The assessment of the usefulness of hemilaminectomy without fenestration in the treatment of thoracolumbar disc disease in chondrodystrophic dogs

The aim of the publication is to assess the effectiveness of the treatment of type I disc extrusion according to Hansen by using the method of hemilaminectomy without fenestration. The evaluated clinical material comprised 36 chondrodystrophic dogs in which 38 surgical procedures were performed. All dogs were administered corticosteroid during the operation. Dachshunds made up to 79% of patients. In 34 cases grainy mass was extracted from the vertebral canal. In two cases it was plaster-like mass and in other two--granulo-chondral. Most often (12 cases) the prolapse of the nucleus pulposus was observed between the first and second lumbar vertebra. There was one case of the postoperative pyogenic infection of the wound. Recovery was observed in all dogs with 3rd grade clinical signs, 17 out of 18 dogs with 4th grade and 8 out of 13 dogs with 5th grade of dysfunction severity. The recovery time of the dog depended in the statistically significant way on the severity of symptoms and the grade of the present disease (p<0.00005). There did not appear to be any statistically significat relationship between the recovery time and the duration of symptoms pre operatively (p=0.42), the time of non-ambulatory status (p=0.27) and the breed of the dog (p=0.81).     

Recurrence of thoracolumbar intervertebral disk extrusion in chondrodystrophic dogs after surgical decompression with or without prophylactic fenestration: 265 cases (1995-1999)

OBJECTIVES: To evaluate a population of chondrodystrophic dogs treated for Hansen type 1 intervertebral disk (IVD) disease by surgical decompression with or without prophylactic fenestration and determine the rate and location of surgically confirmed recurrence of intervertebral disk extrusion. ANIMALS: 265 dogs. STUDY DESIGN: Retrospective study. PROCEDURES: Medical records of dogs that underwent spinal decompression between 1995 and 1999 were reviewed. RESULTS: 3 (4.9%) dogs were euthanatized or died prior to discharge. Fenestration was performed in 252 dogs, including 37 (14.7%) at the site of decompression only, 48 (19%) at 3 to 4 disk spaces, and 167 (66%) at 5 to 7 disk spaces. There were 12 instances of recurrent disk extrusion confirmed by removal of disk at a second surgery 3.5 to 33 months after the first surgery. Recurrence was always at a new disk space, and rates did not significantly differ between dogs that underwent single or multiple fenestrations. Two recurrences were at a previously fenestrated disk space. Seven recurrences were at a site immediately adjacent to a fenestrated disk space, and 5 recurrences were at L4-5. CONCLUSIONS AND CLINICAL RELEVANCE: Prophylactic fenestration is generally successful in preventing future disk extrusions at fenestrated disk spaces. Prospective evaluation is still required to determine whether fenestration decreases the overall rate of recurrence. Prophylactic fenestration could promote disk extrusion at adjacent, nonfenestrated disk spaces. This could have a substantial clinical impact if recurrence develops at L4-5.     

Influence of intervertebral disc fenestration at the herniation site in association with hemilaminectomy on recurrence in chondrodystrophic dogs with thoracolumbar disc disease: a prospective MRI study

Objective— To describe the influence of fenestration at the disc herniation site on recurrence in thoracolumbar disc disease of chondrodystrophoid dogs.
Study Design— Prospective clinical study.
Animals— Chondrodystrophic dogs (n=19).
Methods— Dogs were divided into 2 groups: group 1 (9 dogs) had thoracolumbar disc extrusion (Hansen type I) treated by hemilaminectomy and concomitant fenestration of the affected intervertebral disc and group 2 (10 dogs) had hemilaminectomy without fenestration. All dogs had 3 magnetic resonance imaging (MRI) examinations: preoperatively, immediately postoperatively to assess removal of herniated disc material, and again 6 weeks after surgery.
Results— There were 13 male and 6 female dogs; mean age, 7.1 years. Thoracolumbar disc herniation was confirmed with MRI. Immediate post surgical MRI revealed that the herniated disc removal was complete in all but 1 dog and that fenestration did not lead to complete removal of nucleus pulposus within the intervertebral disc space. On the 3rd MRI examination, none of the group 1 dogs had further disc material herniation at the fenestrated site. Six of the 10 group 2 dogs had a recurrence of herniation leading to clinical signs in 3 dogs (pain in 2 dogs, paresis in 1 dog).
Conclusion— In thoracolumbar disc herniation, fenestration of the affected intervertebral disc space prevents further extrusion of disc material.
Clinical Relevance— Fenestration reduces the risk of early recurrence of disc herniation and associated postoperative complications.     

Tetraparesis following cervical disk fenestration in two dogs

Two dogs were nonambulatory and tetraparetic following cervical disk fenestration used as the treatment for cervical disk disease. Severe pain and cervical muscle fasiculation also were evident. The site of disk extrusion was localized radiographically, and cervical ventral decompression was used to remove the disk material. Recovery in both cases was complete.     

