Spinal Shortening Research Articles

Spinal column shortening with single-stage prone lateral vertebral osteotomy for tethered cord syndrome: illustrative case.

Tethered cord syndrome (TCS) is a rare neurological disorder characterized by longitudinal stretching on the distal end of the spinal cord. The condition commonly manifests in lumbosacral and lower-extremity pain and weakness, sensory disturbances, and incontinence. Traditionally, tethered cord release has been the first-line management for TCS, but retethering and complications such as cerebrospinal fluid leakage are commonly reported. As a result, spinal column shortening (SCS) vertebral osteotomy has emerged as a potential alternative. Herein, the authors describe the first single-stage prone lateral SCS vertebral osteotomy with simultaneous posterior exposure in a 48-year-old male patient with multiple prior direct detethering procedures. The authors highlight the case presentation, operative technique, and postoperative course. Following surgery, there were no immediate surgical complications, and the patient noted clinical improvement in his radicular pain and neurological function. This case further supports SCS vertebral osteotomy as an effective treatment option for patients with TCS. It also demonstrates the potential for a single-stage lateral approach with posterior exposure as a minimally invasive option for spinal shortening procedures. However, further studies using expanded cohorts and assessing various surgical techniques are warranted. https://thejns.org/doi/10.3171/CASE24185.

Could extended laminectomy effectively prevent spinal cord injury due to spinal shortening after 3-column osteotomy?

ObjectiveTo explore whether the laminectomy extension can effectively prevent spinal cord injury (SCI) due to spinal shortening after 3-column osteotomy in goat models.MethodsA total of twenty healthy goats were included and done with 3-column osteotomy of T13 and L1 under the somatosensory evoked potential (SSEP) monitoring. The samples were divided into two groups. The first group underwent regular laminectomy while the second group underwent an extended laminectomy with an extra 10 mm-lamina cranial to L2. The SSEP measured after 3-column osteotomy was set as the baseline, and the SSEP decreased by 50% from the baseline amplitude and/or delayed by 10% relative to the baseline peak latency was set as positive results, which indicated spinal cord injury. The vertebral column was gradually shortened until the SSEP monitoring just did not show a positive result. The height of the initial osteotomy gap (the distance from the lower endplate of T12 to the upper endplate of L2), the shortened distance (△H), the number of spinal cord angulated and the changed angle of the spinal cord (△α) were measured and recorded in each group. Neurological function was evaluated by the Tarlov scores on day 2 postoperatively.ResultsAll the goats except one of the first group due to changes in the SSEP during the osteotomy were included and analyzed. In the first group, the height of the initial osteotomy segment and the safe shortening distances were 61.6 ± 2.6 mm and 35.2 ± 2.6 mm, respectively; the spinal cord of 5 goats was angulated (46.4 ± 6.6°), the other four goats were kinked and not angulated. In the second group, the height of the initial osteotomy segment and the safe shortening distances were 59.8 ± 1.5 mm and 43.3 ± 1.2 mm, respectively, and the spinal cord of ten goats were angulated (97.6 ± 7.2°). There was no significant difference in the height of the initial osteotomy segment between the two groups by using Independent-Samples T-Test, P = 0.095 (P > 0.05); there were significant difference in the safe shortening distance and the changed angle of the spinal cord between the two groups by using Independent-Samples T-Test (both DeltaH and Deltaα of P < 0.001), the difference between their mean were 8.1 mm and 51.2°. Significant difference was found in the number of spinal cord angulation between the two groups through Fisher’s exact test (5/9 vs. 10/10, P = 0.033).ConclusionsAn additional resection of 10 mm-lamina cranial to L2 showed the satisfactory effect in alleviating SCI after 3-column osteotomy. Timely and appropriate extend laminectomy could be a promising therapeutic strategy for SCI attributable to facilitating spinal cord angulation rather than spinal cord kinking and increasing the safe shortening distance.

Partial vertebrectomy with spine shortening for old spondyloptosis at the thoracolumbar spine: a case series study and literature review.

