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Sean M. Lew, Thomas F. Mehalic and Kristin L. Fagone

Object. Far-lateral (extraforaminal) and foraminal disc herniations comprise up to 11% of all herniated intervertebral discs. Operative management can be technically difficult, and the optimum surgical treatment remains controversial. Accessing these lateral disc herniations endoscopically via a percutaneous transforaminal approach offers several theoretical advantages over the more traditional procedures. The object of this study was to assess the safety and efficacy of treating patients with far-lateral and foraminal disc herniations via a percutaneous transforaminal endoscopic approach.

Methods. A retrospective analysis was performed of 47 consecutive patients who underwent surgery via this approach. All procedures were performed after induction of a local anesthetic on an outpatient basis. Outcome was measured with Macnab criteria and by determining a patient's return-to-work status. The median follow-up period was 18 months (range 4–51 months). Excellent or good outcome was obtained in 40 (85%) of 47 patients. Of the 38 patients working before the onset of symptoms, 34 (90%) returned to work. Five patients (11%) experienced poor outcomes and subsequently underwent open procedures at the same level. Of the 10 recipients of Workers' Compensation, Macnab criteria indicated a significantly worse outcome (70% excellent or good), but an excellent return-to-work status was maintained (90%). There were no complications.

Conclusions. Transforaminal percutaneous endoscopic discectomy is safe and efficacious in the treatment of far-lateral and foraminal disc herniations.

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Sean M. Lew, Joseph N. Morgan, Estee Psaty, Daniel R. Lefton, Jeffrey C. Allen and Rick Abbott

Object

The goal of this study was to determine the incidence of radiation-induced cavernomas in children treated for medulloblastoma.

Methods

A retrospective chart and film review was performed for all patients treated for medulloblastoma at the Insitute for Neurology and Neurosurgery/Beth Israel Medical Center between August 1996 and the present. The clinical and radiographic histories of pediatric patients (ages 3–21 years at diagnosis) with a histologically confirmed diagnosis of medulloblastoma who received craniospinal radiation therapy were reviewed.

Fifty-nine patients were identified, with a mean age at radiation treatment of 7.7 years and a mean follow-up time of 7.2 years. The dose to the craniospinal axis was 24 Gy (31 patients) or 36 Gy (28 patients). The radiation energy in the craniospinal axis was provided by photons in 55 patients and protons in four. All patients received a posterior fossa boost of 54 Gy (46 patients) or 72 Gy (13 patients). Twenty-six lesions developed in 18 patients (31%) during the observation period. The cumulative incidence of lesion development was 5.6, 14, and 43%, at 3, 5, and 10 years, respectively. The sites of occurrence were cerebral (20 cases) and cerebellar (six cases). There was no significant correlation between age at diagnosis, sex, craniospinal radiation dose or energy source, and lesion development. Only one patient required surgical intervention for a symptomatic hemorrhagic lesion in the frontal lobe. Histological analysis in this case was consistent with cavernoma.

Conclusions

Cavernomas are common after cranial irradiation in children, and their incidence increases over time. Most of these lesions follow a benign course and do not require intervention.

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Todd C. Hankinson, Anthony M. Avellino, David Harter, Andrew Jea, Sean Lew, David Pincus, Mark R. Proctor, Luis Rodriguez, David Sacco, Theodore Spinks, Douglas L. Brockmeyer and Richard C. E. Anderson

Object

The object of this study was to assess a multiinstitutional experience with pediatric occipitocervical constructs to determine whether a difference exists between the fusion and complication rates of constructs with or without direct C-1 instrumentation.

Methods

Seventy-seven cases of occiput-C2 instrumentation and fusion, performed at 9 children's hospitals, were retrospectively analyzed. Entry criteria included atlantooccipital instability with or without atlantoaxial instability. Any case involving subaxial instability was excluded. Constructs were divided into 3 groups based on the characteristics of the anchoring spinal instrumentation: Group 1, C-2 instrumentation; Group 2, C-1 and C-2 instrumentation without transarticular screw (TAS) placement; and Group 3, any TAS placement. Groups were compared based on rates of fusion and perioperative complications.

Results

Group 1 consisted of 16 patients (20.8%) and had a 100% rate of radiographically demonstrated fusion. Group 2 included 22 patients (28.6%), and a 100% fusion rate was achieved, although 2 cases were lost to follow-up before documented fusion. Group 3 included 39 patients (50.6%) and demonstrated a 100% radiographic fusion rate. Complication rates were 12.5, 13.7, and 5.1%, respectively. There were 3 vertebral artery injuries, 1 (4.5%) in Group 2 and 2 (5.1%) in Group 3.

Conclusions

High fusion rates and low complication rates were achieved with each configuration examined. There was no difference in fusion rates between the group without (Group 1) and those with (Groups 2 and 3) C-1 instrumentation. These findings indicated that in the pediatric population, excellent occipitocervical fusion rates can be accomplished without directly instrumenting C-1.

