The Utility of the Validated Intraoperative Bleeding Scale in Thoracolumbar Spine Surgery: A Single-Center Prospective Study.

STUDY DESIGN: Prospective, single-center study. OBJECTIVE: To evaluate the clinical relevance of the validated intraoperative bleeding severity scale (VIBe) in thoracolumbar spine surgery. METHODS: Adult patients aged 18 through 88 undergoing elective decompression, instrumentation, and fusion of the thoracolumbar spine were prospectively enrolled after informed consent was provided and written consent was obtained. Validated intraoperative bleeding severity scores were recorded intraoperatively. Univariate analysis consisted of Student T-tests, Pearson's χ2 Tests, Fisher's Exact Tests, linear regression, and binary logistic regression. Multivariable regression was conducted to adjust for baseline characteristics and potential confounding variables. RESULTS: A total of N = 121 patients were enrolled and included in the analysis. After adjusting for confounders, VIBe scores were correlated with an increased likelihood of intraoperative blood transfusion (ß = 2.46, P = .012), postoperative blood transfusion (ß = 2.36, P = .015), any transfusion (ß = 2.49, P < .001), total transfusion volume (ß = 180.8, P = .020), and estimated blood loss (EBL) (ß = 409, P < .001). Validated intraoperative bleeding severity scores had no significant association with length of hospital stay, 30-day readmission, 30-day reoperation, 30-day emergency department visit, change in pre- to post-op hemoglobin and hematocrit, total drain output, or length of surgery. CONCLUSION: The VIBe scale is associated with perioperative transfusion rates and EBL in patients undergoing thoracolumbar spine surgery. Overall, the VIBe scale has clinically relevant meaning in spine surgery, and shows potential utility in clinical research. LEVEL OF EVIDENCE: Level II.

Midpoint of C7 Lateral Mass Serves as an Accurate Reference Point for the Placement of T1 Pedicle Screws: An Anatomic Study.

BACKGROUND AND OBJECTIVES: Free-hand placement of T1 pedicle screws can often be challenging. A reliable free-hand technique for placement of T1 pedicle screws can overcome some of the difficulties associated with poor fluoroscopy in this region. The purpose of this study was to propose a novel anatomic landmark for accurate identification of the T1 entry point using the midpoint of the C7 lateral mass as a reference point. Our hypothesis is that the midpoint of the C7 lateral mass is within 1-2 mm of the center of the T1 pedicle. METHODS: Using 3-dimensional reconstruction software, the pedicle of T1 and the lateral mass of C7 were isolated to assess the location of the T1 pedicle relative to the C7 lateral mass. Specifically, the distance between the center of the T1 pedicle and the center of the C7 lateral mass was measured on 40 computed tomography scans. Furthermore, a clinical validation of this technique was performed by assessing the postoperative computed tomography scans of 53 patients undergoing cervicothoracic instrumentation. The Gertzbein and Robbins classification system was used to grade the accuracy of T1 pedicle screw placements in all patients using this technique. RESULTS: The average horizontal deviation + SD from centers of the T1 pedicle and the C7 lateral mass was 0.398 mm ± 0.953 mm. The T1 pedicle on average was slightly medial to the center of the C7 lateral mass. A total of 98.1% of T1 pedicle screws placed in vivo using the free-hand technique were of Grade A. CONCLUSION: In this article, we demonstrate that the center of the C7 lateral mass overlays the T1 pedicle and the optimal entry point is immediately below the midpoint of the C7 lateral mass. This approach provides a practical and accurate landmark in posterior cervicothoracic spine procedures that reduce the need for additional radiation exposure or increased operative time with image-guided techniques.

A 10-Year Retrospective Review on the Use of Prophylactic Spinal Reconstruction in Spinal Surgery Involving High-Risk Patients.

BACKGROUND: Spinal surgeries are being offered to a broader patient population who are both medically and surgically complex. History of prior spinal surgery, advanced age, and presence of comorbidities, such as obesity, malnutrition, steroid use, and tobacco use, are risk factors for postoperative complications. Prophylactic spinal reconstruction at the time of spinal surgery has been shown to have improved outcomes and decreased wound complications; however, outcomes focusing specifically on complex patients with a history of previous spinal surgery (or surgeries) have not been well described. METHODS: This is a retrospective study performed at the University of Maryland Medical Center (Baltimore, MD) of high-risk patients who underwent complex spinal surgery with prophylactic spinal reconstruction from 2011 to 2022. One hundred forty-three consecutive surgeries from 136 patients were included in the study. Patients younger than 17 years or who had an incomplete medical record were excluded. RESULTS: Most patients were female (63.6%) versus male (31.5%). The average American Society of Anesthesiologists score was 3. All but 6 patients (11%) had a history of at least 1 spinal surgery, with nearly half of patients having had between 2 and 5 spinal surgeries. Reconstruction was performed with paraspinous flaps in most cases (n = 133 [93%]). The overall complication rate was 10.5%, with surgical site infection being the most common complication. Seventeen patients (12.5%) underwent reoperation within 90 days of initial surgery. Average length of follow-up was 4.18 months (range, 0.03-40.53 months). CONCLUSIONS: In appropriately selected patients, prophylactic spinal reconstruction offers improved outcomes with decreased wound complications compared with salvage. For large defects, paraspinous flaps are recommended over other reconstructive options. Prolonged drain placement is felt to be protective against complications.

