Justin C. Clark

Surgical outcomes for moyamoya angiopathy at barrow neurological institute with comparison of adult indirect encephaloduroarteriosynangiosis bypass, adult direct superficial temporal artery-to-middle cerebral artery bypass, and pediatric bypass: 154 revascularization surgeries in 140 affected hemispheres

BACKGROUND Untreated, moyamoya angiopathy is a progressive vaso-occlusive process that can lead to ischemic or hemorrhagic stroke. OBJECTIVE To review 1 institutions surgical experience with both direct and indirect bypass (encephaloduroarteriosynangiosis) in adult and pediatric groups. METHODS A retrospective review was conducted of a consecutive series of patients treated for moyamoya angiopathy between 1995 and 2009. RESULTS Thirty-nine adult patients underwent indirect bypass as their initial therapy; 29 adult patients underwent direct bypass. Twenty-four pediatric patients included 20 indirect bypasses and 4 direct bypasses. Overall, 140 hemispheres were treated; 48 patients received revascularization of both hemispheres. There were 14 additional revascularization procedures (10% per hemisphere) performed over a site of continued hypoperfusion postoperatively. Fourteen postoperative ischemic strokes occurred during the entire follow-up (10% per hemisphere), and the Kaplan-Meier analysis was not significantly different between groups (P = .59). Four grafts (9.09%) had failed at radiographic follow-up of the 44 direct bypasses performed. Before the initial surgery, the modified Rankin Scale score was 1.58 ± 0.93, 1.48 ± 0.74, and 1.8 ± 1.1 in the pediatric, adult direct, and adult indirect groups (P = .39). At last follow-up, it was 1.29 ± 1.31, 1.09 ± 0.90, and 1.94 ± 1.51 (P = .04) in the pediatric, adult direct, and adult indirect groups. CONCLUSION This series demonstrates that both direct and indirect bypasses can be equally effective in preventing stroke. However, in adult patients, direct bypass patients had significantly greater improvement in symptoms, as seen in modified Rankin Scale scores. Pediatric patients, despite undergoing predominantly indirect bypasses, fared roughly the same as the adults in the direct bypass group.

Craniocervical arterial dissections as sequelae of chiropractic manipulation: patterns of injury and management

OBJECT Chiropractic manipulation of the cervical spine is a known cause of craniocervical arterial dissections. In this paper, the authors describe the patterns of arterial injury after chiropractic manipulation and their management in the modern endovascular era. METHODS A prospectively maintained endovascular database was reviewed to identify patients presenting with craniocervical arterial dissections after chiropractic manipulation. Factors assessed included time to symptomatic presentation, location of the injured arterial segment, neurological symptoms, endovascular treatment, surgical treatment, clinical outcome, and radiographic follow-up. RESULTS Thirteen patients (8 women and 5 men, mean age 44 years, range 30-73 years) presented with neurological deficits, head and neck pain, or both, typically within hours or days of chiropractic manipulation. Arterial dissections were identified along the entire course of the vertebral artery, including the origin through the V(4) segment. Three patients had vertebral artery dissections that continued rostrally to involve the basilar artery. Two patients had dissections of the internal carotid artery (ICA): 1 involved the cervical ICA and 1 involved the petrocavernous ICA. Stenting was performed in 5 cases, and thrombolysis of the basilar artery was performed in 1 case. Three patients underwent emergency cerebellar decompression because of impending herniation. Six patients were treated with medication alone, including either anticoagulation or antiplatelet therapy. Clinical follow-up was obtained in all patients (mean 19 months). Three patients had permanent neurological deficits, and 1 died of a massive cerebellar stroke. The remaining 9 patients recovered completely. Of the 12 patients who survived, radiographic follow-up was obtained in all but 1 of the most recently treated patients (mean 12 months). All stents were widely patent at follow-up. CONCLUSIONS Chiropractic manipulation of the cervical spine can produce dissections involving the cervical and cranial segments of the vertebral and carotid arteries. These injuries can be severe, requiring endovascular stenting and cranial surgery. In this patient series, a significant percentage (31%, 4/13) of patients were left permanently disabled or died as a result of their arterial injuries.

