Adjacent Segment Disease

After spinal fusion surgery, the fused area of the spine stops moving. This can change how the rest of your spine works. The segments above and below the fused part have to move more to make up for the lost movement. Over time, this added stress can accelerate degeneration in these nearby sections, leading to disc herniation, arthritis in the joints, or narrowing of the space where nerves travel (called stenosis). This can cause pain, discomfort, or other symptoms.

While not everyone who has spinal fusion develops Adjacent Segment Disease, studies suggest that around 30% of patients may show signs of wear and tear in adjacent spinal areas within ten years of their surgery. However, not all of these patients will feel symptoms.

The symptoms of adjacent segment disease depend on the severity of the degeneration and the specific spinal segment affected. Common symptoms include:

1. Localized back or neck pain: Patients may experience pain localized to the neck (cervical spine) or lower back (lumbar spine), depending on the fusion site. The pain often worsens with movement or prolonged activity.
2. Radiating Pain (Radiculopathy): If a nerve root is compressed due to a herniated disc or narrowing of the spinal canal, patients may experience radiating pain down the arms (cervical spine involvement) or legs (lumbar spine involvement).
3. Pain that travels along the spinal cord (Myelopathy): When the spinal cord is compressed it can cause pain that can cause numbness or tingling, weakness in the limbs, difficulty walking, loss of fine motor skills and bladder and bowel dysfunction.
4. Reduced Range of Motion: Stiffness and reduced flexibility in the affected area are common, as the spine compensates for the altered mechanics post-fusion.
5. Functional Limitations: Patients with adjacent segment disease may struggle with daily activities due to chronic pain or neurological impairments, impacting their quality of life.

The development of Adjacent Segment Disease is multifactorial, influenced by both patient-specific and surgical factors:

1. Added stress on the spine: Spinal fusion alters the natural movement of the spine, transferring increased stress to adjacent levels. Over time, this additional mechanical load contributes to wear and tear.
2. Degenerative Changes: Patients with pre-existing mild degeneration in the segments adjacent to the fusion site are at higher risk of developing symptomatic ASD.
3. Surgical Technique and Fusion Level: The number of fused segments and the location of the fusion impact the likelihood of adjacent segment disease. For example, lumbar and cervical fusions are more commonly associated with adjacent segment degeneration. Additionally, surgical techniques that preserve motion, such as artificial disc replacement, may reduce the risk compared to traditional fusion.
4. Age and Genetics: Advanced age and genetic predisposition to degenerative spine conditions increase the likelihood of developing ASD.
5. Lifestyle Factors: Smoking, obesity, and lack of physical activity contribute to accelerated spine degeneration and increase the risk of ASD.

Diagnosing ASD requires a comprehensive evaluation that includes a detailed medical history, physical examination, and imaging studies.

Medical History

Understanding the patient’s surgical history, onset of symptoms, and activities that exacerbate or relieve pain is crucial. Patients with a history of spinal fusion who develop new or worsening symptoms should be evaluated for ASD.

Physical Examination

A thorough physical exam focuses on identifying areas of pain, restricted motion, and nerve-related problems. Tests may include assessing reflexes, muscle strength, and sensory function to detect nerve involvement.

Imaging Studies

• X-rays: Special X-rays taken while you’re bending forward or backward can show if there’s instability in your spine.
• MRI: MRI provides detailed images of the soft tissues, including discs, nerves, and spinal cord to help identify problems like herniated discs, pinched nerves or a compressed spinal cord.
• CT scans: These focus on the bones of the spine help to identify wear and tear on the joints.
• Diagnostic Injections: If needed, Dr. Boden may recommend injections to pinpoint the exact source of your pain. These injections can also help confirm whether ASD is the cause of your symptoms.