Microendoscopic Dorsal Laminectomy for Multi-Level Cervical Intervertebral Disc Protrusions in Dogs

The objective of this study was to evaluate the feasibility and clinical outcomes of microendoscopic dorsal laminectomy for multi-level cervical intervertebral disc protrusions in dogs. Eight client-owned dogs diagnosed with multi-level cervical intervertebral disc protrusions using computed tomography (CT) and magnetic resonance imaging (MRI) were included in this retrospective case series. Microendoscopic dorsal laminectomies (MEL) were performed with an integrated endoscopic system to the cranial and caudal vertebrae of the affected intervertebral joints. Pre- and post-operative neurological status, operation time, intra-operative complications, and postoperative complications were reviewed. Post-operative CT images were obtained to measure the dimensions of laminectomy and compared to those of planned laminectomy. Full endoscopic procedures were feasible in 7 dogs (87.5%) and the laminectomy dimensions were in agreement with pre-operative planning. In all dogs, major intra- and postoperative complications did not occur. Conversion to open surgery was required in one case. Short-term postoperative clinical deterioration was found in two dogs. Long-term clinical outcomes were good and comparable to those reported in previous studies of open dorsal laminectomies. MEL is a promising minimally invasive approach to multi-level cervical dorsal laminectomy for intervertebral disc protrusions. This technique may improve postoperative discomfort compared to the open approach. Further studies are needed to directly compare outcomes between these two approaches.

Ex vivo biomechanical testing of Funkquist B dorsal laminectomy between the sixth and seventh cervical vertebrae in dogs

ABSTRACT: Dorsal laminectomy is routinely performed for spinal cord compressions or stenosis of the cervical vertebral canal. However, despite good results, relevant complications have been described in dogs. Considering the incomplete understanding of the necessity for complementary surgical stabilization after performing laminectomies in the cervical region, this study compared the resistance and range of motion (ROM) of the cervical spinal column subjected to Funkquist B laminectomy between the sixth and seventh vertebrae in dogs. Forty-four cervical vertebral columns (C2-T1) of dogs, with an average weight of 26.2±3.8 kg, were selected using radiography and computed tomography. Four experimental groups (n=11) were established according to the mechanical test: two control groups (flexion and extension control) and two laminectomy groups (flexion and extension laminectomies). Numerical results of the maximum load for measuring the resistance and ROM of the columns of the two control groups and the two laminectomy groups were compared. The laminectomy groups showed a lower maximum load, regardless of the mechanical test performed (P<0.001). The ROM was not influenced by laminectomy, the type of mechanical test (ventral flexion or extension), or its interaction (P<0.05). There was no interaction between the effect of the laminectomy factors (yes or no) and the effect of the mechanical tests for ventral flexion or extension (P<0.05). In conclusion, Funkquist B dorsal cervical laminectomy between C6 and C7 decreases mechanical resistance with a supraphysiological loading force but does not alter the ROM, suggesting that it can be used without additional mechanical stabilization in dogs.

Multiple Undifferentiated Pleomorphic Sarcoma (Malignant Fibrous Histiocytoma) with Extradural Involvement in a 7-Year-Old Labrador Retriever

A 7-year-old castrated male Labrador retriever was referred for evaluation of progressive hind limb paresis of 4 weeks’ duration. On computed tomography and magnetic resonance imaging examination, masses were found in several regions including the lung, right kidney, and peritoneum. Additionally, an extradural mass at the region of T13–L1 was identified, which is assumed to related to the chief complaint, progressive hind limb paresis. With the consent of the owner, a dorsal laminectomy was performed to remove the mass and surrounding tissues for the palliation of the hind limb paresis. Hematoxylin and eosin staining and immunohistochemical examination revealed the mass to be consistent with an undifferentiated (high-grade) pleomorphic sarcoma. The patient presented with recurrence of the hind limb paresis, respiratory discomfort, and urinary incontinence. The owner declined treatment and the dog was euthanized. Systemic metastasis was confirmed on postmortem microscopic examination. To the authors’ knowledge, this is the first report describing multiple undifferentiated high-grade pleomorphic sarcoma with extradural involvement developing into the vertebral canal through the intervertebral space, resulting in spinal damage, in a dog.

Case Report: Spinal Stabilization Surgery Using a Novel Custom-Made Titanium Fixation System for the Spinal Instability Caused by Vertebral Malformation in a Dog

A 2-year-old Maltese was presented with wobbly gait of the pelvic limbs. Based on imaging examinations, a diagnosis of congenital malformation at T5–T8 and severe kyphosis causing spinal cord compression at T6–T7 was made. Dorsal laminectomy and stabilization of T6 and T7 vertebrae were performed. As the size of the vertebrae was small and they were severely deformed, novel custom-made titanium implants were used for spinal stabilization. Clinical signs were resolved 2 weeks after surgery. Although radiographic examination 373 days after surgery showed slight loosening of implants, post-operative course remained uneventful. This report describes the use of novel custom-made titanium implants for spinal fixation surgery in a dog.

