Indicators of a Reduced Intercarotid Artery Distance in Patients Undergoing Endoscopic Transsphenoidal Surgery.

Objective To identify clinicopathologic factors associated with a reduced intercarotid distance (ICD) and subgroups at risk for internal carotid artery injury during transsphenoidal surgery. Design A retrospective case-control study. Setting This study was conducted at the McGill University Health Centre, a university-affiliated tertiary care center. Participants Patients with a sellar or parasellar tumor and nontumor controls were included in the study. Main Outcome Measures The smallest distance between the internal carotid arteries at the clival, cavernous, and paraclinoid segments on coronal magnetic resonance imaging was measured. Demographic profiles, cephalometric measurements, tumor dimensions, and sphenoid configuration were assessed as potential determinants of the ICD. Results A total of 212 cases and 34 controls were analyzed. Widening of the ICD at the three segments of the internal carotid arteries was found in patients with pituitary macroadenomas (p < 0.01). Patients with a growth hormone-secreting adenoma had a markedly reduced ICD at the clivus compared with controls (1.59 cm versus 1.77 cm; p = 0.02; 95% confidence interval [CI], 0.03-0.32). The paraclinoid ICD was reduced in patients with an anterior fossa meningioma (1.24 cm versus 1.33 cm; p = 0.04; 95% CI, 0.01-0.45). Conclusion Identifying clinicopathologic factors affecting the ICD can help surgeons recognize constraints to endoscopic access of the skull base and avoid inadvertent arterial injury.

Supratentorial paraventricular schwannoma.

Intraventricular schwannoma in either infra or supratentorial location is an extremely rare tumor with less than 20 cases described in the literature to date. There is no consensus regarding the origin of this tumor. This paper describes an excised supratentorial schwannoma located on the wall of the left lateral ventricle. The relevant literature is reviewed. A 34-year-old man with no significant medical history presented with a recent episode of right focal motor seizures and weakness of the right lower extremity. Magnetic resonance imaging of the brain demonstrated a heterogeneous enhancing mass in the body of left lateral ventricle mass lesion with vasogenic edema in the adjacent brain parenchyma. The patient underwent a left frontoparietal parasagittal craniotomy with neuronavigational guidance to avoid damage to the primary motor cortex. The tumor originated from the ependymal layer and extended to the body of lateral ventricle. Complete surgical excision of the tumor was achieved. Intraventricular schwannomas are rare tumors amenable to complete surgical excision, having a good prognosis without the need for adjuvant therapy. The recognition of this benign and potentially curable neoplasm and its differentiation from other less favorable tumors is of obvious importance.

The lion's mane sign: surgical results using the bilateral fronto-orbito-nasal approach in large and giant anterior skull base meningiomas.

OBJECT: Concerns about extreme peritumoral edema and its ensuing surgical and perioperative complications led the authors to use the bilateral fronto-orbito-nasal approach to remove midline anterior skull base meningiomas that were larger than 4 cm. The authors hypothesize that extreme vasogenic edema exemplified by finger-like hyperintensities extending into the bifrontal white matter and external capsule and/or the extreme capsule, coined the lion's mane sign (LMS), would help identify patients with a challenging postoperative course. They hypothesize that the LMS would better predict symptomatic postoperative cerebral edema than the edema index (EI). METHODS: This is an observational case series of 9 patients. The authors noted the grade, pathology, tumor volume, EI, and the presence or absence of the LMS in all tumors. They used the intensive unit care (ICU) length of stay as a nonspecific measure reflecting postoperative symptomatic cerebral edema. Comparisons of edema-related postoperative complications and the EI were made between patients with and without an LMS. RESULTS: Bifrontal hyperintensities, extending into at least three-eighths of the length of the external capsules on T2-weighted MRI, seen in 4 of 9 patients, portended a longer postoperative ICU stay. The presence of an LMS better predicted postoperative complications related to cerebral edema than tumor grade, pathology, volume, or EI. CONCLUSIONS: The LMS predicts an increased duration of stay in the ICU after a bilateral fronto-orbito-nasal approach for resection of large and giant anterior skull base meningiomas. Furthermore, the LMS better predicted increased length of stay in the ICU than did the EI.