Minimally invasive transforaminal lumbar interbody fusions and fluoroscopy: a low-dose protocol to minimize ionizing radiation

OBJECT There is an increasing awareness of radiation exposure to surgeons and the lifelong implications of such exposure. One of the main criticisms of minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is the amount of ionizing radiation required to perform the procedure. The goal in this study was to develop a protocol that would minimize the fluoroscopy time and radiation exposure needed to perform an MIS TLIF without compromising visualization of the anatomy or efficiency of the procedure. METHODS A retrospective review of a prospectively collected database was performed to review the development of a low-dose protocol for MIS TLIFs in which a combination of low-dose pulsed fluoroscopy and digital spot images was used. Total fluoroscopy time and radiation dose were reviewed for 50 patients who underwent single-level MIS TLIFs. RESULTS Fifty patients underwent single-level MIS TLIFs, resulting in the placement of 200 pedicle screws and 57 interbody spacers. There were 28 women and 22 men with an average age of 58.3 years (range 32-78 years). The mean body mass index was 26.2 kg/m(2) (range 17.1-37.6 kg/m(2)). Indications for surgery included spondylolisthesis (32 patients), degenerative disc disease with radiculopathy (12 patients), and recurrent disc herniation (6 patients). Operative levels included 7 at L3-4, 40 at L4-5, and 3 at L5-S1. The mean operative time was 177 minutes (range 139-241 minutes). The mean fluoroscopic time was 18.72 seconds (range 7-29 seconds). The mean radiation dose was 0.247 mGy*m(2) (range 0.06046-0.84054 mGy*m(2)). No revision surgery was required for any of the patients in this series. CONCLUSIONS Altering the fluoroscopic technique to low-dose pulse images or digital spot images can dramatically decrease fluoroscopy times and radiation doses in patients undergoing MIS TLIFs, without compromising image quality, accuracy of pedicle screw placement, or efficiency of the procedure.

Pediatric craniovertebral junction trauma.

The craniovertebral junction consists of the occiput, atlas, and axis, along with their strong ligamentous attachments. Because of its unique anatomical considerations, trauma to the craniovertebral junction requires specialized care. Children with potential injuries to the craniovertebral junction and cervical spinal cord demand specific considerations compared to adult patients. Prehospital immobilization techniques, diagnostic studies, and spinal injury patterns among young children can be different from those in adults. This review highlights the unique aspects in diagnosis and management of children with real or potential craniovertebral junction injuries.

Surgical management and clinical outcomes of multiple-level symptomatic herniated thoracic discs

OBJECT Symptomatic herniated thoracic discs (HTDs) are rare, and patients infrequently require treatment of 2 or more disc levels. The authors assess the surgical management and outcomes of patients with multiple-level symptomatic HTDs. METHODS A retrospective review of a prospectively maintained database was performed of 220 consecutive patients treated surgically for symptomatic HTDs. Clinical and surgical results were compared between patients with single-level disease and patients with multiple-level disease and also among the different approaches used for surgical decompression. RESULTS Between 1992 and 2012, 56 patients (mean age 48 years; 26 male, 30 female) underwent 62 procedures for 130 HTDs. Forty-six patients (82%) had myelopathy, and 36 (64%) had thoracic radiculopathy; 24 patients had both conditions in varying degree. Symptom duration averaged 28 months. The surgical approach was dictated by disc size, consistency, and location. Twenty-three thoracotomy, 26 thoracoscopy, and 13 posterolateral procedures were performed. Five patients required a combination of approaches. Patients underwent 2-level (n = 44), 3-level (n = 7), 4-level (n = 4), or 5-level (n = 1) discectomies. Instrumented fusion was performed in 36 patients (64%). Thirteen patients harbored 19 additional discs, which were deemed asymptomatic/nonoperative. The mean hospital stay was 6.5 days. Complete disc resection was verified with postoperative imaging in every patient. The procedural complication rate was 23%, and the nature of complications differed based on approach. No patients had surgery-related spinal cord injury or new myelopathy. At a mean follow-up of 48 months, myelopathy and radiculopathy had resolved or improved at a rate of 85% and 92%, respectively. Using a general linear model, preoperative symptom duration (p = 0.037) and perioperative hospital length of stay (p = 0.004) emerged as negative predictors of myelopathy improvement. Most patients (96%) were satisfied with the surgical results. Compared with 164 patients who underwent single-level HTD decompression, patients requiring surgery for multiple-level HTDs were more often myelopathic (p = 0.012). Surgery for multiple-level HTDs was more likely to require a thoracotomy approach (p = 0.00055) and instrumented fusion (p < 0.0001) and resulted in greater blood loss (p = 0.0036) and higher complication rates (p = 0.0069). The rates of resolution for myelopathy (p = 0.24) and radiculopathy (p = 1.0), however, were similar between the 2 patient groups. CONCLUSIONS The management of multiple-level symptomatic HTDs is complex, requiring individualized clinical decision making. The surgical approaches must be selected to minimize manipulation of the compressed thoracic spinal cord, and a patient may require a combination of approaches. Excellent surgical results can be achieved in this unique and challenging patient population.

