The management of large and giant arteriovenous malformations (AVMs) in patients presenting with nonhemorrhagic neurological deficits secondary to vascular steal phenomenon is challenging and controversial. In many cases, large AVMs cannot be completely excised or cured, leaving patients with residual or partially treated AVMs, the natural history of which is unknown. Additionally, large, diffuse vascular malformations with multiple, small feeders, slow flow, or so-called cerebral proliferative angiopathy represent a related but distinct clinical and angiographic entity that may require a different therapeutic approach than traditional brain AVMs. The current management of children with other conditions of chronic cerebral hypoperfusion, such as moyamoya disease, involves consideration of surgical revascularization to enhance blood flow to the compromised hemisphere. Here, the authors present the case of a young child with a large thalamic vascular malformation who presented with clinical and radiological features of vascular steal and ischemia. In an effort to augment flow to the hypoperfused brain and protect against future ischemia, the authors treated the child with unilateral pial synangiosis. At 12 months, postoperative angiography demonstrated robust neovascularization, and the child has not sustained any further ischemic events. The authors discuss concept of vascular malformation–related hypoperfusion and the utility of indirect revascularization for inoperable vascular malformations presenting with ischemic symptoms.
Large vascular malformation in a child presenting with vascular steal phenomenon managed with pial synangiosis
Michael J. Ellis, Derek Armstrong, and Peter B. Dirks
Cement leakage in pedicle screw augmentation: a prospective analysis of 98 patients and 474 augmented pedicle screws
Jan U. Mueller, Joerg Baldauf, Sascha Marx, Michael Kirsch, Henry W. S. Schroeder, and Dirk T. Pillich
Loosening and pullout of pedicle screws are well-known problems in pedicle screw fixation surgery. Augmentation of pedicle screws with bone cement, first described as early as 1975, increases the pedicle-screw interface and pullout force in osteoporotic vertebrae. The aim of the present study was to identify cement leakage and pulmonary embolism rates in a large prospective single-center series of pedicle screw augmentations.
All patients who underwent cement-augmented pedicle screw placement between May 2006 and October 2010 at the authors' institution were included in this prospective cohort study. Perivertebral cement leakage and pulmonary cement embolism were evaluated with a CT scan of the area of operation and with a radiograph of the chest, respectively.
A total of 98 patients underwent placement of cement-augmented pedicle screws; 474 augmented screws were inserted in 237 vertebrae. No symptomatic perivertebral cement leakage or symptomatic pulmonary cement embolism was observed, but asymptomatic perivertebral cement leakage was seen in 88 patients (93.6%) and in 165 augmented vertebrae (73.3%). Cement leakage most often occurred in the perivertebral venous system. Clinically asymptomatic pulmonary cement embolism was found in 4 patients (4.1%).
Perivertebral cement leakage often occurs in pedicle screw augmentation, but in most cases, it is clinically asymptomatic. Cement augmentation should be performed under continuous fluoroscopy to avoid high-volume leakage. Alternative strategies, such as use of expandable screws, should be examined in more detail for patients at high risk of screw loosening.
Comparison of waterjet dissection and ultrasonic aspiration: an in vivo study in the rabbit brain
Joachim Oertel, Michael Robert Gaab, Dirk-Thomas Pillich, Henry W. S. Schroeder, Rolf Warzok, and Jürgen Piek
Object. The waterjet method of dissection has been shown to enable the precise dissection of the parenchyma vessels while preserving blood in cadaveric pig brains. The waterjet device has also been applied clinically to treat various diseases and disorders without complications. Evidence still remains to be gathered as to how the instrument performs in reducing surgical trauma, intraoperative blood loss, and postsurgical brain edema. In the present study the authors investigate these parameters in a comparison between waterjet dissection and ultrasonic aspiration in the rabbit brain in vivo.
