Cervical spinal stenosis (CSS) describes a condition where the spinal canal in the neck becomes narrower. This narrowing places pressure on the spinal cord and the nerve roots that branch off it. The resulting compression can lead to neurological symptoms affecting the upper and lower extremities. Magnetic Resonance Imaging (MRI) is the standard diagnostic tool for visualizing the cervical spine and assessing the severity of compression.
What Cervical Spinal Stenosis Is
Cervical spinal stenosis involves the mechanical compression of neural structures within the bony spinal column of the neck. This encroachment of space around the spinal cord or nerve roots is typically a result of age-related degenerative changes, often called spondylosis.
The primary structural causes include bulging or herniated intervertebral discs, the thickening of ligaments such as the ligamentum flavum, and the formation of bone spurs (osteophytes) along the vertebrae. These changes reduce the available space for the spinal cord. When compression significantly affects the spinal cord, the resulting dysfunction is termed cervical myelopathy.
Symptoms of CSS include chronic neck pain, numbness or tingling in the arms and hands, and weakness in the upper limbs. Advanced compression can lead to a loss of fine motor skills, clumsiness, and balance or gait disturbance. These symptoms usually develop gradually as degenerative changes progress.
Why MRI Is the Preferred Diagnostic Tool
MRI is the preferred imaging method for evaluating cervical spinal stenosis due to its superior ability to visualize soft tissues. Unlike X-rays or Computed Tomography (CT) scans, which focus on bone, MRI provides detailed contrast for non-bony elements, which is essential since the primary causes of stenosis are soft tissue abnormalities like disc herniations and ligament thickening.
MRI uses strong magnetic fields and radio waves to generate cross-sectional images of the spine without ionizing radiation. This allows clinicians to clearly see the spinal cord, the exiting nerve roots, and the cerebrospinal fluid (CSF) surrounding the cord. MRI accurately pinpoints the location and extent of compression by displaying the relationship between degenerative structures and neural tissue.
The imaging captures the degree of spinal canal narrowing and whether the spinal cord is being deformed. On T2-weighted sagittal images, the CSF appears bright white, creating a natural contrast against the darker spinal cord. Interruption or effacement of this bright CSF signal indicates a reduction in space and serves as a visual marker of stenosis.
Interpreting Severe Stenosis on the MRI
Severe cervical spinal stenosis is defined by specific structural hallmarks. A key indicator of severe central canal stenosis is the complete effacement of the cerebrospinal fluid (CSF) space surrounding the spinal cord. In severe cases, the bright CSF signal seen on T2-weighted images is entirely obliterated at the level of compression, confirming direct contact between the narrowing structures and the spinal cord.
Another finding signifying chronic pressure is abnormal signal intensity within the spinal cord itself, often termed myelomalacia. On T2-weighted sequences, this appears as an increased, bright signal within the cord. This high signal change represents edema or chronic damage to the cord tissue, which is a specific sign of cervical myelopathy.
Radiology reports often include quantitative measurements, with severe stenosis typically corresponding to a sagittal canal diameter of less than 10 millimeters. Severe cases frequently involve compression at multiple adjacent levels (e.g., C4-C5 and C5-C6). This multi-level involvement increases neurological risk and complexity, often leading to a severe designation even if single-level compression might be graded as moderate.
Treatment Pathways Following Severe Diagnosis
When severe cervical spinal stenosis is confirmed by MRI, especially with findings suggesting myelopathy, treatment often leans toward surgical intervention. The primary goal is to prevent further neurological decline and allow for functional recovery by decompressing the spinal cord. Non-surgical management, such as physical therapy or anti-inflammatory drugs, is used for milder stenosis to manage pain, but it cannot reverse severe mechanical compression.
Surgical procedures are designed to create more space within the spinal canal to relieve pressure on the compressed neural tissue. Common options include laminectomy, which removes the back part of the vertebra (lamina) to enlarge the canal, and laminoplasty, which reshapes the lamina to expand the canal using a hinged door effect. Anterior cervical discectomy and fusion (ACDF) removes the disc and bone spurs from the front and stabilizes the segment with a fusion.
The choice of procedure depends on factors like the number of compressed levels and spinal alignment. For multi-level disease, a posterior decompression technique like laminoplasty or laminectomy is often considered. These interventions address the structural cause of the stenosis when severe compression threatens permanent spinal cord dysfunction.