Steve W. Chang

Treatment of distal posterior cerebral artery aneurysms: a critical appraisal of the occipital artery-to-posterior cerebral artery bypass.

OBJECTIVEThis is the largest contemporary series of distal posterior cerebral artery (PCA) aneurysms treated by use of endovascular coiling and stenting as well as surgical clipping, clip wrapping, and bypass techniques. We propose a new treatment paradigm. METHODSThe location, size, type of aneurysm, clinical presentation, treatment, complications, and outcomes associated with 34 distal PCA aneurysms in 33 patients (15 females, 18 males; mean age, 44 years) were reviewed retrospectively. RESULTSThe most common presenting symptom was headache in 19 (58%) followed by contralateral weakness or numbness in 6 (18%) and visual changes in 4 (12%). Eight aneurysms were giant. Of the remaining 26 aneurysms, 17 were fusiform/dissecting, 5 were saccular, and 4 were mycotic. Treatment was primarily endovascular in 22 patients, 12 of whom also had a concomitant surgical bypass procedure. Nine patients underwent microsurgical clipping, and 3 underwent combined treatment of clipping and coiling and/or stenting. There were no significant differences in outcomes between the groups (P = .078). The recurrence rate in patients undergoing coiling was 22% and 0% in patients undergoing clipping. Fourteen aneurysms (41%) involved treatment with an occipital artery-to-PCA bypass or an onlay graft. Compared with their preoperative status, these patients had significantly worse outcomes than those without a bypass (P = .013). CONCLUSIONBypass techniques for the treatment of distal PCA aneurysms are associated with a higher rate of complications than once thought. In our new treatment paradigm, bypass is a last resort and reserved for patients in whom balloon-test occlusion fails, who refuse parent-vessel sacrifice, and who cannot undergo primary stenting with coiling or clip wrapping.

Surgical technique and outcomes in the treatment of spinal cord ependymomas, part 1: intramedullary ependymomas.

BACKGROUND: Intramedullary spinal ependymomas are rare tumors. OBJECTIVE: To provide a large retrospective review in the modern neuroimaging era from a tertiary center where aggressive surgical resection is favored. METHODS: Charts of intramedullary spinal ependymomas treated between 1983 and 2006 were reviewed. RESULTS: Sixty-seven cases were reviewed. The mean age was 45.6 years (range, 11-78 years) with a male-to-female ratio of 2:1. The most common location was the cervical spine, followed by the thoracic and lumbar spine. The average duration of symptoms was 33 months, with the most common symptom being pain and/or dysesthesias, followed by weakness, numbness, and urinary or sexual symptoms. Gross total resection was achieved in 55 patients and a subtotal resection was performed in 12 patients; 9 patients were treated with adjuvant radiation therapy. Mean follow-up was 32 months. The mean McCormick neurological grade at last follow-up was 2.0. The preoperative outcome correlated significantly with postoperative outcome (P < .001). A significant number of patients who initially worsened improved at their 3-month follow-up examination. Outcomes were significantly worse in patients undergoing subtotal resection with or without radiation therapy (P < .05). There were 3 recurrences. The overall complication rate was 34%. The primary complications were wound infections or cerebrospinal fluid leaks. CONCLUSION: Spinal cord ependymomas are difficult lesions to treat. Aggressive surgical resection is associated with a high overall complication rate. However, when gross total resection can be achieved, overall outcomes are excellent and the recurrence rate is low.

Quantitative comparison of Kawase's approach versus the retrosigmoid approach: implications for tumors involving both middle and posterior fossae.