Methods. Thirty-one rabbits received identical bilateral frontal corticotomies, which were created using the waterjet device or an ultrasonic aspirator. The animals were killed 1, 3, or 7 days, or 6 weeks after surgery and their brains were processed for immunohistological analysis. Blood vessel preservation, intraoperative hemorrhage, postsurgical brain edema, and posttraumatic microglial and astoglial reactions were evaluated. Only in animals subjected to waterjet dissection were preserved vessels observed within the corticotomies. In addition, less intraoperative bleeding occurred in animals in which the waterjet was used. The microglial reaction was significantly reduced by waterjet dissection compared with ultrasonic aspiration; however, no difference in edema formation or astrocytic reactivity was observed.
Conclusions. These results demonstrate that waterjet dissection appears to be less traumatic than ultrasonic aspiration with respect to intraoperative hemorrhage and postoperative microglial reactivity in the rabbit model. Nevertheless, no difference in edema formation could be demonstrated. It remains to be proven that the observed differences are of clinical relevance.
Return-to-active-duty rates after anterior cervical spine surgery in military pilots
Charles A. Miller, Jason H. Boulter, Daniel J. Coughlin, Michael K. Rosner, Chris J. Neal, and Michael S. Dirks
Symptomatic cervical spondylosis with or without radiculopathy can ground an active-duty military pilot if left untreated. Surgically treated cervical spondylosis may be a waiverable condition and allow return to flying status, but a waiver is based on expert opinion and not on recent published data. Previous studies on rates of return to active duty status following anterior cervical spine surgery have not differentiated these rates among military specialty occupations. No studies to date have documented the successful return of US military active-duty pilots who have undergone anterior cervical spine surgery with cervical fusion, disc replacement, or a combination of the two. The aim of this study was to identify the rate of return to an active duty flight status among US military pilots who had undergone anterior cervical discectomy and fusion (ACDF) or total disc replacement (TDR) for symptomatic cervical spondylosis.
The authors performed a single-center retrospective review of all active duty pilots who had undergone either ACDF or TDR at a military hospital between January 2010 and June 2017. Descriptive statistics were calculated for both groups to evaluate demographics with specific attention to preoperative flight stats, days to recommended clearance by neurosurgery, and days to return to active duty flight status.
Authors identified a total of 812 cases of anterior cervical surgery performed between January 1, 2010, and June 1, 2017, among active duty, reserves, dependents, and Department of Defense/Veterans Affairs patients. There were 581 ACDFs and 231 TDRs. After screening for military occupation and active duty status, there were a total of 22 active duty pilots, among whom were 4 ACDFs, 17 TDRs, and 2 hybrid constructs. One patient required a second surgery. Six (27.3%) of the 22 pilots were nearing the end of their career and electively retired within a year of surgery. Of the remaining 16 pilots, 11 (68.8%) returned to active duty flying status. The average time to be released by the neurosurgeon was 128 days, and the time to return to flying was 287 days. The average follow-up period was 12.3 months.
Adhering to military service-specific waiver guidelines, military pilots may return to active duty flight status after undergoing ACDF or TDR for symptomatic cervical spondylosis.
Children and television tipovers: a significant and preventable cause of long-term neurological deficits
Raafat R. Yahya, Peter Dirks, Robin Humphreys, James T. Rutka, Michael Taylor, and James M. Drake
Television tipover has recently been recognized as a significant cause of injury in children, and head injury accounts for most of the associated deaths. The authors reviewed their experience with children who sustained head injury from falling televisions.
Children admitted with the diagnosis of head injury related to falling televisions since 1992 were identified from the authors' trauma database, and a retrospective review of the medical records was performed.
Eighteen patients were identified: 13 boys and five girls whose ages ranged from 12 months to 10 years (mean 44 months). The admission Glasgow Coma Scale (GCS) score was 15 in 10 patients. Only three patients had a GCS score of 8 or less (one patient had a score of 4). Neurological examinations were normal in 10 patients; three had cranial nerve deficits and three had otorrhea, otorrhagia, or hemotympanum. Radiological abnormalities included 16 skull fractures, three epidural hematomas, three small subdural hematomas, one intracranial hemorrhage, and three venous obstructions of the transverse—sigmoid sinus. The mean hospital stay was 8.9 days (range 2–39 days). Follow up at 0.2 to 68 months (mean 13.4 months) revealed severe neurological deficits in one patient and cranial nerve deficits of cranial nerves six, seven, or eight in six patients.
