Gabriel Zada

Craniopharyngioma and other cystic epithelial lesions of the sellar region: a review of clinical, imaging, and histopathological relationships.

OBJECT Cystic epithelial masses of the sellar and parasellar region may be difficult to differentiate on a clinical, imaging, or even histopathological basis. The authors review the developmental relationships and differentiating features of various epithelial lesions of the sellar region. METHODS The authors performed a review of the literature to identify previous studies describing the etiological relationships and differentiating features of various cystic sellar lesions, including craniopharyngioma (CP), Rathke cleft cyst, xanthogranuloma, and dermoid and epidermoid cysts. RESULTS There is significant evidence in the literature to support a common ectodermal origin of selected sellar and suprasellar cystic lesions, which may account for the overlap of features and transitional states observed in some cases. Research obtained from animal studies and reports of transitional cystic epithelial masses or lesions crossing over from typical to more aggressive pathological subtypes have collectively provided a solid foundation for this theory. Histological features that signify transitional entities beyond simple benign Rathke cleft cysts include squamous metaplasia, stratified squamous epithelium, and ciliated or mucinous goblet cells in squamous-papillary CPs. Several studies have identified key clinical, imaging, and histopathological features that can be used in the differentiation of these lesions. CONCLUSIONS The pattern of embryological formation of the hypothalamic-pituitary axis plays a major role in its propensity for developing cystic epithelial lesions. Subsequent inflammatory, metaplastic, and neoplastic processes may promote further progression along the pathological continuum, ranging from benign epithelial cysts to aggressive neoplastic cystic CPs. Selected clinical, imaging, and histopathological features can be used collectively to help differentiate these lesions and assign a formal diagnosis, thus accurately guiding further treatment.

Changes in transcranial motor evoked potentials during intramedullary spinal cord tumor resection correlate with postoperative motor function.

OBJECTIVE:Intraoperative monitoring of transcranial motor evoked potentials (TcMEPs) has been investigated recently as a means of preventing motor deficits associated with resection of intramedullary spinal cord tumors (IMSCTs). In this study, we hypothesized that changes in the intraoperative MEPs during tumor resection correlate with postoperative motor function deficits. METHODS:A retrospective record review was conducted for 28 patients who underwent resection of an IMSCT using myogenic or muscle-recorded TcMEPs during a 44-month period. Intraoperative MEP recordings and results from preoperative, immediate postoperative, and subsequent follow-up neurological examinations were analyzed. RESULTS:Of the 28 patients who underwent resection of an IMSCT using TcMEPs, MEP changes occurred in 13 patients (46%). Impaired motor conduction was detected by changes in pattern and duration of the MEP waveform morphology (polyphasic to biphasic in 9 patients and polyphasic to biphasic to loss of MEP response in 5 patients, 1 patient demonstrated both changes) and by an increase in voltage threshold (median, 175 V; range, 100–225 V; n = 22 extremities). Alterations in morphology and reduction in duration of the MEP response persisted despite significant increases in stimulation voltage. In 12 patients, reductions in the complexity and/or loss of the TcMEP waveform correlated with motor grade loss in the immediate postoperative period (P < 0.0001), at discharge (P < 0.001), and at follow-up (P < 0.001). The decrease in the duration of the response correlated with motor grade loss immediately after surgery (P < 0.001), at discharge (P < 0.0001), and at follow-up (P < 0.005). CONCLUSION:These results support the application of distal muscle-recorded TcMEPs to predict the occurrence and severity of postoperative motor deficits during resection of IMSCTs. Attention to such quantitative intraoperative monitoring data may help to minimize postoperative motor deficits by avoiding or correcting excessive spinal cord manipulation and modifying surgical technique during tumor resection.

Intraoperative neurophysiological monitoring during spine surgery: a review.

Spinal surgery involves a wide spectrum of procedures during which the spinal cord, nerve roots, and key blood vessels are frequently placed at risk for injury. Neuromonitoring provides an opportunity to assess the functional integrity of susceptible neural elements during surgery. The methodology of obtaining and interpreting data from various neuromonitoring modalities-such as somatosensory evoked potentials, motor evoked potentials, spontaneous electromyography, and triggered electromyography-is reviewed in this report. Also discussed are the major benefits and limitations of each modality, as well as the strength of each alone and in combination with other modalities, with regard to its sensitivity, specificity, and overall value as a diagnostic tool. Finally, key clinical recommendations for the interpretation and step-wise decision-making process for intervention are discussed. Multimodality neuromonitoring relies on the strengths of different types of neurophysiological modalities to maximize the diagnostic efficacy in regard to sensitivity and specificity in the detection of impending neural injury. Thorough knowledge of the benefits and limitations of each modality helps in optimizing the diagnostic value of intraoperative monitoring during spinal procedures. As many spinal surgeries continue to evolve along a pathway of minimal invasiveness, it is quite likely that the value of neuromonitoring will only continue to become more prominent.

