Lumbar endoscopic spine surgery for persistent genital arousal disorder/genitopelvic dysesthesia resulting from lumbosacral annular tear-induced sacral radiculopathy.

BACKGROUND: Persistent genital arousal disorder/genitopelvic dysesthesia (PGAD/GPD) is characterized by distressing, abnormal genitopelvic sensations, especially unwanted arousal. In a subgroup of patients with PGAD/GPD, cauda equina Tarlov cyst-induced sacral radiculopathy has been reported to trigger the disorder. In our evaluation of lumbosacral magnetic resonance images in patients with PGAD/GPD and suspected sacral radiculopathy, some had no Tarlov cysts but showed lumbosacral disc annular tear pathology. AIM: The aims were 2-fold: (1) to utilize a novel multidisciplinary step-care management algorithm designed to identify a subgroup of patients with PGAD/GPD and lumbosacral annular tear-induced sacral radiculopathy who could benefit from lumbar endoscopic spine surgery (LESS) and (2) to evaluate long-term safety and efficacy of LESS. METHODS: Clinical data were collected on patients with PGAD/GPD who underwent LESS between 2016 and 2020 with at least 1-year follow-up. LESS was indicated because all had lumbosacral annular tear-induced sacral radiculopathy confirmed by our multidisciplinary management algorithm that included the following: step A, a detailed psychosocial and medical history; step B, noninvasive assessments for sacral radiculopathy; step C, targeted diagnostic transforaminal epidural spinal injections resulting in a temporary, clinically significant reduction of PGAD/GPD symptoms; and step D, surgical intervention with LESS and postoperative follow-up. OUTCOMES: Treatment outcome was based on the validated Patient Global Impression of Improvement, measured at postoperative intervals. RESULTS: Our cohort included 15 cisgendered women and 5 cisgendered men (mean ± SD age, 40.3 ± 16.8 years) with PGAD/GPD who fulfilled the criteria of lumbosacral annular tear-induced sacral radiculopathy based on our multidisciplinary management algorithm. Patients were followed for an average of 20 months (range, 12-37) post-LESS. Lumbosacral annular tear pathology was identified at multiple levels, the most common being L4-L5 and L5-S1. Twenty-two LESS procedures were performed in 20 patients. Overall, 80% (16/20) reported improvement on the Patient Global Impression of Improvement; 65% (13/20) reported improvement as much better or very much better. All patients were discharged the same day. There were no surgical complications. CLINICAL IMPLICATIONS: Among the many recognized triggers for PGAD/GPD, this subgroup exhibited lumbosacral annular tear-induced sacral radiculopathy and experienced long-term alleviation of symptoms by LESS. STRENGTHS AND LIMITATIONS: Strengths include long-term post-surgical follow-up and demonstration that LESS effectively treats patients with PGAD/GPD who have lumbosacral annular tear-induced sacral radiculopathy, as established by a multidisciplinary step-care management algorithm. Limitations include the small study cohort and the unavailability of a clinical measure specific for PGAD/GPD. CONCLUSION: LESS is safe and effective in treating patients with PGAD/GPD who are diagnosed with lumbosacral annular tear-induced sacral radiculopathy.

International Society for the Study of Women's Sexual Health (ISSWSH) Review of Epidemiology and Pathophysiology, and a Consensus Nomenclature and Process of Care for the Management of Persistent Genital Arousal Disorder/Genito-Pelvic Dysesthesia (PGAD/GPD).

BACKGROUND: Persistent genital arousal disorder (PGAD), a condition of unwanted, unremitting sensations of genital arousal, is associated with a significant, negative psychosocial impact that may include emotional lability, catastrophization, and suicidal ideation. Despite being first reported in 2001, PGAD remains poorly understood. AIM: To characterize this complex condition more accurately, review the epidemiology and pathophysiology, and provide new nomenclature and guidance for evidence-based management. METHODS: A panel of experts reviewed pertinent literature, discussed research and clinical experience, and used a modified Delphi method to reach consensus concerning nomenclature, etiology, and associated factors. Levels of evidence and grades of recommendation were assigned for diagnosis and treatment. OUTCOMES: The nomenclature of PGAD was broadened to include genito-pelvic dysesthesia (GPD), and a new biopsychosocial diagnostic and treatment algorithm for PGAD/GPD was developed. RESULTS: The panel recognized that the term PGAD does not fully characterize the constellation of GPD symptoms experienced by patients. Therefore, the more inclusive term PGAD/GPD was adopted, which maintains the primacy of the distressing arousal symptoms and acknowledges associated bothersome GPD. While there are diverse biopsychosocial contributors, there is a common underlying neurologic basis attributable to spontaneous intense activity of the genito-pelvic region represented in the somatosensory cortex and its projections. A process of care diagnostic and treatment strategy was developed to guide the clinician, whenever possible, by localizing the symptoms as originating in any of five regions: (i) end organ, (ii) pelvis/perineum, (iii) cauda equina, (iv) spinal cord, and (v) brain. Psychological treatment strategies were considered critical and should be performed in conjunction with medical strategies. Pharmaceutical interventions may be used based on their site and mechanism of action to reduce patients' symptoms and the associated bother and distress. CLINICAL IMPLICATIONS: The process of care for PGAD/GPD uses a personalized, biopsychosocial approach for diagnosis and treatment. STRENGTHS AND LIMITATIONS: Strengths and Limitations: Strengths include characterization of the condition by consensus, analysis, and recommendation of a new nomenclature and a rational basis for diagnosis and treatment. Future investigations into etiology and treatment outcomes are recommended. The main limitations are the dearth of knowledge concerning this condition and that the current literature consists primarily of case reports and expert opinion. CONCLUSION: We provide, for the first time, an expert consensus review of the epidemiology and pathophysiology and the development of a new nomenclature and rational algorithm for management of this extremely distressing sexual health condition that may be more prevalent than previously recognized. Goldstein I, Komisaruk BR, Pukall CF, et al. International Society for the Study of Women's Sexual Health (ISSWSH) Review of Epidemiology and Pathophysiology, and a Consensus Nomenclature and Process of Care for the Management of Persistent Genital Arousal Disorder/Genito-Pelvic Dysesthesia (PGAD/GPD). J Sex Med 2021;18:665-697.

