Association Between Decreased Disc Signal Intensity in Preoperative T₂-Weighted MRI and a 5-Year Outcome after Lumbar Minimally Invasive Discectomy

A total of 39 patients who had undergone microdiscectomy or percutaneous nucleotomy for lumbar disc herniation were examined after a follow-up of 5 years. The overall outcome was satisfactory in 80 % of the patients treated, and only 1 (3 %) patient had been reoperated during the follow-up. Clinical signs and symptoms of lumbar instability were detected in 10 (26 %) patients. All these 39 patients had been examined with lumbar magnetic resonance imaging (MRI) on the day preceding the operation; the presence of disc degeneration was graded as severe, mild or non-existent depending on the visual brightness of the discs on T₂-weighted images, as compared to the signal intensity of the lumbar vertebrae. None of the 12 patients with no preoperative disc degeneration in MRI suffered from postoperative clinical signs and symptoms of instability as compared to 10 (37 %) of the 27 patients with mild or severe disc degeneration suffering from instability (p = 0.04). Thus, the results of the present study imply that the grade of the disc degeneration in preoperative T₂-weighted MR images significantly predicted the occurrence of postoperative clinical instability.

Microinvasive lumbar discectomy - Disc degeneration - Instability

References

• 1 Burton C V, Kirkaldy-Willis W H, Yong-Hing K, Heithoff K B. Causes of failure of surgery on the lumbar spine.  Clin Orthop. 1981;  157 191-199
• 2 Fritsch E W, Heisel J, Rupp S. The failed back surgery syndrome. Reasons, intraoperative findings, and long-term results: A report of 182 operative treatments.  Spine. 1996;  21 626-633
• 3 Frymoyer J W. The role of spine fusion. Question 3.  Spine. 1981;  6 284-290
• 4 Kotilainen E, Valtonen S. Clinical instability of the lumbar spine after microdiscectomy.  Acta Neurochir (Wien). 1993;  125 120-126
• 5 Kotilainen E. Long-term outcome of patients suffering from clinical instability after microsurgical treatment of lumbar disc herniation.  Acta Neurochir (Wien). 1998;  140 108-113
• 6 Dai L. Disc degeneration and cervical instabililty. Correlation of magnetic resonance imaging with radiography.  Spine. 1998;  23 1734-1738
• 7 Kotilainen E, Alanen A, Erkintalo M, Valtonen S, Kormano M. Magnetic resonance image changes and clinical outcome after microdiscectomy or nucleotomy for ruptured disc.  Surg Neurol. 1994;  41 432-440
• 8 Caspar W, Campbell B, Barbier D D, Kretschmer R, Gottfried Y. The Caspar microsurgical discectomy and comparison with a conventional standard lumbar disc procedure.  Neurosurgery. 1991;  28 78-87
• 9 Hijikata S. Percutaneous nucleotomy. A new concept technique and 12 years' experience.  Clin Orthop. 1989;  238 9-23
• 10 Kotilainen E. Microinvasive lumbar disc surgery. A study on patients treated with microdiscectomy or percutaneous nucleotomy for disc herniation.  Ann Chir Gynaecol. 1994;  83 [Suppl 209] 1-50
• 11 Kotilainen E. Percutaneous nucleotomy in the treatment of cervical disc herniation: report of three cases and review.  Minim Invas Neurosurg. 1999;  42 152-155
• 12 Fairbank J CT, Couper J, Davies J B, O'Brien J P. The Oswestry low back pain disability questionnaire.  Physiotherapy. 1980;  66 271-273
• 13 Kotilainen E, Heinänen J, Gullichsen E, Koivunen T, Aro H T. Spondylodesis in the treatment of segmental instability of the lumbar spine with special reference to clinically verified instability.  Acta Neurochir (Wien). 1997;  139 629-635
• 14 Nachemson A L. Instability of the lumbar spine. Pathology, treatment, and clinical evaluation.  Neurosurg Clin North Am. 1991;  2 785-790
• 15 Paris S V. Physical signs of instability.  Spine. 1985;  10 277-279
• 16 Sano S, Yokokura S, Nagata Y, Young S Z. Unstable lumbar spine without hypermobility in postlaminectomy cases. Mechanism of symptoms and effect of spinal fusion with and without spinal instrumentation.  Spine. 1990;  15 1190-1197
• 17 Gibson M J, Buckley J, Mawhinney R, Mulholland R C, Worthington B S. Magnetic resonance imaging and discography in the diagnosis of disc degeneration. A comparative study of 50 discs.  J Bone Joint Surg. 1986;  68-B 369-373
• 18 Modic M T, Masaryk T J, Ross J S, Carter J R. Imaging of degenerative disk disease.  Radiology. 1988;  168 177-186
• 19 Tertti M, Paajanen H, Laato M, Aho H, Kormano M. Disc degeneration in magnetic resonance imaging: a comparative biochemical, histological and radiologic study in cadaver spines.  Spine. 1991;  16 629-634
• 20 Modic M T, Pavlicek W, Weinstein M A, Boumphrey F, Ngo F, Hardy R, Duchesneau P M. Magnetic resonance imaging of intervertebral disk disease. Clinical and pulse sequence considerations.  Radiology. 1984;  152 103-111
• 21 Powell M C, Wilson M, Szypryt P, Symonds E M, Worthington B S. Prevalence of lumbar disc degeneration observed by magnetic resonance in symptomless women.  Lancet. 1986;  2 1366-1367
• 22 Knutsson F. The instability associated with disk degeneration in the lumbar spine.  Acta Radiol. 1944;  25 593-609
• 23 MacNab I. The traction spur: An indicator of segmental instability.  J Bone Joint Surg. 1971;  53A 663-670
• 24 Boden S D, Wiesel S W. Lumbosacral segmental motion in normal individuals. Have we been measuring instability properly?.  Spine. 1990;  15 571-576
• 25 Dvorak J, Panjabi M M, Novotny J E, Chang D G, Grob D. Clinical validation of functional flexion-extension roentgenograms of the lumbar spine.  Spine. 1991;  16 943-950
• 26 Paajanen H, Erkintalo M, Dahlström S, Kuusela T, Svedström E, Kormano M. Disc degeneration and lumbar instability. Magnetic resonance examination of 16 patients.  Acta Orthop Scand. 1989;  60 375-378
• 27 Toyone T, Takahashi K, Kitahara H, Yamagata M, Murakami M, Moriya H. Vertebral bone-marrow changes in degenerative lumbar disc disease. An MRI study of 74 patients with low back pain.  J Bone Joint Surg. 1994;  76-B 757-764
• 28 Bräm J, Zanetti M, Min K, Hodler J. MR abnormalities of the intervertebral disks and adjacent bone marrow as predictors of segmental instability of the lumbar spine.  Acta Radiol. 1998;  39 18-23
• 29 Kotilainen E, Kotilainen P. A microsurgical technique for posterior lumbar interbody fusion: Technical note.  Acta Neurochir (Wien). 1999;  141 767-769

Corresponding Author