Preliminary evaluation of an indwelling epidural catheter for repeat methylprednisolone administration in canine lumbosacral stenosis.

Objective: To determine the complications, outcomes, and patency of a permanent epidural catheter and subcutaneous access port system (ECAPS) as part of conservative management of degenerative lumbosacral stenosis in dogs. Animals and procedure: Medical records of 11 client-owned dogs that underwent an ECAPS insertion were evaluated retrospectively. Clinical signs, complications related to the procedure, and system patency are reported. Results: All dogs had lumbosacral pain at their initial neurological assessment, with comfort levels adequately controlled following epidural infiltrations. None suffered from complications related to the ECAPS procedure. In 10 dogs, there were no malfunctions for the duration of the study. However, in 1 dog, there was a suspected leak at Day 814. The longest duration of patency reported in this study was 870 d (at the time of writing). Conclusion: Placement of an ECAPS is a feasible technique and a viable option to permit repeated epidural injections of steroids in dogs with degenerative lumbosacral stenosis that is managed conservatively. Further studies are required to evaluate complication rates.

Évaluation préliminaire d'un cathéter épidural permanent (à demeure) pour l'administration répétée de méthylprednisolone lors de sténose lombosacrée dégénérative chez le chien. Objectif: Décrire la technique, les complications, les résultats et la perméabilité d'un système composé d'un cathéter épidural et d'un port d'injection sous-cutanée (ECAPS) pour le traitement médical de la sténose lombosacrée dégénérative chez le chien. Animaux et protocole: Les dossiers médicaux de 11 chiens appartenant à des clients ayant subi l'implantation d'un ECAPS ont été évalués de façon rétrospective. Cette étude décrit les signes cliniques, les complications reliées à la procédure et la perméabilité du système. Résultats: Tous les patients inclus présentaient de la douleur lombosacrée à l'examen initial. Le niveau de confort de tous les patients suite aux injections épidurales fut maitrisé de façon adéquate. Aucun des patients n'a subi de complications reliées à l'implantation du système. Le système n'a pas démontré de dysfonctionnement dans le cas de dix patients. Chez un des patients, une fuite fut suspectée au jour 814. La durée maximale de perméabilité enregistrée dans cette étude est de 870 jours (au moment de la rédaction). Conclusion: L'implantation d'un système ECAPS représente une option faisable et viable pour l'administration additionnelle de stéroïdes pour une gestion conservatrice de sténose lombosacrée dégénérative chez les chiens atteints. Des recherches supplémentaires sont requises pour l'évaluation des taux de complications.(Traduit par les auteurs).

Head tilt as a clinical sign of cervical spinal or paraspinal disease in dogs: 15 cases (2000-2021).

OBJECTIVES: To characterise head tilt as a rare clinical sign of cervical spinal or paraspinal disease in dogs. MATERIALS AND METHODS: Retrospective single-centre case-series study of dogs with head tilt and cervical spinal or paraspinal disease in the absence of intracranial abnormalities. Descriptive statistics were used. RESULTS: Fifteen dogs met the inclusion criteria of this study. Median age at onset was 6 years (range 2.5 to 12 years). Onset of neurological signs was mainly chronic (9/15, 60%). Most common presenting complaints included head tilt (9/15, 60%) and cervical hyperaesthesia (8/15, 53%). Most common neurological findings included head tilt (15/15, 100%), generalised proprioceptive ataxia and tetraparesis (6/15, 40%) and cervical hyperaesthesia (8/15, 53%). Diagnoses included post-operative complication of C2 spinal nerve root mass removal (2/15, 13%), C3-C4 intervertebral disc extrusion (2/15, 13%), cervical paraspinal myositis (2/15, 13%) and one of each: C2 vertebral malformation, C2 spinal nerve root mass, C1-C2 meningioma, C2 vertebral fracture, C4-C5 intervertebral disc extrusion, C4 vertebral body mass, C5-C7 osseous-associated cervical spondylomyelopathy, and concurrent C5-C6 and C6-C7 intervertebral disc protrusions. Two dogs were euthanased shortly after diagnosis and two of 15 were dogs lost to follow-up. No post-mortem examination was performed for these cases. For the 11 of 15 remaining dogs, head tilt resolved in eight of 15 (53%) dogs after treatment of the underlying condition and in three of 15 (20%) dogs, it remained static. CLINICAL SIGNIFICANCE: Head tilt can be a rare clinical sign of cervical spinal or paraspinal disease in dogs.