Proposal of a Management Algorithm to Predict the Need for Expansion Duraplasty in American Spinal Injury Association Impairment Scale Grades A-C Traumatic Cervical Spinal Cord Injury Patients.

Expansion duraplasty to reopen effaced subarachnoid space and improve spinal cord perfusion, autoregulation, and spinal pressure reactivity index (sPRX) has been advocated in patients with traumatic cervical spinal cord injury (tCSCI). We designed this study to identify candidates for expansion duraplasty, based on the absence of cerebrospinal fluid (CSF) interface around the spinal cord on magnetic resonance imaging (MRI), in the setting of otherwise adequate bony decompression. Over a 61-month period, 104 consecutive American Spinal Injury Association Impairment Scale (AIS) grades A-C patients with tCSCI had post-operative MRI to assess the adequacy of surgical decompression. Their mean age was 53.4 years, and 89% were male. Sixty-one patients had falls, 31 motor vehicle collisions, 11 sport injuries, and one an assault. The AIS grade was A in 56, B in 18, and C in 30 patients. Fifty-four patients had fracture dislocations; there was no evidence of skeletal injury in 50 patients. Mean intramedullary lesion length (IMLL) was 46.9 (standard deviation = 19.4) mm. Median time from injury to decompression was 17 h (interquartile range 15.2 h). After surgery, 94 patients had adequate decompression as judged by the presence of CSF anterior and posterior to the spinal cord, whereas 10 patients had effacement of the subarachnoid space at the injury epicenter. In two patients whose decompression was not definitive and post-operative MRI indicated inadequate decompression, expansion duraplasty was performed. Candidates for expansion duraplasty (i.e., those with inadequate decompression) were significantly younger (p < 0.0001), were AIS grade A (p < 0.0016), had either sport injuries (six patients) or motor vehicle collisions (three patients) (p < 0.0001), had fracture dislocation (p = 0.00016), and had longer IMLL (p = 0.0097). In regression models, patients with sport injuries and inadequate decompression were suitable candidates for expansion duraplasty (p = 0.03). Further, 9.6% of patients failed bony decompression alone and either did (2) or would have (8) benefited from expansion duraplasty.

An updated management algorithm for incorporating minimally invasive techniques to treat thoracolumbar trauma.

OBJECTIVE: Minimally invasive surgery (MIS) techniques can effectively stabilize and decompress many thoracolumbar injuries with decreased morbidity and tissue destruction compared with open approaches. Nonetheless, there is limited direction regarding the breadth and limitations of MIS techniques for thoracolumbar injuries. Consequently, the objectives of this study were to 1) identify the range of current practice patterns for thoracolumbar trauma and 2) integrate expert opinion and literature review to develop an updated treatment algorithm. METHODS: A survey describing 10 clinical cases with a range of thoracolumbar injuries was sent to 12 surgeons with expertise in spine trauma. The survey results were summarized using descriptive statistics, along with the Fleiss kappa statistic of interrater agreement. To develop an updated treatment algorithm, the authors used a modified Delphi technique that incorporated a literature review, the survey results, and iterative feedback from a group of 14 spine trauma experts. The final algorithm represented the consensus opinion of that expert group. RESULTS: Eleven of 12 surgeons contacted completed the case survey, including 8 (73%) neurosurgeons and 3 (27%) orthopedic surgeons. For the 4 cases involving patients with neurological deficits, nearly all respondents recommended decompression and fusion, and the proportion recommending open surgery ranged from 55% to 100% by case. Recommendations for the remaining cases were heterogeneous. Among the neurologically intact patients, MIS techniques were typically recommended more often than open techniques. The overall interrater agreement in recommendations was 0.23, indicating fair agreement. Considering both literature review and expert opinion, the updated algorithm indicated that MIS techniques could be used to treat most thoracolumbar injuries. Among neurologically intact patients, percutaneous instrumentation without arthrodesis was recommended for those with AO Spine Thoracolumbar Classification System subtype A3/A4 (Thoracolumbar Injury Classification and Severity Score [TLICS] 4) injuries, but MIS posterior arthrodesis was recommended for most patients with AO Spine subtype B2/B3 (TLICS > 4) injuries. Depending on vertebral body integrity, anterolateral corpectomy or mini-open decompression could be used for patients with neurological deficits. CONCLUSIONS: Spine trauma experts endorsed a range of strategies for treating thoracolumbar injuries but felt that MIS techniques were an option for most patients. The updated treatment algorithm may provide a foundation for surgeons interested in safe approaches for using MIS techniques to treat thoracolumbar trauma.

