Real-time navigation guidance with intraoperative CT imaging for pedicle screw placement using an augmented reality head-mounted display: a proof-of-concept study.

OBJECTIVE: Augmented reality (AR) has the potential to improve the accuracy and efficiency of instrumentation placement in spinal fusion surgery, increasing patient safety and outcomes, optimizing ergonomics in the surgical suite, and ultimately lowering procedural costs. The authors sought to describe the use of a commercial prototype Spine AR platform (SpineAR) that provides a commercial AR head-mounted display (ARHMD) user interface for navigation-guided spine surgery incorporating real-time navigation images from intraoperative imaging with a 3D-reconstructed model in the surgeon's field of view, and to assess screw placement accuracy via this method. METHODS: Pedicle screw placement accuracy was assessed and compared with literature-reported data of the freehand (FH) technique. Accuracy with SpineAR was also compared between participants of varying spine surgical experience. Eleven operators without prior experience with AR-assisted pedicle screw placement took part in the study: 5 attending neurosurgeons and 6 trainees (1 neurosurgical fellow, 1 senior orthopedic resident, 3 neurosurgical residents, and 1 medical student). Commercially available 3D-printed lumbar spine models were utilized as surrogates of human anatomy. Among the operators, a total of 192 screws were instrumented bilaterally from L2-5 using SpineAR in 24 lumbar spine models. All but one trainee also inserted 8 screws using the FH method. In addition to accuracy scoring using the Gertzbein-Robbins grading scale, axial trajectory was assessed, and user feedback on experience with SpineAR was collected. RESULTS: Based on the Gertzbein-Robbins grading scale, the overall screw placement accuracy using SpineAR among all users was 98.4% (192 screws). Accuracy for attendings and trainees was 99.1% (112 screws) and 97.5% (80 screws), respectively. Accuracy rates were higher compared with literature-reported lumbar screw placement accuracy using FH for attendings (99.1% vs 94.32%; p = 0.0212) and all users (98.4% vs 94.32%; p = 0.0099). The percentage of total inserted screws with a minimum of 5° medial angulation was 100%. No differences were observed between attendings and trainees or between the two methods. User feedback on SpineAR was generally positive. CONCLUSIONS: Screw placement was feasible and accurate using SpineAR, an ARHMD platform with real-time navigation guidance that provided a favorable surgeon-user experience.

Early Experience With Virtual and Synchronized Augmented Reality Platform for Preoperative Planning and Intraoperative Navigation: A Case Series.

BACKGROUND: Virtual reality (VR) allows for presurgical planning. Intraoperatively, augmented reality (AR) enables integration of segmented anatomic information with neuronavigation into the microsurgical scene to provide guidance without workflow disruption. Combining VR and AR solutions may help guide microsurgical technique to improve safety, efficiency, and ergonomics. OBJECTIVE: To describe a VR/AR platform that provides VR planning and intraoperative guidance via microscope ocular injection of a comprehensive AR overlay of patient-specific 360°/3D anatomic model aligned and synchronized with neuronavigation. METHODS: Custom 360° models from preoperative imaging of 49 patients were utilized for preoperative planning using a VR-based surgical rehearsal platform. Each model was imported to SyncAR, the platform's intraoperative counterpart, which was coregistered with Medtronic StealthStation S8 and Zeiss or Leica microscope. The model was injected into the microscope oculars and referenced throughout by adjusting overlay opacity. For anatomic shifts or misalignment, the overlay was reregistered via manual realignment with known landmarks. RESULTS: No SyncAR-related complications occurred. SyncAR contributed positively to the 3D understanding of patient-specific anatomy and ability to operate. Preoperative planning and intraoperative AR with 360° models allowed for more precise craniotomy planning and execution. SyncAR was useful for guiding dissection, identifying critical structures including hidden anatomy, understanding regional anatomy, and facilitating resection. Manual realignment was performed in 48/49 surgeries. Gross total resection was achieved in 34/40 surgeries. All aneurysm clipping and microvascular decompression procedures were completed without complications. CONCLUSION: SyncAR combined with VR planning has potential to enhance surgical performance by providing critical information in a user-friendly, continuously available, heads-up display format.

