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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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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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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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Ahmad Marashly, Michelle M. Loman, and Sean M. Lew

Stereotactic laser ablation (SLA) is being increasingly used to treat refractory focal epilepsy, especially mesial temporal lobe epilepsy. However, emerging evidence suggests it can be used for extratemporal lobe epilepsy as well.

The authors report the case of a 17-year-old male who presented with refractory nocturnal seizures characterized by bilateral arms stiffening or rhythmic jerking lasting several seconds. Semiology suggested an epileptogenic zone close to one of the supplementary sensory motor areas. Electroencephalography showed seizures arising from the central region without consistent lateralization. Brain imaging showed no abnormality. An invasive evaluation using bilateral stereoelectroencephalography (SEEG) was utilized in 2 steps, first to establish the laterality of seizures, and second to further cover the mesial cingulate region of the right hemisphere. Seizures arose from the middle portion of the right cingulate gyrus. Extraoperative electrical mapping revealed that the seizure onset zone was adjacent to eloquent motor areas. SLA targeting the right midcingulate gyrus was performed. The patient has remained seizure free since immediately after the procedure with no postoperative deficits (follow-up of 17 months).

This case highlights the utility of SEEG in evaluating difficult-to-localize, focal epilepsy. It also demonstrates that the use of SLA can be extended to nonlesional, extratemporal epilepsies.

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Alastair T. Hoyt, Peter S. LaViolette, and Sean M. Lew

Ensuring a stable position of intracranial electrode grids with good proximity to the cortical surface can be a technical challenge in patients with complex anomalous cerebral anatomy. This report illustrates the use of fibrin sealant to secure subdural electrodes to concave cortical surfaces during intracranial electroencephalographic monitoring for localization-related medically intractable epilepsy in a patient with a large arachnoid cyst.

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Elsa V. Arocho-Quinones, Sean M. Lew, and Andrew B. Foy


The management of children with ping-pong skull fractures may include observation, nonsurgical treatments, or surgical intervention depending on the age, clinical presentation, imaging findings, and cosmetic appearance of the patient. There have been 16 publications on nonsurgical treatment using negative pressure with various devices. Herein, the authors report their experience with vacuum-assisted elevation of ping-pong skull fractures and evaluate the variables affecting procedural outcomes.


The authors performed a retrospective chart review of all ping-pong skull fractures treated via vacuum-assisted elevation at the Children’s Hospital of Wisconsin between 2013 and 2017. Data collected included patient age, head circumference, mode of injury, time to presentation, imaging findings, procedural details, treatment outcomes, and complications.


Four neonates and 5 infants underwent vacuum-assisted elevation of moderate to severe ping-pong skull fractures during the study period. Modes of injury included birth-related trauma, falls, and blunt trauma. All patients had normal neurological examination findings and no evidence of intracranial hemorrhage. All fractures were deemed severe enough to require elevation by the treating neurosurgeon. All fractures involved the parietal bone. Skull depressions ranged from 23 to 62 mm in diameter and from 4 to 14 mm in depth. Bone thickness ranged from 0.6 to 1.8 mm. The time from fracture to intervention ranged from 7 hours to 8 days. The Kiwi OmniCup vacuum delivery system was used in all cases. Negative pressures were increased sequentially to a maximum of 500 mm Hg. A greater number of sequential vacuum applications was required for patients with a skull thickness greater than 1 mm at the site of depression and for those undergoing treatment more than 72 hours from fracture onset. Successful fracture elevation was attained in 7 of 9 patients. Two patients required subsequent surgical elevation of their fractures. Postprocedure imaging studies revealed no evidence of complications.


Increasing bone thickness and time from fracture onset to intervention appeared to be the greatest limiting factors to the successful elevation of moderate to severe ping-pong fractures via this vacuum-assisted approach. This procedure is a well-tolerated option that should be considered prior to performing an open repair in cases deemed to require fracture elevation. Future efforts will focus on larger-volume studies to better delineate inclusion and exclusion criteria, and volumetric analysis for better fracture-to-suction device customization.

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

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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.

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


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.


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).


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.


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


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


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.


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.