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Severin Schramm, Aashna Mehta, Kurtis I. Auguste, and Phiroz E. Tarapore

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive technique often used for localization of the functional motor cortex via induction of motor evoked potentials (MEPs) in neurosurgical patients. There has, however, been no published record of its application in pediatric epilepsy surgery. In this study, the authors aimed to investigate the feasibility of nTMS-based motor mapping in the preoperative diagnostic workup within a population of children with medically refractory epilepsy.

METHODS

A single-institution database was screened for preoperative nTMS motor mappings obtained in pediatric patients (aged 0 to 18 years, 2012 to present) with medically refractory epilepsy. Patient clinical data, demographic information, and mapping results were extracted and used in statistical analyses.

RESULTS

Sixteen patients met the inclusion criteria, 15 of whom underwent resection. The median age was 9 years (range 0–17 years). No adverse effects were recorded during mapping. Specifically, no epileptic seizures were provoked via nTMS. Recordings of valid MEPs induced by nTMS were obtained in 10 patients. In the remaining patients, no MEPs could be elicited. Failure to generate MEPs was associated significantly with younger patient age (r = 0.8020, p = 0.0001863). The most frequent seizure control outcome was Engel Epilepsy Surgery Outcome Scale class I (9 patients).

CONCLUSIONS

Navigated TMS is a feasible, effective, and well-tolerated method for mapping the motor cortex of the upper and lower extremities in pediatric patients with epilepsy. Patient age modulates elicitability of MEPs, potentially reflecting various stages of myelination. Successful motor mapping has the potential to add to the existing presurgical diagnostic workup in this population, and further research is warranted.

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Severin Schramm, Aashna Mehta, Kurtis I. Auguste, and Phiroz E. Tarapore

OBJECTIVE

Navigated transcranial magnetic stimulation (nTMS) is a noninvasive technique often used for localization of the functional motor cortex via induction of motor evoked potentials (MEPs) in neurosurgical patients. There has, however, been no published record of its application in pediatric epilepsy surgery. In this study, the authors aimed to investigate the feasibility of nTMS-based motor mapping in the preoperative diagnostic workup within a population of children with medically refractory epilepsy.

METHODS

A single-institution database was screened for preoperative nTMS motor mappings obtained in pediatric patients (aged 0 to 18 years, 2012 to present) with medically refractory epilepsy. Patient clinical data, demographic information, and mapping results were extracted and used in statistical analyses.

RESULTS

Sixteen patients met the inclusion criteria, 15 of whom underwent resection. The median age was 9 years (range 0–17 years). No adverse effects were recorded during mapping. Specifically, no epileptic seizures were provoked via nTMS. Recordings of valid MEPs induced by nTMS were obtained in 10 patients. In the remaining patients, no MEPs could be elicited. Failure to generate MEPs was associated significantly with younger patient age (r = 0.8020, p = 0.0001863). The most frequent seizure control outcome was Engel Epilepsy Surgery Outcome Scale class I (9 patients).

CONCLUSIONS

Navigated TMS is a feasible, effective, and well-tolerated method for mapping the motor cortex of the upper and lower extremities in pediatric patients with epilepsy. Patient age modulates elicitability of MEPs, potentially reflecting various stages of myelination. Successful motor mapping has the potential to add to the existing presurgical diagnostic workup in this population, and further research is warranted.

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Brandon G. Rocque, Bonita S. Agee, Eric M. Thompson, Mark Piedra, Lissa C. Baird, Nathan R. Selden, Stephanie Greene, Christopher P. Deibert, Todd C. Hankinson, Sean M. Lew, Bermans J. Iskandar, Taryn M. Bragg, David Frim, Gerald Grant, Nalin Gupta, Kurtis I. Auguste, Dimitrios C. Nikas, Michael Vassilyadi, Carrie R. Muh, Nicholas M. Wetjen, and Sandi K. Lam

OBJECTIVE

In children, the repair of skull defects arising from decompressive craniectomy presents a unique set of challenges. Single-center studies have identified different risk factors for the common complications of cranioplasty resorption and infection. The goal of the present study was to determine the risk factors for bone resorption and infection after pediatric cranioplasty.