Magnetic resonance imaging and neurologic characterization of combined osseous- and disc-associated cervical spondylomyelopathy in dogs.

BACKGROUND: Although both disc- or osseous-associated forms of cervical spondylomyelopathy (CSM) are observed in the same dogs, this combined form has not been thoroughly evaluated. OBJECTIVES: To describe imaging characteristics of dogs with concurrent disc- and osseous CSM and investigate an association between findings on neurological examination and imaging. ANIMALS: Sixty dogs with disc and osseous-associated CSM from 232 CSM-affected dogs. METHODS: Retrospective study. Dogs diagnosed via high-field MRI with a combination of intervertebral disc (IVD) protrusion and osseous proliferation of articular processes, dorsal lamina, or both were identified. Large and giant breed dogs were grouped according to whether combined compressions were at the same site or different sites. Statistical methods were used to investigate the association and relationship between variables. RESULTS: Thirty-five out of 60 (58%) were large breeds and 22/60 (37%) were giant breeds. Mean and median age was 6.6 and 7 years respectively (range, 0.75-11 years). Forty of the 60 dogs (67%) had concurrent osseous and disc-associated spinal cord compression in the same location. This was considered the main compression site in 32/40 (80%) dogs. Dogs with osseous- and disc-associated compressions at the same site were more likely to have a higher neurologic grade (P = .04). CONCLUSIONS AND CLINICAL IMPORTANCE: A substantial percentage of dogs with CSM present with concomitant IVD protrusion and osseous proliferations, most at the same site. Characterizing this combined form is important in the management of dogs with CSM because it could affect treatment choices.

A novel surgical technique for treatment of cervical vertebral stenotic myelopathy (wobbler syndrome) in a filly.

Cervical vertebral stenotic myelopathy (CVSM), also known as equine wobbler syndrome or cervical ataxia, is a devastating neurological syndrome resulting from compression of the spinal cord at the cervical region. This report describes a novel surgical technique for treatment of 16-month-old Arabian filly with CVSM. The filly showed grade 4 ataxia, hypermetria, weakness of the hind limbs, stumbling during walking, and abnormal gait. Case history, clinical signs and myelography revealed spinal cord compression between the C3 and C4 and C4-C5. The filly underwent a novel surgical interference for decompression and stabilization of the point of stenosis using specially designed titanium plate and intervertebral spacer. Evidence of arthrodesis with absence of complications was confirmed by periodic radiography over eight months of postoperative care. The new technique applied in this cervical surgery was efficient for the decompression and stabilization of the vertebrae, allowing arthrodesis development and remission of the clinical signs. The obtained results encourage further assessment of this novel procedure in horses clinically affected by CVSM.

Postoperative outcomes of combined surgery comprising dorsal laminectomy, transarticular screws, pedicle screws and polymethylmethacrylate for dorsal fixation in 21 dogs with degenerative lumbosacral stenosis.

OBJECTIVE: To retrospectively review the efficacy of combined surgery comprising dorsal laminectomy and dorsal fixation using screws and polymethylmethacrylate as treatment for dogs with degenerative lumbosacral stenosis (DLSS). ANIMALS: 21 client owned dogs diagnosed with DLSS and treated surgically. PROCEDURES: Based on clinical records, signalments, clinical signs, findings from orthopedic and neurological examinations, imaging findings, and postoperative complications were evaluated at the following time points: preoperatively, postoperatively, and 3, 6, 12, 24, and 36 months after surgery. RESULTS: In all 21 cases, clinical signs were alleviated, proprioceptive deficits were improved from 3 months after surgery, and no recurrence of clinical signs was observed during the observation period. Minor complications were observed in 6 cases (28.6%), including implant failure in 2 (9.5%), delayed healing of surgical wounds in 2 (9.5%), seroma in 1 (4.8%), and swelling of the affected area in 1 (4.8%). There was no case with major complications. CLINICAL RELEVANCE: Combined surgery comprising dorsal laminectomy and dorsal fixation using screws and polymethylmethacrylate is a useful treatment that can improve long-term clinical signs in dogs with DLSS.

