Acute Traumatic Spinal Cord Injury in Humans, Dogs, and Other Mammals: The Under-appreciated Role of the Dura

Duraplasty promotes functional recovery by alleviating intraspinal pressure and edema following severe spinal cord compression injury in rabbits: experimental studies

BACKGROUND

After acute traumatic spinal cord injury (tSCI), various surgical strategies have been developed to alleviate elevated intraspinal pressure (ISP) and secondary injury.

PURPOSE

Our study aimed to investigate the impacts of duraplasty and laminectomy on edema progression, perfusion and functional outcomes after severe balloon compression SCI.

STUDY DESIGN

In vivo animal study.

METHODS

Closed balloon compression injuries were induced at the T7 level in rabbits using an inflated volume of 50 μl. Laminectomy (1-level laminectomy: 1-laminectomy; 3-level laminectomy: 3-laminectomy) and duraplasty were performed immediately after model generation. ISP was monitored using a SOPHYSA probe at the epicenter within 7 days post-SCI. Edema progression, perfusion and damage severity were evaluated by serial multisequence MRI scans, behavioral and bladder scores within 8 weeks post-SCI. Blood-spinal cord barrier (BSCB) permeability and histopathology were subsequently analyzed.

RESULTS

After SCI, ISP was steeply elevated in the control and 1-laminectomy groups, peaking at 33.14±4.91 and 31.71±4.50 mmHg at 48 h post-SCI; whereas in the 3-laminectomy and duraplasty groups, ISP peaked at 29.43±4.04 and 12.14±1.86 mmHg (p<.0001) at 72 h post-SCI. MRI and function scores showed that duraplasty significantly reduced the intramedullary lesion length (IMLL) and blood flow reduction ratio, and promoted fiber tract sparing and spinal cord functional recovery (p<.01). Histopathology revealed that duraplasty significantly reduced BSCB permeability, tissue loss and inflammation and promoted axon preservation (p<.01), while it did not increase early scar formation.

CONCLUSIONS

Duraplasty may alleviate secondary SCI and promote functional recovery. This neuroprotective mechanism may be related to reduced ISP and increased perfusion, resulting in reduced edema, BSCB permeability and inflammation and increased nerve fiber tract preservation.

CLINICAL SIGNIFICANCE

Duraplasty may promote functional recovery following severe tSCI patients, but further investigations are needed.

Hemorrhagic encephalopathies and myelopathies in dogs and cats: a focus on classification

The prevalence of hemorrhagic diseases of the central nervous system of dogs and cats is low compared to other diseases such as neoplasia and inflammation. However, the clinical consequences can be devastating. Several etiological and localization-based classification systems have been reported for intracerebral and spinal cord hemorrhage or hematomyelia in humans but similar systems do not exist in veterinary medicine. The authors propose an etiologic classification system for both intraparenchymal hemorrhagic encephalopathy and myelopathy following a review of the literature detailing the presentation, diagnosis, therapy, and prognosis of these diseases. A summary of the investigative and therapeutic approach to these cases is also provided.

Recovery of ambulation in small, nonbrachycephalic dogs after conservative management of acute thoracolumbar disk extrusion

BACKGROUND

Currently, low-level evidence suggests loss of ambulation associated with acute thoracolumbar disk extrusion is best treated by decompressive spinal surgery. Conservative management can be successful, but the proportion of dogs that recover and the fate of herniated material are uncertain.

OBJECTIVES

Determine the proportion of nonambulatory dogs with conservatively treated acute thoracolumbar disk extrusion that recover ambulation and measure the change in spinal cord compression during the first 12 weeks after presentation.

ANIMALS

Seventy-two client-owned nonambulatory dogs with acute thoracolumbar intervertebral disk extrusion.

METHODS

This is a prospective cohort study. Enrolled dogs underwent magnetic resonance imaging at presentation and owners were provided with conservative management recommendations. Imaging was repeated after 12 weeks. Recovery of ambulation was defined as 10 consecutive steps without falling. Spinal cord compression was determined from the cross-sectional area of the vertebral canal and extradural compressive material at the lesion epicenter. The association between recovery and change in compression over the 12-week observational period was examined.

RESULTS

Forty-nine of fifty-one (96%; 95% confidence interval [CI], 87%-99%) of deep pain-positive and 10/21 (48%; 95% CI, 28%-68%) of deep pain-negative dogs recovered ambulation within the 12-week period. The median time to ambulation was 11 and 25 days for deep pain-positive and -negative dogs, respectively. Reduction in spinal cord compression varied among individuals from minimal to complete and apparently was unrelated to the recovery of ambulation.

CONCLUSIONS AND CLINICAL IMPORTANCE

A high proportion of conservatively treated dogs recovered ambulation after conservative management of acute thoracolumbar disk herniation. Recovery was not dependent on the resolution of compression.