Efficacy of Early (≤ 24 Hours), Late (25-72 Hours), and Delayed (>72 Hours) Surgery with Magnetic Resonance Imaging-Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades C and D Acute Traumatic Central Cord Syndrome Caused by Spinal Stenosis.

The therapeutic significance of timing of decompression in acute traumatic central cord syndrome (ATCCS) caused by spinal stenosis remains unsettled. We retrospectively examined a homogenous cohort of patients with ATCCS and magnetic resonance imaging (MRI) evidence of post-treatment spinal cord decompression to determine whether timing of decompression played a significant role in American Spinal Injury Association (ASIA) motor score (AMS) 6 months following trauma. We used the t test, analysis of variance, Pearson correlation coefficient, and multiple regression for statistical analysis. During a 19-year period, 101 patients with ATCCS, admission ASIA Impairment Scale (AIS) grades C and D, and an admission AMS of ≤95 were surgically decompressed. Twenty-four of 101 patients had an AIS grade C injury. Eighty-two patients were males, the mean age of patients was 57.9 years, and 69 patients had had a fall. AMS at admission was 68.3 (standard deviation [SD] 23.4); upper extremities (UE) 28.6 (SD 14.7), and lower extremities (LE) 41.0 (SD 12.7). AMS at the latest follow-up was 93.1 (SD 12.8), UE 45.4 (SD 7.6), and LE 47.9 (SD 6.6). Mean number of stenotic segments was 2.8, mean canal compromise was 38.6% (SD 8.7%), and mean intramedullary lesion length (IMLL) was 23 mm (SD 11). Thirty-six of 101 patients had decompression within 24 h, 38 patients had decompression between 25 and 72 h, and 27 patients had decompression >72 h after injury. Demographics, etiology, AMS, AIS grade, morphometry, lesion length, surgical technique, steroid protocol, and follow-up AMS were not statistically different between groups treated at different times. We analyzed the effect size of timing of decompression categorically and in a continuous fashion. There was no significant effect of the timing of decompression on follow-up AMS. Only AMS at admission determined AMS at follow-up (coefficient = 0.31; 95% confidence interval [CI]:0.21; p = 0.001). We conclude that timing of decompression in ATCCS caused by spinal stenosis has little bearing on ultimate AMS at follow-up.

Efficacy of Ultra-Early (< 12 h), Early (12-24 h), and Late (>24-138.5 h) Surgery with Magnetic Resonance Imaging-Confirmed Decompression in American Spinal Injury Association Impairment Scale Grades A, B, and C Cervical Spinal Cord Injury.

In cervical traumatic spinal cord injury (TSCI), the therapeutic effect of timing of surgery on neurological recovery remains uncertain. Additionally, the relationship between extent of decompression, imaging biomarker evidence of injury severity, and outcome is incompletely understood. We investigated the effect of timing of decompression on long-term neurological outcome in patients with complete spinal cord decompression confirmed on postoperative magnetic resonance imaging (MRI). American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade conversion was determined in 72 AIS grades A, B, and C patients 6 months after confirmed decompression. Thirty-two patients underwent decompressive surgery ultra-early (< 12 h), 25 underwent decompressive surgery early (12-24 h), and 15 underwent decompressive surgery late (> 24-138.5 h) after injury. Age, gender, injury mechanism, intramedullary lesion length (IMLL) on MRI, admission ASIA motor score, and surgical technique were not statistically different among groups. Motor complete patients (p = 0.009) and those with fracture dislocations (p = 0.01) tended to be operated on earlier. Improvement of one grade or more was present in 55.6% of AIS grade A, 60.9% of AIS grade B, and 86.4% of AIS grade C patients. Admission AIS motor score (p = 0.0004) and pre-operative IMLL (p = 0.00001) were the strongest predictors of neurological outcome. AIS grade improvement occurred in 65.6%, 60%, and 80% of patients who underwent decompression ultra-early, early, and late, respectively (p = 0.424). Multiple regression analysis revealed that IMLL was the only significant variable predictive of AIS grade conversion to a better grade (odds ratio, 0.908; confidence interval [CI], 0.862-0.957; p < 0.001). We conclude that in patients with post-operative MRI confirmation of complete decompression following cervical TSCI, pre-operative IMLL, not the timing of surgery, determines long-term neurological outcome.

Perineal and Radicular Pain Caused by Contralateral Sacral Nerve Root Schwannoma: Case Report and Review of Literature.