Sex differences in cervical spinal cord and spinal canal development in Thoroughbred horses.

Cervical vertebral stenotic myelopathy (CVSM), a common cause of cervical spinal cord compression, is a neurological disease characterized by general proprioceptive ataxia and weakness of hindlimbs that tends to develop in young adult Thoroughbred horses. Although male horses seem to be at increased risk for CVSM, the mechanism for the occurrence of sex differences in the prevalence of CVSM is still poorly understood. Hence, we hypothesized that sex differences in the development of cervical spinal cord and spinal canal would affect the development of CVSM. This study aimed to evaluate sex differences in the development of cervical spinal cord and spinal canal in Thoroughbred horses. A total of 29 Thoroughbred horses underwent computed tomographic myelography. Thereafter, the volumes of cervical spinal cord and spinal canal were calculated. Accordingly, male horses had significantly lager cervical spinal cord volume and cervical spinal cord-to-spinal canal volume ratio than those of female horses (P<0.05). Sex differences in the cervical spinal cord-to-spinal canal volume ratio gradually decreased until around 1,400 days of age. Younger male horses have narrower interspace between the cervical spinal cord and spinal canal than younger female horses, suggesting that an imbalanced cervical spinal cord and spinal canal growth is one of the causes of CVSM.

Cervical Vertebral Stenotic Myelopathy.

Cervical vertebral stenotic myelopathy is a common cause of ataxia in horses secondary to spinal cord compression. Early articles describing this problem indicate genetic predisposition as a known risk factor. Further studies have shown the problem is a developmental abnormality which might have genetic predisposition and environmental influences.

Investigation of a contributing factor for cervical vertebral stenotic myelopathy using computed tomography for measuring the cervical vertebral volume.

Thoroughbred horses appear to be particularly predisposed to cervical vertebral stenotic myelopathy (CVSM), also known as wobbler syndrome. We hypothesized that variations in the cervical vertebral volumes can affect the dynamic instability of the cervical vertebrae. This observational study aimed to clarify whether cervical vertebral volume could be considered as a contributing factor in CVSM in Thoroughbred horses. Computed tomography (CT) was used to investigate a total of 21 male Thoroughbred horses (age range, 217-1,002 days; mean, 542.3 days). The study population comprised 17 CVSM horses (age range, 217-1,002 days; mean, 549.8 days) and 4 non-CVSM horses (age range, 244-682 days; mean, 510.5 days). The cervical vertebral volumes of three-dimensional CT were measured using the image-processing software. A significant difference in the variation of cervical vertebral volumes among C2 to C4 and C3 to C5 was identified in the CVSM group (P<0.05). While no significant differences were found in the variation in cervical vertebral volumes among C4 to C6. C3 demonstrated a significantly smaller cervical vertebral volume than C2 and C4 (P<0.05). In the non-CVSM group, no significant differences were found in the variation of cervical vertebral volume among C2 to C4, C3 to C5, and C4 to C6. Our findings suggest that variations in cranial cervical vertebral volume in CVSM male horses can be considered as an important contributing factor in CVSM development.

Imaging characteristics of thoracolumbar spinal stenosis due to articular process hyperplasia and degenerative joint disease in six large breed dogs.

