Georgios Zenonos

Gamma Knife surgery in the treatment paradigm for foramen magnum meningiomas

OBJECT Microsurgical management of foramen magnum meningiomas (FMMs) can be associated with significant morbidity and mortality. Stereotactic radiosurgery may be an efficient and safe alternative treatment modality for such tumors. The object of this study was to increase the documented experience with Gamma Knife surgery (GKS) for FMMs and to delineate its role in an overall management paradigm. METHODS The authors report on their experience with 24 patients harboring FMMs managed with GKS. Twelve patients had primary symptomatic tumors, 5 had asymptomatic but enlarging primary tumors, and 7 had recurrent or residual tumors after a prior surgery. RESULTS Follow-up clinical and imaging data were available in 21 patients at a median follow-up of 47 months (range 3-128 months). Ten patients had measurable tumor regression, which was defined as an overall volume reduction > 25%. Eleven patients had no further tumor growth. Two patients died as a result of advanced comorbidities before follow-up imaging. One patient was living 8 years after GKS but had no clinical evaluation. Ten of 17 symptomatic patients with at least 6 months of follow-up had symptom improvement, and 7 remained clinically stable. Smaller tumors were more likely to regress. No patient suffered an adverse radiation effect after radiosurgery. CONCLUSIONS Gamma Knife surgery was a safe management strategy for small, minimally symptomatic, or growing FMMs as well as for residual tumors following conservative microsurgical removal.

Carotid endarterectomy with primary closure: analysis of outcomes and review of the literature.

BACKGROUND Despite abundant published support of patch angioplasty during carotid endarterectomy (CEA), primary closure is still widely used. The reasons underlying the persistence of primary closure are not quite evident in the literature. OBJECTIVE To present our experience with primary closure in CEA, and provide a rationale for its persistent wide use. METHODS Medical records of all patients undergoing CEA by the senior author (R.F.) were retrospectively reviewed. Follow-up was supplemented with a telephone interview and completion of a structured questionnaire. A review of the current literature was performed. RESULTS From 1998 to 2010, the senior author performed 111 CEAs. Average cross-clamp time was 33 ± 11 minutes. Postoperative complications included 1 non-ST-elevation myocardial infarction and 2 strokes. No deaths, cranial-nerve deficits, or acute reocclusions were observed. After a mean follow-up of 64.6 months (7170.6 case-months), there were 3 contralateral strokes and 7 deaths. There were no ipsilateral strokes or restenoses >50%. Follow-up medication compliance was 94.6% for antiplatelet agents and 91.9% for statins. The outcomes of the current study were comparable to those of the available trials comparing patch angioplasty with primary closure. A careful evaluation of the literature revealed a number of reasons potentially explaining the persistent use of patch angioplasty. CONCLUSION In conjunction with contemporary medical management, primary closure during CEA may yield results comparable or superior to patch angioplasty. Advantages of primary closure include shorter cross-clamp times and elimination of graft-specific complications.

Predictors of functional outcome following treatment of posterior fossa arteriovenous malformations

Posterior fossa arteriovenous malformations (AVM) present particular therapeutic challenges. Studies aimed at clarifying risk of hemorrhage focus on obliteration rates, but few have addressed functional outcomes in these patients. In this study, we aim to explore the predictors of good functional outcome for posterior fossa AVM after treatment. A retrospective review of patients diagnosed with posterior fossa AVM at our institution from 1990 to 2013 was performed, and 61 patients met the inclusion criteria. Functional outcomes were assessed using the modified Rankin Scale (mRS), and mRS ⩽ 1 was defined as good outcome. Within our cohort, 39 patients presented with hemorrhage (64.0%). Spetzler-Martin grades were I (n = 9, 14.8%), II (n = 20, 32.8%), III (n = 22, 36.1%), IV (n = 8, 13.1%), and V (n = 2, 3.3%). Patients were treated with surgery (n = 8), radiosurgery (n = 34), embolization (n = 2) or multimodal therapies (n = 8). Nine patients did not undergo treatment. Average follow-up was 41.9 months. Obliteration of AVM was confirmed in 44.3% of patients (n = 27). Forty-three patients (70.5%) achieved good functional outcomes (mRS ⩽ 1). The absence of pre-treatment symptoms (p < 0.01) and AVM obliteration (p = 0.04) were predictive of good functional outcomes. In contrast, non-hemorrhagic presentation was not a significant predictor (p = 0.60). Asymptomatic presentation and AVM obliteration are associated with good functional outcomes in patients with posterior fossa AVM. Non-hemorrhagic presentation does not necessarily predict good functional outcome. Therefore treatment should not be considered only for those who present with hemorrhage. Posterior fossa AVM should be considered for definitive treatment in order to prevent future hemorrhages and subsequent poor functional outcomes.

