Michael M. McDowell

Outcomes after suboccipital decompression without dural opening in children with Chiari malformation Type I.

OBJECT Symptomatic pediatric Chiari malformation Type I (CM-I) is most often treated with posterior fossa decompression (PFD), but controversy exists over whether the dura needs to be opened during PFD. While dural opening as a part of PFD has been suggested to result in a higher rate of resolution of CM symptoms, it has also been shown to lead to more frequent complications. In this paper, the authors present the largest reported series of outcomes after PFD without dural opening surgery, as well as identify risk factors for recurrence. METHODS The authors performed a retrospective review of 156 consecutive pediatric patients in whom the senior authors performed PFD without dural opening from 2003 to 2013. Patient demographics, clinical symptoms and signs, radiographic findings, intraoperative ultrasound results, and neuromonitoring findings were reviewed. Univariate and multivariate regression analyses were performed to determine risk factors for recurrence of symptoms and the need for reoperation. RESULTS Over 90% of patients had a good clinical outcome, with improvement or resolution of their symptoms at last follow-up (mean 32 months). There were no major complications. The mean length of hospital stay was 2.0 days. In a multivariate regression model, partial C-2 laminectomy was an independent risk factor associated with reoperation (p = 0.037). Motor weakness on presentation was also associated with reoperation but only with trend-level significance (p = 0.075). No patient with < 8 mm of tonsillar herniation required reoperation. CONCLUSIONS The vast majority (> 90%) of children with symptomatic CM-I will have improvement or resolution of symptoms after a PFD without dural opening. A non-dural opening approach avoids major complications. While no patient with tonsillar herniation < 8 mm required reoperation, children with tonsillar herniation at or below C-2 have a higher risk for failure when this approach is used.

Network Effects of Deep Brain Stimulation

The ability to differentially alter specific brain functions via deep brain stimulation (DBS) represents a monumental advance in clinical neuroscience, as well as within medicine as a whole. Despite the efficacy of DBS in the treatment of movement disorders, for which it is often the gold-standard therapy when medical management becomes inadequate, the mechanisms through which DBS in various brain targets produces therapeutic effects is still not well understood. This limited knowledge is a barrier to improving efficacy and reducing side effects in clinical brain stimulation. A field of study related to assessing the network effects of DBS is gradually emerging that promises to reveal aspects of the underlying pathophysiology of various brain disorders and their response to DBS that will be critical to advancing the field. This review summarizes the nascent literature related to network effects of DBS measured by cerebral blood flow and metabolic imaging, functional imaging, and electrophysiology (scalp and intracranial electroencephalography and magnetoencephalography) in order to establish a framework for future studies.

Pial synangiosis for moyamoya syndrome in children with sickle cell anemia: a comprehensive review of reported cases

OBJECT Pediatric patients with sickle cell anemia (SCA) carry a significant risk of developing moyamoya syndrome (MMS) and brain ischemia. The authors sought to review the safety and efficacy of pial synangiosis in the treatment of MMS in children with SCA by performing a comprehensive review of all previously reported cases in the literature. METHODS The authors retrospectively reviewed the clinical and radiographic records in 17 pediatric patients with SCA treated at the Morgan Stanley Childrens Hospital of New York (MSCHONY) who developed radiological evidence of MMS and underwent pial synangiosis between 1996 and 2012. The authors then added any additional reported cases of pial synangiosis for this population in the literature for a combined analysis of clinical and radiographic outcomes. RESULTS The combined data consisted of 48 pial synangiosis procedures performed in 30 patients. Of these, 27 patients (90%) presented with seizure, stroke, or transient ischemic attack, whereas 3 (10%) were referred after transcranial Doppler screening. At the time of surgery, the median age was 12 years. Thirteen patients (43%) suffered an ischemic stroke while on chronic transfusion therapy. Long-term follow-up imaging (MR angiography or catheter angiography) at a mean of 25 months postoperatively was available in 39 (81%) treated hemispheres. In 34 (87%) of those hemispheres there were demonstrable collateral vessels on imaging. There were 4 neurological events in 1590 cumulative months of follow-up, or 1 event per 33 patient-years. In the patients in whom complete data were available (MSCHONY series, n = 17), the postoperative stroke rate was reduced more than 6-fold from the preoperative rate (p = 0.0003). CONCLUSIONS Pial synangiosis in patients with SCA, MMS, and brain ischemia appears to be a safe and effective treatment option. Transcranial Doppler and/or MRI screening in asymptomatic patients with SCA is recommended for the diagnosis of MMS.