Previous studies have reported evidence that thoracolumbar articular process hyperplasia and degenerative joint disease may be a cause of stenotic myelopathy in large breed dogs; however, detailed descriptions of imaging characteristics are currently lacking. The aim of this retrospective, multi-center, case series report was to describe imaging findings in six large breed dogs diagnosed with thoracolumbar articular process hyperplasia and degenerative joint disease causing vertebral canal stenosis. All dogs presented with progressive paraparesis, proprioceptive ataxia of the pelvic limbs, and neuroanatomical localization of T3-L3 myelopathy. All dogs underwent magnetic resonance imaging (MRI) of the thoracolumbar spine and had articular process malformations at T13-L1 (three German Shepherd dogs (GSD) and a Boxer dog) or T12-T13 (two mixed-breed dogs). Five cases were managed surgically. Findings provided more detailed imaging descriptions and supported previously published studies indicating that maldevelopment of articular processes and secondary degenerative changes can be a cause of thoracolumbar spinal stenosis and myelopathy in large breed dogs. While uncommon, this condition should be included as a differential diagnosis for large breed dogs presenting with a T3-L3 myelopathy.

Characteristic computed tomographic myelography findings in 23 Thoroughbred horses.

The purpose of this observational study was to determine the characteristic computed tomographic (CT) myelography findings of cervical vertebral stenotic myelopathy (CVSM) lesions in Thoroughbred horses. A total of 23 Thoroughbred horses (age range, 155-717 days on CT examination; mean, 410.9 days) were analyzed. All 23 Thoroughbred horses underwent unenhanced radiography, radiographic myelography, and CT myelography. Unenhanced radiographs were observed the presence of cervical vertebral malalignment and osseous lesions. Radiographic myelograms were observed for signs of cervical spinal cord compression; additionally, CT myelograms were used to detect cervical vertebral osseous lesions. Ventral compressions were frequently observed in the cranial cervical vertebrae (C2-C4), whereas dorsal compressions were frequently observed in the caudal cervical vertebrae (C5-C7). Furthermore, osseous lesions of the caudal articular process developed more frequently than those of the cranial articular process. CT myelography in Thoroughbred horses is a useful method for detecting CVSM changes.

An objective index for spinal cord compression on computed tomography in Thoroughbred horses.

BACKGROUND: Computed tomographic myelography can be a useful tool for evaluating vertebral canal stenosis. However, an index of spinal cord compression is yet to be established. OBJECTIVES: This observational descriptive study aimed to establish an index for spinal cord compression using computed tomography (CT). METHODS: Twenty-three Thoroughbred horses (age, 155-717 days; weight, 205-523 kg) with suspected cervical vertebral malformation were subjected to computed tomographic myelography in dorsal recumbency using large-bore gantry CT to define the entire cervical vertebrae from C1 to C7. Subsequently, the height of the spinal cord was measured in the sagittal plane reformatted using curved multi-planar reformation (MPR), thereby comparing it with stenotic ratio (i.e. dividing the area of spinal cord by that of the subarachnoid space) measured in the transverse plane. The measurement was performed at the level of each of six intervertebral spaces, for a total of 138 sites. Accordingly, the appropriate cut-off value for spinal cord height was determined using the receiver-operating characteristic curve, from which the area under the curve with 95% confidence interval was estimated. RESULTS: The spinal cord compression cut-off value was 7.06 mm, with an area under curve of 0.84. A weak relationship was observed between spinal cord height and stenotic ratio (R2  = 0.08, p < 0.05). CONCLUSIONS: Following curved MPR, a cut-off value of 7.06 mm may serve as an index for spinal cord compression.

Comparing the clinical presentation and outcomes of dogs receiving medical or surgical treatment for osseous-associated cervical spondylomyelopathy.

