U. Kumar Kakarla

Evolution of surgical approaches in the treatment of petroclival meningiomas: a retrospective review.

OBJECTIVE We examined the surgical approaches used at a single institution to treat petroclival meningioma and evaluated changes in method utilization over time. METHODS Craniotomies performed to treat petroclival meningioma between September of 1994 and July of 2005 were examined retrospectively. We reviewed 46 patients (mean follow-up, 3.6 yr). Techniques included combined petrosal or transcochlear approaches (15% of patients), retrosigmoid craniotomies with or without some degree of petrosectomy (59% of patients), orbitozygomatic craniotomies (7% of patients), and combined orbitozygomatic-retrosigmoid approaches (19% of patients). In 18 patients, the tumor extended supratentorially. Overall, the rate of gross total resection was 43%. Seven patients demonstrated progression over a mean of 5.9 years. No patients died. At 36 months, the progression-free survival rate for patients treated without petrosal approaches was 96%. Of 14 patients treated with stereotactic radiosurgery, none developed progression. CONCLUSION Over the study period, a diminishing proportion of patients with petroclival meningioma were treated using petrosal approaches. Utilization of the orbitozygomatic and retrosigmoid approaches alone or in combination provided a viable alternative to petrosal approaches for treatment of petroclival meningioma. Regardless of approach, progression-free survival rates were excellent over short-term follow-up period.

Human Amniotic Membrane for the Prevention of Intradural Spinal Cord Adhesions: Retrospective Review of its Novel Use in a Case Series of 14 Patients

BACKGROUND Tethering after spinal surgery is caused by adhesions that arise from intradural tissue manipulation. Microsurgical detethering is the only treatment for symptomatic patients, but retethering occurs commonly and no treatment is widely available to prevent this complication. OBJECTIVE To apply human amniotic membrane (HAM) grafts, which are immune-privileged and known to possess antifibrogenic properties, in patients requiring microsurgical detethering. For this first-in-human use, we evaluated the safety and potential efficacy of these grafts for preventing retethering. METHODS We retrospectively reviewed the medical records of all patients who required detethering surgery and received an HAM graft between 2013 and 2016 at our institution after various previous intradural spinal surgeries. In all 14 cases, intradural lysis of adhesions was achieved, an HAM graft was sewn in place intradurally, and a dural patch was closed in a watertight fashion over the graft. RESULTS Fourteen patients had received HAM grafts to prevent retethering. All patients had at least 6 mo of follow-up (mean follow-up, 14 mo). Retethering was noted in only 1 patient. Surgical re-exploration showed that the retethering occurred caudal to the edge of the HAM graft, with no tethering underneath the original graft. No complications were attributed specifically to the HAM graft placement. CONCLUSION This first-in-human series provides evidence that HAM grafts are a safe and potentially efficacious method for preventing retethering after microsurgical intradural lysis of adhesions. These results lay the groundwork for further prospective controlled trials in patients with this difficult-to-treat pathology.

Pedicled Vascularized Clavicular Graft for Anterior Cervical Arthrodesis: Cadaveric Feasibility Study, Technique Description, and Case Report

Study Design. Cadaveric feasibility study. Objective. To assess the anatomic and technical feasibility of rotating a clavicular segment on a sternocleidomastoid muscle (SCM) pedicle into the ventral cervical spine using a cadaveric model and to provide the first clinical case description of performing this procedure. Summary of Background Data. Reconstruction of the anterior cervical spine in patients with a high risk of pseudoarthrosis may require the use of a vascularized bone graft (VBG). A vascularized clavicular graft rotated on an SCM pedicle would afford all the benefits of a VBG without the added morbidity of free-tissue transfer; however, this technique has not been described. Methods. A multidisciplinary team hypothesized that it would be anatomically and technically feasible to rotate a pedicled clavicular bone graft from the bottom of C2 to the top of T2 via an anterior approach. Five cadavers underwent bilateral anterior neck dissections for a total of 10 clavicular graft assessments. A case report describes the use of a clavicular VBG in a patient with a 3-level corpectomy defect and a history of failed fusion. Results. Ten clavicles were rotated on an SCM pedicle. The grafts were either harvested as an entire segment or as the superior two-thirds of clavicle, leaving the inferior one-third in situ with pectoralis attachments intact. All grafts reached from the bottom of C2 to the top of T2. When the entire length of exposed clavicle was mobilized, it could cover five to six levels. The case report highlights technical challenges of this procedure in a living patient and provides the clinical context for its potential utility in the reconstruction of the ventral cervical spine. Conclusion. This surgical technique is best suited for patients with long-segment cervical defects and an increased risk of pseudarthrosis. Further clinical experience with this technique is required before definitive conclusions can be made. Level of Evidence: 5

Age-Based Tailoring of Adult Spinal Deformity Alignment Goals.