Rupture of the dura mater in two dogs caused by the peracute extrusion of a cervical disc

A rupture of the dura mater caused by the peracute extrusion of a cervical disc was diagnosed by myelography in two dogs. In both cases traction on the cervical spine resulted in contrast medium entering the ruptured intervertebral disc from the subarachnoid space. Both dogs became suddenly tetraparetic and unable to ambulate during vigorous exercise, but regained the ability to walk without surgical treatment.     

Discal cysts of the cervical spine in two dogs

Discal cysts, which lie directly over intervertebral discs, are rare. Two old dogs with tetraparesis were referred to our facility. In both animals, magnetic resonance imaging revealed intraspinal extradural cystic mass lesions that were dorsal to degenerative intervertebral discs at the C3-C4 level. These lesions had low signal intensity on T1-weighted images, and high signal intensity on T2-weighted images. A ventral slot approach was used to perform surgical decompression, after which the symptoms improved remarkably. Discal cysts should be included in the differential diagnosis of dogs with cervical pain and tetraparesis. One effective treatment for discal cysts is surgical intervention.     

Magnetic resonance imaging of traumatic intervertebral disc extrusion in dogs

This retrospective study evaluated the magnetic resonance (mr) images of traumatic disc extrusions in 11 dogs. The findings included a reduction in the volume and signal intensity of the nucleus pulposus, focal hyperintensity within the overlying spinal cord on T (2)-weighted mr images, and subtle spinal cord compression, extraneous material or signal change within the vertebral canal. The largest area of hyperintensity in the spinal cord was directly over or close to the affected disc space, appeared asymmetrical and in the majority of cases was less than one vertebra in length. Parenchymal spinal cord haemorrhage was identified in four of the dogs. Vacuum phenomena, evident as a signal void in the centre of the disc, were identified in two of the dogs. The mr images were distinct from those reported for other causes of spinal cord dysfunction.     

A comparison of hemilaminectomy (with concomitant disc fenestration) and dorsal laminectomy for the treatment of thoracolumbar disc protrusion in dogs.

The techniques of hemilaminectomy (with concomitant disc fenestration) and dorsal laminectomy were compared statistically in two groups of 30 dogs with thoracolumbar disc disease. On presentation all the dogs were unable to walk and were graded 1 to 3 according to their degree of neurological dysfunction. Nineteen had a previous history of thoracolumbar pain or hindlimb paresis. Radiography showed a narrowed disc space or extruded calcified disc material in 52 of the dogs and lumbar myelography revealed an extradural mass in 57; 24 of the dogs had clinical or myelographic lateralisation of signs. Hemilaminectomy significantly improved the ability to retrieve protruded disc material compared with dorsal laminectomy, and the removal of protruded disc material significantly improved the degree of recovery. Fenestration significantly reduced the recurrence of thoracolumbar disc disease.     

Presence of residual material following mini-hemilaminectomy in dogs with thoracolumbar intervertebral disc extrusion

Presence of residual material following mini-hemilaminectomy in dogs (n = 9) with spontaneous thoracolumbar intervertebral disc extrusion was prospectively investigated. Volume of extruded disc material within the vertebral canal and the proportion of residual material were determined using pre- and post-operative magnetic resonance imaging. The degree of spinal cord compression, proportion of extradural material considered hemorrhage, and invasion of the articular facets were also determined. Residual material was identified in 44% of the mini-hemilaminectomies. The median percentage of residual material calculated was 7.7% of the preoperative volume. No observed effect of surgical side or site, proportion of extradural material considered hemorrhage, patient weight, and duration of clinical signs was detected.     

Decompressive laminectomy in thoraco-lumbar disc protrusion with paraplegia in the dog

