Headaches can arise from many different causes. A partial list includes stress, lack of sleep, allergies, neck trauma (particularly sports injuries and car accidents), and more. In some cases, the cause may be unknown.
A unique common denominator of headaches has to do with cervical spine anatomy, in particular the upper part of the neck. There are seven cervical vertebrae, and the top three (C1-3) give rise to three nerves that travel into the head. These nerves also share a pain nucleus with the trigeminal nerve (cranial nerve V), which can route pain signals to the brain.
Depending on which nerve is most irritated, the location of the headache can vary. For example, C2—the greater occipital nerve—travels up the back of the head to the top. From there, it can communicate with another nerve (cranial nerve V or the trigeminal nerve), which can refer pain to the forehead and/or behind the eye.
When C1—the lesser occipital nerve—is irritated, pain travels to the back of the head, while irritation to C3—the greater auricular nerve—results in pain to an area just above the ear. When a nerve is pinched, the altered sensation can include pain, numbness, tingling, burning, itching, aching, or a combination of these sensations.
These are classified as cervicogenic headaches (CGH), and as the name implies, the origin of pain/altered sensation arises from the neck.
A 2013 study reviewing the literature on CGH found that manipulation and mobilization improved pain, disability, and function. The most effective approach included manipulation combined with neck-upper back strengthening exercises.
But what about migraine headaches? Migraines are vascular headaches, and some (but not all) are preceded by an aura or a pre-headache warning that may include blurry vision, tingling, strange olfactory sensations, etc. One study of 127 migraine sufferers reported fewer attacks and less medication required by those who received chiropractic care.
The good news is that spinal manipulation is very safe, and a trial is often very rewarding for many types of headaches.