The cervical spine, located in the neck, consists of seven vertebrae that provide support and flexibility for the head. This region allows a wide range of motion. Sometimes, the spaces within this part of the spine can become constricted, a condition often referred to as narrowing. Understanding this narrowing involves recognizing the normal structure and function of the spine.
The Role of C5 and C6 Vertebrae
The cervical spine has seven vertebrae, C1 through C7, enabling head and neck movement. The C5 and C6 vertebrae are in the lower cervical spine, just above C7. This segment is important because it bears significant load and supports the upper cervical spine. An intervertebral disc, a cushion-like structure, lies between the C5 and C6 vertebral bodies, absorbing shock and facilitating movement.
Paired facet joints connect these vertebrae, allowing limited motion. These components protect the spinal cord, which runs through the central vertebral canal. Nerves branch from the spinal cord, exiting through small bony openings called intervertebral foramina.
The C5 and C6 nerve roots emerge at this level and are integral to upper limb function. The C5 nerve contributes to shoulder and elbow flexion and provides sensation to the lateral arm. The C6 nerve governs wrist and elbow flexion, supplying sensation to the thumb side of the forearm and hand. These nerves are part of the brachial plexus, a network supplying the entire upper extremity.
Understanding Spinal Narrowing
Spinal narrowing, medically termed stenosis, occurs when the spaces within the spinal column become constricted, potentially compressing the spinal cord or nerve roots. At the C5-C6 level, this narrowing can manifest as either spinal canal stenosis, affecting the central canal where the spinal cord resides, or foraminal stenosis, impacting the smaller openings (foramina) through which nerve roots exit. This condition frequently develops due to age-related changes in the spine, as intervertebral discs and surrounding structures undergo wear and tear over time.
One common cause is degenerative disc disease, where the intervertebral disc between C5 and C6 loses hydration and height, leading to disc bulging or herniation. As the disc flattens, the vertebrae move closer, which can reduce the space for the spinal cord and nerve roots. The body’s response often involves the formation of bone spurs (osteophytes), bony growths that develop along the edges of the vertebrae and facet joints. These osteophytes can directly encroach upon the spinal canal or neural foramina, further contributing to the narrowing.
Additionally, a herniated disc, where the soft inner material of the disc protrudes, can directly press on nearby nerves or the spinal cord. Ligament thickening, particularly of the ligamentum flavum within the spinal canal, also contributes to stenosis. Over time, this ligament can become thicker and less elastic, reducing the available space within the spinal canal. These changes can lead to significant compression at C5-C6, disrupting spinal cord or nerve root function.
Common Symptoms and Their Origin
Narrowing at C5-C6 can compress C5 or C6 nerve roots, or the spinal cord, leading to symptoms called radiculopathy. These symptoms typically radiate from the neck into the shoulder, arm, and hand, following the specific pathways of the affected nerves. C5 nerve root compression often results in pain and weakness in the shoulder, particularly affecting the deltoid muscle, and can cause sensory changes along the lateral upper arm.
C6 nerve root compression commonly causes pain, numbness, or tingling that extends from the neck into the forearm, thumb, and index finger. Weakness may also occur in muscles controlled by the C6 nerve, such as wrist extensors. The specific patterns of pain and sensory loss are often highly indicative of which nerve root is affected.
Symptoms arise because the compressed nerve’s ability to transmit signals is impaired. Movements that reduce the narrowed space, like extending the neck backward, often worsen pain and neurological symptoms. Discomfort ranges from a dull ache to sharp, shooting pain down the arm, with sensations like “pins and needles” or numbness.
Diagnosis and Treatment Approaches
Diagnosing C5-C6 narrowing begins with a comprehensive physical examination and neurological assessment. A healthcare provider evaluates neck range of motion, arm and hand muscle strength, and reflexes to identify nerve compression. Sensory testing also helps pinpoint the affected nerve root.
Imaging techniques are essential for confirming the diagnosis and determining the precise location and extent of the narrowing. X-rays reveal bone changes like spurs or reduced disc height. Magnetic resonance imaging (MRI) provides detailed soft tissue images, including discs, ligaments, and the spinal cord, effectively visualizing nerve root or spinal cord compression. Computed tomography (CT) scans offer clearer images of bony structures.
Treatment for C5-C6 narrowing typically starts with conservative management. Physical therapy strengthens neck muscles, improves posture, and enhances flexibility to alleviate nerve pressure. Medications, such as non-steroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation, or muscle relaxants for spasms, may be prescribed. Epidural steroid injections deliver anti-inflammatory medication directly to the affected area for temporary pain relief.
If conservative treatments do not provide sufficient relief or if there is evidence of progressive neurological deficit, surgical intervention may be considered. Common surgical procedures include decompression surgeries like anterior cervical discectomy and fusion (ACDF) or cervical disc arthroplasty. ACDF involves removing the damaged disc and fusing the vertebrae, while arthroplasty replaces the disc with an artificial one to preserve motion. These surgeries aim to relieve pressure on compressed nerves or the spinal cord, reducing symptoms and improving function.