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Spine – intervertebral disc disease and ‘wobbler syndrome’

image of Spine – intervertebral disc disease and ‘wobbler syndrome’
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Abstract

Intervertebral disc disease has been the subject of varying nomenclature over the years. The aetiology involved may be relevant. Degenerative, traumatic and infectious causes as well as anatomical/developmental anomalies are recognized. The focus of this chapter is on degenerative disc disease, with an emphasis on IVDH.

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Figures

Image of 22.1
22.1 MRI of a 9-year-old Jack Russell Terrier with Hansen type 1 herniation at L1–2. (a) Sagittal T2W image showing a normally hydrated intervertebral disc at L3–4 and several dehydrated and degenerate discs at other levels, and mild ventral spondylosis at L2–3. The herniated L1–2 disc is amorphous and causes severe spinal cord compression. (b) Transverse T2W image at L1–2 showing severe midline spinal cord compression by the herniated disc material (*).
Image of 22.2
22.2 MRI of a 7-year-old German Shepherd Dog with Hansen type 2 herniation at L1–2. (a) Sagittal T2W image showing mildly dehydrated and degenerate intervertebral discs on either side and a markedly dehydrated and degenerate disc at L1–2 with marked herniation and spinal cord compression. A T2 hyperintense line can be seen in the spinal cord cranial and caudal to the lesion which probably represents truncation artefact. (b) Transverse T2W image at L1–2 showing severe midline spinal cord compression (displacing the spinal cord to the right) by the protruding disc (*).
Image of 22.4
22.4 MRI scan of a 14-year-old cross-breed dog with a discal cyst at C4–5. (a) Sagittal T2W image showing a degenerate, dehydrated and herniated intervertebral disc at C5–6 and a partially dehydrated, collapsed and herniated intervertebral disc at C4–5. There is a hyperintense signal dorsal to the herniated C4–5 intervertebral disc causing spinal cord compression. (b) Transverse T2W image at the C4–5 intervertebral disc showing the severe midline spinal cord compression by the hyperintense ‘discal cyst’ with the ‘seagull’ appearance of the ventral aspect of the spinal cord.
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22.5 MRI scan of a 9-year-old Labrador Retriever with an acute, non-compressive nucleus pulposus herniation at C2–3. (a) Sagittal T2W image showing a normally hydrated intervertebral disc at C3–4 and a partially dehydrated intervertebral disc with reduced volume and signal at C2–3. There is a T2 hyperintensity in the spinal cord just dorsal to the abnormal intervertebral disc without spinal cord compression. (b) Transverse T2W image at C2–3 showing left-sided intramedullary hyperintensity with altered epidural fat signal but without spinal cord compression.
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22.7 Lateral lumbar spine radiograph of an 8-year-old German Shepherd Dog. The L4–5 disc space is narrow, more so dorsally than ventrally (‘wedging’), implying herniation of disc material. There is evidence of mineralization of the dorsal annulus. The superimposed transverse processes opacify the nuclear part of the disc.
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22.8 Lateral lumbar spine radiograph of a 4-year-old Beagle. The intervertebral foramen at the centre of the image is smaller and of a slightly different shape to those cranial and caudal to it, which suggests collapse of the intervertebral disc space at this level and raises the suspicion of intervertebral disc herniation.
Image of 22.9
22.9 Lateral lumbar spine radiograph of a 4-year-old Cocker Spaniel. The L1–2 disc has mineralized and some of the mineralized nuclear material has herniated into the vertebral canal and is seen clearly through the intervertebral foramen. Note the normal but prominent accessory process partially obliterating the T13–L1 intervertebral foramen dorsally.
Image of 22.10
22.10 Lateral lumbar spine radiograph of a 5-year-old Bichon Frise. The L1–2 disc has herniated. A large mineralized mass of disc material is easily seen in the intervertebral foramen. Also note the collapsed intervertebral disc space and reduced articular process joint space.