BACKGROUND: Sacral schwannomas are very rare nerve sheath tumors. Patients usually present with a variety of nonspecific symptoms, which often lead to a delay in diagnosis. Although most schwannomas are benign, they present surgical challenges owing to their proximity to neurologic and other anatomic structures. CASE DESCRIPTION: This 58-year-old female presented with a 2-month old history of left-sided perineal and radicular pain secondary to a right S2 sacral nerve root schwannoma. The sacral mass demonstrated homogenous enhancement with cystic changes in a T2-weighted magnetic resonance imaging sequence. The patient underwent S1-S3 laminectomy and tumor excision through a posterior surgical approach. Intraoperative monitoring was used to distinguish nonfunctional tissue during tumor resection. The patient had an unremarkable postoperative course. CONCLUSIONS: Sacral schwannomas can present with a variety of nonspecific symptoms. They pose unique challenges given their location, size, and involvement of surrounding structures. Complete surgical resection is the main goal of sacral schwannoma treatment. A combined anterior-posterior surgical approach and a multidisciplinary surgical team are associated with improved outcomes.

Intramedullary Lesion Length on Postoperative Magnetic Resonance Imaging is a Strong Predictor of ASIA Impairment Scale Grade Conversion Following Decompressive Surgery in Cervical Spinal Cord Injury.

BACKGROUND: Evidence indicates that, over time, patients with spinal cord injury (SCI) improve neurologically in various degrees. We sought to further investigate indicators of grade conversion in cervical SCI. OBJECTIVE: To detect predictors of ASIA impairment scale (AIS) grade conversion in SCI following surgical decompression. METHODS: In a retrospective study, demographics, clinical, imaging, and surgical data from 100 consecutive patients were assessed for predictors of AIS grade conversion. RESULTS: American Spinal Injury Association motor score was 17.1. AIS grade was A in 52%, B in 29%, and C in 19% of patients. Surgical decompression took place on an average of 17.6 h following trauma (≤12 h in 51 and >12 h in 49). Complete decompression was verified by magnetic resonance imaging (MRI) in 73 patients. Intramedullary lesion length (IMLL) on postoperative MRI measured 72.8 mm, and hemorrhage at the injury epicenter was noted in 71 patients. Grade conversion took place in 26.9% of AIS grade A patients, 65.5% of AIS grade B, and 78.9% of AIS grade C. AIS grade conversion had statistical relationship with injury severity score, admission AIS grade, extent of decompression, presence of intramedullary hemorrhage, American Spinal Injury Association motor score, and IMLL. A stepwise multiple logistic regression analysis indicated IMLL was the sole and strongest indicator of AIS grade conversion (odds ratio 0.950, 95% CI 0.931-0.969). For 1- and 10-mm increases in IMLL, the model indicates 4% and 40% decreases, respectively, in the odds of AIS grade conversion. CONCLUSION: Compared with other surrogates, IMLL remained as the only predictor of AIS grade conversion.

Differentiation of idiopathic spinal cord herniation from dorsal arachnoid webs on MRI and CT myelography.

OBJECTIVE Dorsal arachnoid webs (DAWs) and spinal cord herniation (SCH) are uncommon abnormalities affecting the thoracic spinal cord that can result in syringomyelia and significant neurological morbidity if left untreated. Differentiating these 2 entities on the basis of clinical presentation and radiological findings remains challenging but is of vital importance in planning a surgical approach. The authors examined the differences between DAWs and idiopathic SCH on MRI and CT myelography to improve diagnostic confidence prior to surgery. METHODS Review of the picture archiving and communication system (PACS) database between 2005 and 2015 identified 6 patients with DAW and 5 with SCH. Clinical data including demographic information, presenting symptoms and neurological signs, and surgical reports were collected from the electronic medical records. Ten of the 11 patients underwent MRI. CT myelography was performed in 3 patients with DAW and in 1 patient with SCH. Imaging studies were analyzed by 2 board-certified neuroradiologists for the following features: 1) location of the deformity; 2) presence or absence of cord signal abnormality or syringomyelia; 3) visible arachnoid web; 4) presence of a dural defect; 5) nature of dorsal cord indentation (abrupt "scalpel sign" vs "C"-shaped); 6) focal ventral cord kink; 7) presence of the nuclear trail sign (endplate irregularity, sclerosis, and/or disc-space calcification that could suggest a migratory path of a herniated disc); and 8) visualization of a complete plane of CSF ventral to the deformity. RESULTS The scalpel sign was positive in all patients with DAW. The dorsal indentation was C-shaped in 5 of 6 patients with SCH. The ventral subarachnoid space was preserved in all patients with DAW and interrupted in cases of SCH. In no patient was a web or a dural defect identified. CONCLUSIONS DAW and SCH can be reliably distinguished on imaging by scrutinizing the nature of the dorsal indentation and the integrity of the ventral subarachnoid space at the level of the cord deformity.

Cervical spine injury from gunshot wounds.

