Occipital Nerve Block for Cervicogenic Headaches
Headache is one of the most common complaints received in the primary care practice setting. It is estimated that 5% of the population will seek care for head pain in a given year.1 These patients may present a practitioner with some of his greatest challenges but can also produce some of the greatest rewards when treated successfully.
One percent of headaches are attributed to disorders of the neck.2 According to IHS2 guidelines, these headaches are defined as cervicogenic.3 To fulfill IHS guidelines the following diagnostic criteria must be met:
- pain, referred from a source in the neck and perceived in one or more regions of the head and/or face fulfilling criteria (b) and (c);
- clinical, laboratory and/or imaging evidence of a disorder or lesion within the cervical spine or soft tissues of the neck known to be, or generally accepted as, a valid cause of headache;
- evidence that the pain can be attributed to the neck disorder or lesion based on at least one of the following:
- demonstration of clinical signs that implicate a source of pain in the neck
- abolition of the headache following diagnostic blockade of cervical structure or its nerve supply using placebo or other adequate controls
- Pain resolves within 3 months after successful treatment of the causative disorder or lesion
Clinical Presentation and Diagnosis
The predominant areas of pain presentation with cervicogenic headache are the forehead, the periorbital areas, the vertex of the skull, the temples and the occiput area (see Figure 1). A discussion of the pathogenesis and pathophysiology is beyond the scope of this article but may be found in various neurology and headache texts.
An effective method of detecting occipital neuralgia or cervicogenic headache caused by hyperalgesia of the occipital nerve is to palpate the branches at their superficial distribution near the superior nuchal line and the mastoid notch area. The greater branch will become superficial approximately 2 cm lateral to the bony protuberance near the midline at the superior nuchal line. The lesser distribution becomes superficial near the mastoid notch. Four to five grams of pressure in these areas will produce anything from tenderness to sharp shooting pain at these distribution sites if the nerve is in a state of hyperactivity.
The use of anesthesia to block the occipital nerve branches can prove to be an effective tool in the management of cervicogenic head pains. A method will be described here that is both safe and produces a high rate of success in achieving anesthesia of the occipital nerve branches at their superficial distribution. The practitioner is advised to spend time in review of the anatomy of the posterior head and neck prior to attempting injections in this area.
Occipital Nerve Blockade Technique
Once the source of the patient's pain has been identified and the diagnosis of cervicogenic headache has been made, the tender areas associated with the occipital nerve branches should be localized. The areas are prepped with betadine scrub — followed by alcohol — to insure a sterile injection site. The materials necessary will be a 3 ml syringe, 0.5% marcaine hcl with 1:200K epinephrine, methylprednisolone acetate injectable suspension, 40 mg/ml, and a 27 gauge, 1 inch disposable needle. 1.7 ml of marcaine will be drawn into the syringe. The solution will then be completed by adding 0.3 ml of methylprednisolone acetate to the marcaine for a total volume of 2 ml.
After preparing the injection sites for the greater and lesser branches of the side to be injected and the solution has been properly mixed, a gloved finger is used to identify the specific injection site. For the lesser branch the needle is directed in a lateral, rostral direction maintaining a subcutaneous course (see Figure 2). The patient should be told they may feel a stinging and burning sensation as the needle is placed and the material is being expressed into the tissue. The needle should be inserted to its full length and the solution expressed slowly to insure proper distribution of the medicament, as well as reduce patient discomfort.
Proper aspiration techniques should be utilized prior to expressing the solution. The needle is then redirected superior and medial to facilitate adequate dispersement of the solution. One milliliter of solution is placed per nerve branch site. For the greater distribution of the occipital nerve, the bony protuberance near the midline at the superior nuchal line is located. The injection site will be approximately 2 cm lateral to this landmark. The needle is directed rostrally, maintaining a subcutaneous course (see Figure 3). The needle can be redirected to the medial and lateral directions to insure good distribution of the solution. The same rules for injection speed and aspiration should apply for both injection sites. A successful injection will relieve the patient's head pain and elicit anesthesia of the posterior scalp. The patient should be advised as to the duration of the anesthetic to alleviate potential concerns of prolonged anesthesia. Ice can be placed at the anesthetized sites to reduce post procedure soreness. Usually 10 minutes on and at least 20-30 minutes off is a good protocol for ice therapy.
The occipital nerve blockade is a relatively straightforward procedure with little incidence of adverse events. The procedure can be performed by the general practitioner as well as the specialist. It provides a reasonable alternative when traditional medical and physical therapeutic modalities fail. It also serves as a useful modality to confirm the diagnosis of cervicogenic headache. It is always prudent to spend ample time and thought developing an accurate diagnosis before proceeding to therapeutic options.