The neurosurgical anatomy of the sphenoid sinus and sellar floor in endoscopic transsphenoidal surgery

OBJECT A considerable degree of variability exists in the anatomy of the sphenoid sinus, sella turcica, and surrounding skull base structures. The authors aimed to characterize neuroimaging and intraoperative variations in the sagittal and coronal surgical anatomy of healthy controls and patients with sellar lesions. METHODS Magnetic resonance imaging studies obtained in 100 healthy adults and 78 patients with sellar lesions were reviewed. The following measurements were made on midline sagittal images: sellar face, sellar prominence, sellar angle, tuberculum sellae angle, sellar-clival angle, length of planum sphenoidale, and length of clivus. The septal configuration of the sphenoid sinus was classified as either simple or complex, according to the number of septa, their symmetry, and their morphological features. The following measurements were made on coronal images: maximum width of the sphenoid sinus and sellar face, and the distance between the parasellar and midclivus internal carotid arteries. Neuroimaging results were correlated with intraoperative findings during endoscopic transsphenoidal surgery. RESULTS Three sellar floor morphologies were defined in normal adults: prominent (sellar angle of < 90°) in 25%, curved (sellar angle 90-150°) in 63%, flat (sellar angle > 150°) in 11%, and no floor (conchal sphenoid) in 1%. In healthy adults, the following mean measurements were obtained: sellar face, 13.4 mm; sellar prominence, 3.0 mm; sellar angle, 112°; angle of tuberculum sellae, 112°; and sellar-clival angle, 117°. Compared with healthy adults, patients with sellar lesions were more likely to have prominent sellar types (43% vs 25%, p = 0.01), a more acute sellar angle (102° vs 112°, p = 0.03), a more prominent sellar floor (3.8 vs 3.0 mm, p < 0.005), and more acute tuberculum (105° vs 112°, p < 0.01) and sellar-clival (105° vs 117°, p < 0.003) angles. A flat sellar floor was more difficult to identify intraoperatively and more likely to require the use of a chisel or drill to expose (75% vs 25%, p = 0.01). A simple sphenoid sinus configuration (no septa, 1 vertical septum, or 2 symmetric vertical septa) was noted in 71% of studies, and the other 29% showed a complex configuration (2 or more asymmetrical septa, 3 or more septa of any kind, or the presence of a horizontal septum). Intraoperative correlation was more challenging in cases with complex sinus anatomy; the most reliable intraoperative midline markers were the vomer, superior sphenoid rostrum, and bilateral parasellar and clival carotid protuberances. CONCLUSIONS Preoperative assessment of neuroimaging studies is critical for characterizing the morphological characteristics of the sphenoid sinus, sellar floor, tuberculum sellae, and clivus. The flat sellar type identified in 11% of people) or a complex sphenoid sinus configuration (in 29% of people) may make intraoperative correlation substantially more challenging. An understanding of the regional anatomy and its variability can improve the safety and accuracy of transsphenoidal and extended endoscopic skull base approaches.

Endovascular management of spinal dural arteriovenous fistulas. A review.

OBJECT Spinal dural arteriovenous fistulas (DAVFs) are the most common spinal vascular malformations and can be a significant cause of myelopathy, yet remain inefficiently diagnosed lesions. Over the last several decades, the treatment of spinal DAVFs has improved tremendously due to improvements in neuroimaging, microsurgical, and endovascular techniques. The aim of this paper was to review the existing literature regarding the clinical characteristics, classification, and endovascular management of spinal DAVFs. METHODS A search of the PubMed database from the National Library of Medicine and reference lists of all relevant articles was conducted to identify all studies pertaining to spinal DAVFs, spinal dural fistulas, and spinal vascular malformations, with particular attention to endovascular management and outcomes. RESULTS The ability to definitively treat spinal DAVFs using endovascular embolization has significantly improved over the last several decades. Overall rates of definitive embolization of spinal DAVFs have ranged between 25 and 100%, depending in part on the embolic agent used and the use of variable stiffness microcatheters. The majority of recent studies in which N-butyl cyanoacrylate or other liquid embolic agents were used have reported success rates of 70-90%. Surgical treatment remains the definitive option in cases of failed embolization, repeated recanalization, or lesions not amenable to embolization. Clinical outcomes have been comparable to surgical treatment when the fistula and draining vein remain persistently occluded. Improvements in gait and motor function are more likely following successful treatment, whereas micturition symptoms are less likely to improve. CONCLUSIONS Endovascular embolization is an increasingly effective therapy in the treatment of spinal DAVFs, and can be used as a definitive intervention in the majority of patients that undergo modern endovascular intervention. A multidisciplinary approach to the treatment of these lesions is required, as surgery is required for refractory cases or those not amenable to embolization. Newer embolic agents, such as Onyx, hold significant promise for future therapy, yet long-term follow-up studies are required.

