RU2840361C1 - Method for performing unilateral dorsal laminectomy with preserving spinous, articular processes and supraspinous ligament in dogs - Google Patents

Abstract

FIELD: medicine; veterinary science.

SUBSTANCE: invention refers to medicine, namely veterinary science, particularly veterinary neurology and neurosurgery, and can be used for treating dogs with compression and non-compression spinal cord injuries of various aetiologies. A cutter is used to cut a vertebra between bases of spinous and articular processes to an internal cortical layer. An internal cortical layer is opened and the bone incision is extended cranially or caudally depending on the localization of the compressing factor or the pathological focus. If the compression factor or the pathological focus is localized cranially to the intervertebral disc, a plate of the cranial vertebra is opened between the base of the spinous processes and the base of the articular processes. If localized above the intervertebral disc, the dissection is performed on half the length of the plate of the cranial vertebra and half the length of the plate of the caudal vertebra between the bases of the spinous and articular processes. When localizing a compression factor or a pathological focus caudal to the intervertebral disc, a plate of the caudal vertebra is opened between the base of the spinous processes and the base of the articular processes.

EFFECT: method provides reducing injuries of soft tissue and bone structures, obtaining access to dorsal and dorsolateral parts of the spinal canal in dogs, reduced time for recovery of support ability on pelvic extremities, minimization of biomechanical instability of thoracolumbar spine by performing unilateral dorsal laminectomy with preservation of articular, spinous processes of adjacent vertebrae and supraspinous ligament.

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Description

The invention relates to the field of veterinary medicine, in particular veterinary neurology and neurosurgery, and can be used to treat dogs with compression and non-compression spinal cord injuries of various etiologies.

Pathologies of the vertebral column and spinal cord are the most common cause of neurological deficit in dogs [5]. According to the literature, in dogs, the structure of pathologies of the vertebral column and spinal cord is dominated by compression degenerative-dystrophic, neoplastic and traumatic pathologies (e.g. discopathy, neoplasia and fractures of the vertebral column), leading to compression of the spinal cord and requiring surgical intervention using various decompression techniques, as well as some non-compression diseases (e.g. constrictive myelopathy) [4, 5, 6, 7]. Despite the availability of many different methods of spinal cord decompression (in the thoracolumbar region - dorsal laminectomy, hemilaminectomy, mini-hemilaminectomy and some others), the risk of developing the same or another vertebrogenic pathology remains high both in the area of application of the decompression technique and in topographically adjacent vertebral-motor segments of the spinal column. This can be explained by the destabilizing effect exerted by one or another decompression method on the biomechanics of the spinal column, as well as the impossibility of eliminating the compressive factor or pathological focus due to the complete or partial lack of access to the part of the spinal canal where it is localized. Thus, dorsal laminectomy allows access to the dorsal and dorsolateral parts of the spinal canal, but is considered the most destabilizing decompression technique and often requires stabilization of one or more adjacent vertebral-motor segments by installing a metal structure. Meanwhile, hemilaminectomy allows visualization mainly of the lateral and dorsolateral parts of the spinal canal, and mini-hemilaminectomy - ventral and ventrolateral with loss of access to its dorsal part [6]. In this regard, the development of a method of spinal cord decompression, which simultaneously has a minimal destabilizing effect on the spinal column and allows for full access to the dorsal and dorsolateral parts of the spinal canal, becomes relevant.

A method for treating intervertebral disc herniations in dogs is known (RU Patent No. 2535005, published on 10.12.2014), which includes intravenous administration of a 3-5.5% aqueous solution of lithium chloride at a rate of 2.5-3.5 mmol/kg of the animal's body weight and additionally subcutaneous administration of a 10-30% aqueous solution of polyethylene glycol - 4000 at a rate of 2-4 ml/kg of the animal's body weight every other day for 5-7 days. However, this method for treating intervertebral disc herniations in dogs refers to conservative (drug) therapy [1].

There is also a Method for Treating Spinal Column Injuries in the Thoracic and Lumbar Regions in Dogs and Cats (RU Patent No. 149172, published on 20.12.2014), which involves closed osteosynthesis of the damaged section of the spine with fixation using pins and an external fixation apparatus. The said method is intended exclusively for treating traumatic injuries to the spinal column and does not involve decompression of the spinal cord [2].

The closest analogue of the claimed invention is the Method for treating a herniated thoracolumbar disc in dogs (RU Patent No. 2610069, published on 02/07/2017), which consists of performing a hemilaminectomy followed by removal of a fragment of the nucleus pulposus of the affected intervertebral disc. The main disadvantage of the method is that it provides access primarily to the lateral and dorsolateral parts of the spinal canal without full visualization of its dorsal part [3].