BACKGROUND: This study aimed to compare the clinical presentation, short and long term outcomes of dogs treated surgically or medically for Osseous associated cervical spondylomyelopathy. METHODS: Information collected retrospectively from medical records included signalment, neurological status and treatment type. Surgical treatment consisted of dorsal laminectomy. Medical treatment involved restricted exercise and medication. Improvement or deterioration in neurological status was determined at discharge, re-examination 4-8 weeks post-treatment and by telephone interview with the referring veterinary surgeon or owner at the time of the study, which ranged from 8-54 months following the discharge (median, 16 months). RESULTS: Twenty-four dogs were treated surgically and 30 medically. Neurological grade at clinical presentation was significantly higher in surgically treated dogs (p = 0.004). Transient early postoperative neurological deterioration occurred in 73.1% of surgically treated dogs. For medical cases, long term improvement was seen in 15% of cases, remained static in 40% and deterioration in 45%. Surgical treatment resulted in long term improvement in 67% of cases, remained static in 29% and deterioration in 4% of cases. CONCLUSION: This study suggests that surgery is a favourable treatment option, however, requires intensive post-operative care. Medical treatment was associated with a guarded prognosis but could be a viable treatment option for selected dogs.

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, perioperatively and at long-term follow-up. RESULTS: The most common presurgical 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 out of 21 dogs 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% (1.8 mm ± 2.5 mm pre-surgery to 0.7mm ± 0.9mm post-surgery, p = 0.1585). Mean foraminal width significantly increased 50% long-term (3.3 mm ± 1.0 mm pre-surgery to 5.0 mm ± 0.9 mm 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.

Magnetic resonance imaging and neurological findings in dogs with disc-associated cervical spondylomyelopathy: a case series.

BACKGROUND: Canine cervical spondylomyelopathy can be separated into osseous and disc-associated (DA-CSM) forms. Our aim was to describe the magnetic resonance imaging (using a high-field scanner) and neurological findings in dogs with DA-CSM and investigate a relationship between these findings. RESULTS: Sixty-three dogs were included: 60/63 (95 %) were large breeds, with Doberman Pinschers and males over-represented (70 %). Mean and median age at the time of diagnosis was 7.25 and 7.2 years (range 0.41-12 years). Chronic signs were noted in 52/63 (83 %) dogs, with proprioceptive ataxia the most common. Main site of spinal cord compression was commonly C6-7 or C5-6. Thirty-six (57 %) dogs had various sites of spinal cord compression. Most dogs younger than 6 years of age had a single affected site. Foraminal stenosis was present in 51/63 dogs (81 %). T2-weighted hyperintensity was present in 40/63 dogs (63 %). 88 % of the articular processes showed degenerative changes, which correlated strongly with intervertebral disc degeneration. Ligamentum flavum hypertrophy was seen in 38 % of dogs. No correlation was observed between neurologic signs and number of affected sites. A moderate positive correlation was observed between severity of spinal cord compression and neurologic grade (r 0.48; p < 0.001). CONCLUSIONS: DA-CSM was predominantly observed in older, male Dobermans, with lesions located in the caudal cervical vertebral region. It was also seen in dogs 3 years of age or even younger (8 %). Single compressive lesions were more common in dogs younger than 6 years of age. Many dogs had concomitant changes (e.g.: ligamentum flavum hypertrophy and foraminal stenosis). Most dogs with ligamentum flavum hypertrophy were 6 years or older. A positive correlation was observed between severity of spinal cord compression and neurologic grade, but multilevel compression was not associated with more severe neurologic signs. A very high percentage of dogs had articular process degenerative changes. Possible biomechanical or genetic relationships between degenerative changes in articular processes, ligamentum flavum, and intervertebral discs warrants further investigation.

Accuracy of Placement of Pedicle Screws in the Lumbosacral Region of Dogs Using 3D-Printed Patient-Specific Drill Guides.