High-Definition Fiber Tractography in the Evaluation and Surgical Planning of Lhermitte-Duclos Disease: A Case Report

BACKGROUND Preoperative delineation of normal tissue displacement patterns in Lhermitte-Duclos disease has not been feasible with conventional imaging means. Surgical resection of this type of lesion remains challenging, because the boundaries of the lesion are indistinguishable during surgery. CASE DESCRIPTION The clinical presentation, preoperative and postoperative magnetic resonance imaging (MRI) findings, high-definition fiber tractography (HDFT) and histopathological studies, are presented in a 46-year-old male subject with symptomatic Lhermitte-Duclos disease. HDFT was performed using a quantitative anisotropy-based generalized deterministic tracking algorithm to define fiber tracts. Displacement of the cerebellar and brainstem tracts on the affected side was performed using the unaffected contralateral side as a comparison. The displacement of the normal tissues was not apparent on preoperative MRI but was immediately evident on the preoperative HDFT. Of note, there was a relative paucity of fiber tracts within the lesion. By tailoring our operative boundaries based on the HDFT findings, we were able to spare the displaced fiber tracts when debulking the tumor. Restoration of normal fiber tract anatomy on postoperative HDFT imaging was correlated with clinical resolution of preoperative symptoms. CONCLUSIONS This case report suggests that HDFT may be a powerful surgical planning tool in cases of Lhermitte-Duclos disease, in which the pattern of normal tissue displacement is not evident with conventional imaging, allowing maximal lesion resection without damage to the unaffected tracts. Therefore, this report contributes to solving the greatest challenge when operating on this type of lesion, which has not been resolved in any previous report in our review of the English literature.

Endoscopic transnasal skull base surgery: pushing the boundaries

The endoscopic endonasal approach (EEA) has significantly evolved since its initial uses in pituitary and sinonasal surgery. The literature is filled with reports and case series demonstrating efficacy and advantages for the entire ventral skull base. With competence in ‘minimally invasive’ parasellar approaches, larger and more complex approaches were developed to utilize the endonasal corridor to create maximally invasive endoscopic skull base procedures. The challenges of these more complex endoscopic procedures include a long learning curve and navigating in a narrow corridor; reconstruction of defects presented new challenges and early experience revealed a significantly higher risk of cerebrospinal fluid leak. Despite these challenges, there are many benefits to the EEA including avoidance of brain and neurovascular retraction, improved visualization, a direct corridor onto many tumors and the two-surgeon approach. Most importantly, the EEA provides a midline corridor to directly access tumors, which displace critical neurovascular structures laterally, giving it an inherent advantage of minimizing any manipulation of these structures and thus decreasing their potential injury.

2-Hydroxy-Glutarate 3-Dimensional Functional Spectroscopy in the Evaluation of Isocitrate Dehydrogenase-Mutant Glioma Response to Therapy.