Complications associated with the initial learning curve of minimally invasive spine surgery: a systematic review.

BACKGROUND: There is an inherently difficult learning curve associated with minimally invasive surgical (MIS) approaches to spinal decompression and fusion. The association between complication rate and the learning curve remains unclear. QUESTIONS/PURPOSES: We performed a systematic review for articles that evaluated the learning curves of MIS procedures for the spine, defined as the change in frequency of complications and length of surgical time as case number increased, for five types of MIS for the spine. METHODS: We conducted a systematic review in the PubMed database using the terms "minimally invasive spine surgery AND complications AND learning curve" followed by a manual citation review of included manuscripts. Clinical outcome and learning curve metrics were categorized for analysis by surgical procedure (MIS lumbar decompression procedures, MIS transforaminal lumbar interbody fusion, percutaneous pedicle screw insertion, laparoscopic anterior lumbar interbody fusion, and MIS cervical procedures). As the most consistent parameters used to evaluate the learning curve were procedure time and complication rate as a function of chronologic case number, our analysis focused on these. The search strategy identified 15 original studies that included 966 minimally invasive procedures. Learning curve parameters were correlated to chronologic procedure number in 14 of these studies. RESULTS: The most common learning curve complication for decompressive procedures was durotomy. For fusion procedures, the most common complications were implant malposition, neural injury, and nonunion. The overall postoperative complication rate was 11% (109 of 966 cases). The learning curve was overcome for operative time and complications as a function of case numbers in 20 to 30 consecutive cases for most techniques discussed within this review. CONCLUSIONS: The quantitative assessment of the procedural learning curve for MIS techniques for the spine remains challenging because the MIS techniques have different learning curves and because they have not been assessed in a consistent manner across studies. Complication rates may be underestimated by the studies we identified because surgeons tend to select patients carefully during the early learning curve period. The field of MIS would benefit from a standardization of study design and collected parameters in future learning curve investigations.

MIS TLIF, EndoTLIF, and the Ability of Navigation/Robotics to Enable Spinal Surgery in an Ambulatory Care Setting.

STUDY DESIGN: Technical Report. OBJECTIVE: Performing surgeries in the ambulatory surgery center affords improved efficiencies in terms of cost and speed. However, ambulatory surgery is only successful if complications, re-admissions, and re-operations are avoided. This report describes the San Diego Outpatient Lumbar Fusion Program, a culmination of cumulative incremental improvements in patient selection and patient education, meticulous peri-operative management, minimally invasive techniques together with navigation/robotics. METHODS: Retrospective review of prospectively collected data on 1-2 level minimally invasive transforaminal lumbar interbody fusions (MIS TLIF). RESULTS: Healthy patients (age 72 years old or less, BMI less than 50, ASA 1 or 2) with good social support and reasonable pre-operative function (ODI 50 or less) treated with the MIS TLIF technique can be discharged home in less than 1 midnight with good clinical results. CONCLUSIONS: Relatively young, healthy patients can safely and effectively undergo 1-2 level lumbar fusion surgery in the ASC setting when using contemporary minimally invasive techniques and computer-assisted navigation/robotics.

The current state of minimally invasive spine surgery.

Minimally invasive surgery for spinal disorders is predicated on the following basic principles: (1) avoid muscle crush injury by self-retaining retractors; (2) do not disrupt tendon attachment sites of key muscles, particularly the origin of the multifidus muscle at the spinous process; (3) use known anatomic neurovascular and muscle compartment planes; and (4) minimize collateral soft-tissue injury by limiting the width of the surgical corridor. The traditional midline posterior approach for lumbar decompression and fusion violates these key principles of minimally invasive surgery. The tendon origin of the multifidus muscle is detached, the surgical corridor is exceedingly wide, and significant muscle crush injury occurs with the use of powerful self-retaining retractors. The combination of these factors leads to well-described changes in muscle physiology and function. Minimally invasive posterior lumbar surgery is performed with table-mounted tubular retractors that focus the surgical dissection to a narrow corridor directly over the surgical target site. The path of the surgical corridor is chosen based on anatomic planes, specifically avoiding injury to the musculotendinous complex and the neurovascular bundle. With these relatively simple modifications in the minimally invasive surgical technique, significant improvements have been achieved in intraoperative blood loss, postoperative pain, and surgical morbidity. However, minimally invasive surgical techniques remains technically demanding, and a significant complication rate has been reported during a surgeon's initial learning curve for the procedures. Improvements in surgeon training along with long-term prospective studies will be needed for advancements in this area of spine surgery.

The History of Endoscopic Posterior Lumbar Surgery.

