The human spine is a complex column of bones, discs, ligaments, and muscles that provides flexible support. It features natural curves that help absorb shock, maintain balance, and facilitate movement. The cervical spine, the uppermost section consisting of the seven vertebrae in the neck (C1-C7), normally has a specific inward curve.
This natural curvature in the neck is known as cervical lordosis, a gentle “C” shape where the open part of the curve faces toward the back of the body. This alignment is necessary for keeping the head centered over the torso, which requires less muscular effort. When this natural curve is lost, straightened, or reversed, the resulting condition can lead to significant biomechanical stress and symptoms.
Defining Cervical Kyphosis
Cervical kyphosis is an abnormal forward rounding or a reversal of the natural inward curve (lordosis) of the neck. Instead of the vertebrae forming a backward-facing “C” shape, they curve forward, creating a reversed “C” shape that can resemble a hunch. This change in alignment shifts the head’s center of gravity forward, placing undue strain on the neck muscles and ligaments.
The severity of the deformity is measured using the Cobb angle, typically calculated between the second and seventh cervical vertebrae (C2-C7). This measurement involves drawing lines along the endplates of the most tilted vertebrae in the curve. A measurement of zero degrees indicates a complete straightening of the spine, often described as a military neck, which is a precursor to true kyphosis.
Underlying Causes and Risk Factors
The development of cervical kyphosis is linked to mechanical failure and biological processes, with several distinct causes contributing to the loss of proper alignment. The most common cause in adults is degenerative change, where age-related deterioration of the intervertebral discs leads to mechanical instability. Discs lose water content and height, often collapsing more at the front than the back, which causes the vertebrae to wedge and tilt forward, initiating the kyphotic curve.
A significant cause is iatrogenic, meaning the condition results from a prior medical intervention, specifically spinal surgery. Post-laminectomy kyphosis is a well-documented complication that occurs after a multi-level laminectomy, a procedure that involves removing the posterior bony elements to relieve spinal cord compression. The removal of this posterior bone and associated ligaments disrupts the “posterior tension band,” the stabilizing structure that prevents the neck from collapsing forward.
When the posterior tension band is compromised, the weight of the head exerts a greater compressive force on the front of the spinal column, driving the neck into a kyphotic position. Other risk factors for this post-surgical complication include the removal of four or more vertebral levels, young age, and an existing loss of lordosis before the initial operation. Trauma, such as fractures or severe ligamentous injuries, can also directly cause instability and a collapse into kyphosis.
Less frequently, congenital defects, where the spine forms abnormally before birth, and inflammatory conditions like ankylosing spondylitis can result in the same forward-curving deformity.
Recognizing the Signs and Symptoms
The symptoms of cervical kyphosis vary widely, ranging from mild discomfort to severe neurological deficits, depending on the degree of the curve and the resulting compression. The most common complaint is chronic axial neck pain and fatigue, which stems from the constant, strenuous effort of the posterior neck muscles trying to pull the head backward to maintain an upright gaze. This muscle strain is a direct consequence of the head’s weight being shifted abnormally far forward.
In severe cases, the patient may develop a noticeable “chin-on-chest” deformity, which leads to difficulty maintaining a horizontal gaze. This functional disability requires compensation, often by tilting the head back awkwardly or bending the hips and knees, just to look straight ahead. The forward curvature can also compress the throat, leading to functional issues such as difficulty swallowing (dysphagia) or breathing problems.
When the spinal cord itself is compressed, a condition known as cervical myelopathy can develop, presenting with serious neurological symptoms. These deficits are systemic and may include:
- Loss of fine motor skills, such as struggling to button a shirt or handle coins.
- Gait instability, leading to unsteadiness and an increased risk of falls.
- Numbness.
- Tingling.
- Muscle weakness in the arms and hands.
Treatment Approaches and Management
The management of cervical kyphosis is dictated by the patient’s symptoms, the rigidity of the deformity, and the presence of any neurological compromise. For mild cases that involve only pain and no significant neurological symptoms, conservative management is typically the first step. This approach involves physical therapy to strengthen the neck and back muscles, along with nonsteroidal anti-inflammatory drugs (NSAIDs) or other pain medications to control discomfort.
Physical therapy focuses on improving posture and strengthening the muscles that counterbalance the forward head position. Bracing is rarely effective for correcting a fixed kyphotic deformity in adults, but it may be used to provide temporary support and pain relief. Conservative treatment aims to manage symptoms and improve function, but it cannot reverse a structural bony deformity.
Surgical intervention becomes necessary when there is evidence of spinal cord compression (myelopathy), persistent pain unresponsive to conservative care, or a progressive deformity that severely limits function, such as the inability to maintain a horizontal gaze. The goals of surgery are to decompress the neural elements, restore the natural lordosis, and stabilize the spine using instrumentation and fusion. Procedures can involve an anterior approach (through the front of the neck), a posterior approach (through the back), or a combined approach, chosen based on the location of the compression and the flexibility of the kyphosis.