Acute Thoracolumbar Intervertebral Disc Herniation Research Articles

Results of routine thoracic radiographic examinations rarely impact the plan to proceed with anesthetic procedures in dogs with presumed acute intervertebral disc herniation.

Acute thoracolumbar intervertebral disc herniation (IVDH) constitutes an emergency because associated neurological clinical signs can be progressive, with prognosis dependent on preoperative presence of deep pain perception. Pre-anesthetic thoracic radiographs are routinely performed to evaluate for potential pathology that could result in increased risk or change in overall prognosis. However, due to the emergent nature of this disease, the weight of thoracic radiographic findings on treatment plans for these dogs in unknown. The objective of this study was to investigate the clinical benefit of thoracic radiographs prior to advanced spinal imaging and surgery for acute non-ambulatory dogs with suspected T3-L3 myelopathy. Consecutive dogs presented with presumed acute IVDH between July 2020-July 2022 were identified, and medical records were reviewed retrospectively. Age, body weight, and alteration of treatment plan were compared between the dogs with positive thoracic pathology identified on thoracic radiographs and those with negative thoracic pathology. Only 2/105 dogs had their diagnostic and treatment plans changed due to thoracic radiographic findings. Dogs with radiographic pathology diagnosed (2/16) were more likely to have their treatment plans changed than dogs with no radiographic pathology (0/89) (p = 0.014). The odds of radiographic thoracic pathology were 4.6 times higher in dogs aged 12 years or older [OR 4.6 (95%CI 1.2-17, p = 0.026]. Performing routine thoracic radiography prior to advanced (anesthetized) diagnostic spinal imaging in presumed IVDH cases rarely resulted in a change to the treatment plan, thought eh practice may be clinically relevant in dogs 12 years of age or older.

Prevalence and clinical features of thoracolumbar intervertebral disc-associated epidural hemorrhage in dogs.

BackgroundIntervertebral disc‐associated epidural hemorrhage (EH) in dogs is a poorly understood neurological condition.ObjectiveTo compare the clinical presentation, magnetic resonance imaging (MRI) changes, and clinical outcome of dogs with acute thoracolumbar intervertebral disc herniation (TL‐IVDH) with and without EH.AnimalsOne hundred sixty client‐owned dogs that underwent MRI and hemilaminectomy for acute TL‐IVDH at a private practice in Colorado, including 63 dogs with EH and 97 dogs without EH.MethodsRetrospective review of medical record data from 160 dogs presenting sequentially to a single practice with acute TL‐IVDH that underwent MRI and hemilaminectomy surgery.ResultsSixty‐three of 160 (39%) dogs had confirmed EH. French Bulldogs were significantly overrepresented (23/63; odds ratio [OR]: 4.1; 95% confidence interval [CI]: 1.8‐9.0; P < .001) of the EH cases. Dogs with EH were more likely to present with clinical signs less than 48 hours than were dogs without EH (24‐48 vs 48‐72 hours; OR: 2.4; 95% CI: 1.2‐4.6; P = .02) and were more likely to be nonambulatory on presentation (OR: 2.1; 95% CI: 1.0‐4.1; P = .04). Dogs with EH were more likely to have <50% cross‐sectional spinal cord compression than dogs without EH (OR: 2.3 vs. 0.4; 95% CI: 1.2‐4.4 and 0.2‐0.9, respectively), longer longitudinal spinal cord compression (3 spaces vs 1 space, P < .001), and greater intrinsic spinal cord change (grade 3/severe vs grade 1/mild; P < .001) based on MRI. The location of the intervertebral disc herniation in French Bulldogs with EH was more likely to be thoracolumbar (OR: 10.8; 95% CI: 2.1‐55.7; P = .03).Conclusions and Clinical ImportanceFrench Bulldogs have a high prevalence of intervertebral disc‐associated EH. Dogs with EH have a shorter clinical course and are more likely to be nonambulatory on initial presentation.

