Headaches are common among adults but very considerably in their presentation and in their underlying causes. The International Headache Society introduced a formal classification of headaches a few years ago to simplify diagnoses and accuracy of treatment. Without getting into too much detail, we can categorize headache into two classes: primary and secondary. I'll start with secondary headaches. These headaches are a symptom of a more serious medical condition. They represent an identifiable underlying pathology such as meningitis, an infectious disease of the membranes surrounding the brain, stroke, brain tumor, sinusitis, and so forth. Primary headaches are those which are not symptoms of other illnesses. They are the illness. Common examples are tension headache and migraine headaches. Less common are cluster headaches, which are recurrent severe headaches on one side of the head and stabbing headaches, experienced after eating ice cream, for example. Today, in the context of medical cannabis, I will stick to discussion of chronic forms of primary headaches. By chronic primary headaches, I'm not referring to those experienced occasionally by most healthy people after a sleepless night, insufficient hydration, or at the end of particularly hot or stressful day. Since these headaches appear only occasionally and tend to disappear without any specific treatment, we don't discard them here. Chronic primary headaches tend to be much more complicated and present a therapeutic challenge to both patients and caregivers. The two principle goals when treating headaches are to reduce the frequency, severity, and duration of headache attacks by means of prevention and to abort an existing headache. So, in the case of migraine, a drug will be prescribed for use on a daily basis for prevention, whereas an abortive therapy such as an anti-inflammatory drug, a triptan, or another available anti-migraine drug will be prescribed when a headache occurs and preferably as it starts. Now, let's review the literature on medical cannabis while paying attention to the different types of headaches, which we're already familiar with and to the potentially preventive and abortive qualities of medical cannabis. There are many good reasons to believe that medical cannabis can be effective for various types of headaches. Unfortunately, much like in the case of acute pain, no more than a dozen reports can be found in the medical literature on the effectiveness of medical cannabis for headaches, and these are merely anecdotal or based on small cohorts of patients at most. Following our few examples, three surveys of marijuana smokers in Europe and in the United States show that between five percent and 10 percent of users employed medical cannabis for relief of migraine and other headaches, but it is unclear from these surveys if marijuana was used preventively or abortively. Two French surveys of patients with cluster headaches found that somewhere between a quarter and a half of these patients consume marijuana for their headaches. According to one of these surveys, a clear analgesic effect was reported in only a quarter of these users. A recent American survey of 124 migraine patients, to whom medical cannabis was prescribed, found reduction in headache frequency in nearly 20 percent of the patients and abortive effect leading to termination of headache attack was found in an additional 12 percent. The remaining reports are based on much smaller groups of patients and on single-case reports. In one such study on three patients, smoked medical cannabis relieved chronic headaches similar to or better than other abortive medications, such as aspirin or ergotamine. In another small survey of three patients, migraine attack appeared following cessation of daily marijuana smoking. In one of these patients, remission of headache was reported in response to resuming marijuana use. In two other case reports, one patient with persistent migraine and another with persistent cluster headache responded well to smoked marijuana. An Italian RCT from 2013 studied the effect of the synthetic cannabinoid medication, nabilone, against a very familiar anti-inflammatory drug, ibuprofen, in patients with medication overuse headache. But here, two points deserve consideration. First, nabilone is licensed in several countries mainly for chemotherapy, induced nausea, and vomiting and for wasting syndrome caused by AIDS but not as a pain medication. Second, medication overuse headache is one of the most difficult headache to treat. Many patients who suffer this condition have dealt with tension or migraine headache for many years. They gradually increase the dose of headache medication, reaching a point where they consume very large quantities of analgesics with no real pain relief. Putting an end to pain killers is challenging for many of these patients, and they require a supervised detox program, somewhat similar to the treatment of narcotic drug addictions. In the Italian study, 30 such patients were randomly divided into two groups. One group received nabilone for eight weeks and following a two-week drug free interval, received ibuprofen for an additional eight weeks. The second group received the same drugs but in a reverse order. The measured outcome included reduction in frequency, duration, and intensity of headache pain, as well as reduction in daily consumption of analgesics. Additional parameters include a change in anxiety, depression, drug dependence, and quality of life. Researchers analyzed the results of 26 patients who completed the study, and, as anticipated, found improvement in many outcomes measures in both groups. I say as anticipated because in almost all pain trials, we observe an improvement in measured outcomes just from participation in the study. In the Italian study, nabilone was superior to ibuprofen in reducing the frequency and intensity of headaches. Furthermore, nabilone reduce the level of medication dependence and improve quality of life, whereas ibuprofen did not. Why the results of the study are encouraging, it is difficult to draw broad conclusions due to the small number of patients, limited duration of follow-up, only two weeks after the end of treatment and the fact that nabilone is not equivalent to smoked herbal cannabis. Lastly, a few words on the secondary headaches. Do you recall what we said about secondary headaches? They are symptoms of other conditions, and interestingly, certain types of secondary headaches also seem to respond to medical cannabis. For example, the pressure inside the skull may sometimes increase. This condition is known as increased intracranial pressure and is commonly accompanied by headaches and additional neurological signs and symptoms. Medical cannabis appears to lower increased intracranial pressure and, in so doing, modifies the associated headaches. More on secondary headaches later in our course.