Balloon compression-induced spinal cord injury in canines: a large animal model for spinal cord injury research

Spinal cord injury (SCI) is a life-altering condition that severely impacts an individual's functional capabilities and has significant implications for both the individual and society. Large animal models are crucial for understanding the pathology and biomechanics of SCI. Dogs (Canis lupus familiaris) are promising models for SCI research due to their anatomical and histopathological similarities to humans. Balloon compression is an established method for inducing controlled SCI in canines. In this study, we optimized a balloon compression procedure for inducing SCI in dogs, aiming to develop a reliable model for future in vivo studies. Our methodology successfully induced total motoric loss in canines, observed for seven days, a critical period for therapeutic interventions. Histopathological examinations using Luxol fast blue (LFB) staining revealed total demyelination in intralesional samples, confirming the structural damage caused by balloon compression. We concluded that a balloon compression model at the T10-T11 vertebral level, with an inflated balloon volume of 1.0 ml, induced SCI while minimizing the risk of balloon rupture. Longer duration of compression ensures total paralysis in this model, providing a platform for testing therapeutic interventions during the acute phase of SCI. The canine model generated consistent data and facilitated straightforward observational findings.

Case report: Amniotic fluid-derived mesenchymal stem cell treatment in a dog with a spinal cord injury

Spinal Cord Injury (SCI) refers to complete or incomplete damage to the spinal cord, which comprises the central nervous system. SCI in dogs, like humans, is mostly caused by external trauma, and the degree of impact is dependent on the location of the injury in the spine. Stem cell therapy is a promising avenue for SCI research. In this report, we investigate the therapeutic potential of amniotic fluid-derived mesenchymal stem cells (AF-MSCs) in dogs with spinal cord injuries. A 2-year-old male beagle dog presented with sensory and motor incomplete symptoms resulting in an inability to control the legs, hips, and genitourinary system due to an injury in the lumbar region of the spinal cord. In addition to the administration of surgical decompression, AF-MSCs were directly injected into the damaged spinal tissue. Approximately 15-16 weeks after stem cell transplantation, the dog's hind limb movement improved, and spinal cord regeneration was confirmed through magnetic resonance imaging (MRI). Eventually, the dog was able to walk independently, although not perfectly. In conclusion, AF-MSC-based stem cell transplantation may be beneficial for SCIs.

Case report: Traumatic hemorrhagic cervical myelopathy in a dog

A 1.5-year-old female entire French bulldog was referred for neurological evaluation, further diagnostic tests, and treatment 24 h after a road traffic accident. Initial emergency treatment, diagnostic tests, and stabilization had been performed by the referring veterinarian. Neurological examination revealed severe spastic non-ambulatory tetraparesis and was consistent with a C1-5 myelopathy. A magnetic resonance imaging (MRI) study revealed an irregular to elongated ovoid intramedullary lesion centered over the body of C2. The lesion showed marked signal heterogeneity with a central T2W and T2* hyperintense region, surrounded by a hypointense rim on both sequences. The lesion appeared heterogeneously T1W hypointense. The lesion was asymmetric (right-sided), affecting both white and gray matter. The C2-3 intervertebral disk appeared moderately degenerate with a Pfirrmann grade of 3. No evidence of vertebral fracture or luxation was found on radiographs or MRI of the vertebral column. Additional soft tissue abnormalities in the area of the right brachial plexus were suggestive of brachial plexus and muscle injury. A diagnosis of traumatic hemorrhagic myelopathy at the level of C2 and concurrent brachial plexus injury was formed. Conservative treatment was elected and consisted of physiotherapy, bladder care with an indwelling urinary catheter, repeated IV methadone based on pain scoring (0.2 mg/kg), oral meloxicam 0.1 mg/kg q24h, and oral gabapentin 10 mg/kg q8h. The dog was discharged after 4 days, with an indwelling urinary catheter and oral medication as described. The catheter was replaced two times by the referring veterinarian and finally removed after 10 days. Thereafter, voluntary urination was seen. During the 2 months after the road traffic accident, slow recovery of motor function was seen. The right thoracic limb recovery progressed more slowly than the left limb, also showing some lower motor neuron signs during follow-up. This was judged to be consistent with a right-sided brachial plexus injury. The dog was reported ambulatory with mild residual ataxia and residual monoparesis of the right thoracic limb at the last follow-up 3 months post-injury. This case report highlights the MRI-based diagnosis of traumatic hemorrhagic myelopathy in a dog. A fair short-term outcome was achieved with conservative treatment in this case.

Posterior spinal decompression in adults with spinal cord injury without traumatic compromise of the spinal canal: what is the data?

Background

Spinal cord injury (SCI) can be caused by a variety of factors and its severity can range from a mild concussion to a complete severing of the spinal cord. Τreatment depends on the type and severity of injury, the patient's age and overall health. Reduction of dislocated or fractured vertebrae via closed manipulation or surgical procedures, fixation and removal of bony fragments and debris that compromise the spinal canal are indicated for decompression of the spinal cord and stabilization of the spine. However, when there is no obvious traumatic obstruction of spinal canal, the question arises as to whether laminectomy is needed to be performed to improve neurological outcome.