Dorsal laminectomy was first described in foreign literature by Greene in 1952. There are many modifications of dorsal laminectomy, the essence of which is bilateral removal to varying degrees of spinous processes, plates, cranial and caudal articular processes or pedicles of the vertebrae at the level of the affected spinal motion segment. According to studies, all modifications of dorsal laminectomy can lead to an increase in the biomechanical load on the intervertebral discs and instability of the spinal column in the area of application of the decompression technique, as well as in topographically adjacent spinal motion segments. Without stabilization of the spinal column, this can subsequently lead to progression of neurological deficit, relapse of existing or occurrence of new pathology in the area of decompression or in topographically adjacent spaces [6].

The technical result of the claimed invention is a reduction in trauma to soft tissue and bone structures, access to the dorsal and dorsolateral parts of the spinal canal in dogs, a reduction in the time of restoration of support ability on the pelvic limbs, and a minimization of biomechanical instability of the thoracolumbar spine by performing a unilateral dorsal laminectomy with preservation of the articular, spinous processes of adjacent vertebrae and the supraspinous ligament.

Decompression of the spinal cord according to the declared method of surgical correction of compression and non-compression pathologies is performed under general anesthesia as follows:

1. Based on anamnestic data, neurological examination, radiography and magnetic resonance imaging, the localization and lateralization of the compressive factor or pathological focus is determined for surgical intervention;

2. Fix the animal on the operating table in the prone position. Make a straight linear incision of the skin along the midline dorsally along one spinous process cranial and caudal to the required vertebral-motor segment. Dissect the subcutaneous fat using a blunt method, dissect the thoracoabdominal fascia;

3. The spinous processes and arches of the vertebrae are skeletonized to the articular processes from the paravertebral muscles (longissimus and multifidus muscles), taking into account the lateralization of the compressive factor or pathological focus;

4. Place retractors at opposite ends of the wound to retract soft tissues. Retract the supraspinous ligament with a transversely positioned retractor and remove the yellow ligament from the interanterior space;

5. Using a neurosurgical cutter, mill the vertebral plate between the bases of the spinous and articular processes to the inner cortical layer;

6. Open the inner cortical layer with a surgical hook, extend the bone defect with Kerrison neurosurgical rongeurs more cranially or caudally depending on the localization of the compressive factor or pathological focus. Visualize the dorsal and dorsolateral parts of the spinal canal, perform its revision and eliminate the compressive factor or pathological focus.

To form a cut, adhere to the following boundaries: when the compressing factor or pathological focus is localized cranial to the intervertebral disc, the cut is made mainly in the plate of the cranial vertebra between the base of the spinous and the base of the articular processes; when localized above the intervertebral disc - in half of the plate of the cranial and half of the plate of the caudal vertebrae between the bases of the spinous and articular processes; when localized caudal to the intervertebral disc - mainly in the plate of the caudal vertebra between the base of the spinous and the base of the articular processes.

The use of the described method of surgical correction of compression and non-compression pathologies of the spinal cord in dogs allows to reduce trauma to soft tissue and bone structures, the time of restoration of support ability on the pelvic limbs, biomechanical instability in the thoracolumbar spine and the likelihood of developing complications associated with it in the immediate and late postoperative period without stabilization of the spinal motor segments with a metal structure, provided that they are not unstable before surgery.

The described method was tested on 30 clinically ill dogs with compression and non-compression lesions of the spinal cord in the thoracolumbar spine at the Department of Veterinary Surgery of the Federal State Budgetary Educational Institution of Higher Education "Moscow State Academy of Veterinary Medicine and Biotechnology - Moscow Veterinary Academy named after K.I. Skryabin". It was found that the effectiveness of unilateral dorsal laminectomy with preservation of articular, spinous processes and supraspinous ligament in compression lesions of the spinal cord is 90%. At the same time, no relapses of the same or occurrence of new pathology in the area of application of the decompression method and topographically adjacent vertebral-motor segments were registered.

Clinical examples of the use of the technique

Clinical example #1

Species: dog, breed: pug, age: 6 years, weight: 7 kg. Neurological deficit: grade 3 on the Griffith's scale (ambulatory paraparesis). Final diagnosis: subarachnoid diverticulum at the level of Th8-Th10, located dorsolaterally (mainly to the left) from the spinal cord, and constrictive myelopathy. The animal was placed in a thoracic position, soft tissues were dissected layer by layer at the level of Th9-Th10, the spinous processes and laminae of adjacent vertebrae were skeletonized to the base of the articular processes on the left side. The supraspinous ligament was retracted, the vertebral laminae were milled from the base of the spinous processes to the base of the articular processes, the cut was expanded cranially by half the length of the laminae of the cranial vertebra. Marsupialization of the dura mater and opening of the subarachnoid diverticulum were performed. After the cerebrospinal fluid had drained, the soft tissues were sutured layer by layer. On the 7th day after surgery, the animal showed a grade 2 neurological deficit according to the Griffith's scale (proprioceptive ataxia), and on the 14th day, there was no neurological deficit.