Influence of Duration of Injury on Diffusion Tensor Imaging in Acute Canine Spinal Cord Injury

Diffusion tensor imaging (DTI) quantifies microstructural lesion characteristics, but impact of the interval between spinal cord injury (SCI) and examination on imaging characteristics is unclear. Our objective was to investigate the impact of duration of injury on DTI indices in dogs with acute, spontaneous SCI from thoracolumbar intervertebral disc herniation (IVDH) and explore associations with clinical severity. Twenty-six dogs with acute thoracolumbar IVDH of variable severity who underwent DTI were included. Neurological severity was graded using the modified Frankel Score (0-V). Fractional anisotropy (FA) and mean diffusivity (MD) were calculated on regions of interest within and adjacent to the lesion epicenter. Relationships between FA or MD and duration (injury to imaging interval) or neurological severity were determined using regression analysis and Wilcoxon rank sum. Median age was 6.8 years (1-13), median duration was 1.5 days (1-9), and neurological signs ranged from ambulatory paraparesis (MFS II) to paraplegia with absent pain perception (MFS V). Mean FA was 0.61 ± 0.09 cranial to the lesion, 0.57 ± 0.12 at the epicenter and 0.55 ± 0.10 caudally. Mean MD was 1.18 × 10-3 ± 0.0002 cranially, 1.09 × 10-3 ± 0.0002 at the epicenter, and 1.14 × 10-3 ± 0.0002 caudally. Accounting for neurological severity and age, FA caudal to the epicenter decreased with increasing duration of injury (p = 0.02). Lower MD within the lesion epicenter was associated with worse neurological severity (p = 0.01). Duration of injury should be considered when interpreting DTI results in dogs with acute thoracolumbar IVDH. The MD might differentiate injury severity in the acute setting and be worthy of development as an imaging biomarker.

Association between anesthesia duration and outcome in dogs with surgically treated acute severe spinal cord injury caused by thoracolumbar intervertebral disk herniation.

BackgroundRetrospective research recently identified a possible relationship between duration of surgery and outcome in severely affected dogs treated surgically for acute thoracolumbar intervertebral disk herniation (TL‐IVDH).HypothesisThat increased duration of surgery is associated with poorer outcome in dogs with absent pain perception treated surgically for TL‐IVDH.AnimalsTwo hundred ninety‐seven paraplegic dogs with absent pain perception surgically treated for acute TL‐IVDH.MethodsRetrospective cohort study. Medical records of 5 institutions were reviewed. Inclusion criteria were paraplegia with absence of pain perception, surgical treatment of TL‐IVDH, and 1‐year postoperative outcome (ambulatory: yes or no). Canine data, outcome, and surgery and total anesthesia duration were retrieved.ResultsIn this study, 183/297 (61.6%) dogs were ambulatory within 1 year, 114 (38.4%) dogs failed to recover, including 74 dogs (24.9%) euthanized because of progressive myelomalacia. Median anesthesia duration in dogs that regained ambulation within 1 year of surgery (4.0 hours, interquartile range [IQR] 3.2‐5.1) was significantly shorter than those that did not (4.5 hours, IQR 3.7‐5.6, P = .01). Multivariable logistic regression demonstrated a significant negative association between both duration of surgery and total anesthesia time and ambulation at 1 year when controlling for body weight and number of disk spaces operated on.Conclusions and Clinical ImportanceFindings support a negative association between increased duration of anesthesia and outcome in this group of dogs. However, the retrospective nature of the data does not imply a causal relationship.

Extended durotomy to treat severe spinal cord injury after acute thoracolumbar disc herniation in dogs.