Correction: Self-Administered Behavioral Skills-Based At-Home Virtual Reality Therapy for Chronic Low Back Pain: Protocol for a Randomized Controlled Trial.

[This corrects the article DOI: 10.2196/25291.].

An 8-Week Self-Administered At-Home Behavioral Skills-Based Virtual Reality Program for Chronic Low Back Pain: Double-Blind, Randomized, Placebo-Controlled Trial Conducted During COVID-19.

BACKGROUND: Chronic low back pain is the most prevalent chronic pain condition worldwide and access to behavioral pain treatment is limited. Virtual reality (VR) is an immersive technology that may provide effective behavioral therapeutics for chronic pain. OBJECTIVE: We aimed to conduct a double-blind, parallel-arm, single-cohort, remote, randomized placebo-controlled trial for a self-administered behavioral skills-based VR program in community-based individuals with self-reported chronic low back pain during the COVID-19 pandemic. METHODS: A national online convenience sample of individuals with self-reported nonmalignant low back pain with duration of 6 months or more and with average pain intensity of 4 or more/10 was enrolled and randomized 1:1 to 1 of 2 daily (56-day) VR programs: (1) EaseVRx (immersive pain relief skills VR program); or (2) Sham VR (2D nature content delivered in a VR headset). Objective device use data and self-reported data were collected. The primary outcomes were the between-group effect of EaseVRx versus Sham VR across time points, and the between-within interaction effect representing the change in average pain intensity and pain-related interference with activity, stress, mood, and sleep over time (baseline to end-of-treatment at day 56). Secondary outcomes were global impression of change and change in physical function, sleep disturbance, pain self-efficacy, pain catastrophizing, pain acceptance, pain medication use, and user satisfaction. Analytic methods included intention-to-treat and a mixed-model framework. RESULTS: The study sample was 179 adults (female: 76.5%, 137/179; Caucasian: 90.5%, 162/179; at least some college education: 91.1%, 163/179; mean age: 51.5 years [SD 13.1]; average pain intensity: 5/10 [SD 1.2]; back pain duration ≥5 years: 67%, 120/179). No group differences were found for any baseline variable or treatment engagement. User satisfaction ratings were higher for EaseVRx versus Sham VR (P<.001). For the between-groups factor, EaseVRx was superior to Sham VR for all primary outcomes (highest P value=.009), and between-groups Cohen d effect sizes ranged from 0.40 to 0.49, indicating superiority was moderately clinically meaningful. For EaseVRx, large pre-post effect sizes ranged from 1.17 to 1.3 and met moderate to substantial clinical importance for reduced pain intensity and pain-related interference with activity, mood, and stress. Between-group comparisons for Physical Function and Sleep Disturbance showed superiority for the EaseVRx group versus the Sham VR group (P=.022 and .013, respectively). Pain catastrophizing, pain self-efficacy, pain acceptance, prescription opioid use (morphine milligram equivalent) did not reach statistical significance for either group. Use of over-the-counter analgesic use was reduced for EaseVRx (P<.01) but not for Sham VR. CONCLUSIONS: EaseVRx had high user satisfaction and superior and clinically meaningful symptom reduction for average pain intensity and pain-related interference with activity, mood, and stress compared to sham VR. Additional research is needed to determine durability of treatment effects and to characterize mechanisms of treatment effects. Home-based VR may expand access to effective and on-demand nonpharmacologic treatment for chronic low back pain. TRIAL REGISTRATION: ClinicalTrials.gov NCT04415177; https://clinicaltrials.gov/ct2/show/NCT04415177. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/25291.

Self-Administered Behavioral Skills-Based At-Home Virtual Reality Therapy for Chronic Low Back Pain: Protocol for a Randomized Controlled Trial.

