Postoperative computed tomography and low-field magnetic resonance imaging findings in dogs with degenerative lumbosacral stenosis treated by dorsal laminectomy

Martin Rapp; Charles J. Ley; Kerstin Hansson; Lennart Sjöström

doi:10.3415/VCOT-16-06-0096

Veterinary and Comparative Orthopaedics and Traumatology, Table of Contents

Vet Comp Orthop Traumatol 2017; 30(02): 143-152
DOI: 10.3415/VCOT-16-06-0096

Clinical Communication

Schattauer GmbH

Postoperative computed tomography and low-field magnetic resonance imaging findings in dogs with degenerative lumbosacral stenosis treated by dorsal laminectomy

Authors

Martin Rapp

¹Evidensia Specialistdjursjukhuset Strömsholm, Strömsholm, Sweden
Charles J. Ley

²Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
Kerstin Hansson

²Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
Lennart Sjöström

¹Evidensia Specialistdjursjukhuset Strömsholm, Strömsholm, Sweden

Abstract

Summary

Objectives: To describe postoperative computed tomography (CT) and magnetic resonance imaging (MRI) findings in dogs with degenerative lumbosacral stenosis (DLSS) treated by dorsal laminectomy and partial discectomy.

Methods: Prospective clinical case study of dogs diagnosed with and treated for DLSS. Surgical and clinical findings were described. Computed tomography and low field MRI findings pre- and postoperatively were described and graded. Clinical, CT and MRI examinations were performed four to 18 months after surgery.

Results: Eleven of 13 dogs were clinically improved and two dogs had unchanged clinical status postoperatively despite imaging signs of neural compression. Vacuum phenomenon, spondylosis, sclerosis of the seventh lumbar (L7) and first sacral (S1) vertebrae endplates and lumbosacral intervertebral joint osteoarthritis became more frequent in postoperative CT images. Postoperative MRI showed mild disc extrusions in five cases, and in all cases contrast enhancing non-discal tissue was present. All cases showed contrast enhancement of the L7 spinal nerves both pre- and postoperatively and seven had contrast enhancement of the lumbosacral intervertebral joints and paraspinal tissue postoperatively. Articular process fractures or fissures were noted in four dogs.

Clinical significance: The study indicates that imaging signs of neural compression are common after DLSS surgery, even in dogs that have clinical improvement. Contrast enhancement of spinal nerves and soft tissues around the region of disc herniation is common both pre- and postoperatively and thus are unreliable criteria for identifying complications of the DLSS surgery.

Supplementary Material to this article is available online at https://doi.org/10.3415/VCOT-16-06-0096

Keywords

Computed tomography - magnetic resonance imaging - CT - MRI - postoperative - lumbosacral stenosis - lumbar spine - dorsal laminectomy - canine