Early decompressive laminectomy according to the method previously described (Funkquist, 1962b) has been performed during the period 1963-66 on a large number of cases of thoraco-lumbar disc protrusion with paraplegia at the Department of Surgery of the Royal Veterinary College, Stockholm, Sweden. In the author's own cases, twenty-six of the twenty-seven dogs operated on (96%) regained their ability to walk. Corresponding figures for the total number of cases operated on (including those of the author) by specially trained surgeons are seventy-three of eighty-two or 89%. In control cases treated conservatively twenty-one of forty-one dogs (51%) regained walking ability. In the cases operated on as emergencies by operators with mainly a general surgical training, operation results are conspicuously worse (thirty-one of forty-nine dogs or 63% regained walking ability). Relapse incidence was at least as high after laminectomy as conservative treatment, the former, as a rule, should be followed by a prophylactic disc evacuation in a subsequent operation. Zusammenfassung. Frühzeitige dekompressive Laminektomie nach der früher beschriebenen Methode (Funkquist, 1962) wurde wahrend der Periode 1963–1966 an einer grossen Zahl Fälle von thoracolumbarem Bandscheibenvorfall mit Paraplegie in der Chirurgischen Abteilung der Königlichen Tierärztlichen Akademie in Stockholm, Schweden, durchgeführt. In den Fällen des Autors erlangten 26 der 27 operierten Hunde (96%) ihre Gehfähigkeit wieder. Die entsprechenden Zahlen (einschliesslich der des Autors) für die Gesamtzahl der von Chirurgen mit Spezialausbildung durchgeführten Operationen sind 73 von 82 oder 89%. In den konservativ behandelten Kontrollfällen erhielten 21 von 41 Hunden (51%) ihre Gehfähigkeit zurück. Bei solchen Fällen, die als Notoperationen von Chirurgen hauptsächlich mit allgemeiner chirurgischer Ausbildung behandelt wurden, waren die Operationsergebnisse auffallig schlechter (31 von 49 Hunden oder 63% erhielten die Gehfähigkeit zurück). Da die Rückfallhäufigkeit nach Laminektomie mindestens so hoch ist wie nach konservativer Behandlung, sollte sich an die erstere in der Regel eine prophylaktische Bandscheibenevakuation in einrr späteren Operation anschliessen. Résumé. Une laminectomie précoce de décompression d'après la technique décrite antérieurement (Funkquist, 1962b), a été effectuée au cows de la période de 1963 à 1966 dans un grand nombre de cas de protrusion des disques thoraco-lombaires avec paraplégie au Département de Chirurgie, Veterinary College de Stockholm (Suède). Parmi les cas personnels de l'auteur 26 chiens sur 27 (soit 96%) ont pu remarcher. Le nombre correspondant pour la totalité des cas opérés (y compris ceux de l'auteur) par des chirurgiens entraînés était de 73 sur 82 chiens, soit 89% des cas. Pour les cas témoins la proportion des animaux traités conservativement et ayant pu remarcher, était de 21 sur 41 (51%). Dans les cas opérés en urgence par des opérateurs entraînés surtout en chirurgie générale, les résultats de l'opération étaient nettement moins favorables (31 chiens sur 49 seulement on pu remarcher, soit 63%). La fréquence des rechutes étant au moins aussi forte après laminectomie qu'après le traitement conservateur, on devrait procéder à une ablation du disque à titre prophylactique au cours d'une intervention ultérieure.     

Follow-up study of 100 cases with thoracolumbar disc protrusions treated by lateral fenestration

One hundred-and-seventeen dogs with thoracolumbar disc protrusions were treated by lateral fenestration over a five year period. The results obtained in 100 of these cases are presented. The overall success rate was 87 per cent but only 33 per cent of those with paraplegia and loss of conscious pain sensation regained the use of their hindlimbs.     

Original surgical treatment of thoracolumbar subarachnoid cysts in six chondrodystrophic dogs

Background

Subarachnoid cysts are rare conditions in veterinary medicine, associated with spinal cord dysfunction. Most of the 100 cases of subarachnoid cysts described since the first report in 1968 were apparently not true cysts. Reported cysts are usually situated in the cervical area and occur in predisposed breeds such as the Rottweiler. The purpose of this retrospective study, from May 2003 to April 2012, was to describe the distinctive features of thoracolumbar spinal subarachnoid cysts, together with their surgical treatment and outcome in 6 chondrodystrophic dogs.

Results

Five Pugs and 1 French Bulldog were examined. Images suggestive of a subarachnoid cyst were obtained by myelography (2/6) and computed tomography myelography (4/6), and associated disc herniation was observed in 3/6 dogs. A hemilaminectomy was performed. The protruding disc eventually found in 5/6 dogs was treated by lateral corpectomy. The ventral leptomeningeal adhesions observed in all dogs after durotomy were dissected. No or only mild post-operative neurological degradation was observed. Follow-up studies (7 months to 4 years) indicated good outcome and no recurrence.

Conclusions

All the thoracolumbar subarachnoid cysts described in these 6 chondrodystrophic dogs were associated with leptomeningeal adhesions. Good results seemed to be obtained by dissecting and removing these adhesions. A protruding disc, found here in 5/6 dogs, needs to be ruled out and can be treated by lateral corpectomy.     

The lateral fenestration of canine thoracolumbar disc protrusions: a review of 30 cases

Thirty dogs with disc protrusions in the thoracolumbar region were treated by lateral fenestration of the last three thoracic and first three lumbar discs. The case details and results of treatment are presented.     

Re‐opening the window on fenestration as a treatment for acute thoracolumbar intervertebral disc herniation in dogs

Acute thoracolumbar intervertebral disc herniation in dogs is a common cause of “back” pain, pelvic limb paresis or paralysis and incontinence. Treatment of this condition has long been a source of controversy, especially since the introduction of surgical interventions in the 1950s. Unfortunately, formal clinical trials to compare efficacy of conservative and surgical interventions have never been carried out and the current lack of clinical equipoise on this subject now precludes such a trial on ethical grounds. In this article we re‐examine and discuss earlier published data on recovery associated with the various therapies, focusing on evidence suggesting that decompressive surgery and fenestration may be equally efficacious.