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Mark M. Souweidane

Object

Primary endoscopic procedures for children with intraventricular brain tumors include endoscopic tumor biopsy and endoscopic tumor removal. The simultaneous treatment of hydrocephalus with endoscopic third ventricu-lostomy (ETV) or endoscopic septostomy increases the appeal of a minimally invasive endoscopic approach.

Methods

Eighty-five patients who underwent endoscopic management of an intraventricular brain tumor were identified from a prospective database. Of these patients, 26 were younger than 21 years of age at the time of diagnosis. The surgical technique, its success rate, and patient outcome were assessed. Illustrative cases are used in this study to detail the procedure of endoscopic tumor biopsy and resection.

Endoscopic tumor procedures were successful in 96% of cases (23 of 24 endoscopic tumor biopsy samples and both endoscopic tumor removals). Fourteen simultaneous procedures were performed to treat hydrocephalus successfully. There was no recognized morbidity from the surgical procedures.

Conclusions

Endoscopic surgery in children with intraventricular brain tumors is an effective and safe method for sampling of the lesion and, in select cases, its resection. This minimally invasive technique should be considered in situations in which the patient might thereby avoid a more conventional procedure, given the high rate of success and low morbidity associated with endoscopic management.

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Maria M. Santos and Mark M. Souweidane

The authors report an illustrative case of a purely endoscopic surgical approach to successfully remove a solid choroid plexus papilloma of the third ventricle in an infant. A 10-week-old male infant first presented with transient episodes of forced downward gaze, divergent macrocephaly, a tense anterior fontanel, diastasis of the cranial sutures, and papilledema. Brain MRI revealed a small, multilobulated contrast-enhancing mass situated within the posterior third ventricle, with resultant obstructive hydrocephalus. A purely endoscopic removal of the tumor was performed through a single right frontal bur hole. Intraoperatively, a unique vascular tributary was recognized coming from the tela choroidea and was controlled with coagulation and sharp dissection. Postoperative MRI confirmed complete tumor removal, and the tumor was classified as a choroid plexus papilloma. There has been no evidence of tumor recurrence over 42 months of follow-up. With this case report the authors intended to show that endoscopic surgery can be an additional tool to consider when planning a choroid plexus tumor approach. It seems to be of particular interest in selected cases in which there are concerns about the patient's total blood volume, as in infants with potential hemorrhagic tumors and when it is possible to preoperatively identify a single vascular pedicle that can be approached early in the surgery.

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Konstantinos Margetis and Mark M. Souweidane

Endoscopic resection of colloid cyst in patients with normal-sized ventricular system is challenging, because the limited intraventricular space increases the risk of injuring eloquent nervous structures and critical blood vessels. The utilization of frameless stereotaxy and tissue shaving device facilitates the procedure. An important operative step is the ventricular insufflation that allows for an endoscope introduction without causing inadvertent injury to the caudate nucleus. The attached clip shows the basic operative steps of the procedure. In this clip the solid colloid cyst contents necessitated an en-block colloid cyst resection, in lieu of initially aspirating the cyst contents and subsequently removing the cyst walls.

The video can be found here: http://youtu.be/zzYYZEsd-uk.

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David I. Sandberg, Mark A. Edgar and Mark M. Souweidane

Object. Convection-enhanced delivery (CED) can be used safely to achieve high local infusate concentrations within the brain and spinal cord. The use of CED in the brainstem has not been previously reported and may offer an alternative method for treating diffuse pontine gliomas. In the present study the authors tested CED within the rat brainstem to assess its safety and establish distribution parameters.

Methods. Eighteen rats underwent stereotactic cannula placement into the pontine nucleus oralis without subsequent infusions. Twenty rats underwent stereotactic cannula placement followed by infusion of fluorescein isothiocyanate (FITC)—dextran at a constant rate (0.1 µl/minute) until various total volumes of infusion (Vis) were reached: 0.5, 1, 2, and 4 µl. Additional rats underwent FITC—dextran infusion (Vi 4 µl) and were observed for 48 hours (five animals) or 14 days (five animals). Serial (20-µm thick) brain sections were imaged using confocal microscopy with ultraviolet illumination, and the volume of distribution (Vd) was calculated using computer image analysis. Histological analysis was performed on adjacent sections.