Full Text

References

References
1 Danielsson F., Sjöström L.. Surgical treatment of degenerative lumbosacral stenosis in dogs. Vet Surg 1999; 28: 91-98.
2 Suwankong N., Meij BP., Voorhout G.. et al. Review and retrospective analysis of degenerative lumbosacral stenosis in 156 dogs treated by dorsal laminectomy. Vet Comp Orthop Traumatol 2008; 21: 285-293.
3 Sisson AF., LeCouteur RA., Ingram JT.. et al. Diagnosis of cauda equina abnormalities by using electromyography, discography, and epidurography in dogs. J Vet Intern Med 1992; 6: 253-263.
4 Suwankong N., Voorhout G., Hazewinkel HAW.. et al. Agreement between computed tomography, magnetic resonance imaging, and surgical findings in dogs with degenerative lumbosacral stenosis. J Am Vet Med Assoc 2006; 229: 1924-1929.
5 Ramirez O., Thrall DE.. A review of imaging techniques for canine cauda equina syndrome. Vet Radiol Ultrasound 1998; 39: 283-296.
6 Meij BP., Bergknut N.. Degenerative lumbosacral stenosis in dogs. Vet Clin North Am Small Anim Pract 2010; 40: 983-1009.
7 De Risio L., Sharp NJ., Olby NJ.. et al. Predictors of outcome after dorsal decompressive laminectomy for degenerative lumbosacral stenosis in dogs: 69 cases (1987-1997). J Am Vet Med Assoc 2001; 219: 624-628.
8 Adams WH., Daniel GB., Pardo AD.. et al. Magnetic resonance imaging of the caudal lumbar and lumbosacral spine in 13 dogs (1990-1993). Vet Radiol Ultrasound 1995; 36: 3-13.
9 Moens NMM., Runyon CL.. Fracture of L7 vertebral articular facets and pedicles following dorsal laminectomy in a dog. J Am Vet Med Assoc 2002; 221: 807-810. 800.
10 Malhotra A., Kalra VB., Wu X.. et al. Imaging of lumbar spinal surgery complications. Insights Imaging 2015; 6: 579-590.
11 Salgado R., Van Goethem JWM., van den Hauwe L.. et al. Imaging of the postoperative spine. Semin Roentgenol 2006; 41: 312-326.
12 Van Goethem J., Parizel P., Jinkins J.. Review Article: MRI of the postoperative lumbar spine. Neuroradiology 2002; 44: 723-739.
13 Boden SD., Davis DO., Dina TS.. et al. Contrast-enhanced MR imaging performed after successful lumbar disk surgery: prospective study. Radiology 1992; 182: 59-64.
14 Cervellini P., Curri D., Volpin L.. et al. Computed tomography of epidural fibrosis after discectomy: a comparison between symptomatic and asymptomatic patients. Neurosurgery 1988; 23: 710-713.
15 Montaldi S., Fankhauser H., Schnyder P.. et al. Computed tomography of the postoperative intervertebral disc and lumbar spinal canal: investigation of twenty-five patients after successful operation for lumbar disc herniation. Neurosurgery 1988; 22: 1014-1022.
16 Van Goethem JWM., Van de Kelft E., Biltjes IGGM.. et al. MRI after successful lumbar discectomy. Neuroradiology 1996; 38: S90-96.
17 Jones JC., Banfield CM., Ward DL.. Association between postoperative outcome and results of magnetic resonance imaging and computed tomography in working dogs with degenerative lumbosacral stenosis. J Am Vet Med Assoc 2000; 216: 1769-1774.
18 Golini L., Kircher PR., Lewis FI.. et al. Transarticular fixation with cortical screws combined with dorsal laminectomy and partial discectomy as surgical treatment of degenerative lumbosacral stenosis in 17 dogs: clinical and computed tomography follow-up. Vet Surg 2014; 43: 405-413.
19 Floris R., Spallone A., Aref TY.. et al. Early postoperative MRI findings following surgery for herniated lumbar disc. Part II: A gadolinium-enhanced study. Acta Neurochir 1997; 139: 1101-1107.
20 Pfirrmann CW., Metzdorf A., Zanetti M.. et al. Magnetic resonance classification of lumbar intervertebral disc degeneration. Spine 2001; 26: 1873-1878.
21 Besalti O., Pekcan Z., Sirin YS.. et al. Magnetic resonance imaging findings in dogs with thoracolumbar intervertebral disk disease: 69 cases (1997-2005). J Am Vet Med Assoc 2006; 228: 902-908.
22 Pfirrmann CWA., Dora C., Schmid MR.. et al. MR image-based grading of lumbar nerve root compromise due to disk herniation: reliability study with surgical correlation. Radiology 2004; 230: 583-588.
23 Gödde T., Steffen F.. Surgical treatment of lumbosacral foraminal stenosis using a lateral approach in twenty dogs with degenerative lumbosacral stenosis. Vet Surg 2007; 36: 705-713.
24 Wood BC., Lanz OI., Jones JC.. et al. Endoscopic-assisted lumbosacral foraminotomy in the dog. Vet Surg 2004; 33: 221-231.
25 Sharp NJH., Wheeler SJ.. Lumbosacral disease. In: Small Animal Spinal Disorders: Diagnosis and Surgery. 2nd Edition. Edinburgh: Elsevier Mosby; 2005: 181-209.
26 da Costa RC., Pippi NL., Graça DL.. et al. The effects of free fat graft or cellulose membrane implants on laminectomy membrane formation in dogs. Vet J 2006; 171: 491-499.
27 Lubina ZI., Baranovic S., Karlak I.. et al. The grading model for the assessment of the total amount of epidural fibrosis in postoperative lumbar spine. Eur Spine J 2013; 22: 892-897.
28 Robertson JT.. Role of peridural fibrosis in the failed back: a review. Eur Spine J 1996; 5 (Suppl. 01) S2-6.
29 Fandiño J., Botana C., Viladrich A.. et al. Reoperation after lumbar disc surgery: results in 130 cases. Acta Neurochir 1993; 122: 102-104.
30 Ross JS., Delamarter R., Hueftle MG.. et al. Gadolinium-DTPA-enhanced MR imaging of the postoperative lumbar spine: time course and mechanism of enhancement. Am J Roentgenol 1989; 152: 825-834.
31 Bundschuh CV., Stein L., Slusser JH.. et al. Distinguishing between scar and recurrent herniated disk in postoperative patients: value of contrast-enhanced CT and MR imaging. Am J Neuroradiol 1990; 11: 949-958.
32 An HS., Nguyen C., Haughton VM.. et al. Gadolinium-enhancement characteristics of magnetic resonance imaging in distinguishing herniated intervertebral disc versus scar in dogs. Spine 1994; 19: 2089-2095.
33 Suran JN., Durham A., Mai W.. et al. Contrast enhancement of extradural compressive material on magnetic resonance imaging. Vet Radiol Ultrasound 2011; 52: 10-16.
34 Ross JS., Masaryk TJ., Schrader M.. et al. MR imaging of the postoperative lumbar spine: assessment with gadopentetate dimeglumine. Am J Neuroradiol 1990; 11: 771-776.
35 Bundschuh CV., Modic MT., Ross JS.. et al. Epidural fibrosis and recurrent disk herniation in the lumbar spine: MR imaging assessment. Am J Roentgenol 1988; 150: 923-932.
36 Rothman SL., Glenn WV., Kerber CW.. Postoperative fractures of lumbar articular facets: occult cause of radiculopathy. Am J Roentgenol 1985; 145: 779-784.
37 Quist JJ., Dhert WJ., Meij BP.. et al. The prevention of peridural adhesions. A comparative long-term histomorphometric study using a biodegradable barrier and a fat graft. J Bone Joint Surg Br 1998; 80: 520-526.
38 Freer SR., Scrivani PV.. Postoperative susceptibility artifact during magnetic resonance imaging of the vertebral column in two dogs and a cat. Vet Radiol Ultrasound 2008; 49: 30-34.
39 Lee RKL., Griffith JF., Lau YYO.. et al. Diagnostic capability of low- versus high-field magnetic resonance imaging for lumbar degenerative disease. Spine 2015; 40: 382-391.

Supplementary Material

Online Supplementary Material (PDF) (PDF) (opens in new window)