METHODS

The authors conducted a multicenter retrospective case study that included all patients who underwent cranioplasty to correct a skull defect arising from a decompressive craniectomy at 13 centers between 2000 and 2011 and were less than 19 years old at the time of cranioplasty. Prior systematic review of the literature along with expert opinion guided the selection of variables to be collected. These included: indication for craniectomy; history of abusive head trauma; method of bone storage; method of bone fixation; use of drains; size of bone graft; presence of other implants, including ventriculoperitoneal (VP) shunt; presence of fluid collections; age at craniectomy; and time between craniectomy and cranioplasty.

RESULTS

A total of 359 patients met the inclusion criteria. The patients’ mean age was 8.4 years, and 51.5% were female. Thirty-eight cases (10.5%) were complicated by infection. In multivariate analysis, presence of a cranial implant (primarily VP shunt) (OR 2.41, 95% CI 1.17–4.98), presence of gastrostomy (OR 2.44, 95% CI 1.03–5.79), and ventilator dependence (OR 8.45, 95% CI 1.10–65.08) were significant risk factors for cranioplasty infection. No other variable was associated with infection.

Of the 240 patients who underwent a cranioplasty with bone graft, 21.7% showed bone resorption significant enough to warrant repeat surgical intervention. The most important predictor of cranioplasty bone resorption was age at the time of cranioplasty. For every month of increased age the risk of bone flap resorption decreased by 1% (OR 0.99, 95% CI 0.98–0.99, p < 0.001). Other risk factors for resorption in multivariate models were the use of external ventricular drains and lumbar shunts.

CONCLUSIONS

This is the largest study of pediatric cranioplasty outcomes performed to date. Analysis included variables found to be significant in previous retrospective reports. Presence of a cranial implant such as VP shunt is the most significant risk factor for cranioplasty infection, whereas younger age at cranioplasty is the dominant risk factor for bone resorption.

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Derek G. Southwell, Harjus S. Birk, Paul S. Larson, Philip A. Starr, Leo P. Sugrue, and Kurtis I. Auguste

Hypothalamic hamartomas (HHs) are benign lesions that cause medically refractory seizures, behavioral disturbances, and endocrine dysfunction. Open resection of HHs does not guarantee seizure freedom and carries a relatively high risk of morbidity. Minimally invasive stereotactic laser ablation has recently been described as an effective and safe alternative for HH treatment. Prior studies have not, however, assessed HH lesion size and morphology, 2 factors that may influence treatment results and, ultimately, the generalizability of their findings. In this paper, the authors describe seizure outcomes for 5 pediatric patients who underwent laser ablation of sessile HHs. Lesions were treated using a frameless, interventional MRI-guided approach, which facilitated laser targeting to specific components of these complex lesions. The authors’ experiences in these cases substantiate prior work demonstrating the effectiveness of laser therapy for HHs, while elucidating HH complexity as a potentially important factor in laser treatment planning, and in the interpretation of early studies describing this treatment method.

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Doris D. Wang, Kenneth W. Martin, Kurtis I. Auguste, and Peter P. Sun

Disorders of CSF dynamics such as syringomyelia and obstructive hydrocephalus can be caused by thin mobile obstructive lesions not visible on traditional MRI sequences. New imaging techniques with balanced steady-state free precession (bSSFP) and dynamic imaging with bSSFP cine allow visualization of these pulsatile structures within the CSF space. The authors present 2 cases involving pediatric patients—one who developed presumed idiopathic syringomyelia and one with presumed communicating hydrocephalus in association with Pfeiffer syndrome—who harbored thin dynamic obstructive lesions seen on bSSFP cine studies using 1.5-T MRI.

In combination with traditional CSF cine studies and bSSFP, bSSFP cine sequence was able to detect dynamic membranous adhesions not seen on traditional MRI sequences. These previously undetectable lesions on traditional MRI sequences were the etiology of CSF obstruction, and tailored surgical approaches were performed to avoid shunting in both patients. These reports demonstrate the clinical utility for using these novel imaging tools for the detection of thin adhesions and dynamic lesions in the central nervous system. Balanced SSFP cine sequences can supplement conventional MR modalities to identify these otherwise poorly visualized lesions responsible for presumed communicating hydrocephalus or idiopathic syringomyelia.