OBJECT: Gunshot wounds (GSWs) to the cervical spine have been examined in a limited number of case series, and operative management of this traumatic disease has been sparsely discussed. The current literature supports and the authors hypothesize that patients without neurological deficit need neither surgical fusion nor decompression. Patients with GSWs and neurological deficits, however, pose a greater management challenge. The authors have compiled the experience of the R Adams Cowley Shock Trauma Center in Baltimore, Maryland, over the past 12 years, creating the largest series of such injuries, with a total number of 40 civilian patients needing neurosurgical evaluation. The current analysis examines presenting bone injury, surgical indication, presenting neurological examination, and neurological outcome. In this study, the authors characterize the incidence, severity, and recovery potential of cervical GSWs. The rate of unstable fractures requiring surgical intervention is documented. A detailed discussion of surgical indications with a treatment algorithm for cervical instability is offered. METHODS: A total of 144 cervical GSWs were retrospectively reviewed. Of these injuries, 40 had documented neurological deficits. No neurosurgical consultation was requested for patients without deficit. Epidemiological and clinical information was collected on patients with neurological deficit, including age, sex, timing, indication, type of surgery, initial examination after resuscitation, follow-up examination, and imaging data. RESULTS: Twenty-eight patients (70%) presented with complete neurological deficits and 12 patients (30%) presented with incomplete injuries. Fourteen (35%) of the 40 patients underwent neurosurgical intervention. Twelve patients (30%) required intervention for cervical instability. Seven patients required internal fixation involving 4 anterior fusions, 2 posterior fusions, and 1 combined approach. Five patients were managed with halo immobilization. Two patients underwent decompression alone for neurological deterioration and persistent compressive injury, both of whom experienced marked neurological recovery. Follow-up was obtained in 92% of cases. Three patients undergoing stabilization converted at least 1 American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade and the remaining operative cases experienced small ASIA motor score improvement. Eighteen patients underwent inpatient MRI. No patient suffered complications or neurological deterioration related to retained metal. Three of 28 patients presenting with AIS Grade A improved to Grade B. For those 12 patients with incomplete injury, 1 improved from AIS Grade C to D, and 3 improved from Grade D to E. CONCLUSIONS: Spinal cord injury from GSWs often results in severe neurological deficits. In this series, 30% of these patients with deficits required intervention for instability. This is the first series that thoroughly documents AIS improvement in this patient population. Adherence to the proposed treatment algorithm may optimize neurological outcome and spine stability.

An analysis of deep vein thrombosis in 1277 consecutive neurosurgical patients undergoing routine weekly ultrasonography.

OBJECT: Patients requiring neurosurgical intervention are known to be at increased risk for deep vein thrombosis (DVT) and attendant morbidity and mortality. Pulmonary embolism (PE) is the most catastrophic sequela of DVT and is the direct cause of death in 16% of all in-hospital mortalities. Protocols for DVT screening and early detection, as well as treatment paradigms to prevent PE in the acute postoperative period, are needed in neurosurgery. The authors analyzed the effectiveness of weekly lower-extremity venous duplex ultrasonography (LEVDU) in patients requiring surgical intervention for cranial or spinal pathology for detection of DVT and prevention of PE. METHODS: Data obtained in 1277 consecutive patients admitted to a major tertiary care center requiring neurosurgical intervention were retrospectively reviewed. All patients underwent admission (within 1 week of neurosurgical intervention) LEVDU as well as weekly LEVDU surveillance if the initial study was normal. Additional LEVDU was ordered in any patient in whom DVT was suspected on daily clinical physical examination or in patients in whom chest CT angiography confirmed a pulmonary embolus. An electronic database was created and statistical analyses performed. RESULTS: The overall incidence of acute DVT was 2.8% (36 patients). Of these cases of DVT, a statistically significant greater number (86%) were discovered on admission (within 1-7 days after admission) screening LEVDU (p < 0.05), whereas fewer were documented 8-14 days after admission (2.8%) or after 14 days (11.2%) postadmission. Additionally, for acute DVT detection in the present population, there were no underlying statistically significant risk factors regarding baseline physical examination, age, ambulatory status, or type of surgery. The overall incidence of acute symptomatic PE was 0.3% and the mortality rate was 0%. CONCLUSIONS: Performed within 1 week of admission in patients who will undergo neurosurgical intervention, LEVDU is effective in screening for acute DVT and initiating treatment to prevent PE, thereby decreasing the overall mortality rate. Routine LEVDU beyond this time point may not be needed to detect DVT and prevent PE unless a change in the patient's physical examination status is detected.

Pathophysiology of primary spinal syringomyelia.

