DESCRIBING THE SIZE OF LUMBAR DISC HERNIATIONS USING COMPUTED-TOMOGRAPHY - A COMPARISON OF DIFFERENT SIZE INDEX CALCULATIONS AND THEIR RELATION TO SCIATICA

Study Design. The study compared different methods to measure the abso lute and relative size of lumbar disc herniations on computed tomograp hy scans and their relation to sciatica. Methods. Computed tomography (CT) examinations were done before and at 3 and 24 months after nonope rative treatment in 30 patients with lumbar disc herniations. The size of the herniation was described by different indexes and related to t he degree of sciatica. One index was formed by the area of the herniat ion in relation to the spinal canal (A-index), whereas two indexes wer e formed by linear measurements of the herniation in relation to the s pinal canal in either two (ST-index) or one direction (S-index). Resul ts. Each index was correlated significantly to the degree of sciatica. The area of the herniations decreased markedly over time. Conclusions . Linear measurements of the herniation in two perpendicular direction s provide a practical and accurate way of describing the size of lumba r disc herniations.