Spinal fixation after laminectomy in pigs prevents postoperative spinal cord injury

BACKGROUND: A safe, effective, and ethically sound animal model is essential for preclinical research to investigate spinal medical devices. We report the initial failure of a porcine spinal survival model and a potential solution by fixating the spine. METHODS: Eleven female Dutch Landrace pigs underwent a spinal lumbar interlaminar decompression with durotomy and were randomized for implantation of a medical device or control group. Magnetic resonance imaging (MRI) was performed before termination. RESULTS: Neurological deficits were observed in 6 out of the first 8 animals. Three of these animals were terminated prematurely because they reached the predefined humane endpoint. Spinal cord compression and myelopathy was observed on postoperative MRI imaging. We hypothesized postoperative spinal instability with epidural hematoma, inherent to the biology of the model, and subsequent spinal cord injury as a potential cause. In the subsequent 3 animals, we fixated the spine with Lubra plates. All these animals recovered without neurological deficits. The extent of spinal cord compression on MRI was variable across animals and did not seem to correspond well with neurological outcome. CONCLUSION: This study shows that in a porcine in vivo model of interlaminar decompression and durotomy, fixation of the spine after lumbar interlaminar decompression is feasible and may improve neurological outcomes. Additional research is necessary to evaluate this hypothesis

Intraneural or Extraneural Diagnostic Accuracy of Ultrasound Assessment for Localizing Low-Volume Injection

Background and Objectives: When one is performing ultrasound-guided peripheral nerve blocks, it is common to inject a small amount of fluid to confirm correct placement of the needle tip. If an intraneural needle tip position is detected, the needle can then be repositioned to prevent injection of a large amount of local anesthetic into the nerve. However, it is unknown if anesthesiologists can accurately discriminate intraneural and extraneural injection of small volumes. Therefore, this study was conducted to determine the diagnostic accuracy of ultrasound assessment using a criterion standard and to compare experts and novices in ultrasound-guided regional anesthesia. Methods: A total of 32 ultrasound-guided infragluteal sciatic nerve blocks were performed on 21 cadaver legs. The injections were targeted to be intraneural (n = 18) or extraneural (n = 14), and 0.5 mL of methylene blue 1% was injected. Cryosections of the nerve and surrounding tissue were assessed by a blinded investigator as "extraneural" or "intraneural." Ultrasound video clips of the injections were reviewed by 10 blinded observers (5 experts, 5 novices) independently who scored each injection as either "intraneural," "extraneural," or "undetermined." Results: The mean sensitivity of experts and novices was measured to be 0.84 (0.80-0.88) and 0.65 (0.60-0.71), respectively (P = 0.006), whereas mean specificity was 0.97 (0.94-0.98) and 0.98 (0.96-0.99) (P = 0.53). Conclusions: Discrimination of intraneural or extraneural needle tip position based on an injection of 0.5 mL is possible, but even experts missed 1 of 6 intraneural injections. In novices, the sensitivity of assessment was significantly lower, highlighting the need for focused education

Effectiveness of Sealants in Prevention of Cerebrospinal Fluid Leakage after Spine Surgery: A Systematic Review

Background: Sealants are often used in spine surgery to prevent postoperative cerebrospinal fluid (CSF) leakage. Objective: To investigate the efficacy of sealants in preventing postoperative CSF leakage in spine surgery. Methods: The PubMed, Embase, and Cochrane databases were searched for articles reporting the outcome of patients treated with a sealant for spinal dural repair. The number of patients, indication of surgery, surgical site, applied technique, type of sealant used, and outcome in terms of postoperative CSF leakage were noted for each study. The primary outcome was CSF leakage in general and secondary outcome infection. Results: Forty-one articles were selected with a total of 2542 cases; there were 4 comparative studies with 540 sealed cases and 343 cases with primary suture closure only. The quantity of CSF leakage did not differ between the sealant group (50 of 540, 9.1%) and the group treated with sutures only (48 of 343, 13.8%) (risk ratio [RR], 0.58 [confidence interval [CI], 0.18–1.82]). The infection rate did also not differ between the sealant and primary suture groups (RR, 0.94 [CI, 0.55–1.61]). This result was found in both the intended and the unintended durotomy subgroups. Secondary analysis of all cases showed that endoscopic or minimally invasive surgery had lower CSF leakage rates compared with open surgery regardless of sealant use (RR, 0.18 [CI, 0.05–0.75]). Conclusions: Currently available sealants seem not to reduce the rate of CSF leakage in spine surgery. In endoscopic and minimally invasive surgery, the CSF leakage rate is less frequent compared with open, conventional surgery regardless of sealant use