BACKGROUND: Chronic pain is one of the most common and debilitating health conditions. Treatments for chronic low back pain typically focus on biomedical treatment approaches. While psychosocial treatments exist, multiple barriers prevent broad access. There is a significant unmet need for integrative, easily accessible, non-opioid solutions for chronic pain. Virtual reality (VR) is an immersive technology allowing innovation in the delivery of behavioral pain treatments. Behavioral skills-based VR is effective at facilitating pain management and reducing pain-related concerns. Continued research on these emerging approaches is needed. OBJECTIVE: In this randomized controlled trial, we seek to test the efficacy of a self-administered behavioral skills-based VR program as a nonpharmacological home-based pain management treatment for people with chronic low back pain (cLBP). METHODS: We will randomize 180 individuals with cLBP to 1 of 2 VR programs: (1) EaseVRx (8-week skills-based VR program); or (2) Sham VR (control condition). All participants will receive a VR headset to minimize any biases related to the technology's novelty. The Sham VR group had 2D neutral content in a 3D theater-like environment. Our primary outcome is average pain intensity and pain-related interference with activity, stress, mood, and sleep. Our secondary outcomes include patient-reported physical function, sleep disturbance, pain self-efficacy, pain catastrophizing, pain acceptance, health utilization, medication use, and user satisfaction. We hypothesize superiority for the skills-based VR program in all of these measures compared to the control condition. Team statisticians blinded to treatment assignment will assess outcomes up to 6 months posttreatment using an approach suitable for the longitudinal nature of the data. RESULTS: The study was approved by the Western Institutional Review Board on July 2, 2020. The protocol (NCT04415177) was registered on May 27, 2020. Recruitment for this study was completed in July 2020, and data collection will remain active until March 2021. In total, 186 participants were recruited. Multiple manuscripts will be generated from this study. The primary manuscript will be submitted for publication in the winter of 2020. CONCLUSIONS: Effectively delivering behavioral treatments in VR could overcome barriers to care and provide scalable solutions to chronic pain's societal burden. Our study could help shape future research and development of these innovative approaches. TRIAL REGISTRATION: ClinicalTrials.gov NCT04415177; https://clinicaltrials.gov/ct2/show/NCT04415177. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/25291.

Patient-specific virtual reality technology for complex neurosurgical cases: illustrative cases.

BACKGROUND: Virtual reality (VR) offers an interactive environment for visualizing the intimate three-dimensional (3D) relationship between a patient's pathology and surrounding anatomy. The authors present a model for using personalized VR technology, applied across the neurosurgical treatment continuum from the initial consultation to preoperative surgical planning, then to intraoperative navigation, and finally to postoperative visits, for various tumor and vascular pathologies. OBSERVATIONS: Five adult patients undergoing procedures for spinal cord cavernoma, clinoidal meningioma, anaplastic oligodendroglioma, giant aneurysm, and arteriovenous malformation were included. For each case, 360-degree VR (360°VR) environments developed using Surgical Theater were used for patient consultation, preoperative planning, and/or intraoperative 3D navigation. The custom 360°VR model was rendered from the patient's preoperative imaging. For two cases, the plan changed after reviewing the patient's 360°VR model from one based on conventional Digital Imaging and Communications in Medicine imaging. LESSONS: Live 360° visualization with Surgical Theater in conjunction with surgical navigation helped validate the decisions made intraoperatively. The 360°VR models provided visualization to better understand the lesion's 3D anatomy, as well as to plan and execute the safest patient-specific approach, rather than a less detailed, more standardized one. In all cases, preoperative planning using the patient's 360°VR model had a significant impact on the surgical approach.

Microsurgical Endoscope-Assisted Gravity-Aided Transfalcine Approach for Contralateral Metastatic Deep Medial Cortical Tumors.