Distraction Stabilization of Degenerative Lumbosacral Stenosis: Technique and mid- to long-term outcome in 30 cases

Objective To describe the dorsal laminectomy, annulectomy and distraction stabilization with pins and polymethylmethacrylate technique, its complications and outcome in the management of canine degenerative lumbosacral stenosis. To determine pre- and post-surgical foraminal width and vertebral step changes. Study Design Multi-institutional retrospective clinical study Methods Medical records (2005–2020) of dogs treated (n = 30). Clinical signs, Modified Frankel Score, Texas Spinal Cord Injury Score, pain score (dorsal palpation of spine, tail dorsiflexion), imaging findings and complications were retrieved pre-operatively, peri-operatively and at long-term follow-up. Results The most common pre-surgical imaging findings were: disc protrusion (24/25) and sclerosis of the caudal end-plate of L7 (23/30). On short- to long-term assessment 18/21 exhibited clinical improvement and all exhibited improved pain scores (p < 0.0001). Catastrophic complications occurred in 3 dogs, and major complications occurred in 5, of which 3 required additional surgery. Mean lumbosacral step defect reduced 60% (1.8mm ± 2.5mm pre-surgery to 0.7mm ± 0.9mm post-surgery, p = 0.1585). Mean foraminal width significantly increased 50% long-term (3.3mm ± 1.0mm pre-surgery to 5.0mm ± 0.9mm post-surgery, p < 0.0001). Clinical Significance Dorsal laminectomy, annulectomy and distraction stabilization is a complex procedure which can significantly increase foraminal width, reduce pain and improve gait characteristics in dogs in the short- to long-term, and should be performed by surgeons experienced in lumbosacral pin placement.

Percutaneous endoscopic limited-lumbosacral-dorsal laminectomy in eight dogs – A cadaveric study

This study aimed to investigate the technical feasibility of a percutaneous endoscopic limited-dorsal laminectomy (PELDL) and to evaluate if the decompression and examination of the lumbosacral vertebral canals could be achieved using an endoscope in small dogs. A total of eight fresh canine cadavers were used for the study. Following the injection of a barium and agarose mixture (BA-gel), which simulates intervertebral disc herniation, a PELDL was performed over L7–S1 in these animals. Computed tomography (CT) scans were obtained pre- and postoperatively to evaluate the surgical outcomes. All the procedures were completed with a clear visualisation of the spinal cord and removal of the BA-gel. The mean surgery time for the PELDL was 30.00 ± 12.01 minutes. In two dogs, iatrogenic nerve root injuries were caused by the surgical instruments during the operation. The CT scans showed that the amount of BA-gel removed was sufficient for a spinal-cord decompression. A PELDL could be used for the BA-gel removal to decompress the spinal cord and provide a clear view of the spinal canal. Therefore, it could be used as an alternative surgical option to treat lumbosacral disc disease in dogs.

