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Free access

Letter to the Editor. The Chiari Severity Index and the role of external validation

Jacob K. Greenberg and David D. Limbrick Jr.

Restricted access

Editorial: Neurosurgical winners

Ralph G. Dacey Jr., Gregory J. Zipfel, and David D. Limbrick Jr.

Restricted access

Applications of a robotic stereotactic arm for pediatric epilepsy and neurooncology surgery

Brandon A. Miller, Afshin Salehi, David D. Limbrick Jr., and Matthew D. Smyth

OBJECTIVE

The ROSA device is a robotic stereotactic arm that uses a laser system to register the patient’s head or spine with MR or CT images. In this study, the authors analyze their experience with this system in pediatric neurosurgical applications and present selected cases that exemplify the usefulness of this system.

METHODS

The authors reviewed all cases that utilized the ROSA system at their institution. Patient demographics, pathology, complications, electrode placement, laser ablation, and biopsy accuracy were analyzed. Patient disposition and condition at follow-up were also analyzed.

RESULTS

Seventeen patients underwent 23 procedures using the ROSA system. A total of 87 electroencephalography electrodes were placed, with 13% deviating more than 3 mm from target. Six patients underwent stereotactic needle biopsy, and 9 underwent laser interstitial thermotherapy (LITT). One patient who underwent LITT required a subsequent craniotomy for tumor resection. Another patient experienced an asymptomatic extraaxial hematoma that spontaneously resolved. No patient suffered neurological complications during follow-up. Follow-up from the last procedure averaged 180 days in epilepsy patients and 309 days in oncology patients.

CONCLUSIONS

The precision, ease of use, and versatility of the ROSA system make it well suited for pediatric neurosurgical practice. Further work, including long-term analysis of results and cost-effectiveness, will help determine the utility of this system and if its applications can be expanded.

Open access

Co-occurrence of subcutaneous myxopapillary ependymoma, dermal sinus tract, and filum terminale lipoma: a review of the pathobiology of caudal spinal cord development and spinal cord tethering. Illustrative case

Gabrielle W. Johnson, Yuxiao Xu, Ali Y. Mian, and David D. Limbrick Jr

BACKGROUND

Myxopapillary ependymoma (MPE) is typically benign and found in the conus medullaris and/or filum terminale, although rare cases of subcutaneous and extra-axial MPE have been reported. The co-occurrence of MPE, tethered cord syndrome (TCS) with lipoma of the filum terminale, and a dermal sinus tract is extremely rare, with only 6 reported cases in the literature. Here, the authors present the first case, to their knowledge, of an extra-axial, subcutaneous MPE co-presenting with TCS, lipoma of the filum terminale, and a dermal sinus tract and discuss the underlying pathobiology.

OBSERVATIONS

A 14-month-old male who presented for evaluation of a dermal sinus tract underwent magnetic resonance imaging, which revealed a tethered cord with associated lipoma. At 14 months, the patient underwent spinal cord detethering with resection of his sacral dimple and sinus tract. Histopathological evaluation revealed an incidentally found MPE within the dermal sinus tract.

LESSONS

The authors review the underlying biology of MPEs, tethered cord syndrome, and dermal sinus tracts, and explore possible points of convergence within the developmental pathways that may result in this unique concomitant presentation. Additionally, they suggest that extra-axial MPE may be underappreciated and underdiagnosed; this case suggests that extra-axial MPE may be only effectively diagnosed with histological studies.

Free access

Introduction. Stability and motion: addressing the pathology of Chiari malformation and craniocervical junction

David D. Limbrick Jr., Douglas L. Brockmeyer, Atul Goel, and Jennifer M. Strahle

Free access

Letter to the Editor. Overlapping confidence intervals

Joseph Piatt

Free access

Outcomes for various dural graft materials after posterior fossa decompression with duraplasty for Chiari malformation type I: a systematic review and meta-analysis

Alexander T Yahanda, Laura E Simon, and David D. Limbrick Jr.