In recent years, medicine has undergone a transformation from standardization to personalization. The field of adult spinal deformity (ASD) has followed suit. During the past decade, research dedicated to understanding how specific radiographic parameters impact health-related quality of life (HRQOL) measures has proliferated. It is now well-established that the sagittal contour of the spine is dependent on individual pelvic anatomy and that realignment surgery should be customized to achieve spinopelvic harmony. The relative importance of other individual factors on alignment goals, however, is not as well understood. Researchers particularly are interested in better understanding the influence of patient age on alignment goals. Age-related degeneration leads to predictable changes in sagittal alignment, marked by loss of lumbar lordosis, exaggerated thoracic kyphosis, and compensatory pelvic retroversion. Although these age-related changes are prominent in patients with ASD, they also are seen in asymptomatic volunteers. With surgery, ASD alignment goals typically are targeted at restoring standardized, “ideal” sagittal parameters; however, age-adjusted alignment goals, which incorporate expected degenerative changes, could theoretically result in a more physiologic, age-appropriate alignment, particularly in elderly patients. In a recent publication, Lafage et al. explore the relationship between age and sagittal alignment goals. The authors performed a retrospective analysis of 773 operative and nonoperative ASD patients in the International Spine Study Group database. First, age-specific Oswestry Disability Index (ODI) norms were extrapolated from established Short Form-36 Health Survey Physical

Barrow Innovation Center Case Series: Early Clinical Experience with Novel Surgical Instrument Used To Prevent Intraoperative Spinal Cord Injuries

OBJECTIVE The Barrow Innovation Center comprises an educational program in medical innovation that enables residents to identify problems in patient care and rapidly develop and implement solutions to these problems. Residents involved in this program noted an elevated risk of iatrogenic spinal cord injury during posterior cervical and thoracic procedures. The objective of this study was to describe this complication, and a novel solution was developed through a new innovation training program. METHODS A case report demonstrates the risk of iatrogenic spinal cord injury during posterior cervical decompression and fusion. Solutions to this problem were developed at the innovation center via an iterative process of prototype creation, cadaveric testing, and redesign. Patent law students who partnered with the center wrote and filed a provisional patent protecting the novel prototype designs. RESULTS The concept of a protective shield for the spinal cord was developed, and within only 6 weeks the devices were provisionally patented and used in the operating room. This device was named the Myeloshield. Initial clinical experience indicates that the Myeloshield can be used without impeding the flow of surgery and has the potential to prevent iatrogenic spinal cord injury; this experience is presented through 2 case reports demonstrating the use of Myeloshields in the operating room. CONCLUSIONS This report demonstrates how programs like the Barrow Innovation Center can provide neurosurgery residents with a unique educational experience in medical device innovation and intellectual property development and can serve as an avenue of surgical quality improvement and problem solving.

Vascularized Spinous Process Graft Rotated on a Paraspinous Muscle Pedicle for Lumbar Fusion: Technique Description and Early Clinical Experience

BACKGROUND Vascularized bone grafts (VBGs) are described as having superior osteogenicity, osteoconductivity, and osteoinductivity compared with other graft types and have been used in high-risk patients to augment arthrodesis. Pedicled VBGs are rotated on an intact vascular pedicle and therefore maintain all the benefits of VBGs but avoid many of the challenges and additional morbidity of free-tissue transfer. This study describes a novel surgical technique for rotating vascularized spinous process into the posterolateral space for augmenting arthrodesis in patients undergoing posterolateral fusion (PLF). METHODS A technique is described for rotating the spinous process into the posterolateral space on an intact vascular pedicle of paraspinal muscle. Early clinical and radiographic outcomes are reported for 4 patients who have undergone this procedure. RESULTS Four patients were treated with a single or 2-level PLF combined with posterior, anterior, or lateral interbody fusion and vascularized spinous process graft. Three-month postoperative computed tomography scans demonstrated a dislodged graft in 1 patient and successful arthrodesis in 3 patients. Additional operative time taken for graft harvest and implantation ranged from 22 minutes for the first patient to 6 minutes for the fourth patient. CONCLUSIONS Rotation of vascularized spinous process graft for augmentation of posterolateral arthrodesis in the lumbar spine is a potentially safe, effective surgical technique that results in successful arthrodesis in as little as 3 months but requires further study. This technique is expected to add little additional time or morbidity to the traditional lumbar PLF because it requires no separate incision or additional bone removal.

