Cervicogenic Headache

Etiology

A cervicogenic headache is thought to be referred pain arising from irritation caused by cervical structures innervated by spinal nerves C1, C2, and C3; therefore, any structure innervated by the C1–C3 spinal nerves could be the source of a cervicogenic headache.[6][7][8]

Epidemiology

A cervicogenic headache is a rare chronic headache most common in people 30 to 44 years old. Its prevalence among patients with headaches is 0.4 to 4%, depending on how many criteria are fulfilled and based on many studies.[9] It affects males and females about the same, with a ratio of 0.97 (F/M ratio). Age at onset is thought to be the early 30s, but the age at which the patients seek medical attention and diagnosis is 49.4. Compared with other headache patients, these patients have pericranial muscle tenderness on the painful side and a significantly reduced cervicogenic headache.

Pathophysiology

The C1-C3 nerves relay pain signals to the nociceptive nucleus of the head and neck, the trigeminocervical nucleus. This connection is thought to cause referred pain to the occiput and/or eyes. Aseptic inflammation and neurotransmission within the C-fibers caused by cervical disc pathology are thought to produce and worsen the pain in a cervicogenic headache.

The trigeminocervical nucleus receives afferents from the trigeminal nerve and the upper 3 cervical spinal nerves. Neck trauma, whiplash, strain, or chronic spasms of the scalp, neck, or shoulder muscles can increase the area's sensitivity, similar to the allodynia seen in late chronic migraines. A lower pain threshold makes patients more susceptible to more severe pain. For this reason, early diagnosis and therapeutic intervention are very important.

About 70 percent of cases of cervicogenic headache involve pathology of the C2-3 zygapophyseal joint, making it the most frequent source.[7] Less common sources of cervicogenic headache include the upper cervical intervertebral discs, C3-4 zygapophyseal joints, and lower cervical zygapophyseal joints.[10]

Pathology and trauma to the structures causing referred pain in respective regions served by cervical nerves:

History and Physical

Patients usually complain of unilateral pain without a side shift. It is ordinarily predominant in females. Pain topography usually stems from the neck, spreading to the oculofrontotemporal area with episodes of carrying duration or fluctuating continuous pain increased by head movement. Pain is of variable duration and moderate to severe intensity but not excruciating or throbbing.[11]

Pain can mimic primary headache syndromes such as tension or migraine headaches, although the patient is less likely to complain of sensitivity to light and noise as in migraine headaches. It may be associated with a reduced range of motion of the neck and ipsilateral neck, shoulder, or arm pain. Patients complain that the pain is not resolving with triptan, ergotamine, or indomethacin. Autonomic symptoms such as photophobia, phonophobia, nausea, and vomiting are not as common.

Evaluation

Imaging of the cervical spine is not sensitive enough to diagnose a cervicogenic headache. No specific radiologic abnormalities were found in recent studies such as Pfaffenrath et al. and Fredriksen et al. The most frequent findings in the literature were rectilinearization of the cervical spine and/or disc protrusions. Although not widely used in the clinical world, functional imaging shows hypomobility or hypermobility at a certain cervical spine level. Imaging like magnetic resonance imaging, computed tomography, and/or computed tomography myelography may be ordered to help rule out Chiari malformations, nerve root pathology assessment or identify spinal cord pathology (eg, asymmetric facet arthropathy or rheumatoid changes around the atlantoaxial joint).[12]

The ICHD-3 criteria for cervicogenic headache are as follows:

1. Any headache fulfilling criterion C
2. Clinical and/or imaging evidence of a lesion or disorder in the cervical spine or soft tissues of the neck that can cause a headache
3. Evidence of cause of headache demonstrated by at least 2 of these:
   1. Headache has developed in temporal relation to the appearance of the lesion or the onset of the cervical disorder
   2. Headache has significantly improved or resolved in unison with improvement in or the resolution of the cervical lesion or disorder
   3. Cervical range of motion is reduced, and provocative maneuvers may significantly worsen the headache
   4. Headache is abolished following diagnostic blockade of a cervical structure or its nerve supply
4. Not better accounted for by another ICHD-3 diagnosis[13]