BACKGROUND: Traditional approaches to deep medial cortical tumors utilize transcortical or ipislateral interhemispheric approaches, which can result in cortical damage or retraction injury. To reduce these risks, the microscopic transfalcine approach has been previously described. OBJECTIVE: To describe this approach performed with endoscopic assistance for metastatic tumor resection, demonstrating appropriate and safe tumor resection without injury to the contralateral hemisphere. METHODS: Eleven consecutive patients harboring medial, deep metastatic tumors are reported. Tumor resection was performed with endoscopic assistance with 2 surgeons. Clinical outcomes are recorded. RESULTS: All 11 patients underwent safe tumor resection. Gross total resection was achieved in 73% of patients. The application of the angled endoscope allowed for further tumor resection in 91% of patients. There were no complications in these patients. The contralateral brain did not demonstrate clinical or radiographic injury as well. CONCLUSION: This series suggests that the endoscopic transfalcine approach in the lateral position can be a safe and effective approach for resecting medial interhemispheric metastatic tumors. It allows excellent tumor visualization, eliminates the need for brain retraction, minimizes parenchymal transgression, and improves surgical ergonomics. A familiarity of endoscopy and neuroanesthesia support is helpful when utilizing this approach.

Intercostal Nerve to Long Thoracic Nerve Transfer for the Treatment of Winged Scapula: A Cadaveric Feasibility Study.

There are very few surgical options available for treating a patient with winged scapula caused by a long thoracic nerve (LTN) injury. Therefore, we devised a novel technique based on a cadaveric dissection whereby regional intercostal nerves (ICN) were harvested and transposed to the adjacent LTN in 10 embalmed cadavers (20 sides). The LTN was identified along the lateral border of the serratus anterior and ICNs were identified at the mid-axillary line inferior to the lower edge of the pectoralis major muscle. Along the mid-clavicular line, each ICN was transected and transposed to the adjacent LTN. The length and diameter of each ICN available for mobilization to the LTN were measured. All measurements were made with microcalipers. Within the operative site, the mean proximal and distal diameters of the LTN were 1.6 and 1.1 mm, respectively. The adjacent ICN had a mean diameter of 1.3 mm. On all sides, the ICN branches were easily transposed to the adjacent LTN without any tension. Anastomosis to the LTN was performed to the third through sixth ICN provided each intercostal was preserved and mobilized anteriorly at least as far as the midclavicular line. The end to end size match between donor and LTN was appropriate on all sides. We found that it is feasible to harvest adjacent ICNs and move these to the adjacent LTN. Such a procedure, after being confirmed in patients, might offer a new technique for restoring protraction following an LTN injury.

The subdiaphragmatic part of the phrenic nerve - morphometry and connections to autonomic ganglia.

Few anatomical textbooks offer much information concerning the anatomy and distribution of the phrenic nerve inferior to the diaphragm. The aim of this study was to identify the subdiaphragmatic distribution of the phrenic nerve, the presence of phrenic ganglia, and possible connections to the celiac plexus. One hundred and thirty formalin-fixed adult cadavers were studied. The right phrenic nerve was found inferior to the diaphragm in 98% with 49.1% displaying a right phrenic ganglion. In 22.8% there was an additional smaller ganglion (right accessory phrenic ganglion). The remaining 50.9% had no grossly identifiable right phrenic ganglion. Most (65.5% of specimens) exhibited plexiform communications with the celiac ganglion, aorticorenal ganglion, and suprarenal gland. The left phrenic nerve inferior to the diaphragm was observed in 60% of specimens with 19% containing a left phrenic ganglion. No accessory left phrenic ganglia were observed. The left phrenic ganglion exhibited plexiform communications to several ganglia in 71.4% of specimens. Histologically, the right phrenic and left phrenic ganglia contained large soma concentrated in their peripheries. Both phrenic nerves and ganglia were closely related to the diaphragmatic crura. Surgically, sutures to approximate the crura for repair of hiatal hernias must be placed above the ganglia in order to avoid iatrogenic injuries to the autonomic supply to the diaphragm and abdomen. These findings could also provide a better understanding of the anatomy and distribution of the fibers of that autonomic supply.

Crooke's Changes In Cushing's Syndrome Depends on Degree of Hypercortisolism and Individual Susceptibility.