No animal exhibited a postoperative neurological deficit, and there was no histological evidence of tissue disruption. The Vd increased linearly (range 15.4–55.8 mm3) along with increasing Vi, with statistically significant correlations for all groups that were compared (p < 0.022). The Vd/Vi ratio ranged from 14 to 30.9. The maximum cross-sectional area of fluorescence (range 9.8–20.9 mm2) and the craniocaudal extent of fluorescence (range 2.8–5.1 mm) increased with increasing Vi.

Conclusions. Convection-enhanced delivery can be safely applied to the rat brainstem with substantial and predictable Vds. This study provides the basis for investigating delivery of various candidate agents for the treatment of diffuse pontine gliomas.

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Martin Zonenshayn, Eugene Kronberg and Mark M. Souweidane

Object. The prevalence of deformational, or positional, plagiocephaly has increased during the last decade. Treatments vary among centers, ranging from expectant management to orthotic helmet therapy to craniofacial remodeling. This management variability is partially due to a lack of objective methods with which to measure the severity of plagiocephaly, as well as procedures that are not cumbersome or require radiographic studies. A simple and objective method of determining the degree of cranial deformation has been developed.

Methods. A headband placed around the head was marked with two adjustable points—one denoting the nasion and the other, the inion. A digital camera was used to image the head from a vertex view. The shape of the headband and the area of each hemisphere were then determined by analyzing the image on a personal computer in a semiautomated fashion. A cranial index of symmetry (CIS) was calculated and, by definition, equaled 100% for a perfectly symmetrical head. In this preliminary study, the authors studied eight children referred for evaluation of their plagiocephaly and eight infants referred for noncraniofacial entities.

In the unaffected infants the mean CIS was 96.3 ± 1.3% (± standard deviation). In children with clinical evidence of plagiocephaly, however, the CIS was 81.9 ± 3.4% (p < 0.001). Although the CIS in healthy children was never less than 95%, that in all infants with plagiocephaly was below 90%.

Conclusions. Although preliminary, this objective nonradiographic measurement of cranial symmetry appears to allow grading of the severity of positional plagiocephaly. The aforementioned methodology may potentially be used as an unbiased means of comparing different treatment modalities in longitudinal studies.

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Jeremy C. Wang, Linda Heier and Mark M. Souweidane

Object. Suprasellar arachnoid cysts present unique management problems. The authors retrospectively reviewed six cases, in which endoscopic ventriculocystocisternotomy was performed, to identify specific neuroimaging features that aid both the accurate diagnosis of this entity and the postoperative assessment of fenestration patency.

Methods. Six consecutive children underwent treatment for suprasellar arachnoid cysts. Consistent radiographic features in all cases were identified. Through a single entry site, endoscopic fenestration was performed at both the apical and basal cyst membranes. Outcome was assessed using clinical examination, quantitative changes in cyst size, and triplanar magnetic resonance (MR) imaging with flow-sensitive (long TR) sequences.

In every case, the suprasellar cysts displayed three diagnostic MR imaging features: 1) vertical displacement of the optic chiasm/tracts; 2) upward deflection of the rostral mesencephalon and mammillary bodies; and 3) effacement of the ventral pons. Two patients initially underwent placement of a ventriculoperitoneal shunt before the cysts were recognized, but MR images obtained after shunt placement revealed the cysts. In a mean follow-up period of 26.2 months, all patients improved clinically. Postoperative imaging revealed a mean cyst volume decrease of 52.7% and a return to more normal suprasellar and prepontine anatomy. Flow-sensitive MR imaging confirmed pulsation artifact at all 12 fenestration sites. There was no surgery-related death and no additional cerebrospinal fluid diversion procedure was required.

Conclusions. To aid in the accurate diagnosis of prepontine arachnoid cysts, the authors identified several pathognomonic features on sagittal MR images: vertical deflection of the optic chiasm and mammillary bodies, as well as pontine effacement. Dual endoscopic fenestration into the intraventricular compartment and basal cistern is safe, and it effectively provides symptomatic relief by decreasing the cyst size. Triplanar flow-sensitive MR imaging sequences can confirm fenestration patency without the need for cine-mode MR imaging.