Image of 22.11
22.11 Lateral lumbar spine radiograph of an 11-year-old Springer Spaniel. There is collapse of the L1–2–3 disc spaces with mature ventral and abaxial spondylosis. Calcific material is seen within the ventral vertebral canal at L1–2. This may be a composite shadow from mineralized herniated material and an extension of the spondylosis. The increased opacity of the vertebral endplates may indicate sclerosis or superimposing spondylotic reactions.
Image of 22.12
22.12 Lateral radiograph of the cranial lumbar spine of a 9-year-old Labrador Retriever. The intervertebral disc space and intervertebral foramen at L1–2 are reduced in size. The adjacent endplates of L1 and L2 appear sclerotic and there is moderate ventral spondylosis, suggesting chronicity and excessive motion at this level.
Image of 22.13
22.13 Lateral radiograph of the thoracolumbar junction of an 8-year-old Labrador Retriever. Moderate osteoarthrosis of the articular process joint is seen at this level. This has caused loss of edge sharpness of the composite shadow of the two superimposed joints and some ventrally protruding bony material that may encroach on the vertebral canal.
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22.14 CT (bone window) of a 9-year-old Labrador Retriever with intervertebral disc herniation at L1–2. (a) Sagittal reconstructed image showing the collapsed intervertebral disc space at L1–2 with a lucent gas shadow (vacuum phenomenon) in the disc space and the mineralized herniated disc material in the spinal canal. There is also mild ventral spondylosis. (b) Transverse image at the L1–2 intervertebral disc space showing the vacuum phenomenon and mineralized extruded disc material dorsally.
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22.15 Myelographic views of the lumbar spine of a 4-year-old Cocker Spaniel. (a) On the lateral view the comprehensive loss of thecal contrast medium from cranial L1 to mid L2 confirms the presence of a compressive lesion and/or cord swelling at this level. (b) The ventrodorsal (VD) view shows a large extradural compression on the left, mostly within the vertebral canal of L1. The granular calcification within the narrowed L1–2 disc space confirms the degenerate status of that disc. This case demonstrates cranial migration of the herniated disc material. There is extradural contrast leakage caudal to the compressive lesion.
Image of 22.16
22.16 CT myelographic images (bone window) of a 9-year-old Jack Russell Terrier with intervertebral disc herniation at C4–5. (a) Sagittal reconstructed image showing interruption of the ventral and dorsal contrast columns at C4–5 due to disc herniation, which is seen as an isoattenuating soft tissue opacity dorsal to the intervertebral disc space. There is mild wedging of the intervertebral disc space. There is also mild intervertebral disc herniation at C3–4 and C5–6. (b) Transverse image at the level of the C4–5 intervertebral disc space showing the midline extradural compression.
Image of 22.17
22.17 Transverse MRI scans of an 8-year-old Dachshund with intervertebral disc herniation at L1–2. (a) T2W image showing right-sided herniated heterogeneous material causing moderate spinal cord compression. (b) T1W image before intravenous contrast administration. The herniated material appears isointense to the spinal cord. (c) T1W image after contrast administration. The herniated material is clearly defined and hyperintense following marked homogeneous contrast enhancement.
Image of 22.18
22.18 Median plane sagittal T2W MR images of the intervertebral discs of five dogs. (a–e) The five stages of the Pfirmann classification of intervertebral disc degeneration, Pfirmann grades 1–5, are shown from left to right.
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22.20 MRI scan of a 5-year-old Cocker Spaniel with a L6–7 intervertebral disc extrusion with associated epidural haemorrhage. (a) Sagittal T2W image showing variable degrees of dehydration and degeneration of all the hypointense intervertebral discs. There is disc herniation at L6–7 mixed with haemorrhage, which is seen as a heterogeneous hypo- to hyperintense material. (b) Dorsal T2W image showing right-sided herniated material mixed with haemorrhage extending from cranial L5 to caudal L7.