CONTEXT: Although Crooke's changes in the pituitary corticotrophs were initially described in 1935, the prevalence in which the changes occur in patients with Cushing's syndrome (CS) has not been established. OBJECTIVE: This study aimed to determine the prevalence and assess clinical features associated with the presence or absence of Crooke's changes in a large set of patients with CS. DESIGN: Information from a prospective computer database and retrospective chart review was analyzed. SETTING: The setting was an academic medical center. PATIENTS: Consecutive patients (N = 213) who received surgery with a preoperative diagnosis of Cushing's disease are included. INTERVENTION: The patients received pituitary surgery and specimens obtained underwent pathological analysis. MAIN OUTCOME MEASURE: The presence or absence of Crooke's changes was determined by histopathological analysis of the normal pituitary tissue included with the specimen obtained at surgery. Cortisol production was measured by 24-hour urine cortisol production. RESULTS: Crooke's changes occurred in 144 of 177 patients (81%) with a histologically demonstrated ACTH-staining tumor and in 74% of 213 patients diagnosed with CS who had pituitary surgery. The presence of Crooke's changes correlated with the finding of an ACTH-staining tumor removed at surgery and with the degree of hypercortisolism. Among patients with histologically established ACTH-staining tumors the prevalence of Crooke's changes was particularly high in patients with a 24-h urinary free cortisol (UFC) of at least 4-fold the upper limit of normal, in which 91% of patients had Crooke's changes, compared with 74% of patients whose maximum UFC was less than 4-fold the upper limit of normal (P = .008). CONCLUSIONS: Crooke's changes occur in 75-80% of patients with CS, and depend on the degree of hypercortisolism and individual variability. Almost all patients with UFC at least 4-fold the upper limit of normal have them, whereas with less severe hypercortisolism the expression of Crooke's changes varies from person to person.

Endoscopic and Gravity-Assisted Resection of Medial Temporo-occipital Lesions Through a Supracerebellar Transtentorial Approach: Technical Notes With Case Illustrations.

BACKGROUND: Traditional approaches to medial temporo-occipital intra-axial brain tumors carry the risk of visual or language deficits related to brain retraction or transgression of deep fiber tracts. To reduce these risks, the microscopic supracerebellar transtentorial approach with the patient in the sitting position has been previously described for lesions in relative proximity to the tentorium. OBJECTIVE: We describe this approach performed with endoscopic tumor resection to allow better visualization and a more ergonomic operating position. METHODS: Four consecutive patients harboring a medial temporo-occipital lesion are reported. All were operated on while in the sitting position using frameless navigation and a supracerebellar transtentorial approach. Tumor resection was performed by 2 surgeons with endoscopic visualization. RESULTS: Pathologies included intraparenchymal metastatic melanoma, cavernous hemangioma, and ganglioglioma, as well as an intraventricular metastatic tumor. The distance from the tentorium to the lesion ranged from 1 to 4 mm. Gross total resection was achieved in 3 of the 4 patients. The patient with a metastatic melanoma had an intentional near-total resection given the tumor encasing a branch of the posterior cerebral artery. The patient with the intraventricular tumor sustained a small but symptomatic infarct of the lateral geniculate region, resulting in a visual field deficit. CONCLUSION: This small series suggests that the endoscopic supracerebellar transtentorial approach with the patient in the sitting position can be a safe and effective approach for removing medial temporo-occipital lesions. It allows excellent tumor visualization, eliminates the need for brain retraction, minimizes parenchymal transgression, and improves surgical ergonomics. Significant experience in endoscopy and excellent neuroanesthesia support are recommended before undertaking this approach.

Retrospective analysis of a concurrent series of microscopic versus endoscopic transsphenoidal surgeries for Knosp Grades 0-2 nonfunctioning pituitary macroadenomas at a single institution.

