What is the significance of vertebral level in medical diagnosis and treatment?

The Significance of Vertebral Level in Medical Diagnosis and Treatment

Accurate identification and documentation of vertebral levels is critical for proper diagnosis, treatment planning, and clinical outcomes in patients with spinal pathology, as incorrect level identification can lead to significant morbidity and mortality.

Diagnostic Importance of Vertebral Level

• Vertebral level identification is essential for proper diagnosis of vertebral fractures, with the Genant visual semiquantitative (SQ) method being the current clinical technique of choice for diagnosing and classifying vertebral fracture severity 1
• Accurate vertebral level labeling is crucial when performing Dual-Energy X-ray Absorptiometry (DXA) scans, as incorrect labeling can lead to misdiagnosis of osteoporosis or improper treatment planning 1
• Vertebral levels not adequately visualized during assessment should be excluded from analysis and noted as exclusions in reports to prevent diagnostic errors 1
• Knowledge of anatomy and variants regarding vertebral bodies is essential to adjust automated interpretations of vertebral fracture assessments (VFA) 1

Anatomical Variability and Landmark Identification

• The vertebra prominens (traditionally described as C7) is actually found at C7 in only 48.7% of cases, with significant variability - C6 (35.9%), C5 (10.3%), and even T1 (5.1%) can present as the most prominent vertebra 2
• Traditional surface landmarks for identifying vertebral levels are often unreliable - the first spinous process at the lower end of the nuchal furrow coincides with the vertebra prominens in only 46.8% of female subjects 3
• Sacral dimples have a wide distribution in vertebral level and are unreliable as surface vertebral landmarks, with significant sex differences in their location 3
• MRI-based anatomical landmarks are also unreliable in determining the correct thoracic vertebral level, with only the most superior rib showing high reliability (98% detection, 95% interobserver agreement) 4

Clinical Implications for Pain Diagnosis and Treatment

• Epiduroscopy has been shown to be more reliable (87% of cases) than either clinical evaluation (28%) or MRI (20%) for determining the vertebral level where clinically significant spinal pathology occurs in patients with low back pain and/or radiating pain 5
• The most common level for reproducible pain during epiduroscopy is L4-L5, while L5-S1 is the least common level despite frequent clinical suspicion 5
• Vertebral levels of key bony/cartilaginous structures in the neck often differ from standard anatomical descriptions, which has implications for procedures targeting these structures 6

Imaging Considerations for Vertebral Level Assessment

• For suspected vertebral fractures, plain radiographs of the spine area of interest are the first-line imaging modality (rated 9/9 for appropriateness) 1
• When initial radiographs are negative but clinical suspicion remains high, MRI without contrast is recommended (rated 9/9) or CT without contrast (rated 7/9) 1
• For patients with advanced degenerative changes of the spine with or without scoliosis, QCT of the lumbar spine and hip is recommended (rated 8/9) over standard DXA (rated 7/9) 1
• Vertebral Fracture Assessment (VFA) using DXA is indicated in patients with T-scores less than -1.0 and specific risk factors including age ≥70 years for women or ≥80 years for men, historical height loss >4 cm, self-reported prior vertebral fracture, or glucocorticoid therapy 1

Procedural Significance of Vertebral Level

• For vertebral augmentation procedures, accurate identification of the symptomatic vertebral level is crucial, with physical examination under fluoroscopic guidance sometimes needed to localize pain to a specific anatomic level 1
• Pre-procedural MRI can provide valuable information for determining the need for intervention and for procedural guidance in vertebral augmentation 1
• When there is doubt about the presence of a vertebral fracture or an atypical-appearing vertebral body on VFA, additional imaging such as lateral lumbar and thoracic radiographs should be performed 1
• Comparison with pre-existing images is important to confirm whether a compression fracture is chronic or new 1

Common Pitfalls and Recommendations

• Relying solely on surface anatomical landmarks for vertebral level identification can lead to significant errors due to anatomical variability 2, 3, 4
• The C2 vertebra must be identified and cross-referenced to dedicated thoracic spine MRI, as other MRI-based anatomical landmarks are unreliable 4
• For DXA scans, vertebral levels should be labeled consistently, and the morphology assessment performed must be validated by the operator/interpreter 1
• When monitoring BMD over time, only changes which meet or exceed the least significant change (LSC) should be considered significant, with the maximal acceptable LSC being 5.0% for the total hip and 5.3% for the lumbar spine 1