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Neal Luther, Anders Cohen and Mark M. Souweidane

Object

Concern regarding the ability to accomplish adequate hemostasis during intracranial neuroendoscopy is often cited as a potential obstacle for primary endoscopic tumor management. In this study, the rate of clinically significant hemorrhage encountered as a result of endoscopic surgery for an intraventricular brain tumor is examined.

Methods

A total of 86 patients underwent an endoscopic biopsy procedure or resection of an intraventricular tumor. Recognized hemorrhagic sequelae occurred at a rate of 3.5% per patient. Visual obscuration due to the presence of intraventricular bleeding necessitated aborting the procedure before completion of the objective in two cases. There was a hemorrhagic event resulting in relevant morbidity in one patient, who suffered a bilateral diencephalic stroke after attempted tumor biopsy sampling.

Conclusions

The low hemorrhagic complication rate described in this series counters the misconception surrounding ineffective hemostasis during intracranial endoscopy for tumors and provides further evidence that this minimally invasive approach is a safe alternative to some conventional intracranial approaches.

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Assem M. Abdel Latif and Mark M. Souweidane

OBJECTIVE

Mineralized or desiccated colloid cysts pose some unique challenges to endoscopic removal. The extrusion of the solid matrix into the intraventricular compartment has not been previously reported and, as such, no guidance exists regarding its predilection, prevention, and fate.

METHODS

Postoperative imaging studies in a registry of patients undergoing endoscopic removal of colloid cyst were reviewed to detect any solid matrix within the ventricular compartment. Preoperative images and operative notes were used to determine if any features were predictive. Serial postoperative images and clinical notes were used to characterize the implications of these findings.

RESULTS

From a review of 94 patients, 10 (10.6%) patients had evidence of an extruded intraventricular solid fragment (median follow-up 4 months; range 0.5–115 months). Of the evaluable patients, 7 of 9 patients had T1-weighted hyperintense and T2-weighted hypointense cysts on preoperative scans. Seventy-eight percent of the extrusions were on the same side as the endoscopic entry. Three patients demonstrated early fragment migration, but not after 8 months of radiological follow-up. All evaluable patients demonstrated improvement in their hydrocephalus, and none suffered a complication attributable to the intraventricular extruded fragments.

CONCLUSIONS

Intraventricular extruded colloid fragments can occur after endoscopic resection, with the possible risk demonstrated as cyst hypointensity on preoperative T2-weighted images. The finding does not seem to result in any clinical morbidity, and radiographic involution is the rule. Migratory capacity, however, does exist and justifies a more frequent imaging surveillance schedule and consideration for removal.

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Jeffrey P. Greenfield and Mark M. Souweidane

Object

Endoscopic fenestration has been recognized as an accepted treatment choice for patients with symptomatic arachnoid cysts. The success of this procedure, however, is greatly influenced by individual cyst anatomy and location as well as the endoscopic technique used. This review was conducted to assess what variables influence the treatment success for different categories of arachnoid cysts.

Methods

Thirty-three consecutive patients who underwent endoscopic fenestration for treatment of an intracranial arachnoid cyst were identified from a prospective database. The surgical indications and techniques were reviewed, and surgical success rates and patient outcomes were assessed. Specific examples of each cyst category are included to illustrate the technical aspects of endoscopic cyst fenestration.

Endoscopic fenestration of arachnoid cysts was successful when judged by cyst decompression, and symptom resolution was noted in 32 (97%) of 33 cases. The one patient with short-term treatment failure underwent a successful repetition of the operation. There were no surgery-related morbidities or deaths.

Conclusions

Arachnoid cysts are a relatively benign pathological entity that can be managed by performing endoscopically guided cyst wall fenestrations into the ventricular system or cerebrospinal fluid–containing cisterns. Proper patient selection, preoperative planning of endoscope trajectory, use of frameless navigation, and advances in endoscope lens technology and light intensity combine to make this a safe procedure with excellent outcomes.

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Jothy Kandasamy and Mark Souweidane