Effectiveness of Sealants in Prevention of Cerebrospinal Fluid Leakage after Spine Surgery: A Systematic Review

Background: Sealants are often used in spine surgery to prevent postoperative cerebrospinal fluid (CSF) leakage. Objective: To investigate the efficacy of sealants in preventing postoperative CSF leakage in spine surgery. Methods: The PubMed, Embase, and Cochrane databases were searched for articles reporting the outcome of patients treated with a sealant for spinal dural repair. The number of patients, indication of surgery, surgical site, applied technique, type of sealant used, and outcome in terms of postoperative CSF leakage were noted for each study. The primary outcome was CSF leakage in general and secondary outcome infection. Results: Forty-one articles were selected with a total of 2542 cases; there were 4 comparative studies with 540 sealed cases and 343 cases with primary suture closure only. The quantity of CSF leakage did not differ between the sealant group (50 of 540, 9.1%) and the group treated with sutures only (48 of 343, 13.8%) (risk ratio [RR], 0.58 [confidence interval [CI], 0.18–1.82]). The infection rate did also not differ between the sealant and primary suture groups (RR, 0.94 [CI, 0.55–1.61]). This result was found in both the intended and the unintended durotomy subgroups. Secondary analysis of all cases showed that endoscopic or minimally invasive surgery had lower CSF leakage rates compared with open surgery regardless of sealant use (RR, 0.18 [CI, 0.05–0.75]). Conclusions: Currently available sealants seem not to reduce the rate of CSF leakage in spine surgery. In endoscopic and minimally invasive surgery, the CSF leakage rate is less frequent compared with open, conventional surgery regardless of sealant use

Histological and magnetic resonance imaging assessment of Liqoseal in a spinal in vivo pig model

BACKGROUND Liqoseal (Polyganics, B.V.) is a dural sealant patch for preventing postoperative cerebrospinal fluid (CSF) leakage. It has been extensively tested preclinically and CE (Conformité Européenne) approved for human use after a first cranial in-human study. However, the safety of Liqoseal for spinal application is still unknown. The aim of this study was to assess the safety of spinal Liqoseal application compared with cranial application using histology and magnetic resonance imaging characteristics. METHODS Eight female Dutch Landrace pigs underwent laminectomy, durotomy with standard suturing and Liqoseal application. Three control animals underwent the same procedure without sealant application. The histological characteristics and imaging characteristics of animals with similar survival times were compared to data from a previous cranial porcine model. RESULTS Similar foreign body reactions were observed in spinal and cranial dura. The foreign body reaction consisted of neutrophils and reactive fibroblasts in the first 3 days, changing to a chronic granulomatous inflammatory reaction with an increasing number of macrophages and lymphocytes and the formation of a fibroblast layer on the dura by day 7. Mean Liqoseal plus dura thickness reached a maximum of 1.2 mm (range 0.7-2.0 mm) at day 7. CONCLUSION The spinal dural histological reaction to Liqoseal during the first 7 days was similar to the cranial dural reaction. Liqoseal did not swell significantly in both application areas over time. Given the current lack of a safe and effective dural sealant for spinal application, we propose that an in-human safety study of Liqoseal is the logical next step

Spinal fixation after laminectomy in pigs prevents postoperative spinal cord injury

BACKGROUND: A safe, effective, and ethically sound animal model is essential for preclinical research to investigate spinal medical devices. We report the initial failure of a porcine spinal survival model and a potential solution by fixating the spine. METHODS: Eleven female Dutch Landrace pigs underwent a spinal lumbar interlaminar decompression with durotomy and were randomized for implantation of a medical device or control group. Magnetic resonance imaging (MRI) was performed before termination. RESULTS: Neurological deficits were observed in 6 out of the first 8 animals. Three of these animals were terminated prematurely because they reached the predefined humane endpoint. Spinal cord compression and myelopathy was observed on postoperative MRI imaging. We hypothesized postoperative spinal instability with epidural hematoma, inherent to the biology of the model, and subsequent spinal cord injury as a potential cause. In the subsequent 3 animals, we fixated the spine with Lubra plates. All these animals recovered without neurological deficits. The extent of spinal cord compression on MRI was variable across animals and did not seem to correspond well with neurological outcome. CONCLUSION: This study shows that in a porcine in vivo model of interlaminar decompression and durotomy, fixation of the spine after lumbar interlaminar decompression is feasible and may improve neurological outcomes. Additional research is necessary to evaluate this hypothesis