Methods

A literature review covering all indexed studies published between 2013 and 2023 was performed using keywords to identify the patient group of interest (spinal cord injury, SCI, spinal cord trauma, cervical, thoracic, lumbar, thoracolumbar),central cord syndrome (CCS) and the interventions (laminectomy, laminoplasty, decompression, duroplasty).

Results

This review includes6 observational studies investigating the outcome of posterior spinal decompression in patients suffering from spinal cord injury without traumatic spinal cord stenosis. Most patients already had degenerative stenosis. From a total of 202, 151 patients (74.7%) improved neurologically by at least one grade at ASIA scale, after being treated with either laminectomy, laminoplasty, duroplasty or a combination of these techniques.

Conclusion

Early decompression in SCI patients remains a reasonable practice option and can be performed safely, but no specific evidence supports the use of laminectomy alone. There is emerging evidence that intended durotomy followed by extended meningoplasty may improve the neurological outcome in patients suffering from SCI when meta-traumatic edema is apparent. However, the lack of high-quality evidence and results support the need for further research.

The volume of extruded materials is correlated with neurologic severity in small-breed dogs with type I thoracolumbar intervertebral disk herniation

OBJECTIVE

To assess whether the volume of extruded materials is correlated with neurologic severity in dogs with type I thoracolumbar intervertebral disk herniation (TL-IVDH).

ANIMALS

70 client-owned small-breed dogs with type I TL-IVDH diagnosed between July 1, 2016, and June 30, 2018.

PROCEDURES

For this retrospective cohort study, the medical records of 70 dogs with surgically confirmed type I TL-IVDH were reviewed. The volume and height of the intervertebral disk and the area of the maximal transverse compressed spinal cord were measured using CT myelographic images. For each dog, the volume of the disk immediately cranial to the herniated disk was an internal control. Dogs were grouped on the basis of grade of neurologic severity.

RESULTS

Preoperative grades of neurologic severity were grade 2 in 7 (10%) dogs, grade 3 in 16 (23%) dogs, grade 4 in 28 (40%) dogs, and grade 5 in 19 (27%) dogs. The total volume of the affected intervertebral disks was significantly larger than the internal control. Weak positive correlation was found between the volume of the extruded materials into the vertebral canal and the grade of neurologic severity.

CLINICAL RELEVANCE

Our findings indicated that the total volume of the affected intervertebral disks is larger in dogs with type I TL-IVDH, and the volume of the extruded materials into the vertebral canal is weakly correlated with the neurologic severity.

Elevated intraspinal pressure in traumatic spinal cord injury is a promising therapeutic target

The currently recommended management for acute traumatic spinal cord injury aims to reduce the incidence of secondary injury and promote functional recovery. Elevated intraspinal pressure (ISP) likely plays an important role in the processes involved in secondary spinal cord injury, and should not be overlooked. However, the factors and detailed time course contributing to elevated ISP and its impact on pathophysiology after traumatic spinal cord injury have not been reviewed in the literature. Here, we review the etiology and progression of elevated ISP, as well as potential therapeutic measures that target elevated ISP. Elevated ISP is a time-dependent process that is mainly caused by hemorrhage, edema, and blood-spinal cord barrier destruction and peaks at 3 days after traumatic spinal cord injury. Duraplasty and hypertonic saline may be promising treatments for reducing ISP within this time window. Other potential treatments such as decompression, spinal cord incision, hemostasis, and methylprednisolone treatment require further validation.

Detection and Analysis of Perfusion Pressure through Measuring Oxygen Saturation and Requirement of Dural Incision Decompression after Laminectomy

BACKGROUND

Traumatic spinal cord injury (SCI) can continue and transform long after the time of initial injury. Preventing secondary injury after SCI is one of the most significant challenges, and early intervention to return the blood flow at the injury site can minimize the likelihood of secondary injury.

OBJECTIVE

The purpose of this study is to investigate whether laminectomy can achieve the spinal cord blood flow by measuring the spinal blood oxygen saturation intraoperatively without the presence of light.

METHODS

Between June and August 2021, eight patients were admitted after traumatic spinal cord injury for surgical treatment. We explored the effectiveness of laminectomy and whether the patients required further procedures or not. We used a brain oxygen saturation monitor at the spine injury site under dark conditions.

RESULTS

Eight cervical trauma patients, six males and two females, underwent laminectomy decompression. Three patients' ASIA grade improved by one level, and one patient showed slight motor-sensory improvement. Oxygen saturation was in the normal range.

CONCLUSION

Performing bony decompression can show good results. Therefore, finding an examination method to confirm the improvement of blood perfusion by measuring oxygen saturation at the injury site after laminectomy is essential to avoid other complications.