OBJECT: The object of this study was to compare surgical outcomes and complications in a contemporaneous series of patients undergoing either microscopic or endoscopic transsphenoidal surgery for nonfunctioning pituitary macroadenomas without imaging evidence of cavernous sinus invasion. METHODS: This is a retrospective analysis of a prospectively collected database from a single institution. Data were collected from patients whose surgery had occurred in the period from June 2010 to January 2013. Patients who underwent microscopic or endoscopic surgery for Knosp Grade 0, 1, or 2 nonfunctioning pituitary macroadenomas were included in the study. Patients who had clinically secreting or Knosp Grade 3 or 4 tumors and patients who were undergoing revision surgery were excluded from analysis. Eligible patient records were analyzed for outcomes and complications. Statistical analyses were performed on tumor volume, intraoperative factors, postoperative complications, and degree of resection on 1-year postoperative MRI. The results were used to compare the outcomes after microscopic and endoscopic approaches. RESULTS: Forty-three patients underwent microscopic transsphenoidal surgery, and 56 underwent endoscopic transsphenoidal surgery. There were no statistical differences in the intraoperative extent of resection or endocrinological complications. There were significantly more intraoperative CSF leaks in the endoscopic group (58% vs 16%); however, there was no difference in the incidence of postoperative CSF rhinorrhea (12% microscopic vs 7% endoscopic). Length of hospitalization was significantly shorter in patients undergoing an endoscopic approach (3.0 days vs 2.4 days). Two-month follow-up imaging was available in 95% of patients, and 75% of patients had 1-year follow-up imaging. At 2 months postprocedure, there was no evidence of residual tumor in 79% (31 of 39) and 85% (47 of 55) of patients in the microscopic and endoscopic groups, respectively. At 1 year postprocedure, 83% (25 of 30) of patients in the microscopic group had no evidence of residual tumor and 82% (36 of 44) of those in the endoscopic group had no evidence of residual tumor. CONCLUSIONS: The microscopic and endoscopic techniques provide similar outcomes in the surgical treatment of Knosp Grades 0-2 nonfunctioning pituitary macroadenomas.

Evolution of minimally invasive approaches to the sella and parasellar region.

Introduction Given advancements in endoscopic image quality, instrumentation, surgical navigation, skull base closure techniques, and anatomical understanding, the endonasal endoscopic approach has rapidly evolved into a widely utilized technique for removal of sellar and parasellar tumors. Although pituitary adenomas and Rathke cleft cysts constitute the majority of lesions removed via this route, craniopharyngiomas, clival chordomas, parasellar meningiomas, and other lesions are increasingly removed using this approach. Paralleling the evolution of the endonasal route to the parasellar region, the supraorbital eyebrow craniotomy has also been increasingly used as an alternative minimally invasive approach to reach this skull base region. Similar to the endonasal route, the supraorbital route has been greatly facilitated by advances in endoscopy, along with development of more refined, low-profile instrumentation and surgical navigation technology. Objectives This review, encompassing both transcranial and transsphenoidal routes, will recount the high points and advances that have made minimally invasive approaches to the sellar region possible, the evolution of these approaches, and their relative indications and technical nuances. Data Synthesis The literature is reviewed regarding the evolution of surgical approaches to the sellar region beginning with the earliest attempts and emphasizing technological advances, which have allowed the evolution of the modern technique. The surgical techniques for both endoscopic transsphenoidal and supraorbital approaches are described in detail. The relative indications for each approach are highlighted using case illustrations. Conclusions Although tremendous advances have been made in transitioning toward minimally invasive transcranial and transsphenoidal approaches to the sella, further work remains to be done. Together, the endonasal endoscopic and the supraorbital endoscope-assisted approaches are complementary minimally invasive routes to the parasellar region.