OBJECTIVE: The aim of this study was to report the accuracy of pedicle screw placement using three-dimensional (3D)-printed, patient-specific drill guides in the lumbosacral region of dogs. STUDY DESIGN: This was a retrospective study. Thirty-two pedicle screws were placed in five dogs. Medical records were reviewed between November 2015 and November 2018 for dogs showing clinical signs associated with cauda equina syndrome. Inclusion criteria included preoperative magnetic resonance imaging, pre- and postoperative computed tomography (CT) and dorsal stabilization, with pedicle screws placed using 3D-printed, patient-specific drill guides and polymethylmethacrylate. Screw placement was evaluated for medial or lateral breaching on postoperative CT. RESULTS: Five dogs met the inclusion criteria. Four had degenerative lumbosacral stenosis and one had discospondylitis. All dogs had failed medical management prior to surgery. Of 32 bicortical pedicle screws placed, 30 were fully contained inside the pedicle and 2 were partially breaching the vertebral canal (less than one-third of the screw diameter). Postoperative CT revealed good alignment of L7-S1 in all planes. CONCLUSION: This technique enabled an accurate and safe placement of pedicle screws in the lumbosacral region of dogs with lumbosacral disease. Three-dimensional, printed patient-specific drill guides are a safe and effective method of placing pedicle screws in dogs with lumbosacral disease.

Long-term clinical and magnetic resonance imaging follow-up of dogs with osseous-associated cervical spondylomyelopathy.

BACKGROUND: Osseous-associated cervical spondylomyelopathy (OA-CSM) is a complex disorder with limited long-term survival. The longitudinal progression is currently unknown. OBJECTIVE: To describe changes on magnetic resonance imaging (MRI) over a 2-year minimum period. We hypothesized that spinal lesions would progress in the majority of dogs. ANIMALS: Eleven dogs previously diagnosed with OA-CSM were prospectively studied. Nine dogs were treated medically, whereas 2 were treated surgically. METHODS: Clinical and MRI follow-up were performed with a median time between MRI studies of 30 months (range, 24-54). Morphologic assessment evaluated vertebral canal stenosis, spinal cord compression, foraminal stenosis, and articular processes, among other variables. Morphometric assessment included vertebral canal area, spinal cord area, area of the articular processes, and foraminal height. RESULTS: On follow-up MRI, the most affected site at the initial examination in medically treated dogs had progressed in 4 of 9 dogs, improved in 4, and was unchanged in 3. Clinically, all dogs except 2 medically treated dogs were unchanged to improve at follow-up. Initially, 50 of 60 (83.3%) intervertebral spaces had vertebral canal stenosis, whereas in the follow-up MRI 82.3% did. Of the sites with stenosis, 45.7% were unchanged, 18.6% improved, and 38.9% worsened. Morphometry identified significant decreases in vertebral canal and spinal cord areas at C4-C5 through C6-C7, and significant progression of articular process irregularities at C3-C4 and C6-C7. CONCLUSIONS AND CLINICAL IMPORTANCE: This long-term follow-up study of dogs with OA-CSM did not identify clinical or MRI progression of lesions in the majority of dogs.

Single dose epidural methylprednisolone as a treatment and predictor of outcome following subsequent decompressive surgery in degenerative lumbosacral stenosis with foraminal stenosis.

Alternative treatments to surgery in canine degenerative lumbosacral stenosis (DLSS) remain limited and reliable predictors of outcome are lacking. The aims of this clinical trial were threefold: to assess the usefulness of single epidural steroid injection (ESI) in DLSS, to compare the outcomes of ESI and decompressive surgery, and evaluate ESI as a predictor of outcome following decompressive surgery. Dogs diagnosed with DLSS were prospectively recruited and administered an ESI. If clinical signs persisted or relapsed, decompressive surgery was recommended. Follow-up was obtained. Thirty-two dogs underwent ESI with 17 having subsequent surgery. Improvement after ESI was seen in 27/32 dogs (84.4%), with 17/22 (77.2%) relapsing within 6 months (n = 15/17 relapsing within 2 months). Five dogs failed to respond to ESI and another five (15.6%) presented a persistent post-ESI favourable response (mean follow-up time, 9.4 months). Post-surgical improvement occurred in all dogs. Outcome appeared more favourable following surgical decompression, with a trend towards reduced pain, increased mobility, and greater quality of life score. This study was unable to demonstrate that ESI could predict surgical outcome. ESI was confirmed as an effective treatment in most but not all cases, leading to transient alleviation of clinical signs for longer than previously reported. ESI provided a complete and apparently long-term sustained resolution of clinical signs in a subset of dogs. Despite this, there was indication that surgical decompression can lead to a more favourable outcome. Epidural steroid injection has a role in the management of DLSS dogs, particularly when surgery is not an option.

