The spine provides structural support, allows flexible motion, and protects the spinal cord. A healthy spine features three natural curves to absorb shock and maintain balance. The neck, or cervical spine, naturally forms an inward C-shape, known as lordosis. Cervical kyphosis is an abnormality where this natural inward curve straightens or reverses into an outward curve.
Defining Cervical Kyphosis
The cervical spine is composed of seven vertebrae (C1 through C7). A healthy alignment, termed lordosis, is a concave curve facing backward, typically measuring between 20 and 40 degrees. This configuration allows the head to balance efficiently and is mechanically advantageous for movement.
Cervical kyphosis is diagnosed when the C2-C7 Cobb angle measurement reveals a straight or reversed curve. The Cobb angle is calculated by measuring the angle of intersection between lines drawn parallel to the endplates of the C2 and C7 vertebrae. A positive angle signifies a kyphotic, or forward-hunching, deformity, while a negative value indicates lordosis.
The reversal of the curve places abnormal biomechanical stress on surrounding muscles and ligaments. The severity relates directly to the degree of forward angulation and its impact on the rest of the spinal column. The shift in head position forces the body to use compensatory mechanisms in the thoracic and lumbar spine to keep the eyes level with the horizon.
Primary Causes and Contributing Factors
Cervical kyphosis arises from causes that compromise the structural integrity of the spinal column. Degenerative changes are a common source, where intervertebral discs lose height and water content, particularly at the front. This anterior collapse causes the vertebrae to tip forward, gradually introducing a kyphotic angle.
Trauma, such as a severe whiplash injury or fracture, can acutely destabilize the spine by damaging vertebral bodies or posterior ligaments. A wedge-shaped compression fracture, where the front of the vertebra collapses, immediately forces the spine into a kyphotic position. Less common causes include congenital conditions and systemic diseases like ankylosing spondylitis, which causes fusion in an abnormal posture.
A frequently encountered cause is iatrogenic kyphosis, which develops following previous spinal surgery, most often a laminectomy. This procedure involves removing the bony arch (lamina) on the back of the vertebra to decompress the spinal cord. Removing this posterior element disrupts the spinal column’s natural tension band, leading to instability and progressive forward collapse.
Recognizable Symptoms and Functional Impact
Symptoms of cervical kyphosis are categorized into mechanical and neurological issues, with severity depending on the degree and rigidity of the curvature. Mechanical symptoms include chronic neck pain (axial pain) and muscle fatigue as neck muscles strain to hold the head upright. Patients also experience stiffness and a reduced range of motion, making it difficult to turn or tilt the head.
The most concerning functional impact is potential neurological compromise due to abnormal spinal alignment. The reversed curve can stretch the spinal cord over the anterior vertebral bodies, known as the “bowstring effect.” This can lead to myelopathy, characterized by difficulty with balance, limb weakness, and problems with fine motor skills.
Nerve roots can also become compressed as they exit the spine, causing radiculopathy, which results in pain, numbness, or tingling radiating down the arms and hands. A severe forward tilt of the head impairs the ability to maintain a horizontal gaze, forcing the patient to hyperextend the neck awkwardly. Extreme kyphosis can, in rare instances, affect swallowing (dysphagia) or breathing.
Diagnosis and Treatment Approaches
Diagnosis involves a physical examination and standing lateral X-rays, which are the gold standard for assessing spinal alignment. These images calculate the C2-C7 Cobb angle and measure the C2-C7 Sagittal Vertical Axis (SVA), quantifying the horizontal distance between the C2 vertebra and the lower cervical spine. Dynamic X-rays, taken during neck flexion and extension, help determine if the deformity is flexible or fixed.
Advanced imaging studies provide detail for surgical planning. A Computed Tomography (CT) scan offers high-resolution bone images, useful for evaluating facet joints and identifying fractures or bony spurs. Magnetic Resonance Imaging (MRI) is essential for visualizing soft tissues, including the spinal cord, nerve roots, and discs, and confirming neural compression.
Treatment begins conservatively, focusing on managing pain and improving muscle strength. Non-surgical options include physical therapy to strengthen extensor muscles, pain medications, and anti-inflammatory drugs. Conservative measures are generally ineffective for correcting the structural deformity itself.
Surgical intervention is considered when conservative treatment fails, or when there is evidence of progressive neurological deficit, severe pain, or a major deformity that impairs horizontal gaze. The primary goals of surgery are to decompress the neural elements, correct the abnormal alignment, and stabilize the spine with a fusion. The surgical approach depends on the location of compression and the curve’s flexibility. Rigid deformities often require complex osteotomies (precise bone cuts) to restore the natural lordotic curve.