Divergent Bilateral Posterior Lumbar Interbody Fusion with Cortical Screw Fixation: Description of New Trajectory for Interbody Technique from Midline Exposure

BACKGROUND A major drawback to use of cortical bone trajectory pedicle screws (CBTPSs) with traditional posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion grafts is that traditional graft insertion trajectories require wider posterior exposure. This wider exposure, beyond the limits otherwise required for CBTPS placement, negates a primary benefit of CBTPS fixation. The aim of this study was to define an alternative surgical technique for interbody graft placement that, when used in conjunction with CBTPS fixation, permits both minimal soft tissue dissection and optimal graft placement. METHODS A team of neurosurgeons specializing in treatment of spinal pathologies developed a surgical technique for insertion of bilateral PLIF grafts that complements the principles of CBTPS fixation. This technique is illustrated in a patient undergoing lumbosacral decompression, CBTPS fixation, and 3-column arthrodesis. RESULTS The described technique uses a divergent trajectory of bilateral PLIF grafts rather than the traditional parallel or convergent trajectories. CONCLUSIONS By aiming medially to laterally with the interbody graft, one recapitulates many advantages of CBTPSs, including avoidance of wide tissue dissection, greater intergraft volume available for bone grafting, and greater graft coverage of the hypophyseal ring. The prospective collection of outcome data for patients who undergo lumbosacral fusion using the divergent PLIF technique is ongoing.

Pedicled Vascularized Bone Grafts for Posterior Lumbosacral Fusion: A Cadaveric Feasibility Study and Case Report

STUDY DESIGN Cadaveric feasibility study and case report. OBJECTIVE To determine if it is feasible to rotate pedicled vascularized bone graft (VBG) from L1 to S1 via a posterior approach. VBG has been used to successfully augment fusion rates in various skeletal pathologies. Pedicled VBG has numerous advantages over free-transfer VBG, including the maintenance of a robust vascular supply to the graft without the need for vascular anastomoses. Pedicled VBG options have not been well described for posterior lumbosacral fusion. METHODS A multidisciplinary team of plastic surgeons and neurosurgeons hypothesized that it is feasible to rotate pedicled VBG from L1 to S1 via a posterior approach. In six cadavers, two VBG donor sites were evaluated: posterior element (PE-VBG) and iliac crest (IC-VBG). A single case report of a patient with lumbar Charcot joint treated with IC-VBG is also presented. RESULTS For the PE-VBG, the laminae and spinous processes were mobilized en bloc via Gill laminectomy on a unilateral sacrospinalis pedicle. Mean ± standard deviation (SD) length × width graft dimensions were 2.8±0.48 cm × 2.2±0.81 cm. The inter-transverse process (inter-TP) distance was less than the corresponding lamina length at all levels. For the IC-VBG, iliac crest was mobilized on a quadratus lumborum pedicle. Mean±SD length × width × thickness graft dimensions were 7.7±1.28 cm × 2.2±0.69 cm × 1.5±0.79 cm. The IC-VBGs reached from L1 (T12-S1) to S1 (S1-S3), and all IC-VBGs were able to cover three levels. CONCLUSIONS This feasibility cadaveric study and the case report are the first demonstrations that pedicled VBGs can be successfully applied to posterior lumbosacral spinal arthrodesis. Patients at high risk for nonunion may benefit from these strategies. Further clinical experience with these techniques is warranted. LEVEL OF EVIDENCE Level IV.STUDY DESIGN Cadaveric feasibility study and case report. OBJECTIVE To determine if it is feasible to rotate pedicled vascularized bone graft (VBG) from L1 to S1 via a posterior approach. SUMMARY OF BACKGROUND DATA VBG has been used to successfully augment fusion rates in various skeletal pathologies. Pedicled VBG has numerous advantages over free-transfer VBG, including the maintenance of a robust vascular supply to the graft without the need for vascular anastomoses. Pedicled VBG options have not been well described for posterior lumbosacral fusion. METHODS A multidisciplinary team of plastic surgeons and neurosurgeons hypothesized that it is feasible to rotate pedicled VBG from L1 to S1 via a posterior approach. In six cadavers, two VBG donor sites were evaluated: posterior element (PE-VBG) and iliac crest (IC-VBG). A single case report of a patient with lumbar Charcot joint treated with IC-VBG is also presented. RESULTS For the PE-VBG, the laminae and spinous processes were mobilized en bloc via Gill laminectomy on a unilateral sacrospinalis pedicle. Mean ± standard deviation (SD) length × width graft dimensions were 2.8±0.48 cm × 2.2±0.81 cm. The inter-transverse process (inter-TP) distance was less than the corresponding lamina length at all levels. For the IC-VBG, iliac crest was mobilized on a quadratus lumborum pedicle. Mean±SD length × width × thickness graft dimensions were 7.7±1.28 cm × 2.2±0.69 cm × 1.5±0.79 cm. The IC-VBGs reached from L1 (T12-S1) to S1 (S1-S3), and all IC-VBGs were able to cover three levels. CONCLUSIONS This feasibility cadaveric study and the case report are the first demonstrations that pedicled VBGs can be successfully applied to posterior lumbosacral spinal arthrodesis. Patients at high risk for nonunion may benefit from these strategies. Further clinical experience with these techniques is warranted. LEVEL OF EVIDENCE Level IV.