Image of 22.21
22.21 Postoperative MRI scan of a 7-year-old English Cocker Spaniel 48 hours after L1–2 right-sided hemilaminectomy. (a) Sagittal T2W image showing dorsal compression of the spinal cord due to heterogeneous, mainly hyperintense, material confirmed as a haematoma during revision surgery. All the intervertebral discs are dehydrated and degenerate. (b) Transverse T2W image showing the right-sided hemilaminectomy defects and the heterogeneous haematoma causing dorsolateral right-sided spinal cord (*) compression.
Image of 22.22
22.22 MRI scan of a 5-year-old Dachshund with a lateralized C7–T1 disc herniation. (a) Sagittal T2W image showing multiple dehydrated and degenerate intervertebral discs, more pronounced at C7–T1. There is no evidence of spinal cord compression. (b) Transverse T2W image showing the herniated hypointense disc material (arrowed), lateral to the intervertebral disc, outside the vertebral canal and obscuring the intervertebral foramen. (c) Transverse T1W image allowing easier identification of the hypointense herniated disc material (arrowed).
Image of 22.23
22.23 MRI scan of a 4-year-old English Cocker Spaniel with an intervertebral disc herniation (Hansen type 1) at C2–3. (a) Sagittal T2W image showing partially dehydrated intervertebral discs at C3–4–5 and a deformed, degenerate and dehydrated herniated disc at C2–3 causing moderate ventral spinal cord compression. (b) Transverse T2W image at C2–3 showing the severe left-sided spinal cord (*) compression.
Image of 22.24
22.24 MRI scan of an 8-year-old German Shepherd Dog with an intervertebral disc herniation at T2–3. (a) Sagittal T2W image at T2–3 showing multiple degenerate intervertebral discs and herniation at T2–3 with dorsal displacement of the spinal cord. (b) Transverse T2W image at T2–3 showing severe right-sided ventrolateral spinal cord (*) compression due to the hypointense herniated disc material. The articular process joints are mildly hypertrophic.
Image of 22.25
22.25 MRI scan of an 8-year-old Domestic Shorthair cat with a L5–6 intervertebral disc herniation. (a) Sagittal T2W image showing degenerate and dehydrated intervertebral discs, with hypointense herniated material at L5–6 causing moderate spinal cord compression and intramedullary hyperintensity. There is also ventral spondylosis at L4–5–6. (b) Transverse T2W image at L5–6 showing the left-sided herniated disc material and the intramedullary hyperintensity (*) in the spinal cord.
Image of 22.26
22.26 MRI scan of a 4-year-old Dachshund with a L1–2 intervertebral disc herniation. (a) Sagittal T2W image showing dehydration and degeneration of multiple intervertebral discs and herniated hypointense disc material in the vertebral canal at L1–2. There are marked, diffuse T2 hyperintense, intramedullary changes extending the length of the spinal cord, compatible with myelomalacia. (b) Dorsal T2W image showing the marked and diffuse T2 intramedullary hyperintensity compatible with myelomalacia.
Image of 22.29
22.29 Lateral cervical radiograph of a 7-year-old Dobermann. There is collapse of the intervertebral disc spaces at C5–6 (mild) and C6–7. There is dorsal tipping of the cranial endplate of C6, and C7 appears markedly misshapen. The vertebral canals of C6 and C7 are funnel shaped and the ventral aspect of C7 appears irregular.
Image of 22.30
22.30 MRI scan of the 7-year-old Dobermann shown in Figure 22.29 . (a) Sagittal T2W image showing intervertebral disc dehydration and degeneration at C5–6 and C6–7, with intervertebral disc space collapse and herniation of both discs with moderate spinal cord compression. There are intramedullary hyperintensities at both levels and ventral spondylosis at C6–7. (b–c) Transverse T2W images at the C5–6 and C6–7 intervertebral disc spaces showing herniation of the intervertebral disc with moderate spinal cord compression and intramedullary hyperintensity.