OBJECT: The pathogenesis of syringomyelia in patients with an associated spinal lesion is incompletely understood. The authors hypothesized that in primary spinal syringomyelia, a subarachnoid block effectively shortens the length of the spinal subarachnoid space (SAS), reducing compliance and the ability of the spinal theca to dampen the subarachnoid CSF pressure waves produced by brain expansion during cardiac systole. This creates exaggerated spinal subarachnoid pressure waves during every heartbeat that act on the spinal cord above the block to drive CSF into the spinal cord and create a syrinx. After a syrinx is formed, enlarged subarachnoid pressure waves compress the external surface of the spinal cord, propel the syrinx fluid, and promote syrinx progression. METHODS: To elucidate the pathophysiology, the authors prospectively studied 36 adult patients with spinal lesions obstructing the spinal SAS. Testing before surgery included clinical examination; evaluation of anatomy on T1-weighted MRI; measurement of lumbar and cervical subarachnoid mean and pulse pressures at rest, during Valsalva maneuver, during jugular compression, and after removal of CSF (CSF compliance measurement); and evaluation with CT myelography. During surgery, pressure measurements from the SAS above the level of the lesion and the lumbar intrathecal space below the lesion were obtained, and cardiac-gated ultrasonography was performed. One week after surgery, CT myelography was repeated. Three months after surgery, clinical examination, T1-weighted MRI, and CSF pressure recordings (cervical and lumbar) were repeated. Clinical examination and MRI studies were repeated annually thereafter. Findings in patients were compared with those obtained in a group of 18 healthy individuals who had already undergone T1-weighted MRI, cine MRI, and cervical and lumbar subarachnoid pressure testing. RESULTS: In syringomyelia patients compared with healthy volunteers, cervical subarachnoid pulse pressure was increased (2.7 ± 1.2 vs 1.6 ± 0.6 mm Hg, respectively; p = 0.004), pressure transmission to the thecal sac below the block was reduced, and spinal CSF compliance was decreased. Intraoperative ultrasonography confirmed that pulse pressure waves compressed the outer surface of the spinal cord superior to regions of obstruction of the subarachnoid space. CONCLUSIONS: These findings are consistent with the theory that a spinal subarachnoid block increases spinal subarachnoid pulse pressure above the block, producing a pressure differential across the obstructed segment of the SAS, which results in syrinx formation and progression. These findings are similar to the results of the authors' previous studies that examined the pathophysiology of syringomyelia associated with obstruction of the SAS at the foramen magnum in the Chiari Type I malformation and indicate that a common mechanism, rather than different, separate mechanisms, underlies syrinx formation in these two entities. Clinical trial registration no.: NCT00011245.

Scoliosis research society morbidity and mortality of adult scoliosis surgery.

STUDY DESIGN: A retrospective review. OBJECTIVE: To obtain an assessment of complication incidence using the largest known database of adult scoliosis and to determine whether the rate of complication depends on various clinical parameters. SUMMARY OF BACKGROUND DATA: The Scoliosis Research Society (SRS) morbidity and mortality database has previously been used to assess complication rates in adolescents undergoing scoliosis correction. To better understand complications in adults, degenerative and idiopathic adult scoliosis (AS) cases were studied. METHODS: The SRS morbidity and mortality database was queried to identify cases of AS from 2004 to 2007. Complications were identified and analyzed on the basis of patient type of scoliosis (degenerative vs. adult idiopathic), age, use of osteotomy, revision surgery status, and surgical approach. Age was stratified into less than or equal to 60 and greater than 60. Surgical approach was stratified into anterior only, posterior only, and combined anterior/posterior. RESULTS: A total of 4980 cases of AS were submitted from 2004 to 2007. There were 521 patients with complications (10.5%), and a total of 669 complications (13.4%). The most common complications were dural tear 142 (2.9%), superficial wound infection 46 (0.9%), deep wound infection 73 (1.5%), implant complication 80 (1.6%), acute neurological deficits 49 (1.0%), delayed neurological deficits 41 (0.5%), epidural hematoma 12 (0.2%), wound hematoma 22 (0.4%), pulmonary embolus 12 (0.2%), and deep venous thrombosis 9 (0.2%). There were 17 deaths (0.3%). There were 2555 patients with degenerative and 2425 patients with adult idiopathic scoliosis. Complication rates in these two groups were not significantly different (11.0% and 9.9%, respectively, P = 0.20). Age was not associated with complication rate (P = 0.32). Significantly higher complication rates were identified in osteotomies, revision surgery, and/or combined anterior-posterior surgery (P = 0.0006, 0.006, and 0.03, respectively). CONCLUSIONS: The overall complication rate for AS treatment is 13.4%. Complication rate is significantly higher when osteotomies, revision procedures, and combined anterior/posterior approaches are used. Complication rate is not influenced by scoliosis type or age.

Rates of new neurological deficit associated with spine surgery based on 108,419 procedures: a report of the scoliosis research society morbidity and mortality committee.