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Doris D. Wang, Barlas Benkli, Kurtis I. Auguste, Paul A. Garcia, Joseph Sullivan, A. James Barkovich, Edward F. Chang, and Tarik Tihan

Object

Cortical malformations and inflammatory encephalopathy are among common etiologies for medically refractory epilepsy in children. On rare occasions, lesions can affect an entire cerebral hemisphere while sparing the other; the 2 processes that can manifest in this manner are hemimegalencephaly (HME) and Rasmussen's encephalitis (RE). Although the clinical course and radiological appearance between the 2 disorders are distinct, there is occasional overlapping pathology between RE and cortical migration disorders. One question that arises from these observations is whether RE and HME, diseases with holohemispheric involvement but apparently different etiologies, have any overlapping characteristics.

Methods

The authors performed a retrospective review of all patients with presumed diagnosis of HME or RE who underwent hemispherectomy at University of California, San Francisco, and reviewed their clinical presentation, imaging, and pathology data.

Results

The authors present the clinicopathological features of 14 pediatric patients with unilateral holohemispheric lesions associated with medically refractory epilepsy. Radiological and pathological assessment classified 7 of the patients as having hemimegalencephaly, while the other 7 were diagnosed as having RE. Four of the patients had unusual features suggestive of overlapping developmental and inflammatory (dual) pathology. All patients underwent hemispherectomies. Eight patients (57%) became seizure free (Engel Class I), 5 patients (36%) had rare seizures (Engel Class II), and 1 patient had significant seizure reduction (Engel Class III).

Conclusions

Based on this case series, HME and RE can be distinguished on the basis of their radiological and histological appearance, even though some cases may have overlapping features. Hemispherectomy was effective at eliminating seizures for both HME and RE.

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Ann Marie Flannery, Catherine A. Mazzola, Paul Klimo Jr., Ann-Christine Duhaime, Lissa C. Baird, Mandeep S. Tamber, David D. Limbrick Jr., Dimitrios C. Nikas, Joanna Kemp, Alexander F. Post, Kurtis I. Auguste, Asim F. Choudhri, Laura S. Mitchell, and Debby Buffa

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Catherine A. Mazzola, Asim F. Choudhri, Kurtis I. Auguste, David D. Limbrick Jr., Marta Rogido, Laura Mitchell, and Ann Marie Flannery

Object

The objective of this systematic review and analysis was to answer the following question: What are the optimal treatment strategies for posthemorrhagic hydrocephalus (PHH) in premature infants?

Methods

Both the US National Library of Medicine and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words relevant to PHH. Two hundred thirteen abstracts were reviewed, after which 98 full-text publications that met inclusion criteria that had been determined a priori were selected and reviewed.

Results

Following a review process and an evidentiary analysis, 68 full-text articles were accepted for the evidentiary table and 30 publications were rejected. The evidentiary table was assembled linking recommendations to strength of evidence (Classes I–III).

Conclusions

There are 7 recommendations for the management of PHH in infants. Three recommendations reached Level I strength, which represents the highest degree of clinical certainty. There were two Level II and two Level III recommendations for the management of PHH.

Recommendation Concerning Surgical Temporizing Measures: I. Ventricular access devices (VADs), external ventricular drains (EVDs), ventriculosubgaleal (VSG) shunts, or lumbar punctures (LPs) are treatment options in the management of PHH. Clinical judgment is required. Strength of Recommendation: Level II, moderate degree of clinical certainty.

Recommendation Concerning Surgical Temporizing Measures: II. The evidence demonstrates that VSG shunts reduce the need for daily CSF aspiration compared with VADs. Strength of Recommendation: Level II, moderate degree of clinical certainty.

Recommendation Concerning Routine Use of Serial Lumbar Puncture: The routine use of serial lumbar puncture is not recommended to reduce the need for shunt placement or to avoid the progression of hydrocephalus in premature infants. Strength of Recommendation: Level I, high clinical certainty.

Recommendation Concerning Nonsurgical Temporizing Agents: I. Intraventricular thrombolytic agents including tissue plasminogen activator (tPA), urokinase, or streptokinase are not recommended as methods to reduce the need for shunt placement in premature infants with PHH. Strength of Recommendation: Level I, high clinical certainty.