OBJECTIVE Few quantitative data are available to describe Kawases exposure of the posterior fossa. We used a cadaveric model to compare Kawases and the retrosigmoid approach to the petroclival region. METHODS Eighteen cadaveric specimens were dissected and analyzed (6 retrosigmoid, 6 Kawases, and 6 retrosigmoid intradural suprameatal approaches). Clival and brainstem working areas and surgical freedom were measured. RESULTS The retrosigmoid approach provided a significantly larger clival and brainstem working area than Kawases approach. Surgical freedom at the trigeminal root entry zone, origin of the anterior inferior cerebellar artery, and Dorellos canal was equivalent across approaches. Kawases approach provided the most surgical freedom at the trigeminal porus. However, the addition of a suprameatal extension significantly improved the surgical freedom provided by the retrosigmoid approach. CONCLUSION The retrosigmoid approach is a powerful approach to lesions of the cerebellopontine angle and ventral brainstem. Lesions involving the trigeminal porus and Meckels cave can be approached through Kawases approach or a suprameatal extension of the retrosigmoid approach. Kawases approach is best suited for accessing middle fossa lesions with smaller petroclival components located above the internal auditory canal.

Survival and Functional Outcome After Surgical Resection of Intramedullary Spinal Cord Metastases

OBJECTIVE Intramedullary spinal cord metastasis (ISCM) is a rare manifestation of systemic cancer and data about the optimal management of these lesions are lacking. To clarify the role of surgery, we investigated survival and neurological outcomes after surgical resection of ISCMs. METHODS Between 2003 and 2010, we surgically treated 10 ISCMs in 9 patients. For each patient, we retrospectively collected the following data: demographic variables, history of prior cancer, site of primary cancer, extent of cancer on presentation, degree of resection, preoperative and postoperative spinal cord impairment (American Spinal Injury Association [ASIA] grade), and postoperative survival. We investigated the relationship between these variables, overall survival, and preservation of function. RESULTS Eight ISCMs were treated with gross total resection and two were treated with subtotal resection. Overall postoperative survival was 6.4 ± 9.4 months (mean ± standard deviation), with one patient still alive at last follow-up. Patients with a diagnosis of melanoma had higher mean survival than those with nonmelanoma histology (20.5 ± 13.4 vs. 2.4 ± 1.7 months, P < 0.01). Degree of resection, number of organ systems affected, ambulatory status, and ASIA grade pre operatively or postoperatively, were not significantly associated with survival. Of the nine patients, seven (78%) demonstrated no change in ASIA grade postoperatively, one (11%) improved, and one patient (11%) deteriorated. All patients who were ambulatory preoperatively remained ambulatory postoperatively and at last follow-up. CONCLUSIONS Although ISCM is associated with poor prognosis, survival appears to be greater in patients with melanoma. Surgical resection does not appear to significantly lengthen survival but may be indicated to preserve ambulatory status in symptomatic patients.

Microsurgical management of glomus spinal arteriovenous malformations: pial resection technique: Clinical article.

OBJECT Intramedullary, or glomus, spinal arteriovenous malformations (AVMs) are rare vascular lesions amenable to resection with or without adjuvant embolization. The authors retrospectively reviewed the senior authors (R.F.S.s) surgical series of intramedullary spinal AVMs to evaluate clinical and radiographic outcomes. METHODS Detailed chart and radiographic reviews were performed for all patients with intramedullary spinal AVMs who underwent surgical treatment between 1994 and 2011. Presenting and follow-up neurological examination results were obtained and graded using the modified Rankin Scale (mRS) and McCormick Scale. Surgical technique, outcomes, complications, and long-term angiographic studies were reviewed. RESULTS During the study period, 20 patients (10 males and 10 females) underwent resection of glomus spinal AVMs. The mean age at presentation was 30 ± 17 years (range 7-62 years). The location of the AVMs was as follows: cervical spine (n = 10), thoracic spine (n = 9), and cervicothoracic junction (n = 1). The most common presenting signs and symptoms included paresis or paralysis (65%), paresthesias (40%), and myelopathy (40%). Perioperative embolization was performed in the majority (60%) of patients. Pial AVM resection was performed in 17 cases (85%). Angiographically verified AVM obliteration was achieved in 15 patients (75%). At a mean follow-up duration of 45.4 ± 52.4 months (range 2-176 months), 14 patients (70%) remained functionally independent (mRS and McCormick Scale scores ≤ 2). One perioperative complication occurred, yielding a surgical morbidity rate of 5%. Three symptomatic spinal cord tetherings occurred at a mean of 5.7 years after AVM resection. No neurological decline was observed after endovascular and surgical interventions. No deaths occurred. Long-term angiographic follow-up data were available for 9 patients (40%) at a mean of 67.6 ± 60.3 months (range 5-176 months) following AVM resection. Durable AVM obliteration was documented in 5 (83%) of 6 patients. CONCLUSIONS Intramedullary AVMs may be safely resected with satisfactory clinical and angiographic results. The pial resection technique, which provides subtotal AVM nidus resection, effectively devascularized these lesions, as confirmed on postoperative angiography, without violating the spinal cord parenchyma, thereby potentially reducing iatrogenic injury.

