I recently read a comment from a patient asking a very interesting question - “What is the difference between occipital neuralgia (ON) and cervicogenic headaches (CH)?”
Unfortunately the answer to this question is not a straightforward one. It has been postulated that pain in the head/neck region can be referred from problems in the bony or soft tissues of the neck, but there is still some controversy as to whether cervicogenic headache constitutes a distinct clinical entity. The upper-most cervical nerves and their branches are the most commonly cited sources of CH with the most common source being the C2/C3 levels. The actual definition of cervicogenic headaches is also not firmly established. One accepted way of defining this disorder is by its clinical characteristics. Specifically, it is a unilateral pain of variable severity that is not stabbing and radiates from posterior to anterior. It doesn’t shift from side to side, is brought on by unusual head position or neck motion and may be associated with shoulder or upper extremity pain on the same side. The biggest issue with this definition is that it overlaps with many of the characteristics of other headache disorders such as tension headaches and migraines without aura. Another way of defining CH is by demonstrating a cervical source of pain and confirming that source with a nerve block.
Diagnostic criteria for CH have been established by the Cervicogenic Headache International Study Group (CHISG) and by the International Headache Society (IHS). The former’s criteria require signs or symptoms brought on by awkward head movements or positioning or by pressure over the occipital nuchal structures and possibly confirmed by anesthetic blockade. The IHS criteria mandate that the pain be referred from an identifiable and plausible source in the head/neck (as demonstrated on imaging such as MRI) or by successful blockade of a nerve or cervical structure. Moreover, the pain must resolve within 90 days of successful treatment of the underlying problem. However, the IHS criteria do not define when, where, and how much pain is caused by CH (i.e. the clinical features).
In contrast, most neurologists would define ON in a very specific way. The classic description is that of paroxysmal pain in the distribution of the occipital nerves, sometimes, but not always accompanied by changes in skin sensation in the back of the scalp. The symptoms of ON are also thought to have a character of burning or hypersensitivity that may be constant on top of the intermittent shooting pains described above. These symptoms should be temporarily relieved by occipital nerve blocks.
So what to do with all of this information? Unfortunately, I find these definitions and descriptions minimally helpful since many of the symptoms of ON and other headache disorders for that matter can overlap with those of CH. For example, many of my patients with ON who have been successfully treated with decompression had exacerbation of their pain with awkward head positions and motions because these positions further compressed and irritated the occipital nerves. There are many patients who have unilateral ON. Therefore is ON a subset of CH? From my reading of the literature, most neurologists would seem to disagree, but I am uncertain as to why. Is CH a distinct clinical disorder? As stated above, there is disagreement as to whether it is versus just a descriptor of where the pain is coming from.
All of which brings me to the take home message. When it comes to any disorder, but especially chronic headaches, the only relevant questions in my humble opinion are: 1) can you figure out what’s causing it and 2) if you can, can you do anything about it? You can call the headache whatever you like - migraines without aura, CH, George - the names are irrelevant. With that in mind, I believe that the literature has shown that accurate diagnosis of ON with nerve blocks or Botox is a good predictor of a good result with surgical decompression. Moreover, surgical decompression has been shown to be very effective and have a very low complication rate with good long term results.