Diagnostic anesthetic blocks can sometimes be utilized to confirm the diagnosis but require specialized skills and are not routinely performed.[14]

Treatment / Management

Physical therapy is considered the first line of treatment.[15] Manipulative therapy and therapeutic exercise regimens are effective in treating a cervicogenic headache. According to a study by Jull and Richardson, 72% of patients had reduced 50% or more in headache frequency at the 12-month follow-up, and 42% of patients reported 80% or higher relief of some sort. These manipulative maneuvers stimulate neural inhibitory systems at various levels in the spinal cord and activate descending inhibitory pathways.[16] However, physical therapy may initially worsen the headache. Therefore, treatment should be slowly advanced, including gentle muscle stretching and manual cervical traction. An anesthetic blockade for temporary pain relief may also enhance the patient's tolerance for physical therapy.(A1)

Another option for treating a cervicogenic headache is interventional therapy, which differs depending on the cause of the headache. For example, a lateral atlantoaxial joint intra-articular injection can be useful to diagnose and treat the condition when it has an osteoarthritic or post-traumatic cause. Another cause of a cervicogenic headache is arthritis of the C2-3 facet joint, innervated by a superficial branch of the C3 nerve called the third occipital nerve. This is seen after a whiplash injury from a motor accident. Injection into the facet joint reduces pain. The third occipital nerve block provides temporary cervicogenic headache pain relief, while radiofrequency ablation can relieve long-term pain. Surgery is performed only as a last resort.

There is some evidence that cervical epidural steroid injection has some benefits in treating pain in a cervicogenic headache. Steroids can work in this setting because the pain continues sensitizing the cervical nerve roots and initiates a pain-producing loop involving nerve root and microvascular inflammation as well as mechanically-induced micro-injury.[17] Cervical epidural steroid injections with an interlaminar needle approach at C7-T1 or C6-7 epidural space are relatively safe compared to other interventional cervical procedures. Steroid injections reduced daily NSAID usage at 3 and 6 months. Pharmacological therapy, including pregabalin, duloxetine, and gabapentin, has variable responses.[18] Therapies like coblation and neuromodulation require further studies for validation.[3](A1)

Differential Diagnosis

It is important to distinguish occipital neuralgia from the occipital referral of pain from the atlantoaxial or upper zygapophyseal joints or tender trigger points in neck muscles or their insertions. Occipital neuralgia can produce symptoms indistinguishable from a cervicogenic headache. It typically presents as a sharp pain in the occipital region.[13] The greater occipital nerve is the terminal branch of the dorsal ramus of C2, with contribution from C3, while the lesser occipital nerve is a branch of the dorsal ramus of C3. Treatment of occipital neuralgia includes segmental nerve blocks at C2 and C3, cryoneurolysis, radiofrequency ablation, and neuro-ablation such as dorsal rhizotomy at C1, C2, and C3 and posterior rhizotomy at C1, C2, and C3.

The differential diagnosis for cervicogenic headaches is as follows:

• Tension-type headaches and migraine[19]
• Internal carotid or vertebral artery dissection[20]
• Arnold-Chiari malformation
• Herniated intervertebral disc
• Intramedullary or extramedullary spinal tumor
• Spinal nerve compression or tumor
• Arteriovenous malformation
• Neck-tongue syndrome[21]

Prognosis

Most of the time, the treatments suggested are not curative, and regular visits may be required to monitor the symptoms. Several factors have been associated with better outcomes in patients with cervicogenic headaches, including advanced age, increased intensity of headache with movement, and gainful employment.[22]

Complications

Cervicogenic headaches can become debilitating unless they are properly addressed. In some instances, the condition can become chronic or recurring. In these cases, the patient must contact their clinician for diagnosis and treatment.