Falling televisions result in significant head injuries in children, with substantial short- and long-term sequelae. This injury is easily preventable through simple measures taken by both the manufacturers and caregivers.
Long-term natural history of neurofibromatosis Type 2–associated intracranial tumors
Michael S. Dirks, John A. Butman, H. Jeffrey Kim, Tianxia Wu, Keaton Morgan, Anne P. Tran, Russell R. Lonser, and Ashok R. Asthagiri
Neurofibromatosis Type 2 (NF2) is a heritable tumor predisposition syndrome that leads to the development of multiple intracranial tumors, including meningiomas and schwannomas. Because the natural history of these tumors has not been determined, their optimal management has not been established. To define the natural history of NF2-associated intracranial tumors and to optimize management strategies, the authors evaluated long-term clinical and radiographic data in patients with NF2.
Consecutive NF2 patients with a minimum of 4 years of serial clinical and MRI follow-up were analyzed.
Seventeen patients, 9 males and 8 females, were included in this analysis (mean follow-up 9.5 ± 4.8 years, range 4.0–20.7 years). The mean age at initial evaluation was 33.2 ± 15.5 years (range 12.3–57.6 years). Patients harbored 182 intracranial neoplasms, 164 of which were assessable for growth rate analysis (18 vestibular schwannomas [VSs], 11 nonvestibular cranial nerve [CN] schwannomas, and 135 meningiomas) and 152 of which were assessable for growth pattern analysis (15 VSs, 9 nonvestibular CN schwannomas, and 128 meningiomas). New tumors developed in patients over the course of the imaging follow-up: 66 meningiomas, 2 VSs, and 2 nonvestibular CN schwannomas. Overall, 45 tumors (29.6%) exhibited linear growth, 17 tumors (11.2%) exhibited exponential growth, and 90 tumors (59.2%) displayed a saltatory growth pattern characterized by alternating periods of growth and quiescence (mean quiescent period 2.3 ± 2.1 years, range 0.4–11.7 years). Further, the saltatory pattern was the most frequently identified growth pattern for each tumor type: meningiomas 60.9%, VSs 46.7%, and nonvestibular schwannoma 55.6%. A younger age at the onset of NF2-related symptoms (p = 0.01) and female sex (p = 0.05) were associated with an increased growth rate in meningiomas. The identification of saltatory growth in meningiomas increased with the duration of follow-up (p = 0.01).
Neurofibromatosis Type 2–associated intracranial tumors most frequently demonstrated a saltatory growth pattern. Because new tumors can develop in NF2 patients over their lifetime and because radiographic progression and symptom formation are unpredictable, resection may be best reserved for symptom-producing tumors. Moreover, establishing the efficacy of nonsurgical therapeutic interventions must be based on long-term follow-up (several years).
Corticospinal tract mapping in children with ruptured arteriovenous malformations using functionally guided diffusion-tensor imaging
Report of 3 cases
Michael J. Ellis, James T. Rutka, Abhaya V. Kulkarni, Peter B. Dirks, and Elysa Widjaja
Arteriovenous malformations (AVMs) can lead to distortion or reorganization of functional brain anatomy, making localization of eloquent white matter tracts challenging. To improve the accuracy of corticospinal tract (CST) mapping, recent studies have examined the use of functional imaging techniques to help localize cortical motor activations and use these as seed points to reconstruct CSTs using diffusion-tensor imaging (DTI). The authors examined the role of pretreatment functionally guided DTI CST mapping in 3 children with ruptured AVMs. In 2 patients, magnetoencephalography motor activations were adjacent to the nidus and/or hemorrhagic cavity. However, in 1 child, functional MRI motor activations were detected in both hemispheres, suggestive of partial transfer of cortical motor function. In all children, quantitative analysis showed that fractional anisotropy values and fiber density indices were reduced in the CSTs of the hemisphere harboring the AVM compared with the unaffected side. In 2 children, CST caliber was slightly diminished, corresponding to no motor deficit in 1 patient and a temporary motor deficit in the other. In contrast, 1 child demonstrated marked reduction and displacement of the CSTs, correlating with severe motor deficit. Preoperative motor tractography data were loaded onto the intraoperative neuronavigation platform to guide complete resection of the AVM in 2 cases without permanent neurological deficits. These preliminary results confirm the feasibility of CST mapping in children with ruptured AVMs using functionally guided DTI tractography. Prospective studies are needed to assess the full value of this technique in the risk stratification, prognosis, and multimodality management of pediatric AVMs.