We aimed to report the surgical outcomes of serial cases and retrospectively analyze the value of partial vertebrectomy and spinal shortening in the reduction of old spondyloptosis at the thoracolumbar spine. From 2015 to 2021, eight cases of patients who received a spinal intervention of partial vertebrectomy and spinal shortening for thoracolumbar spondyloptosis over 3 weeks post-trauma were retrospectively summarized. Medical records and surgical outcomes were extracted for clinical safety and efficacy evaluation. Acceptable reduction and immediate stabilization were achieved for all eight cases without causing iatrogenic damage to the viscera. The mean operation time was 3.7 h (range, 3.2-4.2 h) with a mean blood loss average of 1,081 ml (range, 900-1,300 ml). Postoperative stay in the spine department was an average of 11.4 days (range, 8-17 days), followed by an early rehab program. The mean visual analog scale (VAS) for low back pain decreased from 8.0 preoperatively to 1.4 at the last follow-up. The average follow-up period was 19.9 months. As for neurological function recovery, six patients with preoperative ASIA-A status remained unchanged throughout the follow-up period and improvement of one ASIA grade was noted in two patients. At the latest follow-up, sound interbody fusion as well as good alignment of the spinal column were confirmed radiologically in seven patients, while one patient encountered slight re-dislocation 3 months after surgery, but eventually achieved spinal fusion. Partial vertebrectomy and spine shortening via a posterior approach showed good efficacy and safety in the management of old spondyloptosis of the thoracolumbar spine, allowing for a one-step good reduction and spinal fusion for early rehabilitation.

Biomechanical comparison of spinal column shortening - a finite element study

BackgroundAt present, research on spinal shortening is mainly focused on the safe distance of spinal shortening and the mechanism of spinal cord injury, but there is no research on the biomechanical characteristics of different shortening distances. The purpose of this study was to study the biomechanical characteristics of spine and internal fixation instruments at different shortening distances by the finite element (FE) method.MethodsAn FE model of lumbar L1-S was established and referred to the previous in vitro experiments to verify the rationality of the model by verifying the Intradiscal pressure (IDP) and the range of motion (ROM) of the motion segment. Five element models of spinal shortening were designed under the safe distance of spinal shortening, and the entire L3 vertebra and both the upper and lower intervertebral discs were resected. Model A was not shortened, while models B-E were shortened by 10%, 20%, 30% and 50% of the vertebral body, respectively. Constraining the ROM of the sacrum in all directions, a 7.5 N ·m moment and 280 N follower load were applied on the L1 vertebra to simulate the motion of the lumbar vertebrae in three planes. The ROM of the operated segments, the Von Mises stress (VMS) of the screw-rod system, the VMS of the upper endplate at the interface between the titanium cage and the L4 vertebral body, and the ROM and the IDP of the adjacent segment (L5/S) were recorded and analysed.ResultsAll surgical models showed good stability at the operated segments (L1-5), with the greatest constraint in posterior extension (99.3-99.7%), followed by left-right bending (97.9-98.7%), and the least constraint in left-right rotation (84.9-86.3%) compared with the intact model. The VMS of the screw-rod system and the ROM and IDP of the distal adjacent segments of models A-E showed an increasing trend, in which the VMS of the screw-rod system of model E was the highest under flexion (172.5 MPa). The VMS of the endplate at the interface between the cage and L4 upper endplate of models A-E decreased gradually, and these trend were the most obvious in flexion, which were 3.03, 2.95, 2.83, 2.78, and 2.61 times that of the intact model, respectively.ConclusionWhen performing total vertebrae resection and correcting the spinal deformity, if the corrected spine has met our needs, the distance of spinal shortening should be minimized to prevent spinal cord injury, fracture of internal fixations and adjacent segment disease (ASD).

Posterior Injured Vertebra Column Resection and Spinal Shortening for Thoracolumbar Fracture Associated with Severe Spinal Cord Injury: A Retrospective Case-Control Observational Study.