Pediatric cervical spine injuries: a comprehensive review

IntroductionCervical spine injuries can be life-altering issues in the pediatric population. The aim of the present paper was to review this literature.ConclusionsA comprehensive knowledge of the special anatomy and biomechanics of the spine of children is essential in diagnosis and treating issues related to spine injuries.

Preliminary personal experiences with the application of near-infrared indocyanine green videoangiography in extracranial vertebral artery surgery.

INTRODUCTIONWe evaluated the feasibility, usefulness, and limitations of near-infrared indocyanine green (ICG) videoangiography during procedures involving the extracranial vertebral artery (VA). METHODSNine patients (2 women, 7 men; mean age, 55 years) were evaluated at 2 neurosurgical centers. Near-infrared ICG videoangiography was applied during transposition and rerouting of the first segment of VA (V1; n = 6) and during resection of neurinomas near the second (V2; n = 1) and third (V3; n = 2) segments of VA. RESULTSEarly after ICG injection, V1 fluoresced homogenously. The fluorescence of V2 and V3 varied. Without extrinsic compression, these segments appeared as noncontiguous hot spots because the VA runs freely in a periosteal sheath surrounded by a venous plexus that attenuates the fluorescent light. Hot spots corresponded to areas where the artery neared the surface. With extrinsic compression, VA enhanced homogenously because it was pushed against the periosteal layer. During the late phase, the V1 signal was attenuated, whereas the venous plexus surrounding V2 and V3 enhanced homogeneously, thereby masking the VA itself. Near-infrared ICG videoangiography helped to confirm VA patency during transposition and rerouting but was not helpful during VA exposure because the periosteal sheath must already be exposed to detect the VA or its surrounding plexus. After exposure, videoangiography can help to determine the position of the VA within its periosteal sheath. CONCLUSIONVideoangiography can be used to provide information about the patency of the VA and its location within the periosteal sheath to prevent injury during resection of tumor adherent to the periosteal sheath.

Placement of percutaneous thoracic pedicle screws using neuronavigation.

BACKGROUND Percutaneous thoracic pedicle screw fixation is challenging because of the complexity of the spinal anatomy and obscuration of normal surgical landmarks by soft tissue. We report a novel percutaneous technique in which intraoperative Iso-C C-arm navigation was used to treat complex thoracic spinal fractures. METHODS Between March and September 2007, percutaneous thoracic pedicle screw fixation was performed with the assistance of intraoperative Iso-C C-arm fluoroscopy in six patients (two males, four females; mean age=33 years, range=16-61 years) with unstable thoracic fractures. The accuracy of pedicle screw placement was assessed by postoperative computed tomography and graded according to the method of Youkilis et al. RESULTS Five patients had unstable acute traumatic fractures and one had an osteoporotic burst fracture. Altogether, 19 spinal segments (range=2-4/patient) were fixated using 37 pedicle screws. Pedicle screw misplacement was grade II in 16% and grade III in 3%. None of the patients had neurologic consequences due to screw misplacement, and none required conversion to an open procedure or revision of hardware. There was one wound infection. CONCLUSION Percutaneous thoracic pedicle screw fixation with intraoperative neuronavigation for the stabilization of complex spinal fractures is feasible and associated with acceptable rates of accuracy and morbidity.

Gamma Knife surgery for hypothalamic hamartomas and epilepsy: patient selection and outcomes.