A review of selective hypothermia in the management of traumatic brain injury.

OBJECT Traumatic brain injury (TBI) remains a significant cause of morbidity and death in the US and worldwide. Resuscitative systemic hypothermia following TBI has been established as an effective neuroprotective treatment in multiple studies in animals and humans, although this intervention carries with it a significant risk profile as well. Selective, or preferential, methods of inducing cerebral hypothermia have taken precedence over the past few years in order to minimize systemic adverse effects. In this report, the authors explore the current methods available for inducing selective cerebral hypothermia following TBI and review the literature regarding the results of animal and human trials in which these methods have been implemented. METHODS A search of the PubMed archive (National Library of Medicine) and the reference lists of all relevant articles was conducted to identify all animal and human studies pertaining to the use of selective brain cooling, selective hypothermia, preferential hypothermia, or regional hypothermia following TBI. RESULTS Multiple methods of inducing selective cerebral hypothermia are currently in the experimental phases, including surface cooling, intranasal selective hypothermia, transarterial or transvenous endovascular cooling, extraluminal vascular cooling, and epidural cerebral cooling. CONCLUSIONS Several methods of conferring preferential neuroprotection via selective hypothermia currently are being tested. Class I prospective clinical trials are required to assess the safety and efficacy of these methods.

Indocyanine green fluorescence endoscopy for visual differentiation of pituitary tumor from surrounding structures

OBJECT As demonstrated by histological and neuroimaging studies, pituitary adenomas have a capillary vascular density that differs significantly from that of surrounding structures. The authors hypothesized that intraoperative indocyanine green (ICG) fluorescence endoscopy could be used to visually differentiate tumor from surrounding tissues, including normal pituitary gland and dura. METHODS After institutional review board approval, 16 patients undergoing endoscopic transsphenoidal surgery for benign pituitary lesions were prospectively enrolled in the study. A standard endoscopic endonasal approach to the sella was completed. Each patient then underwent endoscopic examination of the sellar dura and then the exposed pituitary adenoma after ICG bolus injection (12.5-25 mg). This examination was performed using a custom endoscope with a near-infrared light source and excitation wavelength filter. RESULTS The authors successfully recorded ICG fluorescence from sellar dura, pituitary, and surrounding structures in 12 of 16 patients enrolled. There were 3 technical failures of intraoperative ICG endoscopy, and 1 patient was excluded following discovery of a dye cross-allergy. A standard dose of 25 mg of ICG in 10 ml of aqueous solution optimized visualization of sellar region microvasculature within 45 seconds of peripheral bolus injection. Adenoma was less fluorescent than normal pituitary gland. Dural invasion by tumor was identifiable by a marked increase in fluorescence compared with native dura. The ICG endoscopic examination added 15-20 minutes of operative time under general anesthesia. There were no complications that resulted from use of ICG or the fluorescent light source. CONCLUSIONS Indocyanine green fluorescence endoscopy shows promise as an intraoperative modality to visually distinguish pituitary tumors from normal tissue and to visually identify areas of dural invasion, thereby facilitating complete tumor resection and minimizing injury to surrounding structures. These results support the continued development of fluorescence endoscopic resection techniques.