To report recovery of ambulation of dogs treated with extended thoracolumbar durotomy for severe spinal cord injury caused by intervertebral disc herniation. Descriptive cohort. Twenty-six consecutive paraplegic dogs presented with loss of deep pain sensation after acute thoracolumbar intervertebral disc herniation. Each dog underwent routine diagnostic assessment and surgery for removal of extradural herniated intervertebral disc, followed by a four-vertebral body length durotomy centered on the herniated disc. Each dog was followed up until it was able to walk 10 steps without assistance or until 6 months after surgery. Sixteen of 26 dogs recovered to walk unaided (all but one also recovered fecal and urinary continence), and six dogs did not; four dogs were lost to follow-up. One dog was euthanized because of signs consistent with progressive myelomalacia. There was no evidence of detrimental effects of durotomy within the period of study. Using Bayesian analysis, we found a point estimate of successful outcome of 71% with 95% credible interval from 52% to 87%. Extended durotomy seemed to improve the outcome of dogs in our case series without increase in morbidity. Extended durotomy appears safe and may improve the outcome of dogs with severe thoracolumbar mixed contusion and compressive injuries associated with acute intervertebral disc extrusion.

A randomized, blinded, prospective clinical trial of postoperative rehabilitation in dogs after surgical decompression of acute thoracolumbar intervertebral disc herniation.

BackgroundExperimental evidence shows benefit of rehabilitation after spinal cord injury (SCI) but there are limited objective data on the effect of rehabilitation on recovery of dogs after surgery for acute thoracolumbar intervertebral disc herniations (TL‐IVDH).ObjectiveCompare the effect of basic and intensive post‐operative rehabilitation programs on recovery of locomotion in dogs with acute TL‐IVDH in a randomized, blinded, prospective clinical trial.AnimalsThirty non‐ambulatory paraparetic or paraplegic (with pain perception) dogs after decompressive surgery for TL‐IVDH.MethodsBlinded, prospective clinical trial. Dogs were randomized (1:1) to a basic or intensive 14‐day in‐house rehabilitation protocol. Fourteen‐day open field gait score (OFS) and coordination (regulatory index, RI) were primary outcomes. Secondary measures of gait, post‐operative pain, and weight were compared at 14 and 42 days.ResultsOf 50 dogs assessed, 32 met inclusion criteria and 30 completed the protocol. There were no adverse events associated with rehabilitation. Median time to walking was 7.5 (2 – 37) days. Mean change in OFS by day 14 was 6.13 (confidence intervals: 4.88, 7.39, basic) versus 5.73 (4.94, 6.53, intensive) representing a treatment effect of −0.4 (−1.82, 1.02) which was not significant, P=.57. RI on day 14 was 55.13 (36.88, 73.38, basic) versus 51.65 (30.98, 72.33, intensive), a non‐significant treatment effect of −3.47 (−29.81, 22.87), P = .79. There were no differences in secondary outcomes between groups.ConclusionsEarly postoperative rehabilitation after surgery for TL‐IVDH is safe but doesn't improve rate or level of recovery in dogs with incomplete SCI.

Transcranial magnetic motor evoked potentials and magnetic resonance imaging findings in paraplegic dogs with recovery of motor function.

BackgroundTranscranial magnetic motor evoked potentials (TMMEP) are associated with severity of clinical signs and magnetic resonance imaging (MRI) findings in dogs with spinal cord disease.HypothesisThat in initially paraplegic dogs with thoracolumbar intervertebral disc herniation (IVDH), MRI findings before surgery and TMMEPs obtained after decompressive surgery are associated with long‐term neurological status and correlate with each other.AnimalsSeventeen client‐owned paraplegic dogs with acute thoracolumbar IVDH.MethodsProspective observational study. TMMEPs were obtained from pelvic limbs and MRI (3T) of the spinal cord was performed at initial clinical presentation. Follow‐up studies were performed ≤ 2 days after reappearance of motor function and 3 months later. Ratios of compression length, intramedullary hyperintensities' length (T2‐weighted hyperintensity length ratio [T2WLR]), and lesion extension (T2‐weighted‐lesion extension ratio) in relation to the length of the 2nd lumbar vertebral body were calculated.ResultsTMMEPs could be elicited in 10/17 (59%) dogs at 1st and in 16/17 (94%) dogs at 2nd follow‐up. Comparison of TMMEPs of 1st and 2nd follow‐up showed significantly increased amplitudes (median from 0.19 to 0.45 mV) and decreased latencies (from 69.38 to 40.26 ms; P = .01 and .001, respectively). At 2nd follow‐up latencies were significantly associated with ambulatory status (P = .024). T2WLR obtained before surgery correlated with latencies at 2nd follow‐up (P = .04).ConclusionsTMMEP reflect motor function recovery after severe spinal cord injury.