Prospective Evaluation of a Low-Dose Radiation Fluoroscopy Protocol for Minimally Invasive Transforaminal Lumbar Interbody Fusion

BACKGROUND: Recent research on radiation exposure in minimally invasive surgery for transforaminal lumbar interbody fusion (MIS TLIF) has led to the development of a low-dose radiation fluoroscopy protocol, with resulting reductions in fluoroscopy times and radiation exposures. OBJECTIVE: To prospectively evaluate a previously reported low-dose radiation fluoroscopy protocol for MIS TLIF. METHODS: A prospective evaluation of the low-dose radiation fluoroscopy protocol for MIS TLIF was performed for 65 consecutive patients. Total fluoroscopy time, radiation dose, and operative times were prospectively analyzed for all enrolled patients. RESULTS: Sixty-five consecutive patients (43 women; 22 men) who underwent an MIS TLIF were prospectively enrolled in this study of the low-dose fluoroscopy protocol. A total of 260 pedicle screws were placed. The mean age of the patients was 63 years (range, 46-82 years). They had a mean operative time of 178.7 minutes (range, 119-247 minutes), a mean fluoroscopic time of 10.43 seconds (range, 5-24 seconds), and a mean radiation dose of 0.295 mGy × m2 (range, 0.092-0.314 mGy × m2). CONCLUSION: The combination of low-dose pulsed images and digital spot images in a low-dose protocol decreases fluoroscopy times and radiation doses in patients undergoing MIS TLIF without compromising visualization of the bony anatomy or the safety and efficiency of the procedure. The application of this low-dose protocol uncouples the otherwise linear relationship between fluoroscopy times and radiation dose. This is due primarily to the use of the digital spot technique. Equal emphasis should be placed on radiation dose and acquisition time to optimize this protocol. ABBREVIATIONS: AP, anteroposterior BMI, body mass index (weight in kilograms divided by height in meters squared [kg/m2]) kVp, kilovoltage potential MIS, minimally invasive surgery MIS TLIF, minimally invasive surgery for transforaminal lumbar interbody fusion ODI, Oswestry Disability Index TLIF, transforaminal lumbar interbody fusion SF-36, 36-Item Short-Form Health Survey VAS, visual analog scale

Indications and Techniques for Spinal Instrumentation in Thoracic Disk Surgery.

Study Design:Retrospective case series. Objective:To identify the indications, techniques, and outcomes for instrumented fusion during thoracic discectomy. Summary of Background Data:Thoracic discectomy may require extensive bone removal to avoid spinal cord manipulation, but the indications and techniques for instrumented fusion during thoracic discectomy remain poorly delineated. Methods:The authors identified 220 consecutive patients who underwent thoracic discectomy between 1992 and 2012. Clinical and radiographic variables were compared between patients who underwent instrumented fusion and patients without instrumentation, and among surgical approaches utilized for discectomy. Results:Patient age for the entire cohort averaged 49±13.01 years, and mean clinical follow-up was 45 months (range, 1–218 mo). Patients underwent 226 thoracic discectomy procedures, including 48 thoracotomy, 136 thoracoscopy, and 42 posterolateral approaches. Seventy-eight patients required instrumented fusion and, compared with patients without instrumentation, were more likely to present with myelopathy (P<0.0001) and harbor giant (P=0.0012), calcified (P=0.019), or transdural (P=0.0004) herniated disks. Surgery with instrumentation resulted in greater blood loss (P<0.0001), longer hospital stay (P<0.0001), and a higher complication rate (22% vs. 9.9%), yet patients in both cohorts had similar rates of symptom resolution postoperatively. Of the patients who underwent thoracic discectomy without instrumentation, 3 (2.1%) developed delayed deformity or instability and required subsequent surgery for fixation and fusion at an average 6.3 months postoperatively (range, 4–8 mo). Patients who underwent instrumented fusion exhibited no nonunions or delayed deformity. Conclusions:Thoracic discectomy without fixation is a reasonable clinical option in carefully selected patients, but instrumented fusion is safe and effective in other patients. Indications for fixation and fusion are thus proposed.

