The Practitioner Le praticien The occasional greater occipital nerve block Gordon Brock, MD, reater occipital nerve block is However, other mechanisms, including FCFP, FRRMS a simple technique used to neck instability, trauma, inflammation Centre de santé et de services both diagnose and treat the and compression by the occipital artery, sociaux du Témiscamingue, greater occipital nerve subtype of oc cip­ may be operative in individual patients.5 Témiscaming, Que G ital neuralgia (itself a basket term for Correspondence to: “neuralgic pain in the distribution of the INCIDENCE Gordon Brock; [email protected] greater or lesser occipital nerve or of the third occipital nerve”).1 The technique No data are available on the incidence This article has been peer is simple and relatively complication­ of occipital nerve neuralgia in the pri­ reviewed. free. Both the greater and lesser occip­ mary care population.5 ital nerves may be blocked, but this arti­ cle will concern itself with block of the SYMPTOMS greater nerve (Fig. 1). Patients often describe an occipital ANATOMY AND headache of relatively recent onset, with PATHOPHYSIOLOGY hard­to­describe, but fairly severe, pain that originates in the upper neck and The greater occipital nerve (or nerve of spreads to the vertex. The disorder may Arnold) is a spinal nerve providing for be bilateral and seems to develop in sensation of the scalp. It arises from the most patients without an obvious pro­ medial branch of the dorsal ramus of the voking cause. The pain tends to be of a C2 nerve (along with the lesser occipital neuropathic quality, described as stab­ nerve) emerging from between the first bing or electric­shock–like, with a dull and second cervical vertebrae. and chronic discomfort often present It then runs posteriorly behind the between the paroxysms. Pain may spinal articular processes and extends appear to be spontaneous, or may be up the neck, over the dorsal surface of provoked by such factors as neck move­ the rectus capitis posterior muscle, then ment, hair brushing or cold.2,5 passes through the trapezius muscle. Ultimately, it exits the trapezius and SIGNS runs subcutaneously to innervate the skin of the posterior portion of the scalp, The key signs are described below.5 from the occiput to the vertex of the • Pressure, palpation or percussion skull2,3 (Fig. 1). over the greater occipital nerve in the The term neuralgia has traditionally area of its emergence, about 1.5 cm been used to mean nerve pain for which below the superior nuchal line and there is no demonstrable pathologic 1.5 cm medial to the lateral border of change in the nerve and the exact patho­ the trapezius (Fig. 2), will provoke physiology is unclear. The currently pain (a Tinel sign) or elicit paresthe­ accepted view is that greater occipital sia over the distribution of the nerve. 152 nerve neuralgia results from the chronic There may be some pain provoked entrapment of the greater occipital nerve on cervical movement, although gen­ by the posterior neck and scalp muscles.4,5 erally not markedly. Can J Rural Med 2014;19(4) © 2014 Society of Rural Physicians of Canada • There may be a decrease in range of motion of Magnetic resonance imaging (MRI) may be the cervical spine along with some local spasms ultimately needed, especially if there is no of the posterior cervical muscle. response to injection (see below). • There may be an area of diminished sensation • Posterior fossa disease. The neurologic exam­ or dysesthesia over the distribution area of the ination may be abnormal. Computed tomogra­ greater occipital nerve, but this is hard to elicit. phy or MRI is indicated. The important fact is that the neurologic exam­ • Myofascial pain syndromes of the trapezius and ination is otherwise normal, and any abnormal­ sternomastoid muscles. This diagnosis is not ity thereof should raise suspicion of a more ser­ mutually exclusive of greater occipital neural­ ious cause of the pain. gia, because compression of the greater occipital nerve within a tense trapezius muscle may be DIAGNOSTIC CRITERIA one of several mechanisms in the pathogenesis of greater occipital neuralgia. In myofascial pain The diagnostic criteria are as follows:5 syndrome there will be a single large tender • Paroxysmal stabbing pain, with or without per­ pressure point, or multiple smaller tender pres­ sistent aching between the paroxysms of pain, sure points, as opposed to the relatively small in the upper neck and posterior occiput, radiat­ area of tenderness over the greater occipital ing to the vertex. nerve that is seen in occipital neuralgia. • Pain reproduced by pressure over the greater • Trigeminal neuralgia. In this case the neuro­ occipital nerve. pathic pain tends to involve the face. • Pain that is eased, at least temporarily, by local anesthetic block of the greater occipital