Background Thoracolumbar spinal fracture associated with severe spinal cord injury (sSCI) is a kind of severe traumatic spine injury. Although various approaches are currently used to treat sSCI-related thoracolumbar fractures, the neurological function of patients has not been significantly improved by surgery. Objective To evaluate the therapeutic effects of the new procedure of posterior injured vertebra column resection (PIVCR) and spinal shortening for the treatment of thoracolumbar fracture associated with sSCI. Methods In this retrospective case-control observational study, we included 66 patients with thoracolumbar fractures associated with sSCI in our institution from January 2015 to December 2017. According to the different surgical approaches, the patients were allocated to group A (n = 32, received simple posterior decompression and fixation) and group B (n = 34, received PIVCR and spinal shortening). All patients' clinical and radiologic outcomes were collected to evaluate retrospectively. The clinical outcomes were gathered, including the intraoperative blood loss, operative time, visual analog scale (VAS) score, and American Spinal Injury Association (ASIA) impairment scale. The radiologic outcomes were collected involving the range of spinal shortening, canal encroachment, heights of the anterior edge of the vertebral body, and the Cobb angle. Results There was no significant difference in the two groups regarding preoperative demographic data, VAS scores, segmental kyphosis Cobb, canal encroachment, and neurological status. The range of spinal shortening in group B was an average 1.57 ± 0.40 cm and 36.45 ± 6.56% of the height of the single spinal motion segment. Due to the characteristics of the surgical procedure, group B got complete decompression of the spinal cord and better postoperative canal decompression than group A. Thus, better clinical outcomes, including neurological improvement, loss of corrective Cobb angle, and VAS improvement, were shown in group B at the follow-up investigation than those in group A (P < 0.05). Conclusion PIVCR and spinal shortening surgical procedure is a safe, reliable, and effective approach to treating thoracolumbar fracture associated with sSCI.

Protective Effect of Extended Laminectomy on Spinal Cord Injury Induced by Spinal Shortening.

This study investigates the effect of extended laminectomy (EL) on spinal cord injury (SCI) caused by spinal shortening, and further, the timing and the optimal length of removal. Dogs received spinal column shortening at T13 segment, following which the control group underwent regular laminectomy while other groups underwent laminectomy with an additional 1-lamina length removed 6h after shortening ("1-lamina EL 6 h"), an extra 1.5-lamina length resected at 6 h or 12 h after shortening ("1.5-lamina EL 6 h" and "1.5-lamina EL 12 h"), and an extra 2-lamina length removed at 6 or 12 h after shortening ("2-lamina EL 6 h" and 2-lamina EL 12 h"), respectively. Somatosensory evoked potential (SSEP) and neurological function were recorded periodically; spinal cord blood flow (SCBF) and nerve cell apoptosis were detected. The results showed that resection of an additional 1-lamina length appeared inadequate to relieve the sharp kinking of the spinal cord, whereas the kinking disappeared with an additional 2-lamina length resection. The "1-lamina EL 6 h" and "1.5-lamina EL 12 h" groups showed no significant differences from the control in latency of SSEP, SCBF, hindlimb function and apoptosis. By contrast, significant recovery of SSEP, SCBF and hindlimb function as well as reduction of apoptosis were presented in other three groups. The "2-lamina EL 6 h" group, in particular, showed the most prominent recovery. In conclusion, an additional resection of two laminae at 6 h after shortening showed the best effect in alleviating SCI. Timely and adequately extended laminectomy could be a potential therapeutic strategy for SCI attributable to spinal shortening.

Minimally Invasive Surgery for Traumatic High-Grade Lateral Spondylolisthesis of L1 with Multiple Spinal Fractures: Closed Reduction and Internal Fixation Using Percutaneous Pedicle Screws.

Background:Traumatic high grade lateral spondylolisthesis at the thoracolumbar junction is an extremely severe injury caused by high-energy trauma, commonly resulting in polytrauma. The treatment of this pathology is challenging, and even death following surgery has been reported. Therefore, it is necessary to focus on making surgical invasion minimal.Methods:A 53-year-old female fell from a height and presented with severe back pain and complete paralysis below L1. Computed tomography (CT) showed a Grade 4 traumatic lateral spondylolisthesis and severe comminution of L1, and mild compression fractures at T9 and L3.Results:First, we performed posterior surgery on the day of the injury to reduce the fracture and stabilize the spinal column using percutaneous pedicle screws (PPS). Twelve days later we resected the L1 vertebral body and inserted a cage with an iliac bone graft using an anterior approach. The estimated blood loss from posterior and anterior surgeries was 320ml and 200ml, respectively. Bony fusion was achieved as seen on CT at the 1-year follow-up.Conclusion:A 2-stage combined posterior-anterior approach using PPS can be performed less invasively, enabling adequate reduction, internal fixation, and anterior reconstruction for patients with high grade traumatic lateral spondylolisthesis without spinal shortening or facet interlocking.