OBJECT The authors present outcomes obtained in patients who underwent Gamma Knife surgery (GKS) at 1 institution as part of a multimodal treatment of refractory epilepsy caused by hypothalamic hamartomas (HHs). METHODS Between 2003 and 2010, 19 patients with HH underwent GKS. Eight patients had follow-up for less than 1 year, and 1 patient was lost to follow-up. The 10 remaining patients (mean age 15.1 years, range 5.7-29.3 years) had a mean follow-up of 43 months (range 18-81 months) and are the focus of this report. Five patients had undergone a total of 6 prior surgeries: 1 transcallosal resection of the HH, 2 endoscopic transventricular resections of the HH, 2 temporal lobectomies, and 1 arachnoid cyst evacuation. In an institutional review board-approved study, postoperative complications and long-term outcome measures were monitored prospectively with the use of a proprietary database. Seven patients harbored Delalande Type II lesions; the remainder harbored Type III or IV lesions. Seizure frequency ranged from 1-2 monthly to as many as 100 gelastic seizures daily. The mean lesion volume was 695 mm(3) (range 169-3000 mm(3), median 265 mm(3)). The mean/median dose directed to the 50% isodose line was 18 Gy (range 16-20 Gy). The mean maximum point dose to the optic chiasm was 7.5 Gy (range 5-10 Gy). Three patients underwent additional resection 14.5, 21, and 32 months after GKS. RESULTS Of the 10 patients included in this study, 6 are seizure free (2 after they underwent additional surgery), 1 has a 50%-90% reduction in seizure frequency, 2 have a 50% reduction in seizure frequency, and 1 has observed no change in seizure frequency. Overall quality of life, based on data obtained from follow-up telephone conversations and/or surveys, improved in 9 patients and was due to improvements in seizure control (9 patients), short-term memory loss (3 patients), and behavioral symptoms (5 patients); in 1 patient, quality of life remains minimally affected. Incidences of morbidity were all temporary and included poikilothermia (1 patient), increased depression (1 patient), weight gain/increased appetite (2 patients), and anxiety (1 patient) after GKS. CONCLUSIONS Of the approximately 150 patients at Barrow Neurological Institute who have undergone treatment for HH, the authors have reserved GKS for treatment of small HHs located distal from radiosensitive structures in patients with high cognitive function and a stable clinical picture, which allows time for the effects of radiosurgery to occur without further deterioration. The lack of significant morbidity and the clinical outcomes achieved in this study demonstrated a low risk of GKS for HH with results comparable to those of previous series.

Lumbar Spinal Fixation with Cortical Bone Trajectory Pedicle Screws in 79 Patients with Degenerative Disease: Perioperative Outcomes and Complications

OBJECTIVE Biomechanical studies demonstrate that cortical bone trajectory pedicle screws (CBTPS) have greater pullout strength than traditional pedicle screws with a lateral-medial trajectory. CBTPS start on the pars and angulate in a mediolateral-caudocranial direction. To our knowledge, no large series exists evaluating the perioperative outcomes and safety of CBTPS. METHODS We retrospectively reviewed all patients who received lumbar CBTPS at our institution. Data were collected regarding patient demographics, use of image guidance, operative blood loss, hospital stay, and postoperative complications. RESULTS A total of 79 patients undergoing CBTPS fusion for degenerative lumbosacral disease with back pain were included in the analysis (42 female, 37 male; October 2011-January 2015). Twenty patients (25.3%) had previous lumbar spine surgery, 39 (49.4%) had a smoking history, and mean body mass index was 28.7. Mean length of stay was 3.5 days, and mean operative blood loss was 306.3 mL. Image guidance was used in 69 (87.3%) cases. A total of 66 (83.5%) fusions were single level, and 54 (68.4%) fusions were single level without previous surgery. There were 9 complications in 7 (8.9%) patients; these included hardware failure, pseudarthrosis, deep vein thrombosis, pulmonary embolism, epidural hematoma, and wound infection. No complications were caused by misplaced screws. Mean follow-up was 13.2 months. CONCLUSIONS As CBTPS becomes increasingly popular among spine surgeons performing lumbar fusion, this report provides an important evaluation of technique safety and acceptable perioperative outcomes.