STUDY DESIGN: Retrospective review of a prospectively collected, multicenter database. OBJECTIVE: To assess rates of new neurologic deficit (NND) associated with spine surgery. SUMMARY OF BACKGROUND DATA: NND is a potential complication of spine surgery, but previously reported rates are often limited by small sample size and single-surgeon experiences. METHODS: The Scoliosis Research Society morbidity and mortality database was queried for spinal surgery cases complicated by NND from 2004 to 2007, including nerve root deficit (NRD), cauda equina deficit (CED), and spinal cord deficit (SCD). Use of neuromonitoring was assessed. Recovery was stratified as complete, partial, or none. Rates of NND were stratified based on diagnosis, age (pediatric < 21; adult ≥ 21), and surgical parameters. RESULTS: Of the 108,419 cases reported, NND was documented for 1064 (1.0%), including 662 NRDs, 74 CEDs, and 293 SCDs (deficit not specified for 35 cases). Rates of NND were calculated on the basis of diagnosis. Revision cases had a 41% higher rate of NND (1.25%) compared with primary cases (0.89%; P < 0.001). Pediatric cases had a 59% higher rate of NND (1.32%) compared with adult cases (0.83%; P < 0.001). The rate of NND for cases with implants was more than twice that for cases without implants (1.15% vs. 0.52%, P < 0.001). Neuromonitoring was used for 65% of cases, and for cases with new NRD, CED, and SCD, changes in neuromonitoring were reported in 11%, 8%, and 40%, respectively. The respective percentages of no recovery, partial, and complete recovery for NRD were 4.7%, 46.8%, and 47.1%, respectively; for CED were 9.6%, 45.2%, and 45.2%, respectively; and for SCD were 10.6%, 43%, and 45.7%, respectively. CONCLUSION: Our data demonstrate that, even among skilled spinal deformity surgeons, new neurologic deficits are inherent potential complications of spine surgery. These data provide general benchmark rates for NND with spine surgery as a basis for patient counseling and for ongoing efforts to improve safety of care.

Short-term morbidity and mortality associated with correction of thoracolumbar fixed sagittal plane deformity: a report from the Scoliosis Research Society Morbidity and Mortality Committee.

STUDY DESIGN: Retrospective review. OBJECTIVE: Our objective was to assess the short-term complication rate in patients undergoing treatment of thoracolumbar fixed sagittal plane deformity (FSPD). SUMMARY OF BACKGROUND DATA: The reported morbidity and mortality for the surgical treatment of thoracolumbar FSPD is varied and based on studies with small sample sizes. Further studies are needed to better assess FSPD complication rate, and the factors that influence it. METHODS: The Scoliosis Research Society (SRS) Morbidity and Mortality Database was queried to identify cases of thoracolumbar FSPD from 2004 to 2007. Complications were analyzed based on correction technique, surgical approach, surgeon experience (SRS membership status used as a surrogate), patient age, and history of prior surgery. RESULTS: Five hundred and seventy-eight cases of FSPD were identified. Osteotomies were performed in 402 cases (70%), including 215 pedicle subtraction osteotomies (PSO), 135 Smith-Petersen osteotomies (SPO), 19 anterior discectomy with corpectomy procedures (ADC), 18 vertebral column resections (VCR), and 15 unspecified osteotomies. There were 170 complications (29.4%) in 132 patients. There were three deaths (0.5%). The most common complications were durotomy (5.9%), wound infection (3.8%), new neurologic deficit (3.8%), implant failure (1.7%), wound hematoma (1.6%), epidural hematoma (1.4%), and pulmonary embolism (1.0%). Procedures including an osteotomy had a higher complication rate (34.8%) than cases not including an osteotomy (17.0%, P < 0.001), and this remained significant after adjusting for the effects of patient age, surgeon experience, and history of prior surgery (P = 0.003, odds ratio = 2.070, 95% CI = 1.291-3.321). Not significantly associated with complication rate were patient age (P = 0.68), surgeon experience (P = 0.18), and history of prior surgery (P = 0.10). Complication rates were progressively higher from no osteotomy (17.0%), to SPO (28.1%), to PSO (39.1%), to VCR (61.1%). CONCLUSION: The short-term complication rate for treatment of FSPD is 29.4%. The complication rate was significantly higher in patients undergoing osteotomies, and more aggressive osteotomies were associated with progressively higher complication rates.

Rates of infection after spine surgery based on 108,419 procedures: a report from the Scoliosis Research Society Morbidity and Mortality Committee.

STUDY DESIGN: Retrospective review of a prospectively collected database. OBJECTIVE: Our objective was to assess the rates of postoperative wound infection associated with spine surgery. SUMMARY OF BACKGROUND DATA: Although wound infection after spine surgery remains a common source of morbidity, estimates of its rates of occurrence remain relatively limited. The Scoliosis Research Society prospectively collects morbidity and mortality data from its members, including the occurrence of wound infection. METHODS: The Scoliosis Research Society morbidity and mortality database was queried for all reported spine surgery cases from 2004 to 2007. Cases were stratified based on factors including diagnosis, adult (≥ 21 years) versus pediatric (<21 years), primary versus revision, use of implants, and whether a minimally invasive approach was used. Superficial, deep, and total infection rates were calculated. RESULTS.: In total, 108,419 cases were identified, with an overall total infection rate of 2.1% (superficial = 0.8%, deep = 1.3%). Based on primary diagnosis, total postoperative wound infection rate for adults ranged from 1.4% for degenerative disease to 4.2% for kyphosis. Postoperative wound infection rates for pediatric patients ranged from 0.9% for degenerative disease to 5.4% for kyphosis. Rate of infection was further stratified based on subtype of degenerative disease, type of scoliosis, and type of kyphosis for both adult and pediatric patients. Factors associated with increased rate of infection included revision surgery (P < 0.001), performance of spinal fusion (P < 0.001), and use of implants (P < 0.001). Compared with a traditional open approach, use of a minimally invasive approach was associated with a lower rate of infection for lumbar discectomy (0.4% vs. 1.1%; P < 0.001) and for transforaminal lumbar interbody fusion (1.3% vs. 2.9%; P = 0.005). CONCLUSION: Our data suggest that postsurgical infection, even among skilled spine surgeons, is an inherent potential complication. These data provide general benchmarks of infection rates as a basis for ongoing efforts to improve safety of care.