Recommendation Concerning Nonsurgical Temporizing Agents. II. Acetazolamide and furosemide are not recommended as methods to reduce the need for shunt placement in premature infants with PHH. Strength of Recommendation: Level I, high clinical certainty.

Recommendation Concerning Timing of Shunt Placement: There is insufficient evidence to recommend a specific weight or CSF parameter to direct the timing of shunt placement in premature infants with PHH. Clinical judgment is required. Strength of Recommendation: Level III, unclear clinical certainty.

Recommendation Concerning Endoscopic Third Ventriculostomy: There is insufficient evidence to recommend the use of endoscopic third ventriculostomy (ETV) in premature infants with posthemorrhagic hydrocephalus. Strength of Recommendation: Level III, unclear clinical certainty.

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Lissa C. Baird, Catherine A. Mazzola, Kurtis I. Auguste, Paul Klimo Jr., and Ann Marie Flannery

Object

The objective of this systematic review was to examine the existing literature to compare differing shunt components used to treat hydrocephalus in children, find whether there is a superior shunt design for the treatment of pediatric hydrocephalus, and make evidence-based recommendations for the selection of shunt implants when placing shunts.

Methods

Both the US National Library of Medicine PubMed/MEDLINE database and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words chosen to identify publications comparing the use of shunt implant components. Abstracts of these publications were reviewed, after which studies meeting the inclusion criteria were selected. An evidentiary table was compiled summarizing the selected articles and quality of evidence. These data were then analyzed by the Pediatric Hydrocephalus Systematic Review and Evidence-Based Guidelines Task Force to consider evidence-based treatment recommendations.

Results

Two hundred sixty-nine articles were identified using the search parameters, and 43 articles were recalled for full-text review. Of these, 22 papers met the study criteria for a comparison of shunt components and were included in the evidentiary table. The included studies consisted of 1 Class I study, 11 Class II studies, and 10 Class III studies. The remaining 21 articles were excluded.

Conclusions

An analysis of the evidence did not demonstrate a clear advantage for any specific shunt component, mechanism, or valve design over another.

Recommendation: There is insufficient evidence to demonstrate an advantage for one shunt hardware design over another in the treatment of pediatric hydrocephalus. Current designs described in the evidentiary tables are all treatment options. Strength of Recommendation: Level I, high degree of clinical certainty.

Recommendation: There is insufficient evidence to recommend the use of a programmable valve versus a nonprogrammable valve. Programmable and nonprogrammable valves are both options for the treatment of pediatric hydrocephalus. Strength of Recommendation: Level II, moderate degree of clinical certainty.

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Dario J. Englot, Seunggu J. Han, John D. Rolston, Michael E. Ivan, Rachel A. Kuperman, Edward F. Chang, Nalin Gupta, Joseph E. Sullivan, and Kurtis I. Auguste

Object

Resection is a safe and effective treatment option for children with pharmacoresistant focal epilepsy, but some patients continue experience seizures after surgery. While most studies of pediatric epilepsy surgery focus on predictors of postoperative seizure outcome, these factors are often not modifiable, and the reasons for surgical failure may remain unclear.

Methods

The authors performed a retrospective cohort study of children and adolescents who received focal resective surgery for pharmacoresistant epilepsy. Both quantitative and qualitative analyses of factors associated with persistent postoperative seizures were conducted.

Results

Records were reviewed from 110 patients, ranging in age from 6 months to 19 years at the time of surgery, who underwent a total of 115 resections. At a mean 3.1-year follow-up, 76% of patients were free of disabling seizures (Engel Class I outcome). Seizure freedom was predicted by temporal lobe surgery compared with extratemporal resection, tumor or mesial temporal sclerosis compared with cortical dysplasia or other pathologies, and by a lower preoperative seizure frequency. Factors associated with persistent seizures (Engel Class II–IV outcome) included residual epileptogenic tissue adjacent to the resection cavity (40%), an additional epileptogenic zone distant from the resection cavity (32%), and the presence of a hemispheric epilepsy syndrome (28%).

Conclusions

While seizure outcomes in pediatric epilepsy surgery may be improved by the use of high-resolution neuroimaging and invasive electrographic studies, a more aggressive resection should be considered in certain patients, including hemispherectomy if a hemispheric epilepsy syndrome is suspected. Family counseling regarding treatment expectations is critical, and reoperation may be warranted in select cases.