S omatic mutations of the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2, respectively) are found in approximately 80% of World Health Organization (WHO) grade II/III gliomas and secondary glioblastomas (WHO grade IV). These mutations result in overreduction of a-ketoglutarate to the putative oncometabolite 2-hydroxyglutarate (2HG). The accumulation of 2HG in cells is thought to play a key role in accelerating malignant transformation by promoting DNA hypermethylation, which in turn leads to genome-wide derangements in the epigenetic control of gene expression. Because IDH-mutant gliomas have been found to have a favorable overall prognosis compared with wild-type tumors, the accumulation of 2HG in tumor cells has been studied as a predictive biomarker of IDH-mutant tumors. Noninvasive detection of 2HG with magnetic resonance spectroscopy (MRS) has gone through multiple phases. Although initial studies focused on the diagnostic and prognostic values of 2HG, a more recent study suggests that this molecule could be used for early identification of response to treatment. Andronesi et al hypothesized that the decrease in 2HG levels as a result of antitumor therapy could be measureable by MRS. They performed a prospective longitudinal imaging study in 25 patients with IDH-mutant glioma receiving adjuvant radiation and chemotherapy. Using a newly developed 3-dimensional MRS imaging protocol, they were able to achieve optimal temporal stability and spatial coverage of 2HG quantification, overcoming many of the limitations related to the single-vortex or single-slice methods. More specifically, 3dimensional spectroscopy for 2HG has been shown to eliminate the sampling bias encountered in the other methods by taking into consideration the heterogeneity of the tumor. Next, Andronesi et al proposed functional spectroscopic maps as a metric to quantify spatiotemporal changes of metabolite levels. The changes in these maps were correlated to changes in the patients’ Karnofsky Performance Status during treatment. In addition, the 2HG functional spectroscopic map changes were compared against other imaging modalities for determining treatment response such as the Revised Assessment in Neuro-Oncology criteria, diffusion magnetic resonance imaging, or other spectroscopic indices. As hypothesized, even within 1 to 3 months after completion of therapy, the investigators found a significant decrease in the mean 2HG levels on posttreatment scans compared with pretreatment scans. Larger posttreatment decreases in the ratios of 2HG to creatinine were observed in lower-grade (WHO grades II/III) and smaller gliomas. Remarkably, significant changes were not observed in the same time frame in any of the other measured metabolites. This was true even for choline, a widely measured metabolite used as an index of tumor progression. The investigators therefore concluded that 2HG might actually be more sensitive to treatment effect than other metabolites in the early posttreatment period. In addition, this study established a significant correlation between the changes in 2HG levels and functional outcomes. More specifically, the fractional volume of decreased ratios of 2HG to creatinine significantly correlated with increases in the patients’ Karnofsky Performance Status. Accordingly, the investigators concluded that 2HG has the potential to serve as an objective end point to assess early response to treatment, which would be complementary to conventional clinical outcome criteria in IDH-mutant clinical trials. The findings described could also facilitate future clinical trials involving novel drugs targeting IDH-mutant gliomas (eg, selective R132H-IDH1 inhibitors and DNA demethylating agents). The study represents a valuable radiogenomic paradigm with promising future clinical applications. The small number of subjects harboring different grades of glioma, however, limits the generalizability of the conclusions. Future prospective studies recruiting more subjects with different histological types and for longer periods of time are necessary to validate these findings but also to further define the role 2HG spectroscopy as a surrogate of response to treatment.

Left Sylvian Fissure Epidermoid Cyst Presenting with Progressive Aphasia

INTRODUCTION Epidermoid cysts within the sylvian fissure are extremely rare. Expressive aphasia and neurocognitive dysfunction because of mass effect have never been reported previously. CASE PRESENTATION We discuss the case of a 53-year-old male who presented with an acute episode of expressive aphasia and vision changes along with progressive headaches and cognitive slowing over the 2.5 years prior to presentation. A detailed neurologic examination revealed subtle conductive aphasia, as well as mild short-term memory dysfunction. Magnetic resonance imaging revealed a cystic mass consistent with epidermoid cyst within the left sylvian fissure. High-definition fiber tractography showed that the arcuate fasciculus was stretched by the tumor. A left frontotemporal craniotomy allowed for near-total excision of the cyst and led to rapid and complete resolution of symptoms. CONCLUSION Although rare, epidermoid cysts of the dominant sylvian fissure can present with progressive aphasia due to mass effect on the arcuate fasciculus. Despite the long-standing symptoms, surgical resection can lead to their complete resolution.