Image of 22.31
22.31 MRI scan of a 5-year-old Dalmatian with DAWS at C5–6. (a) Sagittal T2W image showing intervertebral disc degeneration, dehydration and herniation at C5–6. There is ventral compression and dorsal compression due to hypertrophy of the interarcuate ligament. The spinal cord appears mildly hyperintense at the level of the compression. (b) Transverse T2W image and (c) T1W image at C5–6 showing the ventral and dorsal spinal cord compression but also a right-sided synovial cyst dorsolateral to the spinal cord (arrowed) that is T2 hyperintense and T1 hypointense.
Image of 22.32
22.32 MRI scan of the 7-year-old Dobermann shown in Figure 22.30 after application of traction to the neck. (a) Sagittal T2W image showing resolution of the spinal cord compression at both sites. Transverse T2W images at (b) C5–6 and (c) C6–7 showing the resolution of the spinal cord compression after traction.
Image of 22.34
22.34 Lateral cervical radiograph of an 8-year-old Great Dane with calcification of the intervertebral discs at C3–4–5 and osteoarthrosis of the articular process joints at C4–5 and C5–6.
Image of 22.35
22.35 MRI scan of the same Great Dane as in Figure 22.34 with vertebral canal stenosis due to soft tissue and bony proliferative change at C4–5–6. (a) Sagittal T2W image showing dorsal spinal cord compression at C4–5–6 due to hypertrophy of the articular facets. There is intervertebral disc degeneration at C3–4–5. (b–c) Transverse T2W images at C4–5 and C5–6 showing dorsal (b) and dorsolateral (c) spinal cord compression due to hypertrophy of the articular facets. The articular process joints are remodelled at both levels, with loss of the T2 hyperintense signal from the synovial joints.
Image of 22.36
22.36 MRI scan of a 1-year-old Mastiff with vertebral canal stenosis due to bony compression at C4–5. (a) Sagittal T2W image showing severe dorsal compression of the spinal cord due to dorsal arch malformation and hypertrophy. Note the marked focal T2 intramedullary hyperintensity at the level of the compression. (b) Transverse T2W image showing severe dorsal spinal cord (*) compression.
Image of 22.38
22.38 Immediate postoperative radiographs of an 8-year-old Dobermann with dynamic DAWS at C5–6–7. (a) Lateral cervical radiograph showing implant positioning and distraction of both intervertebral spaces by bone autografts. (b) VD cervical radiograph showing the angulation of the screws away from the vertebral canal. The outline of the partial ventral slots performed can be seen at both levels.
Image of 22.39
22.39 Follow-up transverse CT images in a bone window following cervical myelography of the 8-year-old Dobermann with dynamic DAWS shown in Figure 22.38 , 2 months after distraction/fusion surgery at C5–6 and C6–7. The dog had been presented for recurrent cervical pain. (a) At the level of mid C6 the screw is well positioned, avoiding the vertebral canal and intervertebral foramen. (b) At the caudal end of C6 a screw is causing moderate canal encroachment without spinal cord compression. (c) At the caudal end of C5 a screw is causing severe encroachment with spinal cord compression.
Image of 22.40
22.40 Lateral caudal cervical radiograph of a 6-year-old Labrador Retriever taken 6 weeks after surgery in which a collapsed disc space with associated herniation was distracted using a screw and washer. The screw has failed and there is fissuring of the bone cement used to stabilize the cervical spine.
Image of 22.41
22.41 Lateral radiograph of the caudal cervical spine after a myelogram in an 8-year-old Dobermann previously treated by distraction–fusion at C5–6 using a screw and washer. The disc at C6–7 has subsequently failed, causing a further compression. This is the so-called ‘domino effect’.
Image of 22.42
22.42 Postoperative MRI scan of a 1-year-old Mastiff following dorsal laminectomy from caudal C4 to mid C6 for treatment of vertebral canal stenosis due to articular process joint and pedicle malformation and soft tissue hypertrophy. (a) Sagittal T2W image showing dorsal compression of the spinal cord by heterogeneous tissue that appears mainly hyperintense. (b) Transverse T2W image showing dorsal spinal cord (*) compression by tissue that was found to be an infected seroma at the time of revision surgery.

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