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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.

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

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James T. Rutka

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Michael Anthony Ciliberto, David Limbrick, Alexander Powers, Jeffrey B. Titus, Rebecca Munro and Matthew D. Smyth

Object

Intractable epilepsy is a significant burden on families and on the cognitive development and quality of life (QOL) of patients. Periinsular hemispherotomy (PIH) for medically intractable epilepsy can benefit patients who qualify for this procedure. The ideal hemispherotomy candidate has ipsilateral ictal and interictal epileptiform activity, unilateral MR imaging abnormalities, contralateral hemiplegia, and a normal contralateral hemisphere. However, certain patients present with a mixed picture of bilateral electroencephalography (EEG) findings and severe intractable epilepsy, prompting consideration of a more aggressive treatment approach. This report introduces the possibility of surgery for patients who normally would not meet criteria for this treatment modality.

Methods

In this retrospective chart review, the authors report on 7 patients with bilateral seizure onset noted on routine or video-EEG monitoring. A QOL phone questionnaire, based on the Quality of Life in Childhood Epilepsy tool, was administered to a parent. The authors reviewed each patient's chart for surgical complications, changes in examination, QOL, limited neuropsychological outcomes, and seizure outcomes. They also investigated each chart for MR imaging and EEG findings as well as the patient's epilepsy clinic notes for seizure semiology and frequency.

Results

All patients enjoyed a decrease in seizure frequency and a subjective increase in QOL after PIH. Five patients (71%) achieved Engel Class I or II seizure control. The mean follow-up was 3.64 years (2–5.3 years). One patient is now off all antiseizure medication. No patient had a decrement in Full Scale IQ on postsurgical testing, and 2 (28.5%) of 7 individuals had increased adaptive and social functioning. Postsurgical examination changes included hemiplegia and homonymous hemianopia.

Conclusions

Hemispherotomy in patients with intractable epilepsy is generally reserved for individuals with unilateral epileptiform abnormalities or lesions on MR imaging. Seven patients in this study benefited from surgery despite bilateral seizure onset with improvement in seizure control and overall QOL. Thus, bilateral ictal onset does not necessarily preclude consideration for hemispherotomy in selected patients with severe medically refractory epilepsy.

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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.

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Thomas L. Beaumont, David D. Limbrick Jr., Keith M. Rich, Franz J. Wippold II and Ralph G. Dacey Jr.

OBJECTIVE

Colloid cysts are rare, histologically benign lesions that may result in obstructive hydrocephalus and death. Understanding the natural history of colloid cysts has been challenging given their low incidence and the small number of cases in most reported series. This has complicated efforts to establish reliable prognostic factors and surgical indications, particularly for asymptomatic patients with incidental lesions. Risk factors for obstructive hydrocephalus in the setting of colloid cysts remain poorly defined, and there are no grading scales on which to develop standard management strategies.

METHODS

The authors performed a single-center retrospective review of all cases of colloid cysts of the third ventricle treated over nearly 2 decades at Washington University. Univariate analysis was used to identify clinical, imaging, and anatomical factors associated with 2 outcome variables: symptomatic clinical status and presentation with obstructive hydrocephalus. A risk-prediction model was defined using bootstrapped logistic regression. Predictive factors were then combined into a simple 5-point clinical scale referred to as the Colloid Cyst Risk Score (CCRS), and this was evaluated with receiver-operator characteristics.

RESULTS

The study included 163 colloid cysts, more than half of which were discovered incidentally. More than half of the incidental cysts (58%) were followed with surveillance neuroimaging (mean follow-up 5.1 years). Five patients with incidental cysts (8.8%) progressed and underwent resection. No patient with an incidental, asymptomatic colloid cyst experienced acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly half (46.2%) of symptomatic patients presented with hydrocephalus. Eight patients (12.3%) presented acutely, and there were 2 deaths due to obstructive hydrocephalus and herniation. The authors identified several factors that were strongly correlated with the 2 outcome variables and defined third ventricle risk zones where colloid cysts can cause obstructive hydrocephalus. No patient with a lesion outside these risk zones presented with obstructive hydrocephalus. The CCRS had significant predictive capacity for symptomatic clinical status (area under the curve [AUC] 0.917) and obstructive hydrocephalus (AUC 0.845). A CCRS ≥ 4 was significantly associated with obstructive hydrocephalus (p < 0.0001, RR 19.4).