Extradural Synovial Cyst of the Cervical Spine in a Saint Bernard

Background: Extradural synovial cysts (ESC) originate from an extrusion of the synovium in unstable or degenerated joints. In the spine, this condition can cause neurological signs such as hyperesthesia, proprioceptive ataxia and paresis. Since extradural presentations of synovial cysts are unusual in dogs, the aim of this manuscript is to report a case of extradural synovial cyst of the cervical spine, as well as the clinical findings, diagnosis, surgical treatment and clinical evolution after therapy.Case: A 3-year-old spayed Saint Bernard weighing 60 kg was presented to a Veterinary Medical Teaching Hospital with a history of acute paraparesis that evolved to non-ambulatory tetraparesis five days after the appearance of the first clinical signs. Neurological examination revealed non-ambulatory tetraparesis, normal muscle tone and segmental spinal reflexes in the thoracic and pelvic limbs, as well as cervical pain associated with limited neck movement. According to the neurological examination, the likely lesion location was the C1-C5 spinal cord segment. The differential diagnosis list included intervertebral disc disease, caudal cervical spondylomyelopathy, neoplasm, infectious or noninfectious inflammatory disease, and cystic diseases. Complete blood (cell) count and serum biochemistry tests were within reference limits. The cerebrospinal fluid analysis revealed 35 mg/dL of protein (< 30 mg/dL) and 27 cells (up to 5 cells/mm3) with a predominance of lymphocytes. In plain radiography, bone proliferations of the C4 (caudal) C5 (cranial) articular processes were observed and, in myelography, extradural spinal cord compression was evident between C4-C5 on the right side. The animal underwent dorsal laminectomy for spinal cord decompression. An extradural synovial cyst and proliferated articular processes were removed. At 1,281 days after surgery, the dog was clinically normal and presented no neurological deficits.Discussion: The etiology of synovial cysts has not been well established. However, it is believed that osteoarthritic degeneration associated with joint mobility could cause a rupture in the articular capsule, leading to a synovial membrane protrusion, which would fill with synovial fluid and compress spinal structures. ESC in the cervical region have been reported, often associated with cervical neoplasm. The case we report had no evidence of bone or intervertebral disc compression in myelographic and radiographic exams, abnormalities that would appear in cervical neoplasm. The patient underwent dorsal laminectomy to confirm the presumptive diagnosis and decompress the spine. In the histopathological exam, the cystic material consisted of connective fibrous tissue with a synovial cell lining layer, compatible with synovial cysts. The fluid drained during surgery was also analyzed, showing similarities to synovial fluid drained from other conventional joints. Cerebrospinal fluid analysis revealed mononuclear pleocytosis, a common finding in ESC. The ESC should be included in the differential diagnosis of dogs with cervical myelopathy, especially in young animals and large breeds. A myelographic exam is an important but not definitive auxiliary tool for diagnosis and the therapeutic plan. Dorsal laminectomy is an effective technique for treating ESC.

Closed spinal dysraphism in a 6-month-old mixed breed dog

The term spinal dysraphism defines an incomplete fusion or a bone defect that affects the neural structures of the spinal cord due to a neural tube malformation. A 6-month-old, male, mixed-breed dog, was evaluated for paraparesis, pelvic limb proprioceptive ataxia, faecal and urinary incontinence. A neurological examination indicated an L4-S3 spinal cord segment lesion. A thoracolumbar and lumbosacral spine magnetic resonance imaging was performed and a closed spinal dysraphism, with the presence of a lipomyelomeningocele, was detected. The magnetic resonance imaging showed an entire narrowing passage and a fibrous mass stemming from a wedge-shaped gap in the caudal region of the dorsal lamina of the L4 vertebra, leaving the spinal canal towards the skin surface in the region where the skin stigma was observed. A dorsal laminectomy was performed, the spinal cord was exposed, and the entire fibrous mass was excised. Three months postoperatively, the patient had a complete resolution of the urinary and faecal incontinence showing only a residual mild paraparesis, which remained six months after surgery. The surgical procedure resulted in the satisfactory recovery of the neurological signs.

Extradural Peripheral Nerve Sheath Tumour at T7 Level in a 2-Year-Old Dog

The aim of this report is to describe an unusual localization of nerve sheath tumour (NST), clinical presentation, imaging, surgical management, and outcome in a 2-year-old dog. A 2-year-old female American Staffordshire Terrier presented with nonambulatory paraparesis, thoracolumbar hyperaesthesia, hindlimb hyperreflexia, and mild muscle atrophy. Computed tomography and magnetic resonance imaging revealed an extradural mass at T7-T8, without vertebral lesions. Surgical treatment consisted in resection of the soft tissue mass through dorsal laminectomy. The dog was ambulatory within 24 hours and free of recurrence at 18 months postoperatively. Histopathologic and features of immunohistochemistry were consistent with NST. The NST of this report was similar to those described before, but exhibited unusual characteristics, such as being extradural, without extension into intervertebral foramina, and being located in an atypical region (T7-T8). Moreover, survival time and relapse-free interval are greater than previously reported for similar cases.

Multiple Cartilaginous Exostoses Causing Severe Cervical Myelopathy in a Puppy Dog

This study aimed to report a case of multiple cartilaginous exostoses (MCE) causing severe cervical myelopathy in a puppy dog. An 80-day-old Dachshund cross weighing 2.2 kg presented with progressive development of non-ambulatory tetraparesis, proprioceptive ataxia in all four limbs, and cervical hyperesthesia. Multiple calcified masses in the cervical spine at the levels of C1–C2 and C4–C7, with several points of spinal cord compression, were identified. Ventral atlantoaxial fusion was performed. Four days later, four masses were surgically removed by dorsal laminectomy of C1–C2 and C4–C7, and a right facetectomy between C4 and C5 was performed. Multiple cartilaginous exostoses were confirmed by histopathological examination. Thirty-six months after surgery, the patient showed no recurrence of neurological signs. Ventral atlantoaxial fusion, and surgical removal of MCE masses followed by decompression was effective on alleviating clinical sings in the short and medium term.