common but devastating side effects include intracranial hemorrhage, stroke, infection, and motor weakness which typically resolves over 1 to 6 months.
Microvascular decompression is a very invasive technique involving craniectomy. The goal of the procedure is to try to restore normal anatomy by removing a vascular loop compressing a nerve. The role of microvascular decompression in cluster is not as well defined as in trigeminal neuralgia. Microvascular decompression of the trigeminal nerve with or without microvascular decompression or section of the nervus intermedius was recently reported to be effective in chronic cluster headache. However, long-term follow-up saw the success rate decrease to 46.6%. Repeat procedures were not beneficial.
Gamma knife radiosurgery
Gamma knife is a form of neurosurgery in which the trigeminal nerve (the nerve that causes cluster headache) is injured by a beam of radiation. (See Figure 1) This procedure can be done as an outpatient and typically only takes several hours to complete. At present only a handful of medical institutions have gamma knife capabilities.
Only one study has looked at the use of gamma knife in cluster and the results were promising. What is attractive about this technique is that it can be done in an outpatient setting and appears to have a low complication rate. However, no one yet knows what the true delayed complications of gamma knife are, especially in young patients. The impression is that it works initially but there are high relapse rates (return of cluster pain) bringing to question if this treatment strategy is indeed useful in cluster. More studies are necessary.
Anatomy of cluster headache. The hypothalamus is activated and this turns on the trigeminal nerve and autonomic systems. The trigeminal nerve activation leads to pain in and around the eye. The autonomic system activation leads to eye tearing and nasal discharge that occur during a cluster headache. For surgical treatment gamma knife radiosurgery injures the trigeminal nerve. In deep brain stimulation a stimulator is placed into the hypothalamus.
Deep brain / hypothalamic stimulation
A truly investigational surgical treatment for cluster headache has been carried out by an Italian group. Based upon studies suggesting the hypothalamus as a generator of cluster headache, a stimulator was placed into the hypothalamus of six study patients with refractory cluster headache to see if stimulating the hypothalamus could stop a patient from having cluster headaches. (See Figure 1) The researchers found that once the stimulator was turned on the cluster headaches started to disappear. In some patients pain relief was immediate while in others it took up to four months to have the patient become pain-free. So far the patients have had no side effects with the stimulator. This treatment is completely experimental at present and is not available anywhere in the United States because it needs to be better studied for safety issues. What this study does represent is that a better understanding of what causes cluster headache can lead to better treatment options for patients.