Transnasal endoscopic approach to the pediatric craniovertebral junction and rostral cervical spine: case series and literature review

The endoscopic transnasal approach to the rostral pediatric spine and craniovertebral junction is a relatively new technique that provides an alternative to the traditional transoral approach to the anterior pediatric spine. In this case series, the authors provide 2 additional examples of patients undergoing endoscopic transnasal odontoidectomies for ventral decompression of the spinal cord. Both patients would have required transection of the palate to undergo an effective transoral operation, which can be a cause of significant morbidity. In one case, transnasal decompression was initially incomplete, and decompression was successfully achieved via a second endoscopic transnasal operation. Both cases resulted in significant neurological recovery and stable long-term spinal alignment. The transnasal approach benefits from entering into the posterior pharynx at an angle that often reduces the length of postoperative intubation and may speed a patients return to oral intake. Higher reoperation rates are a concern for many endoscopic approaches, but there are insufficient data to conclude if this is the case for this procedure. Further experience with this technique will provide a better understanding of the indications for which it is most effective. Transcervical and transoral endoscopic approaches have also been reported and provide additional options for pediatric anterior cervical spine surgery.

Hemorrhagic complications of ventriculostomy: incidence and predictors in patients with intracerebral hemorrhage

OBJECT Ventriculostomy--the placement of an external ventricular drain (EVD)--is a common procedure performed in patients with acute neurological injury. Although generally considered a low-risk intervention, recent studies have cited higher rates of hemorrhagic complications than those previously reported. The authors sought to determine the rate of postventriculostomy hemorrhage in a cohort of patients with intracerebral hemorrhage (ICH) and to identify predictors of hemorrhagic complications of EVD placement. METHODS Patients with ICH who underwent EVD placement and had both pre- and postprocedural imaging available for analysis were included in this study. Relevant data were prospectively collected for each patient who satisfied inclusion criteria. Variables with a p < 0.20 on univariate analyses were included in a stepwise logistic regression model to identify predictors of postventriculostomy hemorrhage. RESULTS Sixty-nine patients were eligible for this analysis. Postventriculostomy hemorrhage occurred in 31.9% of patients. Among all patients with intraparenchymal hemorrhage, the mean hemorrhage volume was 0.66 ± 1.06 cm(3). Stratified according to ventricular catheter diameter, patients treated with smaller-diameter catheters had a significantly greater mean hemorrhage volume than patients treated with larger-diameter catheters (0.84 ± 1.2 cm(3) vs 0.14 ± 0.12 cm(3), p = 0.049). Postventriculostomy hemorrhage was clinically significant in only 1 patient (1.4%). Overall, postventriculostomy hemorrhage was not associated with functional outcome or mortality at either discharge or 90 days. In the multivariate model, an age > 75 years was the only independent predictor of EVD-associated hemorrhage. CONCLUSIONS Advanced age is predictive of EVD-related hemorrhage in patients with ICH. While postventriculostomy hemorrhage is common, it appears to be of minor clinical significance in the majority of patients.