Modification of Wright’s Technique for C2 Translaminar Screws Based on Medical Imaging Analysis

Background: To describe and explain the improvement of Wright C2 transforaminal screw fixation technique. Methods: 23 male patients and 10 female patients (a total of 33 patients, average age of 55 years) were implanted with lamina screws on one side or both sides by improved technique. Adopt improved technology, there is a simple hole in the middle of the lateral brain plate, and the screw can be seen directly to prevent the spine from being invaded. Results: With the improved technique, 169 minutes (90–210 minutes) is the average operation time, and 136 ml (80–420 minutes) is the estimated average blood loss. Average length of 26.5 mm (range 24–30) plate screws. After an average follow-up of 12.4 (1.5–30) months, all patients achieved good clinical outcomes. Conclusions: To modify the Wright’s technique, an additional unicortical “hole” was in the middle of the backplane. Through this improved technique, the screw can be directly seen to be inserted into the dorsal cortex of the lamina, thereby reducing the risk of invading the spinal canal and shortening the operation time.

Letter to the Editor Regarding “A Reliable Nomogram Model to Predict the Recurrence of Chronic Subdural Hematoma After Burr Hole Surgery”

Single-stage spinal correction without previous neurosurgical intervention has been attempted in patients with scoliosis associated with syringomyelia (SM). However, evidence to demonstrate its potential influence on associated SM from direct spinal correction is still lacking. The aim of the present study was to explore the role of spinal shortening in the prognosis of SM-associated scoliosis after single-stage spinal correction without previous neurosurgical intervention.Patients with SM-associated scoliosis without previous neurological intervention, who had undergone posterior direct instrumental correction (PDIC) without osteotomy and posterior vertebral column resection (PVCR) at a single center, were selected for comparative analysis. The basic demographic and pre- and postoperative imaging data of the spinal deformity and SM at the final follow-up were compared separately for the 2 different spinal correction procedures.A total of 23 patients were included in the final analysis: 13 had undergone PDIC and 10 had undergone PVCR. The mean follow-up period was 6.2 years (range, 5–9 years). At the final follow-up, the mean corrective rate of scoliosis and kyphosis was 65.7% and 48.4%, respectively. Obvious SM reduction was achieved in 11 patients (47.8%), with an average reduction of 37.3%. No patient experienced neurologic deterioration or had required further neurosurgical intervention for SM during follow-up. The patients who had undergone PVCR had had much more severe scoliosis (98.8° vs. 60.5°; P = 0.000) and kyphosis (74.8° vs. 43.6°; P = 0.032). Moreover, 80.0% of the patients who had undergone PVCR had experienced obvious SM improvement compared with 23.1% of those who had undergone PDIC (P = 0.007).The reduction of spinal cord tension is an important factor influencing SM improvement. As the most powerful spinal-shortening osteotomy, PVCR can effectively correct severe spinal deformities and improve associated SM. Single-stage posterior spinal correction can be a potential choice for selected patients with scoliosis and untreated SM using strict inclusion criteria, which will not only achieve safe spinal correction but could also steadily improve and stabilize SM.

Spinal-Shortening Process Positively Improves Associated Syringomyelia in Patients with Scoliosis After Single-Stage Spinal Correction

Single-stage spinal correction without previous neurosurgical intervention has been attempted in patients with scoliosis associated with syringomyelia (SM). However, evidence to demonstrate its potential influence on associated SM from direct spinal correction is still lacking. The aim of the present study was to explore the role of spinal shortening in the prognosis of SM-associated scoliosis after single-stage spinal correction without previous neurosurgical intervention. Patients with SM-associated scoliosis without previous neurological intervention, who had undergone posterior direct instrumental correction (PDIC) without osteotomy and posterior vertebral column resection (PVCR) at a single center, were selected for comparative analysis. The basic demographic and pre- and postoperative imaging data of the spinal deformity and SM at the final follow-up were compared separately for the 2 different spinal correction procedures. A total of 23 patients were included in the final analysis: 13 had undergone PDIC and 10 had undergone PVCR. The mean follow-up period was 6.2 years (range, 5-9 years). At the final follow-up, the mean corrective rate of scoliosis and kyphosis was 65.7% and 48.4%, respectively. Obvious SM reduction was achieved in 11 patients (47.8%), with an average reduction of 37.3%. No patient experienced neurologic deterioration or had required further neurosurgical intervention for SM during follow-up. The patients who had undergone PVCR had had much more severe scoliosis (98.8° vs. 60.5°; P= 0.000) and kyphosis (74.8° vs. 43.6°; P= 0.032). Moreover, 80.0% of the patients who had undergone PVCR had experienced obvious SM improvement compared with 23.1% of those who had undergone PDIC (P= 0.007). The reduction of spinal cord tension is an important factor influencing SM improvement. As the most powerful spinal-shortening osteotomy, PVCR can effectively correct severe spinal deformities and improve associated SM. Single-stage posterior spinal correction can be a potential choice for selected patients with scoliosis and untreated SM using strict inclusion criteria, which will not only achieve safe spinal correction but could also steadily improve and stabilize SM.