Early decompressive craniectomy for severe penetrating and closed head injury during wartime
Randy S. Bell, Corey M. Mossop, Michael S. Dirks, Frederick L. Stephens, Lisa Mulligan, Robert Ecker, Christopher J. Neal, Anand Kumar, Teodoro Tigno, and Rocco A. Armonda
Decompressive craniectomy has defined this era of damage-control wartime neurosurgery. Injuries that in previous conflicts were treated in an expectant manner are now aggressively decompressed at the far-forward Combat Support Hospital and transferred to Walter Reed Army Medical Center (WRAMC) and National Naval Medical Center (NNMC) in Bethesda for definitive care. The purpose of this paper is to examine the baseline characteristics of those injured warriors who received decompressive craniectomies. The importance of this procedure will be emphasized and guidance provided to current and future neurosurgeons deployed in theater.
The authors retrospectively searched a database for all soldiers injured in Operations Iraqi Freedom and Enduring Freedom between April 2003 and October 2008 at WRAMC and NNMC. Criteria for inclusion in this study included either a closed or penetrating head injury suffered during combat operations in either Iraq or Afghanistan with subsequent neurosurgical evaluation at NNMC or WRAMC. Exclusion criteria included all cases in which primary demographic data could not be verified. Primary outcome data included the type and mechanism of injury, Glasgow Coma Scale (GCS) score and injury severity score (ISS) at admission, and Glasgow Outcome Scale (GOS) score at discharge, 6 months, and 1–2 years.
Four hundred eight patients presented with head injury during the study period. In this population, a total of 188 decompressive craniectomies were performed (154 for penetrating head injury, 22 for closed head injury, and 12 for unknown injury mechanism). Patients who underwent decompressive craniectomies in the combat theater had significantly lower initial GCS scores (7.7 ± 4.2 vs 10.8 ± 4.0, p < 0.05) and higher ISSs (32.5 ± 9.4 vs 26.8 ± 11.8, p < 0.05) than those who did not. When comparing the GOS scores at hospital discharge, 6 months, and 1–2 years after discharge, those receiving decompressive craniectomies had significantly lower scores (3.0 ± 0.9 vs 3.7 ± 0.9, 3.5 ± 1.2 vs 4.0 ± 1.0, and 3.7 ± 1.2 vs 4.4 ± 0.9, respectively) than those who did not undergo decompressive craniectomies. That said, intragroup analysis indicated consistent improvement for those with craniectomy with time, allowing them, on average, to participate in and improve from rehabilitation (p < 0.05). Overall, 83% of those for whom follow-up data are available achieved a 1-year GOS score of greater than 3.
This study of the provision of early decompressive craniectomy in a military population that sustained severe penetrating and closed head injuries represents one of the largest to date in both the civilian and military literature. The findings suggest that patients who undergo decompressive craniectomy had worse injuries than those receiving craniotomy and, while not achieving the same outcomes as those with a lesser injury, did improve with time. The authors recommend hemicraniectomy for damage control to protect patients from the effects of brain swelling during the long overseas transport to their definitive care, and it should be conducted with foresight concerning future complications and reconstructive surgical procedures.
