Far lateral lumbar disc extrusion: MRI findings and surgical treatment

Summary

This case report describes the magnetic resonance imaging (MRI) findings and the treatment of a far lateral extrusion of disc material at the sixth and seventh lumbar vertebrae (L6-L7) in a five-year-old male Alpine Dachsbracke dog referred to our hospital for investigation of the complaint of a one week progressive lameness in the left pelvic limb and poorly localized back pain. An extra-foraminal left lateral disc herniation impinging on the sixth lumbar nerve root was diagnosed by MRI examinations. Due to the far lateral position of the extruded disc material on MRI, surgical opening of the spinal canal was not necessary. Removal of the herniated soft disc material impinging on the L6 nerve root, and fenestration of the L6-L7 disc was performed laterally. To the author’s knowledge ‘far-lateral’ disc herniation beyond the neuroforamen without any spinal canal contact has not been described in dogs until now. A complete recovery with no evidence of pain was achieved only after a couple of weeks after surgery. We acknowledge that it is possible that other pathological mechanisms may have contributed to clinical signs and to a delayed recovery.

Keywords

Far lateral extrusion of disc material - extraforaminal disk herniation - MRI - poorly localized - back pain

• References

• 1 Brisson BA. Intervertebral disc disease in dogs. Vet Clin North Am Small Anim Pract 2010; 40: 829-858.
• 2 Bray JP, Burbidge HM. The canine intervertebral disk: part one: structure and function. J Am Anim Hosp Assoc 1998; 34: 55-63.
• 3 Sharp NJH, Wheeler SJ. editors. Small Animal Spinal Disorders: Diagnosis and Surgery. London: Elsevier Mosby; 2005
• 4 Bagley RS, Pluhar GE, Alexander JE. Lateral intervertebral disk extrusion causing lameness in a dog. (Comments. Shores A). J Am Vet MedAssoc 1994; 205: 181-183 discussion 183-185.
• 5 Porchet F, Fankhauser H, de Tribolet N. Clinical aspects of extraforaminal lumbar disc hernia. Aktuelle Probl Chir Orthop 1994; 44: 47-50.
• 6 Broom MJ. Foraminal and extraforaminal lumbar disk herniations. Clin Orthop Relat Res 1993; (289): 118-126.
• 7 Bagley RS, Pluhar GE, Alexander JE. Lateral intervertebral disc extrusion causing lameness in a dog. J Am Vet Med Assoc 1994; 205: 181-183.
• 8 Felts JF, Prata RG. Cervical disk disease in the dog: intraforaminal and lateral extrusions. J Am Anim Hosp Assoc 1983; 19: 755-760.
• 9 Bagley RS, Tucker RL, Harrington ML. Lateral and foraminal disk extrusion in dogs. Compend Contin Edu Pract Vet 1996; 18: 795-805.
• 10 Bray JP, Burbidge HM. The canine intervertebral disk. Part two: Degenerative changes--nonchondrodystrophoid versus chondrodystrophoid disks. J Am Anim Hosp Assoc 1998; 34: 135-144.
• 11 Bergknut N. Intervertebral disc degeneration in dogs. PhD Thesis. Utrecht (The Netherlands): Utrecht University; 2011
• 12 Epstein NE. Foraminal and far lateral lumbar disc herniations: surgical alternatives and outcome measures. Spinal Cord. 2002; 40: 491-500.
• 13 Schnapper A, Waibl H. Morphometrische Untersuchungen an den thorakolumbalen Disci intervertebrales des Dackels [Morphometric studies of the thoracolumbar intervertebral discs of the Dachshund. Kleintierpraxis 1998; 43: 727-802.
• 14 Chambers JN, Selcer BA, Sullivan SA. et al. Diagnosis of lateralized lumbosacral disc herniation with magnetic resonance imaging. J Am Anim Hosp Assoc 1997; 33: 296-299.
• 15 Gibbons SE, Macias C, De Stefani A. et al. The value of oblique versus ventrodorsal myelographic views for lesion lateralization in canine thoracolumbar disc disease. J Small Anim Pract 2006; 47: 658-662.
• 16 Bos AS, Brisson BA, Holmberg DL. et al. Use of the ventrodorsal myelographic view to predict lateralization of extruded disk material in small-breed dogs with thoracolumbar intervertebral disk extrusion: 104 cases (2004-2005). J Am Vet Med Assoc 2007; 230: 1860-1865.
• 17 Olby NJ, Munãna KR, Sharp NJ. et al. The computed tomographic appearance of acute thoracolumbar intervertebral disc herniations in dogs. Vet Radiol Ultrasound 2000; 41: 396-402.
• 18 Israel SK, Levine JM, Kerwin SC. et al. The relative sensitivity of computed tomography and myelography for identification of thoracolumbar intervertebral disk herniations in dogs. Vet Radiol Ultrasound 2009; 50: 247-252.
• 19 Heo DH, Lee MS, Sheen SH. et al. Simple oblique lumbar magnetic resonance imaging technique and its diagnostic value for extraforaminal disc herniation. Spine (Phila Pa 1976) 2009; 34: 2419-2423.
• 20 Toombs J, Waters D. Intervertebral Disc Disease. In: Slatter D. editor. Textbook of Small Animal Surgery. Philadelphia, PA: Saunders; 1993. p. 1193-1209.
• 21 Ohmori K, Kanamori M, Kawaguchi Y. et al. Clinical features of extraforaminal lumbar disc herniation based on the radiographic location of the dorsal root ganglion. Spine 2001; 26: 662-666.
• 22 Kobayashi S, Meir A, Kokubo Y. et al. Ultrastructural analysis on lumbar disc herniation using surgical specimens: role of neovascularization and macrophages in hernias. Spine (phila pa 1976) 2009; 34: 655-657.
• 23 Arai I, Mao G-P, Otani K. et al. Indomethacin blocks the nucleus pulposus-induced effects on nerve root function. An experimental study in dogs with assessment of nerve conduction and blood flow following experimental disc herniation. Eur Spine J 2004; 13: 691-694.
• 24 Takahashi N, Yabuki S, Aoki Y. et al. Pathomechanisms of nerve root injury caused by disc herniation: an experimental study of mechanical compression and chemical irritation. Spine (Phila Pa 1976) 2003; 28: 435-441.
• 25 Niv D, Devor M. Refractory neuropathic pain: The nature and extent of the problem. Pain Practice 2006; 6: 3-9.
• 26 Mathews KA. Neuropathic pain in dogs and cats: if only they could tell us if they hurt. In: Vet Clin North Am Small Anim Pract 2008; 38: 1365-1414.