Posterolateral Debridement and Anterior Reconstruction by Limited Spinal Shortening in Thoracic Spine Infections

Background: Spinal infection is a very dangerous type of skeletal infection as it may be complicated with spin neurological deficit or spinal deformity, so early diagnosis and treatment is very important. Purpose: The aim of the current work was to evaluate the result of posterolateral debridement and anterior reconstruction by limited spinal shortening in thoracic spine infections. Patients and Methods: This retrospective clinical study included a total of 10 patients, 5 men and 5 women with thoracic spinal infection, attending at Sohag University Hospital. This study was conducted between 2003 and 2009. All patients were operated in the prone position through a single posterior midline exposure. Posterior stabilization by transpedicular screw fixation was performed. Medial 3 centimeters of 1 or 2 ribs were excised unilaterally. Anterior circumspinal dissection enables debridement of the lesion and evacuation of any abscess. Then, reconstruction of the anterior column was performed by limited spinal shortening followed by posterior fusion. Results: Causative organisms were TB in 8 patients, Staph aureus in 1 patient and bacteriologic testing of intraoperative samples did not find germs in 1 patient. Mean follow up was 90.3 months (range; 67- 150 months). No active infection occurred tell the end of follow up. Seven patients got neurological improvement. Two complications were encountered: kyphosis progression and temporary neurological deterioration. Conclusion: In cases of thoracic spinal infections, single posterolateral exposure is sufficient to debride the infected material, decompress the neural elements, and reconstruct the spine. Limited spinal shortening allows anterior reconstruction without the need for bone grafting.

Spinal shortening, a case revisited 20 years later

Spinal shortening, a case revisited 20 years later

181. Spinal shortening osteotomy as a major factor to improve associated syrinx in scoliotic patient with Chiari 1 Malformation (CM-1)

BACKGROUND CONTEXT Recently, one-stage posterior spinal correction without previous neurosurgical decompression has being used more popularly to treat scoliosis with CM-1 & syringomyelia (SM). But there is still lack of evidences to demonstrate potential influences to associated syrinx. PURPOSE To explore and identify factors that could influence the prognosis of syrinx in scoliotic patient with CM-1 & cervical SM. STUDY DESIGN/SETTING Retrospective case control study. PATIENT SAMPLE A total of 23 scoliotic patients with CM-1 & cervical SM, more than 5 years follow-up were performed after one-stage posterior spinal correction without previous neurosurgical decompression. OUTCOME MEASURES Continuity correction Chi-square and independent t test were used for comparative analysis between two groups. METHODS For the 23 patients, according to each selected MRI transverse imaging, syrinx tension ratio (STR) was calculated by STR = (trans diameter of syrinx + sagittal diameter of syrinx) / (trans diameter of cord + sagittal diameter of cord). The average STR value from C2, C4, C6 levels was used to reflect the size and tension of syrinx. STR reduction ≥ 20% was defined as a boundary of postop syrinx improvement. Based on the final follow-up (≥5 yrs), the cases were divided into two groups by cervical syrinx improvement or not. Then the preop demographics (gender, age), imaging data (apex, main scoliosis, kyphosis, deformity angular ratio, STR), surgical correction details (with/without spinal shortening osteotomy, coronal and sagittal correction rates) and final follow-up periods were compared between the two groups. RESULTS The average follow-up period of all cases was 6.2 yrs (5-9 yrs) and none experienced deterioration of neurological function. At the final follow-up, syrinx improvement was detected in 47.8% of patients (11/23) and 52.2% without improvement (12/23). Between the two groups, there were differences in age at surgery and with/without spinal shortening osteotomy in surgical process (P 0.05). CONCLUSIONS For the scoliotic patients with CM-1 & SM being treated by one-stage posterior spinal surgical correction, using spinal shortening osteotomy to reduce spinal cord tension is a major factor to influence postop associated syrinx improvement without neurosurgical decompression. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Spinal shortening osteotomy for adult tethered cord syndrome evaluated by intraoperative ultrasonography

