One of the most common sequelae (consequences) of whiplash is chronic neck pain/headaches. Why do these symptoms occur? Likely, because the nuchal muscles will suddenly tighten as the head is rocked violently and the soft structures that pass through and around these muscles are affected. Nerves are like wet noodles - they are soft and pliable, but the neck muscles and fascia that covers these muscles is tough and tight to begin with to allow stabilization and efficient mobilization of those bowling balls we call our heads. If you think about the force it would take to tear a wet noodle, you get a sense for how easy it could be to injure an occipital nerve.
However, as many out there can attest the work up of these patients is often negative. Why is that? The answer lies in what I believe to be the underlying cause of this chronic pain/headache which is a traction (i.e. stretch) injury to the occipital nerves. Even with high resolution MRIs (see previous post on why the MRI may be negative), the relatively small occipital nerves (greater, lesser and third) are hard to image accurately. Therefore, a negative MRI may rule out an injury to the nuchal ligaments, bones, and/or muscles, but it cannot rule out a small tear to already tiny nerve(s). Moreover, since the above-mentioned occipital nerves are purely sensory (i.e. they don’t move any muscles, only provide sensation to the scalp and back of the ears), the primary symptoms tend to be pain which cannot be objectively measured with a CT scan/MRI or blood test. Since many practitioners don’t recognize the impact of a traction injury to these sensory nerves, management is often empirical.
For these reasons and others, patients are often treated with a combination of pharmacologic agents, PT, chiropractic manipulation, cervical collars, etc. Certainly many patients do get better with these conservative modalities, but given the sheer numbers we are talking about, many thousands do not. However, if you believe as I do that the issue may be a tear within a small nerve causing intra-neural scarring, or a small tear within a muscle surrounding that nerve that causes subsequent scarring and narrowing of the canals through which these nerves usually pass (hence compression), then the above-mentioned modalities will not work for obvious reasons. If there is mechanical compression on a nerve, that compression must be physically and precisely removed or permanent damage may occur. The take home message is that when all other potential causes of chronic neck pain/headaches post-whiplash have been ruled out, think of occipital neuralgia as a possible cause. A consultation with an experienced peripheral nerve surgeon should then follow and ON ruled out as a possible cause. The good news is that if ON is felt to be the culprit, there are safe and effective procedures that can provide significant relief.