Evaluation of L7-S1 nerve root pathology with low-field MRI in dogs with lumbosacral foraminal stenosis.

OBJECTIVE: To describe low-field MRI findings associated with lumbosacral foraminal stenosis and radiculopathy and correlate these with clinical signs. STUDY DESIGN: Retrospective study. ANIMALS: Client-owned dogs (n = 240) that underwent a clinical examination and standardized MRI protocol of the lumbosacral junction. METHODS: Medical records of dogs with degenerative lumbosacral stenosis with neurological clinical evaluation and MRI of the lumbosacral junction were used to describe imaging pathologies and relate them to clinical status. RESULTS: In total, 480 L7 neuroforamina were evaluated. A loss of foraminal fat signal was identified in 364 of 480 neuroforamina of which 87.9% (n=320) showed also concurrent nerve root changes. Magnetic resonance imaging features of L7 radiculopathy included nerve root enlargement and hyperintensity to surrounding connective tissue in dorsal oblique gradient echo short time inversion recovery sequences and specific changes in shape, size, or position of the nerve root in transverse T1-weighted sequences. Radiculopathy was noted as a consequence of either circumferential (entrapment) or focal (impingement) foraminal stenosis. Lateral vertebral spondylotic and intervertebral facet joint changes were the most common underlying spinal and neuroforaminal pathologies. Clinical signs were present in the ipsilateral hind leg in 85% (n = 65) of dogs with unilateral lumbosacral imaging findings. CONCLUSION: A loss of foraminal fat signal was likely to be associated with L7 radiculopathy and foraminal stenosis. Unilateral lesions were generally associated with clinical signs on the ipsilateral limb. CLINICAL SIGNIFICANCE: Loss of foraminal fat signal revealed by low-field MRI should prompt the assessment of concurrent radiculopathy and underlying stenosis, and in coherence with clinical findings, when is combined with clinical findings, improves the diagnosis of lumbosacral foraminal stenosis.

The effects of foraminotomy and intervertebral distraction on the volume of the lumbosacral intervertebral neurovascular foramen: An ex vivo study.

Degenerative lumbosacral stenosis in dogs frequently involves L7-S1 foraminal stenosis and L7 nerve root compression. Surgical techniques to decompress the L7 nerve root include foraminotomy and intervertebral distraction. The objective of this study was to compare the effect of foraminotomy and intervertebral distraction on the total, cranial, and caudal compartmental volumes of the L7-S1 intervertebral neurovascular foramen (NF). CT images were obtained from eight canine lumbosacral (L5-CD1) specimens in the following sequential conditions: native spine (1), after dorsal laminectomy and partial discectomy of L7-S1 (2), after L7-S1 foraminotomy (3), after distraction with an interbody cage between L7 and S1 (4), after cage distraction stabilized with pedicle screw-rod fixation in neutral (5) and flexed position (6). The volume of the complete NF and its cranial and caudal subcompartments were calculated using the CT images and statistically compared between conditions. P < 0.05 was considered statistically significant. The volume of the complete NF was significantly increased after foraminotomy (mean ± standard deviation (146.8 ± 26.5%, P < 0.01) and after distraction (Condition 4, 121.0 ± 19.1%; Condition 5, 116.6 ± 29.3 %; Condition 6, 119.0 ± 21.8 %; P = 0.01) with no difference between the distraction conditions. Foraminotomy induced a significantly larger increase in total NF volume compared to distraction. Foraminotomy, but not distraction, induced a significant increase in volume of the cranial subcompartment (158.2 ± 33.2 %; P < 0.01). Foraminotomy is more effective in increasing the foraminal volume and especially the cranial subcompartment, which is where the L7 nerve root traverses the NF. Hence, foraminotomy may be more effective in decompressing the L7 nerve root.