The cervical spine, or neck, is composed of seven vertebrae, labeled C1 through C7. The C5 and C6 vertebrae are located in the lower half of the neck and form a segment that allows for significant movement, making it susceptible to wear and tear. When issues arise in this spinal segment, the resulting pain can be “referred” to the head, a condition known as a cervicogenic headache. This referred pain occurs because the sensory nerves from the neck and the head share common pathways in the nervous system.
The Neural Pathway Connecting Neck and Head
The mechanism for how neck pain causes headaches involves a neurological phenomenon called convergence. Sensory information from the upper cervical spinal nerves (C1 through C3) travels to the brainstem, relaying sensations from the neck’s structures. This sensory input converges with signals carried by the trigeminal nerve, which supplies sensation to the face and head.
The meeting point for these nerves is the trigeminocervical nucleus, located in the upper spinal cord and lower brainstem. This nucleus acts like a shared switchboard where pain signals from the neck and head are processed together. When the C5-C6 segment is irritated, it can affect the upper cervical nerves, sending pain signals to this nucleus. Because of this anatomical overlap, the brain misinterprets the signal as originating from the facial or cranial areas, resulting in a headache felt behind the eye or in the temple.
Common Structural Problems at C5 and C6
The C5-C6 segment is frequently stressed, making it vulnerable to various structural issues. One common problem is degenerative disc disease, where the cushioning disc between the vertebrae loses hydration and height. This loss of disc space can narrow the openings for the nerve roots, leading to irritation.
Facet joint arthropathy is another frequent cause of pain at this level, involving the small joints connecting the back of the vertebrae. As the cartilage wears down, the joints become inflamed and may develop bone spurs, which irritate surrounding nerves. Inflammation from these degenerated joints can send pain signals that travel up the neural pathway to the head.
Acute issues, such as a disc herniation, occur when the inner disc material pushes out and directly presses on a cervical nerve root. Even without direct nerve compression, the inflammation and biomechanical instability caused by these structural changes can trigger a referred headache. Spinal stenosis, which is the narrowing of the spinal canal, can also contribute by placing pressure on the spinal cord or nerve roots.
Symptoms of Cervicogenic Headaches
A cervicogenic headache originates from the neck and has distinct characteristics that differentiate it from migraines or tension headaches. The pain typically starts in the neck or the back of the head and then radiates forward. This radiating pain often spreads to the forehead, the temple, or the area around the eye on the same side as the neck irritation.
The pain is usually one-sided (unilateral) and rarely switches sides during a single episode. The intensity is often described as non-throbbing and moderate. The headache is frequently triggered or worsened by specific neck movements or by maintaining a sustained, awkward posture, such as prolonged desk work.
Patients frequently report a reduced range of motion and stiffness in the neck. Pressure applied to tender spots in the upper neck or at the base of the skull can reproduce or worsen the head pain. Unlike migraines, symptoms like sensitivity to light and sound or nausea are typically absent or much less pronounced.
Diagnosis and Management Approaches
Diagnosis begins with a comprehensive physical examination and detailed medical history. A healthcare provider will test the neck’s range of motion and palpate the neck and upper back muscles to identify localized tenderness that triggers the head pain. Imaging studies, such as X-rays, CT scans, or MRI, are used to identify underlying structural changes at C5 and C6.
While imaging can reveal issues like disc degeneration or facet joint arthritis, it does not definitively confirm the headache’s origin. The most specific diagnostic test is a targeted anesthetic nerve block. If the headache pain is temporarily abolished or significantly reduced after an injection of a local anesthetic near the suspected painful structure in the cervical spine, it confirms the neck as the source of the pain.
Management typically begins with conservative treatment focused on reducing inflammation and improving neck function. Physical therapy is a primary approach, incorporating exercises to strengthen deep neck muscles, improve posture, and restore normal range of motion. Medications like non-steroidal anti-inflammatory drugs (NSAIDs) or muscle relaxers may be used for short-term pain relief during acute flare-ups. If conservative treatments are insufficient, interventional procedures such as epidural steroid injections or radiofrequency ablation may be considered to target inflamed nerves or joints directly.