Vol. 16 Issue 7
Treating Headaches With Cervical Injections
Lower cervical intramuscular injections with bupivacaine appear to relieve a spectrum of headache types. Clinical experience suggests that the technique is safe and effective in the primary care outpatient setting.
Headache is a common complaint of patients presenting in primary care. In fact, headache is the seventh most common chief complaint in primary care offices and costs U.S. society more than $13 billion annually.1,2 Recent studies suggest that stimulation of the trigeminovascular system is involved in most migraine, cluster and tension-type headaches.3 Some current therapeutic approaches involve medications that have side effects such as cognitive impairment and extrapyramidal reactions or that enable opiate dependency. These limitations create a need for safe and effective therapeutic alternatives to address headache pain in the primary care setting.
Despite the knowledge that localized neck pain frequently can be relieved by cervical trigger-point intramuscular injections, until recently little information had been available about the effects of lower cervical paravertebral injections on headache pain. It was first recognized in 1996 and initially reported in 2003 that bilateral lower cervical paraspinous intramuscular injections with bupivacaine appeared to consistently relieve a spectrum headache types, as well as consistently relieve orofacial pain.4,5 Subsequent clinical experience suggests that bilateral cervical intramuscular injection with bupivacaine is a safe and effective therapeutic intervention for the symptomatic treatment of headache pain in the outpatient setting.
Performing the Procedure
The lower cervical injection procedure is accomplished using the following technique.5,6 After a sterile field is prepared by swabbing with an antiseptic solution over the lower cervical and upper thoracic dorsal spine, 1.5 mL of 0.5% bupivacaine HCl is injected into each location using a 1.5-inch 25-gauge needle.
The needle is inserted 1 to 1.5 inches into the paraspinous musculature, 2 to 3 cm bilateral to the spinous process of the sixth or seventh cervical vertebra. The bupivacaine is injected slowly to minimize patient discomfort. The selected volume of 1.5 mL of bupivacaine is based on clinician preference, and the entire amount is deposited completely in a single injection location.
As with any injection procedure, anatomic landmarks must be carefully identified, aspiration must occur before injection and appropriate precautions must be taken to help avoid potential vasodepressor syncope. Since the therapeutic response to the injection typically is unambiguous, alternative headache therapies generally are initiated within 20 to 30 minutes if the patient reports that pain relief is inadequate or incomplete.
Relief of Headache Pain
Initially, this technique had been used to evaluate the safety and efficacy of cervical intramuscular anesthetic injections in a select group of patients with intractable head or face pain.5 Despite the small number of patients on whom it was used, this technique rapidly relieved pain in patients who had been debilitated by migraine headache, tension-type headache, chronic daily headache, postherpetic neuralgia and trigeminal neuralgia.5 The nausea, photophobia and phonophobia associated with migrainous headaches dissipated within a few minutes after injection. In addition, two to three subsequent injections performed two weeks apart resulted in a marked reduction in headache frequency and severity that was sustained over several months.
Based on the promising results of their initial study,5 Mellick and colleagues6 conducted a one-year retrospective review of 417 patients treated in an academic emergency department with lower cervical intramuscular 0.5% bupivacaine injections. Complete headache relief occurred in 271 patients (65.1%), and partial headache relief occurred in 85 patients (20.4%) (Table). No significant relief was reported in 57 patients (13.7%), and headache worsening was described in four patients (1%). Overall a therapeutic response was reported in 356 of 417 patients (85.4%). Headache relief typically was rapid, with many patients reporting complete relief in five to 10 minutes. Associated signs and symptoms such as nausea, vomiting, photophobia, phonophobia and allodynia also were relieved in many patients.
Supplemental bupivacaine injections were performed on 37 patients.6 These injections typically were performed on patients who had had an incomplete and often unilateral therapeutic response to the first set of injections. Twenty-two (59.5%) of the 37 patients who received a supplemental injection (usually unilateral) experienced headache relief. Side effects were few and included muscle soreness at the injection site, transient weakness of posterior neck muscles, relief of associated neck pain and brightening of vision.
Among the study's limitations are that no placebo control group was included and that rescue therapies were initiated within 20 to 30 minutes if the injection had not relieved the headache.6 A percentage of the reported headache relief responses undoubtedly were related to a placebo effect,6 which was not measured in this retrospective review study. While the recognized placebo effect of headache pain management is significant, the observed response is much greater than placebo effects reported in a headache placebo study.7 Many prospective pharmaceutical studies document pain relief at two hours. Because injected patients were treated in a busy emergency department, they either had been discharged or had been treated with one or more rescue medications two hours after injection.
The mechanism of headache relief following lower cervical paraspinous bupivacaine injections is unknown. Relief of headache pain and associated signs and symptoms including allodynia suggest that the trigeminocervical neurons play an important role in pain-signal transmission from structures above the neck.5 Activation of the trigeminovascular system increasingly is being considered as the common final pathway for a spectrum of headache types.8-11
Other research has shown that headaches can be alleviated by spinal injections at higher levels. Third occipital nerve blocks, injections at the lateral aspect of the atlantoaxial joints, second cervical nerve root ganglion blocks and methylprednisone injection near the greater and lesser occipital nerves have been documented to relieve headaches.12-15 Relief of frontal headache associated with upper cervical nerve and occipital nerve blockade also may be the result of a trigeminal pain-relief response similar to that obtained from bupivacaine blockade of dorsal cervical rami at the seventh cervical vertebra.5
A Safe, Effective Headache Therapy
Bilateral lower cervical paraspinous injections with 0.5% bupivacaine has been shown to provide either partial or complete headache relief, with a total therapeutic response of 85.4%. The headache relief typically is accompanied by interruption of associated signs and symptoms, including allodynia. While the therapeutic mechanism is unknown, it is possible that a sensitized trigeminocervical complex somehow is quieted by this relatively simple procedure.
Most important is that this procedure appears to provide a safe and effective alternative for symptomatic relief of acute headache in primary care.
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Scott A. Martin is a professor at PA program at the Medical College of Georgia (MCG) School of Allied Health Sciences in Augusta, Ga. Brenda D. Oswald is director of the emergency medicine PA residency program in the department of emergency medicine at the MCG School of Medicine. Larry B. Mellick is a professor in the department of emergency medicine at the MCG School of Medicine. The authors have indicated no relationships to disclose related to the contents of this article.