Throughout its evolution, spine surgery has migrated toward less invasiveness. For posterior lumbar surgery, percutaneous techniques together with endoscopic visualization allow for the smallest surgical corridor. Initially, this approach utilized the natural entry point into the spinal canal via the transforaminal approach via Kamin's triangle. The interlaminar endoscopic technique was subsequently developed to address central disc herniations at L5-S1, where the transforaminal approach can be challenging to reach the surgical pathology. More recently, the dual portal posterior lumbar endoscopic technique provides for yet another method of performing posterior lumbar surgery, expanding its versatility, including the treatment of spinal stenosis. In addition to treating disc pathology, percutaneous endoscopic lumbar interbody fusions are now performed in select patients in the ambulatory surgery setting. Despite the dramatic advantages of advanced minimally invasive procedures, the adoption of endoscopic spine surgery in everyday practice has lagged. The main obstacle to adoption appears to be the difficult learning curve of endoscopic surgery combined with the fact that traditional microdiscectomy surgery remains one of the most successful operations in our treatment armamentarium. The successful future of endoscopic spine surgery will depend on our ability to address the learning curve problem. In the future, this problem may be addressed through the use to computer-assisted navigation, robotic assistance, and an integrated operating room suite that improves the efficiencies and ergonomics of increasingly complex surgical treatment strategies.

Use of navigation-assisted fluoroscopy to decrease radiation exposure during minimally invasive spine surgery.

BACKGROUND: Minimally invasive surgery decreases postoperative pain and disability. However, limited views of the surgical field require extensive use of intraoperative fluoroscopy that may expose the surgical team to higher levels of ionizing radiation. PURPOSE: To assess the feasibility and safety of navigation-assisted fluoroscopy during minimally invasive spine surgery. STUDY DESIGN: A combined cadaveric and human study comparing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) using navigation-assisted fluoroscopy with standard intraoperative fluoroscopy to determine differences in surgical times and radiation exposures. METHODS: Eighteen fresh cadaveric spines underwent unilateral MIS TLIF by using either navigation-assisted fluoroscopy or standard fluoroscopy. Times for specific surgical steps were compared. In addition, a prospective short-term evaluation of the intraoperative and perioperative results of 10 patients undergoing navigation-assisted MIS TLIF (NAV group) compared with a retrospective review of 8 patients undergoing MIS TLIF performed by using standard fluoroscopy (FLUORO group). RESULTS: In the cadaveric study, the times were similar between the NAV group and the FLUORO group for most key steps. No statistically significant differences were obtained for approach, exposure, screw insertion, facetectomy/decompression, or total surgical times. Statistically significant differences were obtained for the setup time and total fluoroscopy time. The setup time for the NAV group averaged 9.67 (standard deviation [SD], 3.74) minutes compared with 4.78 (SD, 2.11) minutes for the FLUORO group (p=.034). The total fluoroscopy time was higher for the FLUORO group compared with the NAV group (41.9 seconds vs. 28.7 seconds, p=.042). Radiation exposure was undetectable when navigation-assisted fluoroscopy is used (NAV group). In contrast, an average 12.4 milli-REM (mREM) of radiation exposure is delivered to the surgeon during unilateral MIS TLIF procedure without navigation (FLUORO group). In the clinical series, the total fluoro time for the NAV group was 57.1 seconds (SD, 37.3; range, 18-120) compared with 147.2 seconds (SD, 73.3; range, 73-295) for FLUORO group (p=.02). No statistically significant differences are noted for operating time, estimated blood loss, or hospital stay. No inadvertent durotomies, postoperative weakness, or new radiculopathy were noted in the NAV group. One inadvertent durotomy was encountered in the FLUORO group that was repaired intraoperatively without clinical sequelae. CONCLUSION: The use of navigation-assisted fluoroscopy is feasible and safe for minimally invasive spine surgery. Radiation exposure is decreased to the patient as well as the surgical team.

Altered bioreactivity and limited osteoconductivity of calcium sulfate-based bone cements in the osteoporotic rat spine.

BACKGROUND CONTEXT: Previous studies documenting the osteoconductive nature of calcium sulfate (CaSO(4))-based biomaterials have been largely limited to animal models exhibiting nonosteoporotic bone biology. In addition to diminished bone mineral density (BMD) and altered bone microarchitecture, the osteoporosis phenotype is associated with a proinflammatory and pro-osteolytic state. Thus, osteoporosis may elicit an amplified bioreactivity to common orthopedic biomaterials, potentially limiting their full osteoconductive capabilities in vivo. PURPOSE: The purpose of this study is to test the hypothesis that CaSO(4)-based bone cements exhibit altered bioreactivity and limited osteoconductivity in response to osteoporotic conditions. STUDY DESIGN: 1) Microcomputed tomography (micro-CT) radiomorphometry study and 2) histological analysis. METHODS: Our laboratory has previously established a preclinical model of osteoporosis using the rodent osteoporotic spine (OS). Caudal vertebral defects were filled with either CaSO(4) or CaSO(4)/CaPO(4) (Hybrid) cement for each group (n=4). Over 8 weeks, cement resorption profiles, BMD, average cortical thickness, average trabecular thickness, average trabecular spacing, and diaphyseal bone volume fraction were assessed via micro-CT radiomorphometry. Histological analysis was performed on vertebrae obtained postsurgery and at Week 8. RESULTS: Both materials displayed an accelerated cement resorption profile after implantation into the OS vertebrae. Hybrid cement exhibited slower resorption compared with that of CaSO(4) under both normal female rats (NL) and OS conditions. The cement-mediated bone augmentation observed in the NL spine was altered under OS conditions. CONCLUSIONS: This study suggests that cement bioreactivity is heightened and osteoconductivity may be limited in a preclinical model of the OS. The disparity between the two resorption profiles suggests that this accelerated cement resorption is a material-dependent phenomenon. The proinflammatory and pro-osteolytic bone environment associated with the osteoporosis disease state may contribute to the accelerated resorption and altered osteoconductivity exhibited by both materials. Future study of potential biomaterials intended for use within the OS may necessitate further exploration of the relationship between biomaterial performance and osteoporosis bone biology.