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.

Effect of anesthesia-associated hypotension on neurologic outcome in dogs undergoing hemilaminectomy because of acute, severe thoracolumbar intervertebral disk herniation: 56 cases (2007-2013).

OBJECTIVE To evaluate the effect of anesthesia-associated hypotension on final motor and urinary function in paraplegic dogs without nociception that underwent hemilaminectomy because of acute, severe thoracolumbar intervertebral disk herniation (IVDH). DESIGN Retrospective case series. ANIMALS 56 paraplegic dogs with acute thoracolumbar IVDH and absent nociception. PROCEDURES Medical records were reviewed, and signalment, history, anesthetic details, and results of serial neurologic assessments performed for at least 4 weeks after surgery were recorded. Motor function was retrospectively scored with a 5-point scale, and urinary function was scored with a 3-point scale. Hypotension was defined as MAP ≤ 60 mm Hg or SAP ≤ 80 mm Hg for at least 2 consecutive readings 5 minutes apart. Associations between hypotension and outcome were assessed by use of the Fisher exact test. RESULTS Thirty-three (59%) patients experienced hypotension during anesthesia. Thirty-four (61%) patients (20/33 with and 14/23 without hypotension) regained ambulation. Whether dogs regained motor or urinary function was not significantly associated with the occurrence of hypotension (P = 0.35 and P = 0.86, respectively), the duration of hypotension (P = 0.213 and P = 0.274), or the lowest blood pressure recorded (P = 0.556 and P = 0.699). CONCLUSIONS AND CLINICAL RELEVANCE For this group of dogs undergoing hemilaminectomy because of acute, severe thoracolumbar IVDH, anesthesia-associated hypotension was not significantly associated with whether dogs regained motor or urinary function after surgery. However, normotension should be the goal in all patients with spinal cord injuries, especially patients undergoing general anesthesia.

The prognostic value of cerebrospinal fluid characteristics in dogs without deep pain perception due to thoracolumbar disc herniation

Providing a pre-operative prognosis for dogs presented with absent deep pain perception (DPP) is extremely challenging, as the overall recovery rates widely vary. This study assesses the possible correlation between the severity of spinal cord injury and CSF cytology in 31 paraplegic dogs presented with absent DPP due to acute thoracolumbar intervertebral disc herniation (TL-IVDH). All dogs underwent surgical decompression immediately following diagnosis. CSF TNCC, macrophage percentage and macrophage to monocyte (MΦ:M) ratio were significantly higher in dogs that failed to regain DPP within 10 days post-operatively and in dogs that failed to regain ambulation at the end of the study period (P < 0.05). MΦ:M of 0.73 and higher corresponded to a sensitivity of 54% and specificity of 100% for prediction of a negative long-term outcome. CSF TNCC, macrophage percentage and MΦ:M ratio effectively predicted regaining DPP and the long-term outcome in dogs that lost DPP due to acute TL-IVDH.

Associations between cerebrospinal fluid biomarkers and long-term neurologic outcome in dogs with acute intervertebral disk herniation

To examine associations between CSF biomarkers, initial neurologic dysfunction, and long-term ambulatory outcome in dogs with acute intervertebral disk herniation (IVDH). Prospective clinical study. 54 dogs with acute thoracolumbar IVDH and 16 clinically normal dogs. For each dog, variables, including CSF myelin basic protein (MBP), lactate, calcium, glucose, and total protein concentrations; nucleated cell count; and creatine kinase (CK) and aspartate aminotransferase activities, were measured. For dogs with thoracolumbar IVDH, initial neurologic function was characterized by use of a modified Frankel score (MFS; determined on a scale of 0 to 5, where 0 represented paraplegia with no deep nociception and 5 represented paraspinal hyperesthesia only). Long-term follow-up was assessed. Among dogs with thoracolumbar IVDH, those with CSF CK activity ≤ 38 U/L had a 35-fold increase in the odds of long-term ambulation, compared with the odds in dogs with CSF CK activity > 38 U/L, adjusting for neurologic functioning at the evaluation. The CSF lactate, calcium, and glucose concentrations and aspartate aminotransferase activity were not predictive of long-term ambulatory outcome. Data analysis revealed that long-term functional recovery was > 98% for affected dogs, regardless of their initial MFS, when CSF CK activity was ≤ 38 U/L and MBP concentration was ≤ 3 ng/mL. In dogs with acute thoracolumbar IVDH, CSF CK activity and MBP concentration appeared to be prognostic indicators and, along with initial MFS, can be used to predict long-term ambulatory outcome.