Cardioversion-Responsive Ventriculoatrial Shunt Malfunction Precipitated by Atrial Fibrillation

BACKGROUND Ventriculoatrial shunts are common alternatives for patients who cannot tolerate ventriculoperitoneal shunts. The majority of ventriculoatrial shunt malfunctions are related to mechanical problems. We report an interesting case of ventriculoatrial shunt malfunction due to elevated central venous pressure from new-onset atrial fibrillation. METHODS After the patient was confirmed to have ventriculomegaly, he was taken to the operating room for exploration of his ventriculoatrial shunt; there were no obstructions. Subsequently, the patient was cardioverted to normal sinus rhythm for his new onset atrial fibrillation. RESULTS The clinical syndrome and ventriculomegaly both resolved after the patients atrial fibrillation was corrected with chemical cardioversion. CONCLUSIONS The cause of this patients VA shunt malfunction was likely associated with his new onset atrial fibrillation.

Infrasellar Endoscopic Endonasal Approach for a Pituitary Adenoma Extending into the Third Ventricle, with Anterior Displacement of the Pituitary Gland

Objectives The current video presents the nuances of the infrasellar endoscopic endonasal approach for a pituitary adenoma extending into the third ventricle, with anterior displacement of the pituitary gland. Design The video analyzes the presentation, preoperative workup and imaging, surgical steps and technical nuances of the surgery, the clinical outcome, and follow‐up imaging. Setting The patient was treated by a skull base team consisting of a neurosurgeon and an ENT surgeon at a teaching academic institution. Participants The case refers to 73‐year‐old female patient who was found to have a sellar mass after failure of vision to improve with cataract surgery. She also reported a several‐month history of progressive loss of vision along with daily retro‐orbital headaches. The adenoma extended into the clivus as well as in the retrosellar and suprasellar regions, eroding into the floor of the third ventricle. The normal gland was displaced anteriorly. Main Outcome Measures The main outcome measures consisted of reversal of patient symptoms (headaches and visual disturbance), recurrence‐free survival based on imaging, as well as absence of any complications. Results The patients headaches and visual fields improved. There was no evidence of recurrence. Conclusion The infrasellar endoscopic endonasal approach is safe and effective for pituitary adenomas extending into the third ventricle, with anterior displacement of the pituitary gland. The link to the video can be found at: https://youtu.be/zp_06mEyRvY.

Endoscopic Endonasal Transoculomotor Triangle Approach for the Resection of a Pituitary Adenoma with Ambient Cistern Extension

Objectives The current video presents the nuances of the endoscopic endonasal transoculomotor triangle approach for the resection of a pituitary adenoma with extension into the ambient cistern. Design The video analyzes the presentation, preoperative workup and imaging, surgical steps and technical nuances of the surgery, the clinical outcome, and follow‐up imaging. Setting The patient was treated by a skull base team consisting of a neurosurgeon and an ENT surgeon at a teaching academic institution. Participants The case refers to a 62‐year‐old female who presented with vision loss and headaches, and was found to have a pituitary adenoma with extension into the ambient cistern. Main Outcome Measures The main outcome measures consist of the reversal of the patient symptoms (headaches), the recurrence‐free survival based on imaging, as well as the absence of any complications. Results The patients headaches improved. There was no evidence of recurrence. Conclusions The endoscopic endonasal transoculomotor triangle approach is safe and effective for addressing pituitary tumors which extend into the ambient cistern. The link to the video can be found at: https://youtu.be/EBLwEWhohxY.