Long-term growth and alignment after occipitocervical and atlantoaxial fusion with rigid internal fixation in young children

OBJECT The long-term consequences of atlantoaxial (AA) and occipitocervical (OC) fusion and instrumentation in young children are unknown. Anecdotal reports have raised concerns regarding altered growth and alignment of the cervical spine after surgical intervention. The purpose of this study was to determine the long-term effects of these surgeries on the growth and alignment of the maturing spine. METHODS A multiinstitutional retrospective chart review was conducted for patients less than or equal to 6 years of age who underwent OC or AA fusion with rigid instrumentation at 9 participating centers. All patients had at least 3 years of clinical and radiographic follow-up data and radiographically confirmed fusion. Preoperative, immediate postoperative, and most recent follow-up radiographs and/or CT scans were evaluated to assess changes in spinal growth and alignment. RESULTS Forty children (9 who underwent AA fusion and 31 who underwent OC fusion) were included in the study (mean follow-up duration 56 months). The mean vertical growth over the fused levels in the AA fusion patients represented 30% of the growth of the cervical spine (range 10%-50%). Three different vertical growth patterns of the fusion construct developed among the 31 OC fusion patients during the follow-up period: 1) 16 patients had substantial growth (13%-46% of the total growth of the cervical spine); 2) 9 patients had no meaningful growth; and 3) 6 patients, most of whom presented with a distracted atlantooccipital dislocation, had a decrease in the height of the fused levels (range 7-23 mm). Regarding spinal alignment, 85% (34/40) of the patients had good alignment at follow-up, with straight or mildly lordotic cervical curvatures. In 1 AA fusion patient (11%) and 5 OC fusion patients (16%), we observed new hyperlordosis (range 43°-62°). There were no cases of new kyphosis or swan-neck deformity, evidence of subaxial instability, or unintended subaxial fusion. No preoperative predictors of these growth patterns or alignment were evident. CONCLUSIONS These results demonstrate that most young children undergoing AA and OC fusion with rigid internal fixation continue to have good cervical alignment and continued growth within the fused levels during a prolonged follow-up period. However, some variability in vertical growth and alignment exists, highlighting the need to continue close long-term follow-up.

Traumatic brain injury in pediatric patients: evidence for the effectiveness of decompressive surgery

Traumatic brain injury (TBI) is the current leading cause of death in children over 1 year of age. Adequate management and care of pediatric patients is critical to ensure the best functional outcome in this population. In their controversial trial, Cooper et al. concluded that decompressive craniectomy following TBI did not improve clinical outcome of the analyzed adult population. While the study did not target pediatric populations, the results do raise important and timely clinical questions regarding the effectiveness of decompressive surgery in pediatric patients. There is still a paucity of evidence regarding the effectiveness of this therapy in a pediatric population, and there is an especially noticeable knowledge gap surrounding age-stratified interventions in pediatric trauma. The purposes of this review are to first explore the anatomical variations between pediatric and adult populations in the setting of TBI. Second, the authors assess how these differences between adult and pediatric populations could translate into differences in the impact of decompressive surgery following TBI.

Arteriovenous malformation-associated aneurysms in the pediatric population

OBJECT Conventional cerebral angiography and treatment for ruptured arteriovenous malformations (AVMs) in children are often performed in a delayed fashion. In adults, current literature suggests that AVM-associated aneurysms may be more likely to hemorrhage than isolated AVMs, which often leads to earlier angiography and endovascular treatment of associated aneurysms. The nature of AVM-associated aneurysms in the pediatric population is virtually unknown. In this report, the authors investigate the relationship of associated aneurysms in a large group of children with AVMs. METHODS Seventy-seven pediatric patients (≤ 21 years old) with AVMs were treated at the Columbia University Medical Center between 1991 and 2010. Medical records and imaging studies were retrospectively reviewed, and associated aneurysms were classified as arterial, intranidal, or venous in location. Clinical presentation and outcome variables were compared between children with and without AVM-associated aneurysms. RESULTS A total of 30 AVM-associated aneurysms were found in 22 children (29% incidence). Eleven were arterial, 9 intranidal, and 10 were venous in location. There was no significant difference in the rate of hemorrhage (p = 0.91) between children with isolated AVMs (35 of 55 [64%]) and children with AVM-associated aneurysms (13 of 22 [59%]). However, of the 11 children with AVM-associated aneurysms in an arterial location, 10 presented with hemorrhage (91%). An association with hemorrhage was significant in univariate analysis (p = 0.045) but not in multivariate analysis (p = 0.37). CONCLUSIONS Associated aneurysms are present in nearly a third of children with AVMs, and when arterially located, are more likely to present with hemorrhage. These data suggest that early angiography with endovascular treatment of arterial-based aneurysms in children with AVMs may be indicated.