Cerebrospinal Fluid Myelin Basic Protein as a Prognostic Biomarker in Dogs with Thoracolumbar Intervertebral Disk Herniation

Release of myelin basic protein (MBP) into the cerebrospinal fluid (CSF) is associated with active demyelination and correlates with outcome in various neurological diseases. To describe associations among CSF MBP concentration, initial neurological dysfunction, and long-term ambulatory outcome in dogs with acute thoracolumbar intervertebral disk herniation (IVDH). Fifty seven [corrected] dogs with acute thoracolumbar IVDH and 16 clinically normal dogs. Prospective case series clinical study. Signalment, initial neurological dysfunction as determined by a modified Frankel score (MFS), and ambulatory outcome at >3-month follow-up were recorded. Cisternal CSF MBP concentration was determined by an ELISA. Associations were estimated between CSF MBP concentration and various clinical parameters. Dogs with thoracolumbar IVDH that did not ambulate at follow-up had a higher CSF MBP concentration (median, 3.56 ng/mL; range, 0.59-51.2 ng/mL) compared with control dogs (median, 2.22 ng/mL; range, 0-3.82 ng/mL) (P=.032). A CSF MBP concentration of >or=3 ng/mL had a sensitivity of 78% and specificity of 76% to predict an unsuccessful outcome based on receiver-operating characteristics curve analysis (area under the curve=0.688, P=.079). Affected dogs with a CSF MBP concentration>or=3 ng/mL had 0.09 times the odds of ambulation at follow-up compared with affected dogs with CSF MBP concentration<3 ng/mL when adjusted for initial MFS (95% confidence interval 0.01-0.66, P=.018). These results would suggest that CSF MBP concentration may be useful as an independent prognostic indicator in dogs with thoracolumbar IVDH.

Adverse effects and outcome associated with dexamethasone administration in dogs with acute thoracolumbar intervertebral disk herniation: 161 cases (2000–2006)

To determine complications and neurologic outcomes associated with dexamethasone administration to dogs with surgically treated thoracolumbar intervertebral disk herniation, compared with dogs not receiving dexamethasone. Retrospective case series. 161 dogs with surgically confirmed thoracolumbar disk herniation. Medical records from 2 hospitals were used to identify dogs that had received dexamethasone < 48 hours prior to admission (dexamethasone group dogs), dogs that received glucocorticoids other than dexamethasone < 48 hours prior to admission (other-glucocorticoid group dogs), and dogs that received no glucocorticoids (nontreatment group dogs). Signalment, neurologic injury grade, laboratory data, and complications were extracted from medical records. Dexamethasone group dogs were 3.4 times as likely to have a complication, compared with other-glucocorticoid or nontreatment group dogs. Dexamethasone group dogs were 11.4 times as likely to have a urinary tract infection and 3.5 times as likely to have diarrhea, compared with other-glucocorticoid or nontreatment group dogs. No differences in neurologic function at discharge or recheck evaluation were detected among groups. Results indicated that treatment with dexamethasone before surgery is associated with more adverse effects, compared with treatment with glucocorticoids other than dexamethasone or no treatment with glucocorticoids, in dogs with thoracolumbar intervertebral disk herniation. In this study population, no difference in outcome was found among groups. These findings suggest that the value of dexamethasone administration before surgery in dogs with thoracolumbar disk herniation should be reconsidered.