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Sean M. Lew

The author reports the details in 2 cases of infants with familial cerebral cavernomatosis who presented in dire condition from hemorrhagic posterior fossa cavernous malformations.

In Case 1, a 4-month-old boy presented with opisthotonos, gaze palsy, and lethargy. Magnetic resonance imaging revealed a multilobulated cavernous malformation in the fourth ventricle with evidence of bleeding and obstructive hydrocephalus. In Case 2, a 7-month-old girl presented with lethargy, followed by rapid neurological decline. Imaging demonstrated a large lesion involving both the brainstem and cerebellum, with obstructive hydrocephalus. Both patients required immediate surgical intervention, and external ventricular drainage and posterior fossa craniotomies were performed. Both patients made excellent recoveries. These cases suggest that infants in families with suspected or confirmed familial cerebral cavernomatosis should be screened at an early age.

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Bruce A. Kaufman, Anne E. Matthews, Marike Zwienenberg-Lee and Sean M. Lew

Object

The authors report a retrospective review of their experience using nonpenetrating titanium anastomotic clips for dural closure in 27 pediatric cases (26 patients) of spinal surgery for a variety of diagnoses. The goal of this review was to define the utility of these clips in pediatric neurosurgical spinal procedures, identify complications of their use, and assess the effects on postoperative imaging because of their use.

Methods

Institutional review board approval was obtained for a retrospective chart review of all patients in whom titanium dural clips had been utilized. Patients were identified over a 2-year period using hospital and clinic records, and data were collected on the patient demographics, surgical diagnosis and procedure, durotomy location and length, and adjunctive closure methods. Postoperative complications were assessed. When available, postoperative imaging data were reviewed.

Results

Twenty-six patients underwent 27 operations over a 20-month period. They ranged in age from 2.5 months to 18.5 years, with a median age of 3.2 years and an average age of 5.8 years. The operative diagnosis was some form of spinal dysraphism in 19 patients, with a syrinx or dural tear in 2 patients each, and an arachnoid cyst in 3 cases; 1 patient had a tumor resected. Operative levels included lumbosacral (19), thoracic (7), and cervical (1). Dural exposure was limited to 1 laminar level in 16 cases, 2 levels in 8, and 3 levels in 1; 2 cases involved focal dural tears. A combination of additional hemostatic and tissue sealant materials was applied over the clips in 16 cases. One patient required reoperation 13 months after clip placement. Prior clip use did not make subsequent exposure and opening more complicated. No significant complications were identified in the follow-up period ranging from 1 to 24 months. There were no documented CSF leaks. The clips are not easily seen on plain radiographs and did not cause artifacts or distortion on either CT or MR imaging.

Conclusions

Nonpenetrating titanium anastomotic clips afford an effective means of closure while limiting the exposure needed, and thus allowing more minimally invasive approaches. In tight spaces, dural closure is accomplished more easily and faster with the clips as compared with conventional suturing. No significant complications were seen from clip use, and the clips did not interfere with postoperative imaging.

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Jessica S. Lin, Sean M. Lew, Charles J. Marcuccilli, Wade M. Mueller, Anne E. Matthews, Jennifer I. Koop and Mary L. Zupanc

Object

The object of this study was to evaluate surgical outcome in a select group of patients with medically refractory epilepsy who had undergone corpus callosotomy combined with bilateral subdural electroencephalography (EEG) electrode placement as the initial step in multistage epilepsy surgery.

Methods

A retrospective chart review of 18 children (ages 3.5–18 years) with medically refractory symptomatic generalized or localization-related epilepsy was undertaken. A corpus callosotomy with subdural bihemispheric EEG electrode placement was performed as the initial step in multistage epilepsy surgery. All of the patients had tonic and atonic seizures; 6 patients also experienced complex partial seizures. All of the patients had frequent generalized epileptiform discharges as well as multifocal independent epileptiform discharges on surface EEG monitoring. Most of the patients (94%) had either normal (44%) MR imaging studies of the brain or bihemispheric abnormalities (50%). One patient had a suspected unilateral lesion (prominent sylvian fissure).

Results

Of the 18 patients who underwent corpus callosotomy and placement of subdural strips and grids, 12 progressed to further resection based on localizing data obtained during invasive EEG monitoring. The mean patient age was 10.9 years. The duration of invasive monitoring ranged from 3 to 14 days, and the follow-up ranged from 6 to 70 months (mean 35 months). Six (50%) of the 12 patients who had undergone resection had an excellent outcome (Engel Class I or II). There were no permanent neurological deficits or deaths.

Conclusions

The addition of invasive monitoring for patients undergoing corpus callosotomy for medically refractory epilepsy may lead to the localization of surgically amenable seizure foci, targeted resections, and improved seizure outcomes in a select group of patients typically believed to be candidates for palliative surgery alone.