Intra- and Perioperative Complications Associated with Endoscopic Spine Surgery: A Multi-Institutional Study.

OBJECTIVE: To report on intra- and perioperative complications associated with working channel endoscopic spine surgery. METHODS: This study is a retrospective chart review of a multi-institutional patient cohort operated on by surgeons within the Endoscopic Spine Study Group between May 2010 and June 2017. RESULTS: Our study cohort consists of a total of 553 consecutive cases with an average age of 57 years. The most common procedure was an endoscopic discectomy (n = 377, 68%) followed by foraminotomy (n = 156, 28.2%), unilateral laminotomy for bilateral decompression (n = 55, 9.9%), and lateral recess decompression (n = 29, 5.2%). Overall, the rate of intra- and perioperative complications was 2.7%. There were 3 durotomies (0.54%), 2 epidural hematomas (0.36%), 2 patients developed a complex pain disorder (0.36%), 4 recurrent disc herniations within 3 months (1.1%), 4 systemic complications (1.1%), and no wound infections. No risk factors were identified with regards to age, sex, approach, or number of segments. CONCLUSIONS: Endoscopic spine surgery is associated with a favorable rate of intra- and perioperative complications compared with reported rates of minimally invasive ortraditional open spine surgeries. Our report proposes safe and effective strategies for management of these complications.

Conversion of sea urchin spines to Mg-substituted tricalcium phosphate for bone implants.

The skeleton of sea urchin spines is composed of large single crystals of Mg-rich calcite, which have smooth, continuously curved surfaces and form a three-dimensional fenestrated mineral network. Spines of the echinoids Heterocentrotus trigonarius and Heterocentrotus mammillatus were converted by the hydrothermal reaction at 180 degrees C to bioresorbable Mg-substituted tricalcium phosphate (beta-TCMP). Due to the presence of Mg in the calcite lattice, conversion to beta-TCMP occurs preferentially to hydroxyapatite formation. The converted beta-TCMP still maintains the three-dimensional interconnected porous structures of the original spine. The main conversion mechanism is the ion-exchange reaction, although there is also a dissolution-reprecipitation process that forms some calcium phosphate precipitates on the surfaces of the spine network. The average fracture strength of urchin spines and converted spines (beta-TCMP) in the compression tests are 42 and 23MPa, respectively. In vivo studies using a rat model demonstrated new bone growth up to and around the beta-TCMP implants after implantation in rat femoral defects for 6 weeks. Some new bone was found to migrate through the spine structural pores, starting from the outside of the implant through the pores at the edge of the implants. These results indicate good bioactivity and osteoconductivity of the porous beta-TCMP implants.

Conversion of bulk seashells to biocompatible hydroxyapatite for bone implants.

Strombus gigas (conch) shells and Tridacna gigas (Giant clam) shells have dense, tailored structures that impart excellent mechanical properties to these shells. In this investigation, conch and clam seashells were converted to hydroxyapatite (HAP) by a hydrothermal method at different temperatures and for different conversion durations. Dense HAP structures were created from these shells throughout the majority of the samples at the relative low temperature of approximately 200 degrees C. The average fracture stress was found to be approximately 137-218MPa for partially converted conch shell samples and approximately 70-150MPa for original and converted clamshell samples, which is close to the mechanical strength of compact human bone. This indicates that the converted shell samples can be used as implants in load-bearing cases. In vivo tests of converted shell samples were performed in rat femoral defects for 6 weeks. The microtomography images at 6 weeks show that the implants did not move, and untreated control defects remain empty with no evidence of a spontaneous fusion. Histological study reveals that there is newly formed bone growing up to and around the implants. There is no evidence of a fibrosis tissue ring around the implants, also indicating that there is no loosening of the implants. In contrast, the untreated controls remain empty with some evidence of a fibrosis ring around the defect hole. These results indicate good biocompatibility and bioactivity of the converted shell implants.

A rat osteoporotic spine model for the evaluation of bioresorbable bone cements.