Outcomes of 33 patients from the wars in Iraq and Afghanistan undergoing bilateral or bicompartmental craniectomy
Robert D. Ecker, Lisa P. Mulligan, Michael Dirks, Randy S. Bell, Meryl A. Severson, Robin S. Howard, and Rocco A. Armonda
There are no published long-term data for patients with penetrating head injury treated with bilateral supratentorial craniectomy, or supra- and infratentorial craniectomy. The authors report their experience with 33 patients treated with bilateral or bicompartmental craniectomy from the ongoing conflicts in Iraq and Afghanistan.
An exploratory analysis of Glasgow Outcome Scale (GOS) scores at 6 months in 33 patients was performed. Follow-up lasting a median of more than 2 years was performed in 30 (91%) of these patients. The association of GOS score with categorical variables was explored using the Wilcoxon rank-sum test or Kruskal-Wallis analysis of variance. The Spearman correlation coefficient was used for ordinal/continuous data. To provide a clinically meaningful format to present GOS scores with categorical variables, patients with GOS scores of 1–3 were categorized as having a poor outcome and those with scores of 4 and 5 as having a good outcome. This analysis does not include the patients who died in theater or in Germany who underwent bilateral decompressive craniectomy because those figures have not been released due to security concerns.
All patients were men with a median age of 24 years (range 19–46 years) and a median initial Glasgow Coma Scale (GCS) score of 5 (range 3–14). At 6 months, 9 characteristics were statistically significant: focus of the initial injury, systemic infection, initial GCS score, initial GCS score excluding patients with a GCS score of 3, GCS score on arrival to the US, GCS score on dismissal from the medical center, Injury Severity Score, and patients with cerebrovascular injury. Six factors were significant at long-term follow-up: focus of initial injury, systemic infection, initial GCS score excluding patients with a GCS score of 3, GCS score on arrival to the US, and GCS score on dismissal from the medical center. At long-term follow-up, 7 (23%) of 30 patients had died, 5 (17%) of 30 had a GOS score of 2 or 3, and 18 (60%) of 30 had a GOS score of 4 or 5.
In this selected group of patients who underwent bilateral or bicompartmental craniectomy, 60% are independent at long-term follow-up. Patients with bifrontal injury fared best. Systemic infection and cerebrovascular injury corresponded with a worse outcome.
Vascularity and angiogenesis as predictors of growth in optic pathway/hypothalamic gliomas
Ute Bartels, Cynthia Hawkins, Jing Ma, Michael Ho, Peter Dirks, James Rutka, Derek Stephens, and Eric Bouffet
The authors’ aim in conducting this study was to investigate retrospectively the prognostic significance of angiogenic features in optic pathway/hypothalamic gliomas (OPHGs) in children.
Patients were identified in whom a diagnosis of OPHG was made using pathological analysis at the Toronto Hospital for Sick Children between 1985 and 2002. Tumor specimens were reviewed for diagnostic accuracy and adequacy of the specimen. Sections were immunostained with factor VIII to assess microvessel density (MVD). A ratio of α–smooth muscle actin to factor VIII immunostaining was calculated to arrive at a vascular maturity index (VMI). Vascular endothelial growth factor (VEGF) and VEGF receptor (VEGFR) immunostaining were performed to evaluate angiogenic factors. In addition, the MIB-1 labeling index (LI) was used to assess proliferation. These factors were evaluated with respect to progression-free survival (PFS).
Forty-one of 60 patients originally identified had adequate samples and follow up for inclusion in the study. Of these, eight patients had coexisting neurofibromatosis Type 1. Twenty-eight patients experienced tumor progression after the initial treatment (surgery with or without adjuvant treatment). Thirty-eight patients are still alive. A high MVD (> 21 vessels/1.2 mm2) was associated with a significantly higher rate of progression compared with a low MVD (< 21 vessels/1.2 mm2; p = 0.017). Microvessel density was also predictive of reduced PFS on multivariate analysis stratified for extent of resection (p = 0.04), and VMI as well as intensity and distribution of VEGF and VEGFR staining and the MIB-1 LI were not significantly associated with PFS.
These findings suggest that MVD is the best current predictor of PFS in incompletely resected OPHGs. This information highlights the importance of angiogenesis in regard to low-grade gliomas.