Evolution of Minimally Invasive Approaches to the Sella and Parasellar Region

Introduction: Given advancements in endoscopic image quality, instrumentation, surgical navigation, skull base closure techniques, and anatomical understanding, the endonasal endoscopic approach has rapidly evolved into a widely utilized technique for removal of sellar and parasellar tumors. Although pituitary adenomas and Rathke cleft cysts constitute the majority of lesions removed via this route, craniopharyngiomas, clival chordomas, parasellar meningiomas, and other lesions are increasingly removed using this approach. Paralleling the evolution of the endonasal route to the parasellar region, the supraorbital eyebrow craniotomy has also been increasingly used as an alternative minimally invasive approach to reach this skull base region. Similar to the endonasal route, the supraorbital route has been greatly facilitated by advances in endoscopy, along with development of more refined, low-profile instrumentation and surgical navigation technology. Objectives: This review, encompassing both transcranial and transsphenoidal routes, will recount the high points and advances that have made minimally invasive approaches to the sellar region possible, the evolution of these approaches, and their relative indications and technical nuances. Data Synthesis: The literature is reviewed regarding the evolution of surgical approaches to the sellar region beginning with the earliest attempts and emphasizing technological advances, which have allowed the evolution of the modern technique. The surgical techniques for both endoscopic transsphenoidal and supraorbital approaches are described in detail. The relative indications for each approach are highlighted using case illustrations. Conclusions: Although tremendous advances have been made in transitioning toward minimally invasive transcranial and transsphenoidal approaches to the sella, furtherwork remains to be done. Together, the endonasal endoscopic and the supraorbital endoscope-assisted approaches are...

Harvest of autologous clavipectoral fascia for use in duraplasty: cadaveric feasibility study.

Techniques and materials for repair of dural defects following neurosurgical procedures vary. Given higher complication rates with nonautologous duraplasty materials, most authors strongly recommend autologous grafts. To expand the arsenal of possible materials available to the neurosurgeon, we propose the use of autologous clavipectoral fascia as an alternative donor for duraplasty. Eight embalmed adult cadavers underwent dissection of the pectoral region. A 12-cm curvilinear skin incision was made 2 cm inferior to the nipple in males and along the inferior breast edge in females. Dissection was continued until the clavipectoral fascia was encountered, and a tissue plane was developed between this fascia and the deeper pectoralis major muscle. Sections of clavipectoral fascia were used for duraplasty in the same specimens. In all specimens, removal of clavipectoral fascia was easily performed with tissue separation between the overlying fascia and underlying muscle. Only small adhesions were found between the fascia and underlying muscle, and these were easily transected. No obvious gross neurovascular injuries were identified. Large portions of clavipectoral fascia were available, and at least a 10 × 10-cm piece (average thickness, 1.2 mm) was easily harvested for all specimens. Clavipectoral fascia shares characteristics with materials such as pericranium and fascia lata that have been used successfully in duraplasty, and most importantly, it is autologous. Theoretically, using clavipectoral fascia would reduce the risk of muscle herniation. It offers an alternative source for autologous dural grafting when other sources are unavailable or exhausted. Clinical experience with this fascia is warranted.

External landmarks for identifying the drainage site of the vein of Labbé: application to neurosurgical procedures.

INTRODUCTION: The vein of Labbé is an important structure of the lateral cortical surface. However, to date, studies aimed at providing external landmarks for aiding in its identification have been scant. Therefore, the present study focussed on establishing reliable bony landmarks for localizing this deeper lying venous structure. MATERIALS AND METHODS: Fifteen adult cadavers (30 sides) underwent dissection of the lateral cortical brain surface with special attention given to the drainage site of the vein of Labbé into the transverse sinus. Measurements of the distance from this site to surrounding external bony landmarks were then made. RESULTS: We found that this drainage site into the transverse sinus was 0.8-1.5 cm (mean 1.1 cm, SD 0.567) superior to the superior border of the zygomatic arch and 2 - 5 cm (mean 2.9 cm, SD 0.713) posterior to the opening of the external auditory meatus. Statistically, there was no significance between left and right sides or between sexes. CONCLUSIONS: We found that the junction between the vein of Labbé and transverse sinus may be variable. Nonetheless, additional landmarks found in this study for identifying the junction may aid in its earlier identification during surgery, potentially decreasing operative morbidity.

The anterior atlantodental ligament: its anatomy and potential functional significance.