BACKGROUND CONTEXT: As the aging population increases, the rising prevalence of osteoporosis-related spine fractures will have a dramatic impact on health care. At present, mainstay treatment relies on systemic medications intended to prevent diminishing bone mineral density (BMD) and bone mass. However, an adjunctive treatment strategy is to target specific areas of the skeletal system that are prone to clinically significant osteoporotic fractures. We term this strategy the "local treatment of osteoporosis" or osteoplasty. Potential use of osteoplasty involves the percutaneous injection of bioresorbable and bioactive bone cements into bones at risk of sustaining osteoporotic fractures. Calcium sulfate (CaSO(4)) is among the candidate bioresorbable bone cements with the material attributes desirable for potential application with osteoplasty, yet previous studies on the osteoconductive properties of CaSO(4) have been limited to animal models exhibiting normal bone biology and architecture. However, osteoporotic bone physiology may potentially interfere with the material properties of common osteoconductive biomaterials, such as that of CaSO(4). To further test this hypothesis, a suitable animal model is needed to evaluate the in vivo behavior of potential biomaterials in osteoporotic bone. PURPOSE: The purpose of this study is to evaluate the caudal (proximal tail) rat vertebral body as an appropriate system for the in vivo evaluation of bone cement performance in the osteoporotic spine. STUDY DESIGN: (1) Micro-computed tomography radiomorphometry study and (2) biomechanical vertebral compression analysis. METHODS: Female Sprague Dawley rats were ovarectomized (OVX) at age 8 weeks and subsequently maintained on a low-calcium diet for 3 months. Normal nonovarectomized female rats (NL) of similar age and size were maintained on regular rodent feed. Micro-CT analysis was performed on both the lumbar and caudal vertebrae (levels 5-7) of both groups. The following bone radiomorphometric parameters were determined: bone mineral density (BMD), average cortical thickness (ACT), average trabecular thickness (TbTh), and average trabecular spacing (TbSp). Strength and stiffness of both NL and OVX vertebral bodies were assessed under axial compression at 0.1 mm/s, whereas displacement (mm) and force (N) were measured at 10 Hz until completion to failure. After the implantation of an injectable form of CaSO(4) bone cement into caudal vertebrae, radiomorphometric analysis of cement volume, based on its unique CT absorption profile, was performed over the 8-week time period, as well as the subsequent bone response of both NL and OVX caudal vertebrae to CaSO4. RESULTS: OVX caudal vertebrae showed an 18% decrease in BMD, a 28% decrease in diaphyseal ACT, a 55% decrease in TbTh, and a 2.4-fold increase in TbSp compared with NL (p<.05). Additionally, lumbar vertebrae exhibited a 21% decrease in BMD, a 24% decrease in anterior body ACT, a 48% decrease in TbTh, and a 4.7-fold increase in TbSp (p<.05). Failure testing of OVX caudal vertebral bodies revealed a 29% decrease in strength and a 60% decrease in stiffness compared with NL (p<.01). After implantation into OVX caudal vertebrae, CaSO(4) cement exhibited a 50% decrease in initial cement volume at 2 weeks and complete resorption by 4 weeks, whereas CaSO(4) injected into NL vertebrae exhibited a 79% decrease in initial cement volume at 4 weeks, trace amounts at 6 weeks, and complete resorption by 8 weeks. At 8 weeks, NL vertebrae implanted with CaSO(4) cement exhibited increased cortical bone thickness compared with NL sham vertebrae. This CaSO(4) cement-mediated bone augmentation was altered in osteoporotic vertebrae that exhibited porous irregular cortical bone not noted in cement-treated NL vertebrae or OVX sham vertebrae. CONCLUSIONS: Future investigation of potential biomaterials intended for the local treatment of osteoporosis will require their study within an appropriate osteoporosis animal model. The OVX rat caudal spine exhibits pathologic bone changes consistent with the osteoporosis phenotype, including decreased BMD, diminished trabecular network density, cortical thinning, and decreased mechanical strength. These derangements in bone microarchitecture and physiology may contribute toward the accelerated cement resorption and altered bone response to CaSO4 observed in this study. Important advantages of the OVX rat caudal spine are the rapid and minimally invasive surgical exposure of the vertebral body and the ease of cement injection. We propose that the OVX rat caudal spine represents a valuable and cost-effective tool in the armamentarium of investigators evaluating biomaterials designed for implantation into the osteoporotic spine.

A Comparison of Different Minimally Invasive and Open Posterior Spinal Procedures Using Volumetric Measurements of the Surgical Exposures.

STUDY DESIGN: A Prospective observational study. SUMMARY OF THE BACKGROUND DATA: Minimally invasive (MI) spine surgery techniques strive to minimize the damage to paraspinal soft tissues. Previous studies used only the length of the surgical incision to quantify the invasiveness of certain MI procedures. However, this method does not take into account the volume of muscle tissue that is dissected and retracted from the spine to achieve sufficient exposure. To date, no simple method has been reported to measure the volume of the surgical exposure and to quantify the degree of surgery invasiveness. STUDY OBJECTIVES: To obtain and compare volumetric measures of various MI and open posterior-approached spinal surgical exposures. METHODS: The length, the depth, and the volume of the surgical exposure were obtained from 57 patients who underwent either open or MI posterior lumbar surgery. MI procedures included the following: tubular discectomy, laminotomy, and transforaminal interbody fusion. Open procedures included the following: discectomy, laminectomy, transforaminal interbody fusion, or posterior-lateral instrumented fusion. Four attending spine surgeons at our unit performed the surgeries. To reduce variability, only single-level procedures performed between L4 and S1 vertebrae were used. The volume of exposure was obtained by measuring the amount of saline needed to fill the surgical wound completely once the surgical retractors were deployed and opened. RESULTS: The average volumes in mililiters of exposure for a single-level MI procedure ranged from 9.8±2.8 to 75±11.7 mL and were significantly smaller than the average volumes of exposure for a single level open procedures that ranged from 44± 21 to 277±47.9 P<0.001. The average skin-incision lengths for single-level MI procedures ranged from 1.7±0.2 to 7.7±1.6 cm and were significantly smaller than the average skin-incision lengths for open procedures [5.2±1.4 (Table 3) to 11.3±2 cm, P<0.001]. The measured surgical depths were similar in MI and open groups (P=0.138). MI decompression and posterior fusion procedures yielded 92% and 73% reductions in the volumes of exposure, respectively. However, absolute differences in exposure volumes were larger for fusion (202 mL) compared with decompression alone (110.7 mL). CONCLUSIONS: Direct volumetric measurement of the surgical exposure is obtained easily by measuring the amount of saline needed to fill the exposed cavity. Using this method, the needed surgical exposure of different spinal procedures can be quantified and compared. This volumetric measurement combined with the measure of retraction force, the duration of retraction, and the impact on soft tissue vascularity can help build a model that assesses the relative invasiveness of different spinal procedures.