Clinical example #2

Species: dog, breed: crossbreed, age: 6 years, weight: 20 kg. Neurological deficit: grade 4 on the Griffith's scale (paraplegia with preserved deep pain sensitivity). Final diagnosis: intervertebral disc extrusion at the L3-L4 level, located dorsally (with slight lateralization to the right side) from the spinal cord. The animal was placed in a thoracic position, soft tissues were dissected layer by layer at the L3-L4 level, the spinous processes and laminae of adjacent vertebrae were skeletonized to the base of the articular processes on the right side. The supraspinous ligament was retracted, the vertebral laminae were milled from the base of the spinous processes to the base of the articular processes, the cut was widened caudally by half the length of the laminae of the caudal vertebra. The extruded material was evacuated, and the soft tissues were sutured layer by layer after revision of the spinal canal. On the 7th day after surgery, the animal showed a grade 1 neurological deficit according to the Griffith's scale (mild propriodeficit); on the 14th day, there was no neurological deficit.

Clinical example #3

Species: dog, breed: husky, age: 4 years, weight: 28 kg. Neurological deficit: grade 5 on the Griffith's scale (paraplegia with absence of deep pain sensitivity). Final diagnosis: fracture of the L1 vertebral arch on the left with fragments wedging into the spinal canal and spinal cord edema at this level. The animal was placed in a thoracic position, soft tissues were dissected layer by layer at the L1-L2 level, the spinous processes and laminae of adjacent vertebrae were skeletonized to the base of the articular processes on the right side. The supraspinous ligament was retracted, the vertebral laminae were milled from the base of the spinous processes to the base of the articular processes, the cut was widened cranially by half the length of the laminae of the cranial vertebra and caudally by half the length of the laminae of the caudal vertebra. The spinal canal was revised and the wedged bone fragments were removed. The soft tissues were sutured layer by layer. On the 7th day after the surgery, the animal showed a grade 2 neurological deficit according to the Griffith's scale (proprioceptive ataxia); on the 14th day, there was no neurological deficit.

List of sources:

1. Patent. RU 2535005 U1, IPC A61K 31/25. Method for treating intervertebral disc herniations in dogs / Kozlov N.A.; applicant and patent holder Kozlov N.A.; declared 2013.06.11; published 2014.12.10; effective date: 2014.12.10 - 1 p.

2. Patent. RU 149172 U1, IPC A61B 17/56. Method for treating injuries of the spinal column in the thoracic and lumbar region in dogs and cats / Kiselev I.G.; applicant and patent holder Kiselev I.G.; declared 2014.07.21; published 2014.12.20; start of validity: 2014.12.20 - 1 p.

3. Patent. RU 2610069 C2, IPC A61D 1/00. Method for treating herniated thoracolumbar intervertebral disc in dogs / Ulanova N.V., Chernov A.V.; applicant and patent holder Ulanova N.V., Chernov A.V.; declared 2015.05.26; published 2017.02.07; effective date: 2017.02.07.

4. Battaray B. Hemilaminectomy with resection of the fibrous ring (anulectomy) versus partial discectomy for chronic protrusions of intervertebral discs in the thoracolumbar region in dogs // Scientific notes of the Kazan State Academy of Veterinary Medicine named after N.E. Bauman. 2019. N1. P. 35-40.

5. Pozyabin S.V., Kozlov N.A., Kachalin M.D. et al. Neurological etiology in the structure of lameness on the pelvic limbs in dogs // Veterinary science, animal science and biotechnology. 2020. N12. P. 6-11.

6. Huska J. Comparison of Hemilaminectomy and Mini-Hemilaminectomy in Dogs with Thoracolumbar Intervertebral Disc Extrusion using Computed Tomography and Magnetic Resonance Imaging: An Anatomical and Radiological Study. Thesis for the degree of Doctor of Veterinary Science in Clinical Studies and Veterinary Medicine. Guelph: University of Guelph, 2012. 168 p.

7. Jeffery N.D., Harcourt-Brown T.R., Barker A.K. et al. Choices and Decisions in Decompressive Surgery for Thoracolumbar Intervertebral Disk Herniation // Vet. Clin. North Am. Small. Anim. Pract. 2018. Vol. 48(1). P. 169-186.

Claims (1)

A method for performing unilateral dorsal laminectomy with preservation of the spinous, articular processes and supraspinous ligament in dogs, characterized in that a cut is made in the vertebra between the bases of the spinous and articular processes to the inner cortical layer with a burr, the inner cortical layer is opened and the bone incision is extended more cranially or caudally depending on the localization of the compressive factor or pathological focus; if the compressive factor or pathological focus is localized more cranially than the intervertebral disc, the lamina of the cranial vertebra is opened between the base of the spinous and the base of the articular processes; if localization is above the intervertebral disc, the opening is performed to half the length of the lamina of the cranial vertebra and half the length of the lamina of the caudal vertebra between the bases of the spinous and articular processes; when the compressive factor or pathological focus is localized caudally to the intervertebral disc, the plate of the caudal vertebra between the base of the spinous process and the base of the articular process is opened.