Incidence of unintended durotomy in spine surgery based on 108,478 cases.

BACKGROUND: Unintended durotomy is a common complication of spinal surgery. However, the incidences reported in the literature vary widely and are based primarily on relatively small case numbers from a single surgeon or institution. OBJECTIVE: To provide spine surgeons with a reliable incidence of unintended durotomy in spinal surgery and to assess various factors that may influence the risk of durotomy. METHODS: We assessed 108,478 surgical cases prospectively submitted by members of the Scoliosis Research Society to a deidentified database from 2004 to 2007. RESULTS: Unintended durotomy occurred in 1.6% (1745 of 108 478) of all cases. The incidence of unintended durotomy ranged from 1.1% to 1.9% on the basis of preoperative diagnosis, with the highest incidence among patients treated for kyphosis (1.9%) or spondylolisthesis (1.9%) and the lowest incidence among patients treated for scoliosis (1.1%). The most common indication for spine surgery was degenerative spinal disorder, and among these patients, there was a lower incidence of durotomy for cervical (1.0%) vs thoracic (2.2%; P = .01) or lumbar (2.1%, P < .001) cases. Scoliosis procedures were further characterized by etiology, with the highest incidence of durotomy in the degenerative subgroup (2.2% vs 1.1%; P < .001). Durotomy was more common in revision compared with primary surgery (2.2% vs 1.5%; P < .001) and was significantly more common among elderly (> 80 years of age) patients (2.2% vs 1.6%; P = .006). There was a significant association between unintended durotomy and development of a new neurological deficit (P < .001). CONCLUSION: Unintended durotomy occurred in at least 1.6% of spinal surgeries, even among experienced surgeons. Our data provide general benchmarks of durotomy rates and serve as a basis for ongoing efforts to improve safety of care.

Morbidity and mortality in the surgical treatment of six hundred five pediatric patients with isthmic or dysplastic spondylolisthesis.

STUDY DESIGN: Retrospective analysis of prospectively collected database. OBJECTIVE: To analyze the rate of complications, including neurologic deficits, associated with operative treatment of pediatric isthmic and dysplastic spondylolisthesis. SUMMARY OF BACKGROUND DATA: Pediatric isthmic and dysplastic spondylolisthesis are relatively uncommon dis-orders. Several prior studies have suggested a high rate of complication associated with operative intervention. How-ever, most of these studies were performed with sufficiently small sample sizes such that the presence of one complication could significantly affect the overall rate. The Scoliosis Research Society (SRS) prospectively collects morbidity and mortality (M&M) data from its members. This multicentered, multisurgeon database permits analysis of the surgical treatment of this relatively rare condition on an aggregate scale and provides surgeons with useful information for preoperative counseling. METHODS: Patients who underwent surgical treatment for isthmic or dysplastic spondylolisthesis from 2004 to 2007 were identified from the SRS M&M database. Inclusion criteria for analysis included age ≤ 21 and a primary diagnosis of isthmic or dysplastic spondylolisthesis. RESULTS: Of 25,432 pediatric cases reported, there were a total of 605 (2.4%) cases of pediatric dysplastic (n ∇ 62, 10%) and isthmic (n ∇ 543, 90%) spondylolisthesis, with a mean age of 15 years (range, 4-21). Approximately 50% presented with neural element compression, and less than 1% of cases were revisions. Surgical procedures included fusions in 92%, osteotomies in 39%, and reductions in 38%. The overall complication rate was 10.4%. The most common complications included postoperative neurologic deficit (n ∇ 31, 5%), dural tear (n ∇ 8, 1.3%), and wound infection (n ∇ 12, 2%). Perioperative deep venous thrombosis and pulmonary embolus were reported in 2 (0.3%) and 1 (0.2%) patients, respectively. There were no deaths in this series. CONCLUSION: Pediatric isthmic and dysplastic spondylolisthesis are relatively uncommon disorders, representing only 2.4% of pediatric spine procedures in the present study. Even among experienced spine surgeons, surgical treatment of these spinal conditions is associated with a relatively high morbidity.