Misplacement of Stent Into Epidural Venous Plexus With Resultant Cauda Equina Syndrome and Open Surgical Treatment: A Case Report

BACKGROUND AND IMPORTANCE Endovascular therapy has proven to be a safe, minimally invasive treatment for multiple etiologies, but proper precautions must be taken to avoid complications. When complications occur, they should be promptly identified and corrected when possible. This case report describes endovascular stents misplaced into the epidural spinous venous plexus rather than the iliofemoral arteries, causing cauda equina syndrome, as well as the spinal procedure performed to treat the resulting spinal canal compression. CLINICAL PRESENTATION A 67-yr-old man had undergone what he thought was iliofemoral arterial stenting at an outside hospital for peripheral vascular disease. He presented 8 d later to our hospital with cauda equina syndrome comprising back pain, right L5 radiculopathy, perianal numbness, urinary retention, and constipation. Scans demonstrated stents deployed into the venous system, traversing the spinal canal and the right L5-S1 neural foramen, resulting in severe spinal canal stenosis, right L5-S1 foraminal stenosis, and moderate left S1-S2 foraminal stenosis. The patient underwent an L5-S1 laminectomy with full right L5-S1 facetectomy and left S1-S2 medial facetectomy, with associated L5-S1 posterolateral fusion with fixation to remove the stent and decompress the neural elements. CONCLUSION Although stent misplacement is an uncommon complication of endovascular therapy, this case demonstrates the importance of ensuring access to the proper vessel before stent placement. Once this complication was recognized, safe removal of the stents was possible and the patient demonstrated meaningful postoperative improvement in symptoms and strength.

Novel Surgical Treatment Strategies for Unstable Lumbar Osteodiscitis: A 3-Patient Case Series

BACKGROUND Lumbar osteomyelitis frequently affects patients with medical comorbidities and poor preoperative health. Surgery is indicated when medical management fails or patients present with spinal instability or neural compromise. Successful arthrodesis can be difficult and sometimes requires alternative surgical techniques. OBJECTIVE To report 3 novel methods, each illustrated by a case, for achieving arthrodesis for lumbar osteomyelitis. METHODS A retrospective review was performed of 3 cases of surgical treatment of lumbar osteomyelitis. Novel aspects of the surgical techniques are reported, as are perioperative clinical details and imaging results. RESULTS In the first patient, a vascularized iliac crest graft on a quadratus lumborum pedicle was rotated into the posterolateral fusion bed of the affected level. In the second, an anterior approach with debridement of affected lumbar levels was followed by rotation of a vascularized iliac crest graft on an iliacus muscle pedicle into the anterior lumbar defect. In the third, a structural, nonvascularized iliac crest graft was harvested via a lateral approach to provide better surgical access, and an autologous tricortical bone graft was obtained for placement in the debridement defect. Follow-up imaging suggested successful early incorporation of all the grafts in the fusion beds. CONCLUSION Patients with multiple risk factors for pseudarthrosis and recurrent infection often require alternative surgical strategies to augment fusion. These 3 novel methods for lumbar debridement, fixation, and fusion using vascularized or nonvascularized autograft accommodate posterior, anterior, and lateral surgical approaches. Further experience with these techniques is required to compare outcomes with those of traditional techniques.