Clinical manifestations and MRI findings of patients with hydrated and dehydrated lumbar disc herniation

RATIONALE AND OBJECTIVES: In addition to the expected appearance of degenerated discs that become dehydrated, hydrated intervertebral disc herniations are sometimes encountered in radiologic practice. This study was undertaken to evaluate the clinical manifestations and MRI findings of hydrated and dehydrated herniated intervertebral discs. MATERIALS AND METHODS: This cross-sectional single-institution study included 73 patients with dehydrated (group I) and hydrated (group II) lumbar disk herniation. The criteria for hydrated and dehydrated disc herniation were subjective criteria compared to the normal signal of intervertebral discs. A herniated disc has been regarded to be hydrated if more than two thirds of it was hypersignal in T2-weighted images, while more than two thirds of a dehydrated disc was hyposignal on T2-weighted images. RESULTS: The mean weight of patients in group I was greater than that of patients in group II (69.3 versus 64.2 kg, P < 0.05). Also, patients in group I tended to be older than those in group II (35.2 versus 28.9 years). Regarding physical activity, a greater number of patients in group II had intense physical activity compared to group I patients (25% versus 13.2%, respectively; P < 0.05). The duration of radicular pain and back pain was significantly greater in group I than in group II (485 versus 202 and 1346 versus 242 days, respectively; P < 0.05). CONCLUSION: Hydrated intervertebral disc herniation tends to be associated with younger age, lighter body weight, shorter duration of radicular pain, and more intense physical activity compared to dehydrated intervertebral disc herniation. These findings may suggest other mechanisms rather than degenerative changes for hydrated disc herniation.