A Novel Collaborative Protocol for Successful Management of Penile Pain Mediated by Radiculitis of Sacral Spinal Nerve Roots From Tarlov Cysts.

INTRODUCTION: Since 14 years of age, the patient had experienced extreme penile pain within seconds of initial sexual arousal through masturbation. Penile pain was so severe that he rarely proceeded to orgasm or ejaculation. After 7 years of undergoing multiple unsuccessful treatments, he was concerned for his long-term mental health and for his future ability to have relationships. AIM: To describe a novel collaboration among specialists in sexual medicine, neurophysiology, and spine surgery that led to successful management. METHODS: Collaborating health care providers conferred with the referring physician, patient, and parents and included a review of all medical records. MAIN OUTCOME MEASURE: Elimination of postpubertal intense penile pain during sexual arousal. RESULTS: The patient presented to our sexual medicine facility at 21 years of age. The sexual medicine physician identifying the sexual health complaint noted a pelvic magnetic resonance imaging report of an incidental sacral Tarlov cyst. A subsequent sacral magnetic resonance image showed four sacral Tarlov cysts, with the largest measuring 18 mm. Neuro-genital testing result were abnormal. The neurophysiologist hypothesized the patient's pain at erection was produced by Tarlov cyst-induced neuropathic irritation of sensory fibers that course within the pelvic nerve. The spine surgeon directed a diagnostic injection of bupivacaine to the sacral nerve roots and subsequently morphine to the conus medullaris of the spinal cord. The bupivacaine produced general penile numbness; the morphine selectively decreased penile pain symptoms during sexual arousal without blocking penile skin sensation. The collaboration among specialties led to the conclusion that the Tarlov cysts were pathophysiologically mediating the penile pain symptoms during arousal. Long-term follow-up after surgical repair showed complete symptom elimination at 18 months after treatment. CONCLUSION: This case provides evidence that (i) Tarlov cysts can cause sacral spinal nerve root radiculitis through sensory pelvic nerve and (ii) there are management benefits from collaboration among sexual medicine, neurophysiology, and spine surgery subspecialties. Goldstein I, Komisaruk BR, Rubin RS, et al. A Novel Collaborative Protocol for Successful Management of Penile Pain Mediated by Radiculitis of Sacral Spinal Nerve Roots From Tarlov Cysts. Sex Med 2017;5:e203-e211.

Validity and reliability of a novel patient reported outcome tool to evaluate post-operative dysphagia, odynophagia, and voice (DOV) disability after anterior cervical procedures.

BACKGROUND: Existing evaluative instruments for dysphagia, odynophagia, and voice disturbance are cumbersome, focus pre-dominately on dysphagia, and often require administration by a certified Speech Pathologist. This study was conducted to utilize widely accepted instruments such as the American Speech and Hearing Association's National Outcomes Measurement System (NOMS) and VAS pain scales to validate a novel, patient-reported instrument that quantifies the severity of post-operative dysphagia, odynophagia, and voice disabilities (DOV). METHODS: The DOV was developed and subjected to multiple rounds of face and content validation by representative patient cohorts and a panel of clinical experts. An established, prospective clinical registry was utilized to collect pre and post-operative VAS-swallow related pain and DOV measurements for subjects with recent anterior cervical procedures (n=25 content validation, n=20 criterion validation), or recent lumbar decompressions (n=33). NOMS evaluations were performed by a certified Speech Language Pathologist on the first post-operative day after minimally invasive anterior approaches to cervical reconstruction were performed in the criterion validation cohort. RESULTS: Content validity: Subjects with a recent anterior cervical procedure reported a significant increase in post-operative dysphagia (pre-op: 0.13±0.35, post-op: 1.08±1.41, p=0.01), odynophagia (pre-op: 0.24±0.69, post-op: 0.84±0.90, p=0.001), and voice (pre-op: 0.10±0.41, post-op: 0.88±0.92, p=0.0004) disturbance. In contrast, subjects with a recent lumbar procedure did not demonstrate a significant increase in post-operative dysphagia, odynophagia, or voice disturbance (p>0.05).Criterion validity: Chi-squared contingency testing for independence between converted NOMS and DOV instrument scores accepted linkage between the two instruments for dysphagia X2(DF: 12, n=20, Expected: 21.03, Observed: 24.4, p: 0.02) and voice X2(DF: 6, n=20, Expected: 12.60, Observed: 21.28, p: 0.002) dimensions. Similarly, converted swallow related VAS and DOV odynophagia instruments demonstrated linkage X2(DF: 9, n=20, Expected: 16.92, Observed: 24.21, p: 0.004).Internal Reliability: Chronbach's alpha coefficient of reliability was 0.74 between all DOV survey dimensions. CONCLUSIONS: The DOV survey is a valid patient-reported instrument to rapidly and reliably detect post-operative swallow and voice dysfunction.

High-molecular-weight hyaluronan inhibits macrophage proliferation and cytokine release in the early wound of a preclinical postlaminectomy rat model.