Reduction in upper-extremity tone after lumbar selective dorsal rhizotomy in children with spastic cerebral palsy

OBJECT Randomized clinical trials have established that lumbar selective dorsal rhizotomy (SDR) reduces lower-extremity tone and improves functional outcome in children with spastic cerebral palsy. Significant data exist to support a secondary effect on upper-extremity function in patients with upper-extremity spasticity. The effects of SDR on upper-extremity tone, however, are not well characterized. In this report, the authors sought to assess changes in upper-extremity tone in individual muscle groups after SDR and tried to determine if these changes could be predicted preoperatively. METHODS The authors retrospectively reviewed 42 children who underwent SDR at Columbia University Medical Center/Morgan Stanley Childrens Hospital of NewYork-Presbyterian between 2005 and 2011. Twenty-five had upper-extremity spasticity. All underwent pre- and postoperative examination for measuring tone (Modified Ashworth Scale) and assessing functional outcome. Follow-up examinations with therapists were performed at least once at a minimum of 2 months postoperatively (mean 15 months). RESULTS In the upper extremities, 23 (92%) of 25 patients had improvements of at least 1 Ashworth point in 2 or more independent motor groups on the Modified Ashworth Scale, and 12 (71%) of 17 families surveyed reported increases in motor control or spontaneous movement. The mean Modified Ashworth Scale scores for all upper-extremity muscle groups demonstrated an improvement from 1.34 to 1.22 (p < 0.001). Patients with a mean preoperative upper-extremity tone of 1.25-1.75 were most likely to benefit from reduction in tone (p = 0.0019). Proximal and pronator muscle groups were most likely to demonstrate reduced tone. CONCLUSIONS In addition to improvements in lower-extremity tone and function, SDR has demonstrable effects on upper extremities. Greater than 90% of our patients with elevated upper-extremity tone demonstrated reduction in tone in at least 2 muscle groups postoperatively. Patients with a mean Modified Ashworth Scale upper-extremity score of 1.25-1.75 may encounter the greatest reduction in upper-extremity tone.

Demographic and clinical predictors of multiple intracranial aneurysms in patients with subarachnoid hemorrhage

OBJECTIVE Pathophysiological differences that underlie the development and subsequent growth of multiple aneurysms may exist. In this study, the authors assessed the factors associated with the occurrence of multiple aneurysms in patients presenting with aneurysmal subarachnoid hemorrhage (SAH). METHODS Consecutive patients presenting with aneurysmal SAH between 1996 and 2012 were prospectively enrolled in the Subarachnoid Hemorrhage Outcome Project. Patients harboring 1, 2, or 3 or more aneurysms were stratified into groups, and the clinical and radiological characteristics of each group were compared using multivariate logistic regression. RESULTS Of 1277 patients with ruptured intracranial aneurysms, 890 had 1 aneurysm, 267 had 2 aneurysms, and 120 had 3 or more aneurysms. On multinomial regression using the single-aneurysm cohort as base case, risk factors for patients presenting with 2 aneurysms were female sex (relative risk ratio [RRR] 1.80, p < 0.001), higher body mass index (BMI) (RRR 1.02, p = 0.003), more years of smoking (RRR = 1.01, p = 0.004), and black race (RRR 1.83, p = 0.001). The risk factors for patients presenting with 3 or more aneurysms were female sex (RRR 3.10, p < 0.001), higher BMI (RRR 1.03, p < 0.001), aneurysm in the posterior circulation (RRR 2.59, p < 0.001), and black race (RRR 2.15, p = 0.001). Female sex, longer smoking history, aneurysms in the posterior circulation, BMI, and black race were independently associated with the development of multiple aneurysms in our adjusted multivariate multinomial model. CONCLUSIONS Significant demographic and clinical differences are found between patients presenting with single and multiple aneurysms in the setting of aneurysmal SAH. These predictors of multiple aneurysms likely reflect a predisposition toward inflammation and endothelial injury.