OBJECTIVE

Posterior fossa decompression with duraplasty (PFDD) is often used for Chiari malformation type I (CM-I), but outcomes associated with different dural graft materials are not well characterized. In this meta-analysis, the authors examined complication rates and outcomes after PFDD for CM-I for autografts and four types of nonautologous grafts.

METHODS

A literature search of numerous electronic databases (Ovid Medline, Embase, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database, NHS Economic Evaluation Database, and ClinicalTrials.gov) was performed to identify articles detailing complications for dural graft materials after PFDD. Whenever available, data were also extracted regarding the need for revision surgery, symptom changes after PFDD, and syrinx size changes after PFDD. All searches were compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), Institute of Medicine, Standards for Systematic Reviews, Cochrane Handbook for Systematic Reviews of Interventions, and Peer Review of Electronic Search Strategies guidelines. There were no exclusion criteria based on patient age or presence or absence of syringomyelia.

RESULTS

The current evidence surrounding outcomes for various dural graft materials was found to be of low or very low quality. Twenty-seven studies were included, encompassing 1461 patients. Five types of dural graft materials were included: autograft (n = 404, 27.6%), synthetic (n = 272, 18.6%), bovine pericardium (n = 181, 12.4%), collagen-based (n = 397, 27.2%), and allograft (n = 207, 14.2%). Autograft was associated with a significantly lower rate of pseudomeningocele compared to collagen-based grafts, allografts, and nonautologous grafts in aggregate. Autograft was also associated with the lowest rates of aseptic meningitis, infectious meningitis, and need for revision PFDD, though these associations did not reach statistical significance. No other graft comparisons yielded significant results. Autograft and nonautologous graft materials yielded similar rates of revision surgery and produced similar improvements in postoperative symptoms and syrinx size.

CONCLUSIONS

Autograft was the dural graft material that most frequently had the lowest rate of complications and was associated with significantly lower rates of pseudomeningocele compared to collagen-based graft, allograft, and nonautologous graft materials. Autografts and nonautologous grafts yielded similar outcomes for revision surgery, symptoms, and syrinx size. Large prospective studies comparing different graft materials are needed to accurately and precisely characterize outcomes for individual graft types.

Restricted access

External validation of the Chicago Chiari Outcome Scale

Clinical article

Chester K. Yarbrough, Jacob K. Greenberg, Matthew D. Smyth, Jeffrey R. Leonard, Tae Sung Park, and David D. Limbrick Jr.

Object

Historically, assessment of clinical outcomes following surgical management of Chiari malformation Type I (CM-I) has been challenging due to the lack of a validated instrument for widespread use. The Chicago Chiari Outcome Scale (CCOS) is a novel system intended to provide a less subjective evaluation of outcomes for patients with CM-I. The goal of this study was to externally validate the performance of the CCOS.

Methods

Patients undergoing surgery for CM-I between 2001 and 2012 were reviewed (n = 292). Inclusion criteria for this study were as follows: 1) patients receiving primary posterior fossa decompression; 2) at least 5.5 months of postoperative clinical follow-up; and 3) patients ≤ 18 years of age at the time of surgery. Outcomes were evaluated using the CCOS, along with a “gestalt” impression of whether patients experienced significant improvement after surgery. A subgroup of 118 consecutive patients undergoing operations between 2008 and 2010 was selected for analysis of interrater reliability (n = 73 meeting inclusion/exclusion criteria). In this subgroup, gestalt and CCOS scores were independently determined by 2 reviewers, and interrater reliability was assessed using the intraclass correlation coefficient (ICC) and kappa (κ) statistic.