BACKGROUND CONTEXT: Failed back syndrome, a condition that affects 3-14% of postoperative spine patients, is characterized by the recurrence of radicular pain after spinal decompression. The source of this pain in some patients is thought by many investigators to be the result of epidural scarring and nerve root tethering, but this is controversial. We have previously demonstrated that in a disc-injury model the untreated postlaminectomy rats develop a significant proliferative fibrous response at 8 weeks with spinal nerve scarring to the disc and adjacent pedicle, and increased sensitivity to tactile allodynia testing in the related sensory dermatome. Topical high-molecular-weight hyaluronan (HMW HA) moderates both the proliferative fibrosis and the behavioral pain response. PURPOSE: Our purpose is to study the time-related changes in the proinflammatory cytokine and monocyte/macrophage profiles in the epidural space in the early postlaminectomy untreated and HMW HA gel treated groups. STUDY DESIGN/SETTING: A modified rat laminectomy with disc injury model was employed to assess epidural fibrosis between and around the spinal nerves using a quantitative immunohistochemistry assessment approach along with correlative enzyme-linked immunosorbent assay analysis. METHODS: Lumbar laminectomies at L5 and L6 with a L5-L6 disc injury were performed on 120 adult male Sprague-Dawley rats. The rats were then randomized into one of two groups: untreated and treated. The treatment group received a one-time topical application of 0.1 cc of HMW HA gel directly to the laminectomy site just before wound closure. The rats were then randomly subdivided into survival periods of 24 hours, 72 hours, and 7 days. Immunohistochemistry was performed on fresh frozen sections and stained for interleukin-1 beta (IL-1beta) and monocytes/macrophages (ED-1) using monoclonal antibodies and 3, 3' diaminobenzidine (DAB) chromogen. The amount of stain in each specimen was then quantified using the National Institutes of Health computer imaging analysis system. RESULTS: The semiquantified data from the histological specimens demonstrated significant decreases in the IL-1beta and IL-6 infiltration observed at 24 hours in the epidural space and around the right nerve root (p=.0296 and 0.0195, respectively) in the HA gel treated group. Additionally, significant decreases in the monocyte/macrophage infiltration were observed at 72 hours in the epidural space around the left nerve root (p=.0039) and right nerve root (p=.0072) in the HA gel treated group. At 7 days, IL-1beta, IL-6, and macrophage infiltration of the wound had declined in both the HA gel and the untreated groups. The enzyme-linked immunosorbent assay data support the same pattern as seen in the histological results. CONCLUSION: These results demonstrate that treatment of postlaminectomy wounds with HMW HA gel decreases the number of monocytes and macrophages and the concentration of certain cytokines in the early inflammatory phase of healing. There are several plausible explanations for this effect. First, the HMW HA may block the interaction of short-chain low-molecular-weight HA with proinflammatory cell surface receptors. The interaction of these short-chain oligo-HA fragments, upon cell-surface receptor binding, induces changes in inflammatory cells that lead to increased cell motility and migration into the wound area. Second, the addition of exogenous HMW HA may cause a dilution effect in the wound, thereby decreasing the concentration of inflammatory cells in the extracellular matrix of the region of injury. Finally, the migration of inflammatory cells may be decreased in the viscous environment of the HMW HA. The first explanation is believed by the authors of this paper to be the more likely mechanism. HMW HA probably mutes the proinflammatory effects of the low-molecular weight fragments, leading to decreased inflammation, and thus decreased fibrosis and scar formation noted in the chronic model.

Minimally invasive lumbar decompression-the surgical learning curve.

Commentary On: Ahn J, Iqbal A, Manning BT, Leblang S, Bohl DD, Mayo BC, et al. Minimally invasive lumbar decompression-the surgical learning curve. Spine J 2016:16:909-16. (in this issue).

Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Expandable Technology: A Clinical and Radiographic Analysis of 50 Patients.

OBJECTIVE: Interbody cage implantation during minimally invasive surgery for transforaminal lumbar interbody fusion (MIS TLIF) presents challenges. Expandable cages when collapsed facilitate insertion; subsequent expansion in situ optimizes endplate contact. This report describes clinical and radiographic outcomes of MIS TLIF with an expandable cage. METHODS: Researchers retrospectively analyzed prospective data from 50 patients (62 operative levels) when an expandable interbody spacer was combined with transpedicular posterior stabilization. Clinical outcomes, fusion rates, incidence of reoperation, and device-related complications were obtained from clinical and radiographic records. RESULTS: Mean patient age was 58.1 years (56.2% female). In all, 76% (38/50) underwent 1-level fusion, and 24% (12/50) 2-level fusion. Average operative time was 239.9 ± 86.9 minutes for 1-level and 350.3 ± 74.9 minutes for 2-level procedures; average hospital stay overall was 2.5 ± 1.7 days, with no intraoperative complications reported. Mean visual analogue scale and Oswestry Disability Index scores decreased significantly from preoperative to all postoperative assessment times (6, 12, and 24 months) (P < 0.05). Intervertebral disc height (8.3 ± 2.7 vs. 11.3 ± 1.9 mm) increased significantly, with increases sustained over 24 months (P < 0.05). Postoperative radiographs showed no evidence of cage migration, subsidence, or collapse and suggested fusion at all operative levels by 12 months and 24 months (93%, 54/58; 97%, 28/29), respectively. CONCLUSIONS: An expandable interbody cage led to significant improvement in clinical and radiographic outcomes after MIS TLIF, including intervertebral disc height restoration and high fusion rates, with no evidence of device-related complications.

Topical high-molecular-weight hyaluronan and a roofing barrier sheet equally inhibit postlaminectomy fibrosis.