Dealing with the Aneurysmal Remnants After Endovascular Treatment

Since the adoption of endovascular coiling techniques to treat intracranial aneurysms in the 1990s, endovascular therapies have steadily increased in popularity. The publication of the results of the International Subarachnoid Aneurysm Trial (ISAT) (1) led to a rapid increase in the number of patients with aneurysms treated with endovascular coiling. As experience with these techniques has increased, so has awareness of their deficiencies. One of the most concerning characteristics of the endovascular treatment of cerebral aneurysms is the rate of recurrence of previously treated aneurysms. Initially thought to be a rare event, aneurysmal recurrence after endovascular therapy is now believed to occur at a substantial rate (1, 4, 8, 10-12). More important, the endovascular treatment of certain subtypes of aneurysms, such as large, partially thrombosed aneurysms, is believed to result in aneurysm recurrence in 30% of patients as early as 17 months from the initial coiling procedure (2). Because this rate of recurrence is not inconsequential, much energy has been spent determining the rate of aneurysmal recurrence, as well as the risk of bleeding from an aneurysmal recurrence.

Fellowship training in the United States and Europe.

that “Scholarly productivity is a key component in academic advancement;” therefore, full professors should have higher h-index scores than associate and assistant professors. In the paper, the authors speculate as to why no significant difference was found between mean h-index scores of neurological surgeons who completed fellowships and those who did not. The reasons provided included the fact that the research produced by nonfellowship trained neurosurgeon targeted a broader audience, whereas the fellowship trained neurosurgeon’s research would target a more focused audience. However, the authors do not discuss the role that the length of time since graduation from residency has on h-index scores. Specifically, the fact that the authors report that “Post-residency fellowship training in neurological surgery is a relatively recent phenomenon.” It may be that the research produced by non-fellowship-trained neurosurgeons has been in circulation longer than the research of fellowship-trained neurosurgeons, which would have given the articles from the nonfellowship-trained neurosurgeons more time to be cited, thus artificially elevating the h-index scores of the non-fellowship-trained neurosurgeons. In order to more effectively answer this question, it is our opinion that Agarwal, et al., should consider utilizing the h(10) index, as defined by Ponce, et al. in order to compare fellowship vs non-fellowship trained academic neurosurgeons (4). Using this modified index could help to determine whether the lack of difference between fellowshipand non-fellowship-trained neurosurgeons was solely a function of time, with fellowship-trained neurosurgeons being in the group whose articles have been in circulation for less time. In this era of increased awareness of healthcare costs and outcomes, all neurosurgery positions are coming under greater scrutiny from both the government and the general public. Certainly, academic positions are under both professional and administrative pressure to hire and retain the future leaders of neurosurgery. Any metric that can reliably assist academic M AN US CR IP T AC CE PT ED ACCEPTED MANUSCRIPT Clark et al. 6 programs in their search to hire productive candidates will be invaluable. At the very least, the article by Agarwal, et al. provides a benchmark for the mean h-index score of academic neurosurgeons at the assistant, associate, and full professor levels. At the core of this endeavor is an attempt by the authors to provide insight into how academic neurosurgery within the United States can be further strengthened through the identification and hiring of highly productive academic neurosurgeons.

Provisional Ipsilateral Expandable Rod for Disc Space Distraction in Minimally Invasive Transforaminal Lumbar Interbody Fusion: Operative Technique

BACKGROUND: Lumbar disc degeneration may be so advanced and asymmetrical that transforaminal access to the interbody space is limited. The extent of collapse may compromise the capacity to restore disc height and coronal balance in minimally invasive approaches. Although a variety of distractors are available for open approaches, currently there is no feasible distractor that is functional within a minimally invasive retractor. OBJECTIVE: To describe the development of a provisional ipsilateral expandable rod for use in minimally invasive surgery for transforaminal lumbar interbody fusions to optimize access to the disc space, thereby facilitating placement of an interbody spacer. METHODS: The authors report the clinical and radiographic data for 30 patients (3 open and 27 minimally invasive surgeries) with advanced degenerative disc disease in whom a provisional ipsilateral expandable rod was used to restore coronal balance and maintain disc height for interbody preparation and placement. Preoperative disc heights were measured, and the height of interbody spacer recorded. Mean restoration of disc heights was calculated. RESULTS: The provisional ipsilateral expandable rod was successfully applied in both open exposures and within a minimally invasive retractor. The mean preoperative disc height was 4.9 mm (range, 1-9 mm), the mean height of the spacer inserted was 11.1 mm (range, 8-15 mm), and the mean increase in disc height was 6.2 mm (range, 5-11 mm). CONCLUSION: A provisional ipsilateral expandable rod is feasible in either minimally invasive or open approaches. It has the capacity to maintain the disc height achieved by paddle distractors. This facilitates both the disc preparation and optimizes restoration of disc height and interbody spacer placement. ABBREVIATIONS: MIS, minimal invasive surgery TLIF, transforaminal lumbar interbody fusion