BackgroundSpinal shortening osteotomy (SSO) reduces the tension indirectly in the spinal cord and minimizes perioperative complications. However, the most effective and safe length to which the spine can be shortened is still unknown. In our practice, we use somatosensory-evoked potentials, motor-evoked potentials, and intraoperative ultrasonography when performing SSO. This study aimed to introduce the clinical outcomes of our SSO technique for tethered cord syndrome (TCS) in adults. MethodsThis retrospective study included 7 adult patients (2 males and 5 females) with TCS treated between December 2010 and December 2018. The average age and average preoperative duration were 40 and 5 years, respectively. All patients received SSO with somatosensory-evoked potentials, motor-evoked potentials, and ultrasonography. After surgery, all patients were followed for an average of 4 years. ResultsThe mean operation time was 328 (284–414) min for SSO. The mean blood loss was 828 ml (501–1252 ml). Postoperative bony fusion was confirmed in all patients. Postoperative computed tomography (CT) demonstrated an average of 16 mm (11–20 mm) of spinal column shortening, compared with preoperative CT. Clinical improvements were obtained in all 7 cases, and there was no case of exacerbation. An indicator of shortening is that the ultrasonography gives pulsation and relaxation of the spinal cord. There were no abnormalities observed while monitoring the spinal cord. ConclusionsSpinal shortening should be done under somatosensory-evoked potentials, motor-evoked potentials, and intraoperative ultrasonography to obtain safe and sufficient shortening.

Relationship between the laminectomy extension and spinal cord injury caused by acute spinal shortening: goat in vivo experiment.

To investigate the relationship between different types of laminectomy extension and spinal cord injury subsequent to acute spinal shorting after 3-column osteotomy in living goat model. A total of 18 healthy goats were selected, and a procedure of bivertebral column resections and total laminectomy of T13 and L1 was completed followed by different laminectomy extensions under the somatosensory evoked potential (SSEP) monitoring. The samples were divided into three groups according to types of subsequent laminectomy extension. In the first group (enlarged resection of upper lamina group), laminectomy extension was performed on 10mm caudal to T12; in the second group (equidistant enlarged resection of upper and lower lamina group), laminectomy extension was performed on 5mm caudal to T12 and 5mm cranial to L2 simultaneously; and in the third group (enlarged resection of lower lamina group), laminectomy extension was performed on 10mm cranial to L2. The SSEP measured after vertebral resection was set as the baseline, and the SSEP decreased by 50% from the baseline amplitude and/or delayed by 10% relative to the baseline peak latency was set as positive results, which indicated spinal cord injury. Spinal column was gradually shortened until the SSEP monitoring just did not show a positive result. The shortened distance (ΔH) and the changed angle of the spinal cord buckling (Δα) were measured in each group. Neurologic function was recorded by the Tarlov scores at 2days after the surgery. The safe shortening distances of three groups were 38.6 ± 1.2mm, 41.5 ± 0.7mm, 43.7 ± 0.8mm, respectively; the corresponding changed angles of the spinal cord buckling were 62.8 ± 6.9°, 82.8 ± 7.5°, and 98.5 ± 7.0°. Significant differences of ΔH and Δα were found among the three groups by LSD multiple comparison test (P < 0.05). Strong correlation between ΔH and Δα was shown in each group by Pearson's correlation test. Different laminectomy extensions after 3-column osteotomy have different effects on the prevention of SCI caused by acute spinal shortening. The enlarged resection of lower lamina is superior to equidistant enlarged resection of upper and lower laminas which is superior to enlarged resection of upper lamina in preventing SCI. These slides can be retrieved under Electronic Supplementary Material.

Safe range of shortening the middle thoracic spine, an experimental study in canine.