BACKGROUND CONTEXT: The relevance of epidural fibrosis to failed back surgical outcomes remains controversial. Previous studies on the correlation between epidural fibrosis and clinical outcome after laminectomy are inconclusive, and clinical approaches applied to reduce postlaminectomy spinal canal scarring have produced mixed outcomes. PURPOSE: Improved preclinical models are required to address the fundamental question of the relationship between postlaminectomy fibrosis and chronic pain. This study is directed at establishing small animal postlaminectomy models characterized by significantly reduced scar within the spinal canal postoperatively. Such preclinical models are offered as a platform for future studies to explore the potential relationship between postlaminectomy epidural fibrosis and persistent neuropathy with its potential for altered spinal mechanisms for pain processing, so-called spinal facilitation. Such experiments could be constructed in these models for comparison of pain behavior and its underlying neurochemistry both in the presence and absence of extensive postlaminectomy epidural scar. STUDY DESIGN/SETTING: A modified rat laminectomy model was employed to assess epidural fibrosis using a quantitative biochemical collagen assessment approach along with correlative histology. This group served as the control for comparison with groups in which antifibrotic measures were employed. We compared antifibrotic efficacy of a bioabsorbable roofing barrier sheet placed over the laminectomy defect with topical high-molecular-weight hyaluronan (HMW HA) gel, each applied postoperatively to prevent proliferative epidural scarring. Routine biomechanical tensile strength testing was employed to assess wound-healing strength. METHODS: A bilateral laminectomy (L5 and L6) with associated unilateral disc injury (L5-L6) was performed in 98 male Harlan Sprague-Dawley rats. The laminectomy models described incorporated a unilateral disc injury at L5-L6 because herniated disc material has been shown to contribute proinflammatory cytokines in the postoperative wound. Five groups were employed for the study: 1) normal controls without surgery; 2) a laminectomy-disc injury group without treatment; 3) a laminectomy-disc injury group treated with topical HMW HA gel; 4) a laminectomy-disc injury group treated with 0.2-mm thick bioabsorbable roofing barrier sheet in which a protected space was maintained between overlying paraspinous muscles and the dura and 5) a 0.02-mm thin barrier sheet treatment group in which the sheet was placed directly on the dura. The animals were sacrificed at 3- and 8-week postoperative intervals for analysis. The dissected specimens were studied biochemically for hydroxyproline content to estimate total collagen within the canal and on the dura between L4 and L7. Additional specimens were prepared histologically and stained with Masson-Goldner Trichrome stain to confirm presence of proliferative collagen and to describe the presence or absence of wound-healing scar adherence to the dura. The surgical incisions were studied biomechanically by uniaxial tensile testing to determine ultimate force, strain and prefailure stiffness. Statistics were performed using analysis of variance. RESULTS: Gross appearance and histology studies showed that the untreated laminectomy group demonstrated postoperative scar formation that is adherent between the wound and the dorsum of the dura mater in both 3- and 8-week groups. Proliferative scar was substantially increased grossly between the 3- and 8-week intervals. By gross observation there was adherence of the L5 spinal nerve to the underlying disc and adjacent pedicle on the disc injury side. Gross observation of treatment groups, in contrast, disclosed that both the 0.2-mm thick roofing barrier sheet and topical HMW HA gel each prevented scar attachment to the dural sleeve at both the 3- and 8-week postoperative intervals. Furthermore, both the HMW HA gel and 0.2-mm thick roofing barrier sheet treatment groups had significant reduction of total collagen content in the laminectomy specimens measured biochemically at the two time periods compared with the untreated controls. Histologically, the HMW HA gel and the 0.2-mm thick barrier sheet findings were consistent with the gross observations concerning lack of adherence between scar of the overlying wound and the dura. Notably, both the 0.2- and the 0.02-mm barrier sheets became enveloped by a fibrotic envelope consistent with a foreign body reaction. In the group in which the 0.02-mm thin sheet was placed within the canal on top of the dura, there was an increase of fibrosis around the sheet within the canal leading to a space-occupying mass within the canal. Although the 0.2-mm thick roofing barrier placed external to the canal became enveloped by scar, it appeared to attract proliferative scar away from the epidural space, leaving the dura relatively free of scarring or adherence to overlying tissues. The mechanical properties of the incisional wound increased significantly between 3 and 8 weeks. The ultimate strength, stress, strain and stiffness of the several groups were similar at each time point. CONCLUSION: These results provide two preclinical rat laminectomy models of potential usefulness for the future study of the relevance of epidural fibrosis to behaviorally defined pain states, and for the study of the potential of an altered neurochemical signature in postlaminectomy pain conditions. Such preclinical models have become standard in studies of pain behavior and its neurochemistry in preclinical sciatic nerve and spinal nerve injury models, and should be of utility in the studies of postlaminectomy fibrosis. There was progressive scar proliferation and maturation in the untreated postlaminectomy group in the postoperative interval between 3 and 8 weeks. HMW HA gel applied topically and a 0.2-mm thick bioabsorbable Macropore sheet used as a roofing barrier each significantly reduced postlaminectomy proliferative scar without affecting the integrity of incisional wound healing. However, if the 0.02-mm thin barrier sheet used in this study is placed within the canal in contact with the dura and adjacent to the pedicles, the process of reabsorption results in a fibrotic mass within the canal. The preferred barrier sheet placement for this model is clearly in a roofing position bridging over the open epidural space. It must be placed in a manner to block off the paraspinous muscle healing response and still leave a gap between the sheet and the dura.