CONCLUSIONS

Patients with incidentally discovered colloid cysts can experience both lesion enlargement and symptom progression or less commonly, contraction and symptom regression. Incidental lesions rarely cause acute obstructive hydrocephalus or sudden neurological deterioration in the absence of antecedent trauma. Nearly one-half of patients with symptomatic colloid cysts present with obstructive hydrocephalus, which has an associated 3.1% risk of death. The CCRS is a simple 5-point clinical tool that can be used to identify symptomatic lesions and stratify the risk of obstructive hydrocephalus. External validation of the CCRS will be necessary before objective surgical indications can be established. Surgical intervention should be considered for all patients with CCRS ≥ 4, as they represent the high-risk subgroup.

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David D. Limbrick Jr., Lissa C. Baird, Paul Klimo Jr., Jay Riva-Cambrin and Ann Marie Flannery

Object

The objective of this systematic review was to examine the existing literature comparing CSF shunts and endoscopic third ventriculostomy (ETV) for the treatment of pediatric hydrocephalus and to make evidence-based recommendations regarding the selection of surgical technique for this condition.

Methods

Both the US National Library of Medicine and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words specifically chosen to identify published articles detailing the use of CSF shunts and ETV for the treatment of pediatric hydrocephalus. Articles meeting specific criteria that had been determined a priori were examined, and data were abstracted and compiled in evidentiary tables. These data were then analyzed by the Pediatric Hydrocephalus Systematic Review and Evidence-Based Guidelines Task Force to consider treatment recommendations based on the evidence.

Results

Of the 122 articles identified using optimized search parameters, 52 were recalled for full-text review. One additional article, originally not retrieved in the search, was also reviewed. Fourteen articles met all study criteria and contained comparative data on CSF shunts and ETV. In total, 6 articles (1 Class II and 5 Class III) were accepted for inclusion in the evidentiary table; 8 articles were excluded for various reasons. The tabulated evidence supported the evaluation of CSF shunts versus ETV.

Conclusions

Cerebrospinal fluid shunts and ETV demonstrated equivalent outcomes in the clinical etiologies studied.

Recommendation: Both CSF shunts and ETV are options in the treatment of pediatric hydrocephalus. Strength of Recommendation: Level II, moderate clinical certainty.

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Hari S. Raman, David D. Limbrick Jr., Wilson Z. Ray, Dean W. Coble, Sophie Church, Ralph G. Dacey Jr. and Gregory J. Zipfel

OBJECTIVE

The challenging nature of neurosurgical residency necessitates that appropriate measures are taken by training programs to ensure that residents are properly progressing through their education. Residents who display a pattern of performance deficiencies must be identified and promptly addressed by faculty and program directors to ensure that resident training and patient care are not affected. While studies have been conducted to characterize these so-called “problem residents” in other specialties, no current data regarding the prevalence and management of such residents in neurosurgery exist. The purpose of this study was to determine the rate and the outcome of problem residents in US neurosurgical residency programs and identify predictive risk factors that portend a resident’s departure from the program.

METHODS

An anonymous nationwide survey was sent to all 108 neurosurgical training programs in the US to assess a 20-year history of overall attrition as well as the management course of problem residents, including the specific deficiencies of the resident, management strategies used by faculty, and the eventual outcome of each resident’s training.

RESULTS

Responses were received from 36 centers covering a total of 1573 residents, with the programs providing a mean 17.4 years’ worth of data (95% CI 15.3–19.4 years). The mean prevalence of problem residents among training programs was 18.1% (95% CI 14.7%–21.6%). The most common deficiencies recognized by program directors were poor communication skills (59.9%), inefficiency in tasks (40.1%), and poor fund of medical knowledge (39.1%). The most common forms of program intervention were additional meetings to provide detailed feedback (93.9%), verbal warnings (78.7%), and formal written remediation plans (61.4%). Of the identified problem residents whose training status is known, 50% graduated or are on track to graduate, while the remaining 50% ultimately left their residency program for other endeavors. Of the 97 residents who departed their programs, 65% left voluntarily (most commonly for another specialty), and 35% were terminated (often ultimately training in another neurosurgery program). On multivariable logistic regression analysis, the following 3 factors were independently associated with departure of a problem resident from their residency program: dishonesty (OR 3.23, 95% CI 1.67–6.253), poor fund of medical knowledge (OR 2.54, 95% CI 1.47–4.40), and poor technical skill (OR 2.37, 95% CI 1.37–4.12).

CONCLUSIONS

The authors’ findings represent the first study to characterize the nature of problem residents within neurosurgery. Identification of predictive risk factors, such as dishonesty, poor medical knowledge, and/or technical skill, may enable program directors to preemptively act and address such deficiencies in residents before departure from the program occurs. As half of the problem residents departed their programs, there remains an unmet need for further research regarding effective remediation strategies.

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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.

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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.