To determine the safe range of shortening the spinal column at middle thoracic spine and to observe the changes in blood-spinal cord barrier (BSCB), microglia/macrophage activation and inducible nitric oxide synthase (iNOS) activity after shortening-induced spinal cord injury. Dogs were allocated to four groups. Group A (control) underwent laminectomy of T7 without shortening the spinal column. Groups B, C and D had 1/3, 1/2, and 2/3 of T7 resected, respectively, followed by spinal shortening. Somatosensory evoked potential (SSEP) and hind-limb function were recorded periodically for 14days after operation. Spinal cord blood flow (SCBF) and BSCB were detected at the acute phase of shortening. Microglia/macrophage reactions and iNOS activity were observed by immunohistochemistry. Shortening of 1/3 of a vertebral height caused no significant changes in SSEP and hind-limb function after operation, whereas shortening of 1/2 of the height caused SSEP abnormality and paraparesis, and severe neurologic deficit of hind-limb was observed when the shortening reached 2/3 of the height. SCBF increased temporarily and showed a trend of recovery when the shortening was within 1/2 of a vertebral segment height. When it reached 1/2 or 2/3 of the height, SCBF at 6h post-operation was 86.33% or 74.95% of the baseline, and an increasing BSCB permeability was observed. In the subsequent 7days, obvious activation of macrophage and increased number of iNOS-positive cells were observed. It is safe to shorten the spinal cord within 1/3 of a vertebral height in middle thoracic spine under two-segment laminectomy in canine. The BSCB disruption, macrophage activation, and increased iNOS activity were observed in the acute phase of the injury. These slides can be retrieved under Electronic Supplementary Material.

Effect of Spinal Shortening for Protection of Spinal Cord Function in Canines with Spinal Cord Angulation.

BackgroundPosterior vertebral column resection (PVCR) has been widely used as a treatment for severe spinal deformity. By using the canine model of vertebral column resection, this study explored the effect of spinal shortening on blood flow and function of the spinal cord during spinal cord angulation.Material/MethodsThe canine model of L1 vertebral column resection was constructed with the PVCR technique. The canines were divided into 5 groups according to the degree of shortening: the 0/4 group, the 1/4 group, the 2/4 group, the 3/4 group, and the control group. Spinal cord blood flow, neuroelectrophysiology, HE staining, nitric oxide, and endothelin-1 were measured during the procedure of vertebral column resection and spinal cord angulation.ResultsThe results showed that, in the 1/4 group and the 2/4 group, the blood flow of the spinal cord decreased by 16.5% and 10.6%, respectively, with no obvious damage in the spinal cord; in the 0/4 group and the 3/4 group, the blood flow decreased by 23.5% and 23.1%, respectively, with significant damage in the spinal cord.ConclusionsWhen the spinal cord is shortened by 1/4 to 2/4, the tolerance of the spinal cord can increase and spinal cord injury resulting from angulation can be avoided. However, when the shortening reaches 3/4, it is harmful to the spinal cord. Proper shortening of the spinal cord by 1/4 to 2/4 may increase the tolerance of the spinal cord to the damage caused by angulation during PVCR.

Intraoperative Neuromonitoring During Adult Spinal Deformity Surgery: Alert-Positive Cases for Various Surgical Procedures

Study DesignRetrospective study. ObjectivesTo analyze intraoperative neuromonitoring (IONM) alerts in various surgical procedures and clarify incidences and causes of IONM alarms in consecutive adult spinal deformity (ASD) surgeries. Summary of Background DataASD surgery has a high neurologic complication rate. IONM may play a role in identifying and preventing neurologic complications. MethodsThis study included 275 consecutive ASD patients treated by posterior corrective fusion who had been followed up for more than two years. We divided the patients into 1) the PCO group: multiple posterior column osteotomies; and 2) the 3CO group: three-column osteotomy including pedicle subtraction osteotomy and vertebral column resection. We set a 70% amplitude reduction as the alarm point for transcranial electrical stimulation motor-evoked potentials (Tc-MEPs) using 32-channel IONM. ResultsThe PCO and 3CO groups included 162 and 113 cases, respectively. IONM revealed 32 cases (11.6%) of Tc-MEP alerts, 10.4% in the PCO group, and 13.2% in the 3CO group. Postoperative follow-ups revealed 15 cases (5.5%) of new neurologic deficits, 4.9% in the PCO group, and 6.2% in the 3CO group. Most IONM alarms in the PCO group appeared at the time of rod rotation maneuvers, and 88.9% of alarms were selective for MEP decrease. In contrast, IONM alarms in the 3CO group appeared at the time of spinal shortening, and 80% were global MEP decreases. Immediately after the alarm, neurologic deficits might be rescued by foraminal decompression after rod rotation and by adjusting the length of spinal shortening. Overall, more than 50% of cases with IONM alerts were rescued by intraoperative additional management. ConclusionIONM reduced the incidence of neurologic complications in ASD surgery. Spinal surgeons should recognize the type of muscle derivation and respond to such alerts by performing appropriate corrections reflecting the mechanism underlying the neural damage. Level of EvidenceLevel IV.