OBJECTIVE: Knowledge of the anatomy of the ligaments that unite the head to the neck is important to the clinician who treats patients with lesions in this region. Although the anatomy and function of the majority of these ligaments have been well described, some are relatively unknown. One of these includes the anterior atlantodental ligament (AADL). Our goal was to increase knowledge about the AADL. METHODS: We dissected the craniocervical junction in sixteen adult cadavers and paid special attention to the presence and anatomy of the AADL. RESULTS: The AADL was found in 81.3% of specimens. The attachment of each ligament was consistent and traveled between the base of the anterior dens to the posterior aspect of the anterior arch of the atlas in the midline and just inferior to the fovea dentis. In 38.5% of specimens, there was some connection between the AADL and the anterior atlanto-occipital membrane. The ligament was roughly 4 × 4 × 4 mm in all specimens. With transection of the transverse ligament, the AADL could be made taut with posterior distraction of the dens. In addition, with left and right rotation of the atlantoaxial joint, the AADL became taut (less than 10°) before any tautness of the alar ligaments in all specimens. CONCLUSIONS: The AADL appears to resist posterior displacement of the dens and, with the alar ligaments, resists rotation. When present, the AADL contributes to the predental space. Knowledge of this ligament may aid in further understanding craniocervical stability and help in differentiating normal anatomy from pathology via imaging modalities.

A rare intraosseous arteriovenous malformation of the spine.

The authors report the case of a patient with an intraosseous spinal arteriovenous malformation (AVM) presenting as an epidural mass lesion that was causing spinal cord compression. The 59-year-old woman had bilateral numbness, weakness, and hyperreflexia of both legs. Magnetic resonance imaging revealed intermediate T1 signal and hyperintense T2 signal involving the right transverse process, bilateral pedicles, and T-5 spinous process; the lesion's epidural extension was causing severe canal compromise and cord displacement. Coil embolization was performed, and the patient underwent resection, after which preoperative symptoms improved. Histopathological analysis revealed a benign vascular proliferation consistent with an intraosseous spinal AVM. On review of the literature, the authors found this case to be the second intraosseous spinal AVM, and the first in a patient whose clinical presentation was consistent with that of a mass lesion of the bone.

Anatomy of the ilioinguinal and iliohypogastric nerves with observations of their spinal nerve contributions.

Proper anesthesia and knowledge of the anatomical location of the iliohypogastric and ilioinguinal nerves is important during hernia repair and other surgical procedures. Surgical complications have also implicated these nerves, emphasizing the importance of the development of a clear topographical map for use in their identification. The aim of this study was to explore anatomical variations in the iliohypogastric and ilioinguinal nerves and relate this information to clinical situations. One hundred adult formalin fixed cadavers were dissected resulting in 200 iliohypogastric and ilioinguinal nerve specimens. Each nerve was analyzed for spinal nerve contribution and classified accordingly. All nerves were documented where they entered the abdominal wall with this point being measured in relation to the anterior superior iliac spine (ASIS). The linear course of each nerve was followed, and its lateral distance from the midline at termination was measured. The ilioinguinal nerve originated from L1 in 130 specimens (65%), from T12 and L1 in 28 (14%), from L1 and L2 in 22 (11%), and from L2 and L3 in 20 (10%). The nerve entered the abdominal wall 2.8 ± 1.1 cm medial and 4 ± 1.2 cm inferior to the ASIS and terminated 3 ± 0.5 cm lateral to the midline. The iliohypogastric nerve originated from T12 on 14 sides (7%), from T12 and L1 in 28 (14%), from L1 in 20 (10%), and from T11 and T12 in 12 (6%). The nerve entered the abdominal wall 2.8 ± 1.3 cm medial and 1.4 ± 1.2 cm inferior to the ASIS and terminated 4 ± 1.3 cm lateral to the midline. For both nerves, the distance between the ASIS and the midline was 12.2 ± 1.1 cm. To reduce nerve damage and provide sufficient anesthetic for nerve block during surgical procedures, the precise anatomical location and spinal nerve contributions of the iliohypogastric and ilioinguinal nerves need to be considered.