nerve. NERVE BLOCK PROCEDURE Imaging is generally not required to make the diagnosis. Nerve block of the greater occipital nerve is both diagnostic and therapeutic.2,6 DIFFERENTIAL DIAGNOSIS As with all injections, contraindications include infection or cellulitis over the injection site, or al lergy The differential diagnosis of pain in the occipital to any of the components of the local anesthetic. area includes the following: 1. Prepare the equipment you will need (Fig. 3): • Cervical spine disease (i.e., osteoarthritis, neo­ • a 3–5 mL syringe with a 25­gauge 5/8" or plasm or injury). There will likely be more 1­1/2" needle, depending on the patient’s size prominent symptoms of cervical spine disease. • 1–3 mL of 1% or 2% lidocaine and 1 mL (40 mg) of methylprednisolone solution • your usual skin­preparation materials for Greater occipital nerve sterile technique 2. As always, the best anxiolytic is a careful expla­ nation by the physician. Lesser occipital nerve Trapezius muscle 153 Fig. 1. Greater and lesser occipital nerves and needle posi- tion for the block. Fig. 2. Point of tenderness of the greater occipital nerve. Can J Rural Med 2014;19(4) . 3 I use a height­adjustable surgical tray. My tech­ CAVEAT nique is usually to position the patient sitting, with neck and thorax flexed, resting the forehead on the As mentioned earlier, anesthetic block of the nerve forearms, which are on the surgical tray (Fig. 4). is both diagnostic and therapeutic. However, it 4. Prepare the skin with your usual method. should be appreciated that relief of the pain by 5. Identify the point of tenderness of the nerve, about greater occipital nerve block (the “final common 1.5 cm below the superior nuchal line, 1.5 cm med­ pathway”) is not 100% specific for pain that is of a ial to the lateral border of the trapezius (Fig. 2). presumed idiopathic neuralgic origin. Any of the 6. Introduce the needle there at a 90˚ angle to the mechanisms for occipital nerve pain — as men­ skin; insert until the bone (skull) is hit and then tioned in the “Differential diagnosis” section — withdrawal slightly. Aspirate to ensure there is such as trapezius muscle spasm, could still be no return of blood (the occipital artery lies just underlying and require treatment in its own right. laterally) or cerebrospinal fluid (Figs. 1 and 5). 7. Inject 1 mL of solution over the nerve, then COMPLICATIONS about 1 mL to the left of the nerve and a further 1 mL to the right, in a semilunar configuration. Because of the superficial location of the nerve and 8. After the needle is withdrawn, maintain pressure the ease of injection, complications, besides inadver­ over the injection site, to “bathe” the nerve in the tent intravascular injection, are few. There may be solution and maintain hemostasis, because of the some transient paresthesia due to irritation of the rich vascularity of the scalp. nerve by the needle or bleeding. Most patients 9. Evaluate the patient after 15 minutes. Relief of are able to drive and return to work immediately the pain previously produced by pressure over afterwards.5 the nerve is indicative of a successful injection. 10. Explain to the patient that there will be relief of the pain for several hours, but pain will return in a few hours because of the effect of the lidocaine wearing off. The patient can use ice and ace ta­ minophen for the local pain. The patient can be told to expect relief lasting for several months or longer, beginning in 1–2 days. Fig. 4. Position the patient. 154 Fig. 3. Equipment needed for the nerve block procedure. Fig. 5. Introduce the needle. Can J Rural Med 2014;19(4) Acknowledgements: The author thanks Liz Colborne, RN, ments/90734989/Greater+Occipital+Nerve+Block.pdf (accessed 2014 for her help in the photography for this article. May 14). Competing interests: None declared. 3. Anatomy Expert. Greater occipital nerve. Available: www .anatomy expert.com/structure_detail/6552/22186 (accessed 2014 May 12). REFERENCES 4. Janis JE, Hatef DA, Ducic I, et al. The anatomy of the greater occipital nerve. Plast Reconstr Surg 2010;126:1563-72. 1. Classification IHS. Occipital neuralgia. Available: h ttp://ihs -classification.org/en/02_klassifikation/04_teil3/13.08.00_facial 5. UpToDate. Occipital neuralgia. Available: www.uptodate.com / pain.html (accessed 2014 May 14). contents /occipital-neuralgia (accessed 2014 May 06). 2. Ward JB. Greater occipital nerve block. Semin Neurol 2003;23:59- 6. Beliveau P. Infiltations. Montréal: Editions Sciences et Culture; 62. Available: https://wiki.umms.med.umich.edu/download /attach 1990. p. 42-3. Life, death and whatever else ... snippets from a medical life Muna ar-Rushdi, MD, MSc, DLSHTM, CCFP Greenwood, NS AN EMBROIDERED LIFE A HUNTER’S JOURNEY That is my cousin My nephew She stitched herself an ordered He sits on his bed Myself and meticulous life.