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Mohammad-Ali Jazayeri, John N. Jensen and Sean M. Lew

The authors report on the case of a 6-week-old boy who presented with infantile spasms. At 2.5 months of age, the patient underwent a right hemispherectomy. Approximately 3 months postoperatively, the patient presented with left coronal craniosynostosis. Subsequent cranial vault remodeling resulted in satisfactory cosmesis. Four years after surgery, the patient remains seizure free without the need for anticonvulsant medications. The authors believe this to be the first reported case of iatrogenic craniosynostosis due to hemispherectomy, and they describe 2 potential mechanisms for its development. This case suggests that, in the surgical treatment of infants with intractable epilepsy, minimization of brain volume loss through disconnection techniques should be considered, among other factors, when determining the best course of action.

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Paul Klimo Jr., Anne Matthews, Sean M. Lew, Marike Zwienenberg-Lee and Bruce A. Kaufman

Object

Various surgical interventions have been described to evacuate chronic subdural collections (CSCs) of infancy. These include transfontanel percutaneous aspiration, subdural drains, placement of bur hole(s) with or without a subdural drain, and shunting. Shunt placement typically provides good long-term success (resolution of the subdural fluid), but comes with well-known early and late complications. Recently, the authors have used a mini–osteoplastic craniotomy technique with the goal of definitively treating these children with a single surgery while avoiding the many issues associated with a shunt. They describe their procedure and compare it with the traditional bur hole technique.

Methods

In this single-institution retrospective study, the authors evaluated 26 cases involving patients who underwent treatment for CSC. Preoperative, intraoperative, and postoperative data were reviewed, including radiographic findings (density of the subdural fluid and ventricular and subarachnoid space size), neurological examination findings, and intraoperative fluid description. The primary outcome was treatment failure, defined as the patient requiring any subsequent surgical intervention after the index procedure (minicraniotomy or bur hole placement).

Results

Fifteen patients (10 male and 5 female; median age 5.1 months) collectively underwent 27 minicraniotomy procedures (each procedure representing a hemisphere that was treated). In the bur hole group, there were 11 patients (6 male and 5 female; median age 4.6 months) with 18 hemispheres treated. Both groups had subdural drains placed. The average follow-up for each treatment group was just over 7 months. Treatment failure occurred in 2 patients (13%) in the minicraniotomy group compared with 5 patients (45%) in the bur hole group (p = 0.09). Furthermore, the 2 patients who had treatment failure in the minicraniotomy group required 1 subsequent surgery each, whereas the 5 in the bur hole group needed a total of 9 subsequent surgeries. Eventually, 80% of the patients in the minicraniotomy group and 70% of those in the bur hole group had resolution of the subdural collections on the last imaging study.

Conclusions

The minicraniotomy technique may be a superior technique for the treatment of CSCs in infants compared with bur hole evacuation. The minicraniotomy provides greater visualization of the subdural space and allows more aggressive evacuation of the fluid, better irrigation of the space, the ability to fenestrate any accessible membranes safely, and continued egress of fluid into the subgaleal space. Although this preliminary report has obvious limitations, evaluation of this technique may be worthy of a prospective, multiinstitutional collaborative effort.

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Brandon G. Rocque, Kaushik Amancherla, Sean M. Lew and Sandi Lam

Cranioplasty is routinely performed following decompressive craniectomy in both adult and pediatric populations. In adults, this procedure is associated with higher rates of complications than is elective cranial surgery. This study is a review of the literature describing risk factors for complications after cranioplasty surgery in pediatric patients. A systematic search of PubMed, Cochrane, and SCOPUS databases was undertaken. Articles were selected based on their titles and abstracts. Only studies that focused on a pediatric population were included; case reports were excluded. Studies in which the authors assessed bone flap storage method, timing of cranioplasty, material used (synthetic vs autogenous), skull defect size, and/or complication rates (bone resorption and surgical site infection) were selected for further analysis. Eleven studies that included a total of 441 cranioplasties performed in the pediatric population are included in this review.

The findings are as follows: 1) Based on analysis of pooled data, using cryopreserved bone flaps during cranioplasty may lead to a higher rate of bone resorption and lower rate of infection than using bone flaps stored at room temperature. 2) In 3 of 4 articles describing the effect of time between craniectomy and cranioplasty on complication rate, the authors found no significant effect, while in 1 the authors found that the incidence of bone resorption was significantly lower in children who had undergone early cranioplasty. Pooling of data was not possible for this analysis. 3) There are insufficient data to assess the effect of cranioplasty material on complication rate when considering only cranioplasties performed to repair decompressive craniectomy defects. However, when considering cranioplasties performed for any indication, those in which freshly harvested autograft is used may have a lower rate of resorption than those in which stored autograft is used. 4) There is no appreciable effect of craniectomy defect size or patient age on complication rate.

There is a paucity of articles describing outcomes and complications following cranioplasty in children and adolescents. However, based on the studies examined in this systematic review, there are reasons to suspect that method of flap preservation, timing of surgery, and material used may be significant. Larger prospective and retrospective studies are needed to shed more light on this important issue.