Occipital NeuralgiaOccipital Neuralgia is another cause of bouts of severe headache.The theory is that it is due to irritation, usually trauma, to the greater occipital nerve. The greater occipital nerve sits at the back of the skull, and the nerve is usually very tender to touch. The pain is a sharp, shooting pain, and can be associated with altered sensation over the back of the skull. People with this headache will sometimes avoiding lying on their back, as pain is worse when pressure is applied to the back of the head. To clinch the diagnosis, the pain must be relieved by injection of local anaesthetic to "freeze" the nerve. Other than previous trauma, no cause is usually found.
The problem is that other conditions can mimic occipital neuralgia. It is only one of many causes of pain in the back of the head. To make things more complicated, there are arguments between experts about whether the diagnosis of occipital neuralgia has a scientific basis. The people who do not believe in the term "occipital neuralgia" are of the opinion that the pain that originates form the neck - called cervicogenic headache. My own view is that most of the cases that look like occipital neuralgia are better called cervicogenic headache. In cervicogenic headache the source of the head pain is from the joints (called facet joints or zygapophysial joints) of the vertebrae of the cervical spine. There are a few people with a very tender occipital nerve where there was a clear localised injury to the very back of the head, or prolonged compression from wearing a helmet. In cases like that I think the term occipital neuralgia is perfectly sound. Occipital neuralgia, in my own practice, is much rarer than proper cervicogenic headache.
Where is the Occipital Nerve?You can locate the entry point of the occipital nerve by finding the inion.(1) Place a finger in the middle of the back of your neck. (2) Slide the finger up towards the head. (3) The first bony prominence at the back of the head you feel as you move up is the inion. Approximately one inch to the side and one inch down from that point are the entry points of the greater occipital nerve (there is one on each side). (See picture below) If you test pin prick sensation over the back of the skull you can find increased sensitivity to the pain of pin-prick in the affected area. In others you find reduced sensitivity to pin prick. Other than that examination is normal. It worth checking neck rotation and looking at head posture for clues of atlanto-axial joint disease. There is also a rare condition called the Neck Tongue Syndrome which causes sudden severe pain in the back of the head and neck associated with brief sensory disturbance in the tongue.
What is not so commonly known is that there is very little experimental evidence to support the theory that entrapment of the greater occipital nerve in the subcutaneous tissues is the cause of the condition. Some experts e.g. Bogduk, suggests that this type of neuralgia is more likely to be a manifestation of c2 root pain i.e. c2 neuralgia. Certainly, if there is abnormal neck rotation or other neurological signs to suggest structural neurological disease, then a structural cause deeper inside should be sought. What else can look like this?These isolated cases have been reported where typical pain of neuralgia was found alongside these diseases:
In my own practice I can recall cases of high cervical myelitis having some occipital pain, but I have never aggressively chased the other diagnoses as neurological signs have not been prominent enough for me to justify imaging. Almost everyone I see with this type of pain has nothing worse than either a previous trauma to the back of the head or worn out facet joints. TreatmentTreatment is usually a mix of the following approaches:
A nerve block usually consists of a mix of 40-80 mg of methylprednisolone (a strong steroid) and lidocaine or bupivicaine (local anesthetics like those used by a a dentist) This mix, usually 5-10mls in volume is injected around the entry points of the greater occipital nerves. Local hair loss is the only commonly reported side-effect if methylprednisolone is used (about 2% risk). If the person with occipital neuralgia symptoms has diabetes, their blood sugar may increase in the week following methylprednisolone injection. If frequent attacks are occurring, the next step in treatment depends whether they don't like needles or don't like taking tablets. If the real reason for the pain is facet joint damage, then a facet neurolysis procedure could offer a more permanent reduction in pain. Facet Joint Neurolysis is usually only available in specialist pain centres. I can usually persuade someone to try a week or two of anti-inflammatory tablets. Long term use of Gabapentin is sometimes more difficult, as you need to take them regularly to get any benefit. Local anaesthetic injections to the back of the head can be very helpful, but even if they do not prove the diagnosis, as almost any headache condition can be reduced by an injection to freeze the greater occipital nerve.
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