Incidence Trends in the Anatomic Location of Primary Malignant Brain Tumors in the United States: 1992–2006

BACKGROUND This study sought to determine incidence trends of the anatomical origin of primary malignant brain tumors. METHODS Incidence data for histologically confirmed brain tumors were obtained from the Los Angeles County Cancer Surveillance Program (LAC), the California Cancer Registry (CCR), and the National Cancer Institutes Surveillance, Epidemiology, and End Results (SEER) program for 1992 to 2006. Age-adjusted incidence rates (AAIR) and annual percent changes (APC) were calculated by histologic subtypes and anatomic subsites. Statistical analyses were performed using the SEER*Stat analytic software and SAS statistical software. RESULTS Increased AAIRs of frontal (APC +2.4% to +3.0%, P ≤ 0.001) and temporal (APC +1.3% to +2.3%, P ≤ 0.027) lobe glioblastoma multiforme (GBM) tumors were observed across all registries, accompanied by decreased AAIRs in overlapping region GBMs (-2.0% to -2.8% APC, P ≤ 0.015). The AAIRs of GBMs in the parietal and occipital lobes remained stable. The AAIR of cerebellar GBMs increased according to CCR (APC +11.9%, P < 0.001). The AAIR of all gliomas, which includes all anatomical subsites, decreased (-0.5% to -0.8% APC, P ≤ 0.034). Low-grade and anaplastic astrocytomas demonstrated decreased AAIRs in the majority of brain regions. CONCLUSIONS Data from 3 major cancer registries demonstrate increased incidences of GBMs in the frontal lobe, temporal lobe, and cerebellum, despite decreased incidences in other brain regions. Although this may represent an effect of diagnostic bias, the incidence of both large and small tumors increased in these regions. The cause of these observed trends is unknown.

Long-term outcomes and patterns of tumor progression after gamma knife radiosurgery for benign meningiomas.

OBJECTTo characterize the timing and patterns of long-term treatment failure after Gamma Knife radiosurgery (GKRS) for benign meningiomas. METHODSData were retrospectively reviewed in 116 patients who underwent 136 GKRS treatments for benign intracranial meningiomas from 1996 to 2004. Patients with atypical or malignant meningiomas were excluded. Surgical resection preceded GKRS in 72 patients (62%). The median tumor volume was 3.4 cm3, and the median prescription dose to the 50% isodose line was 16 Gy. RESULTSThe median follow-up time was 75 months (range, 4–146 months). Overall tumor control was achieved in 128 of 136 lesions (94%), of which tumor size was stable in 68% and decreased in 26%. Seven patients experienced disease progression in 8 tumors, occurring at a mean time of 90 months. The overall 5-year and 10-year actuarial tumor control rate was 98.9% and 84%, respectively. Characteristics corresponding to tumor progression included insufficient tumor coverage (98% vs 93%, P = .007), cavernous sinus lesions, and meningiomatosis. Complications after GKRS developed in 8% of patients, in whom the mean tumor volume was nearly double that in patients with no adverse effects (11 vs 5.7 cm3, P = .003). CONCLUSIONSGKRS demonstrates excellent long-term tumor control in the management of benign meningiomas. Tumor progression occurred at a mean time of 7.5 years after GKRS, reinforcing the need for long-term surveillance despite initial tumor control. Treatment failure was related to undercoverage of lesions in the majority of cases, with the remainder demonstrating evidence of abnormal tumor biology.

Rathke cleft cysts: a review of clinical and surgical management.

The aim of this paper is to provide a comprehensive review of clinical, imaging, and histopathological features, as well as operative and nonoperative management strategies in patients with Rathke cleft cysts (RCCs). A literature review was performed to identify previous articles that reported surgical and nonsurgical management of RCCs. Rathke cleft cysts are often incidental lesions found in the sellar and suprasellar regions and do not require surgical intervention in the majority of cases. In symptomatic RCCs, the typical clinical presentation includes headache, visual loss, and/or endocrine dysfunction. Visual field testing and endocrine laboratory studies may reveal more subtle deficiencies associated with RCCs. When indicated, the transsphenoidal approach typically offers the least invasive and safest method for treating these lesions. Various surgical strategies including cyst wall resection, intralesional alcohol injection, and sellar floor reconstruction are discussed. Although headache and visual symptoms frequently improve after surgical drainage of RCCs, hypopituitarism and diabetes insipidus are less likely to do so. A subset of more aggressive, atypical RCCs associated with pronounced clinical symptoms and higher recurrence rates is discussed, as well as the possible relationship of these lesions to craniopharyngiomas. Rathke cleft cysts are typically benign, asymptomatic lesions that can be monitored. In selected patients, transsphenoidal surgery provides excellent rates of improvement in clinical symptoms and long-term cyst resolution. Complete cyst wall resection, intraoperative alcohol cauterization, and sellar floor reconstruction in the absence of a CSF leak are not routinely recommended.