Proper Responding Strategies to Neuromonitoring Alerts During Correction Step in Posterior Vertebral Column Resection Patients With Severe Rigid Deformities Can Reduce Postoperative Neurologic Deficits.

Retrospective study. To analyze the intraoperative neuromonitoring (IOM) changes in posterior vertebral column resection (PVCR) for severe rigid deformity patients, and describe our stepwise responding strategies. Obvious neurological deficit risk accompanied with PVCR correction has been emphasized repeatedly. The records of 46 patients who underwent PVCR achieved IOM were reviewed. IOM alerts triggered responding protocols: (1) exchange the convex corrective rod to concave stabilizing rod, (2) appropriate compression for spinal shortening, (3) reversed in situ rod bending, (4) translation technique and unisegmental derotation, (5) adjacent segmental resection. The overall scoliotic correction rate was 65.4% (from 112 ± 28.6 to 39 ± 13.4) and segmental kyphotic correction rate was 64.2% (from 101 ± 37.3 to 36 ± 19.2). During correction step, somatosensory-evoked potential warning (3) and somatosensory-evoked potential/transcranial motor-evoked potential warning (8) were detected in 11 patients (23.9%). Probable cause identification including rule out IOM technical factors, residual impingement, and if there was unstable spinal column (1), spinal cord excessive tension on concave side (3), and the excessive opposite spinal displacement between two aspects of resected area (7). After rod change (1), compression (2), bending (3), derotation (3), and adjacent resection (2), all IOM changes went to under warning criteria. All 11 patients revealed neurologically intact postoperatively. There was no difference of correction rate between IOMs alert or not. However, adult, extremely severe or sharp angular curves tend to be more common in IOM alert patients. As three-dimensional spinal column divided and relinked in PVCR, and the correction maneuvers were restricted on single dimension, inevitably resulted in spinal cord tension changes and spinal column opposite displacement. To timely identify them, prompt interventions should be performed, and even enlarge the resected area to reduce the abrupt turning tendency of the spinal cord. 5.

Spinal Shortening for Recurrent Tethered Cord Syndrome via a Lateral Retropleural Approach: A Novel Operative Technique.

Spine shortening via vertebral osteotomy (SSVO) for recurrent tethered cord syndrome (TCS) is a novel surgical technique that avoids the complication profile associated with revision detethering. While SSVO has previously been described via a posterior approach, we describe a lateral retropleural approach for SSVO in recurrent TCS in a 21-year-old female.Our patient presented with progressive lower extremity weakness, bowel and bladder incontinence, and back pain in the setting of childhood repair of myelomeningocele and two previous detethering procedures. SSVO was offered to the patient as further detethering was deemed to have significant risk. A discectomy at T11-T12 via the lateral retropleural approach was performed, followed by a T12 partial corpectomy removing the vertebral body down to the inferior aspect of the T12 pedicle, followed by the removal of the ipsilateral pedicle. The T10, T11, L1, and L2 pedicle screws were then placed in the prone position and temporary rods were placed for temporary stability, followed by a laminectomy at T12 and a facetectomy for posterior element release. The remaining pedicle was removed, permanent rods were sequentially placed, and spinal column shortening was achieved by compression against the rods. Standing lateral radiographs demonstrated 19 millimeters (mm) of shortening after the intervention. The patient remained at her neurologic baseline postoperatively. At the six-month follow-up, the patient reported decreased lower extremity radicular pain and improved bowel and bladder function.This operative report demonstrates that SSVO via a lateral retropleural approach is a viable treatment for the recurrence of TCS. The advantages of this minimally invasive approach compared to the posterior approach are direct access to the vertebral body and disc space, avoiding the need to operate around the spinal cord. Further studies are necessary to assess this minimally invasive approach to spinal shortening and to see if a complete minimally invasive approach is possible.