Results

The median CCOS score was 14, and 67% of patients had improved gestalt scores after surgery. Overall, the CCOS was effective at identifying patients with improved outcome after surgery (area under curve = 0.951). The interrater reliability of the CCOS (ICC = 0.71) was high, although the reliability of the component scores ranged from poor to good (ICC 0.23–0.89). The functionality subscore demonstrated a low ICC and did not add to the predictive ability of the logistic regression model (likelihood ratio = 1.8, p = 0.18). When analyzing gestalt outcome, there was moderate agreement between raters (κ = 0.56).

Conclusions

In this external validation study, the CCOS was effective at identifying patients with improved outcomes and proved more reliable than the authors' gestalt impression of outcome. However, certain component subscores (functionality and nonpain symptoms) were found to be less reliable, and may benefit from further definition in score assignment. In particular, the functionality subscore does not add to the predictive ability of the CCOS, and may be unnecessary. Overall, the authors found the CCOS to be an improvement over the previously used assessment of outcome at their institution.

Restricted access

Complete versus anterior two-thirds corpus callosotomy in children: analysis of outcome

Clinical article

Laleh Jalilian, David D. Limbrick Jr., Karen Steger-May, Jim Johnston, Alex K. Powers, and Matthew D. Smyth

Object

The goal of this study was to evaluate the efficacy of anterior versus complete sectioning of the corpus callosum in children suffering from medically refractory epilepsy. The authors report seizure outcome in patients who underwent anterior two-thirds or complete corpus callosotomy (CC) during the period 1995–2008 at St. Louis Children's Hospital.

Methods

The medical records of 27 children and adolescents with a minimum follow-up of 6 months were retrospectively evaluated with respect to seizure status, anticonvulsant outcomes, and subjective results. Preoperatively, patients suffered from a variety of seizure types that occurred daily, weekly, or episodically. The male/female ratio was 19:8, and patients ranged in age between 3 and 19 years (mean 9.93 years). Seizure outcome, parental assessment of daily function, and changes in the number of prescribed antiepileptic drugs were all assessed.

Results

Fifteen patients underwent an initial anterior two-thirds CC, and 12 underwent a complete CC. Of the 15 patients who underwent an anterior CC, 7 went on to receive a posterior CC. Seizure control was superior in children undergoing a complete CC (91%, Class I–III) versus an anterior two-thirds CC (75%, Class I–III). Seizure types most affected by CC included atonic, myoclonic, and absence. The number of postoperative antiepileptic drugs did not significantly change following CC in either the anterior only or complete groups. One patient experienced a transient disconnection syndrome that resolved within 4 weeks, and 4 patients experienced mild hemiparesis and speech delays that resolved with therapy. Three patients experienced surgical complications requiring a second operation. The overall daily function and attentiveness of the patients improved.

Conclusions

A complete CC should be considered as the initial procedure in lower-functioning children afflicted by absence, atonic, or myoclonic seizures. Severely affected higher-functioning children may also benefit from a complete CC, without clinically significant disconnection syndromes. A completion posterior CC may benefit patients in whom a prior anterior CC has failed.

Restricted access

Spontaneous resolution of Chiari malformation Type I in monozygotic twins

Report of 2 cases

Jeffrey H. Miller, David D. Limbrick Jr., Matthew Callen, and Matthew D. Smyth

The spontaneous resolution of isolated tonsillar ectopia in Chiari malformation Type I (CM-I) is a known and reported entity in 2 previous single study case reports. However, it has not been previously described in monozygotic twins. Two children, ~ 1 year of age with CM-I and presumed episodes of pallid syncope or breath-holding spells presented for neurosurgical evaluation. Although Chiari decompression was considered, the authors decided to proceed with conservative management with close follow-up due to the uncertain nature of these episodes. Approximately 4 years later, both children's symptoms had resolved. Repeated MR imaging examinations also showed spontaneous resolution of the malformation in both girls. These cases emphasize that when patients with CM-I present with atypical symptoms, spontaneous resolution or improvement is possible, which may influence the decision to pursue a trial of nonsurgical management. The possible pathophysiological mechanisms and genetic influences of CM-I are also briefly discussed.