Pre- and postoperative magnetic resonance imaging appearance of the normal residual pituitary gland following macroadenoma resection: Clinical implications.

BACKGROUND: To assess the relationship between the preoperative magnetic resonance imaging (MRI) appearance of the normal residual pituitary gland (NRPG) and pituitary functional outcome following transsphenoidal resection of pituitary macroadenomas. METHODS: We retrospectively reviewed the medical records of 100 consecutive patients with a pituitary macroadenoma, who underwent transsphenoidal resection. The preoperative configuration of the displaced NRPG was stratified as superior, superolateral or lateral. The extent of postoperative restitution of the NRPG was divided into four groups: Group 1 - normal residual gland or almost normal; Group 2 - more than 50% restitution; Group 3 - less than 50% of the normal residual gland; and Group 4 - barely visible or absent residual gland. The pre- and postoperative NRPG appearance was correlated with pituitary functional status. RESULTS: Preoperatively, the NRPG was identifiable in 79 patients, with extrasellar displacement in 53%. The displacement pattern was superior in 8%, superolateral in 32%, and lateral in 58% of the patients. If the NRPG was displaced laterally, the ipsilateral cavernous sinus was not invaded by the pituitary macroadenoma. Partial or complete pituitary function was lost in 6 / 23 (26.1%) patients with superior or superolateral displacement of the NRPG, compared to only 1 / 36 (2.8%) patients without superior displacement of the NRPG (P = 0.025). Progressive postoperative reconstitution of the NRPG was related to the preservation of the pituitary hormonal axis (Pearson Chi-Square P < 0.001). CONCLUSIONS: Progressive displacement of the NRPG preoperatively, and lack of restitution of the NRPG on postoperative MRI appeared to correlate with the postoperative pituitary functional loss.

Experimental image-guided endoscopic pituitary surgery: a useful learning model.

OBJECTIVES: The purpose of this study, which combined image guidance and endocscopic pituitary surgery (EPS), was to test its practicability as a learning tool to acquire the necessary skills in an experimental setting. METHODS: Ten cadaver-heads were explored using a standard endoscopic transsphenoidal surgical technique combined with the InstaTrak 3500 (GE Medical Systems, Lawrence, MA, USA) image guidance system. The time taken for the experimental setup and the optic-radiologic correlations of topographic landmarks were recorded and photographed. RESULTS: The average time for setting up the system was 11.9 min+/-2.0, which included head fixation, headset positioning, registration, calibration and verification of the system. With the guidance of the navigation system, the ostium, sellar floor and adjacent structures encountered during EPS could be identified easily and were reflected on the 3D-CT images accurately. CONCLUSION: The experimental model validated the practicability of image guidance combined with EPS. The non-invasive interactive computer-assisted CT-guided navigational system facilitated the surgical procedure by providing precise spatial relationship between instrument position and adjacent structures. This combination is a useful teaching and learning tool in the cadaver and in patients will be useful, particularly for complex cases and redo-surgery.

Endoscopic pituitary surgery with and without image guidance: an experimental comparison.

BACKGROUND: The combination of image guidance and endoscopy is the newest trend in pituitary surgery. To assess the impact of image guidance on EPS, we measured and calculated the accuracy of the system and compared some critical surgical steps with and without image guidance under experimental conditions in terms of surgical time and precision. METHODS: Twenty cadaver heads were explored by standard endoscopic transsphenoidal surgical technique. Optic-radiologic correlations of topographic landmarks were photographed, and the system accuracy and actual visual accuracy were recorded. Some important anatomical parameters were measured in surgical field and on navigation system, and the differences were calculated and analyzed. Some critical surgical steps were recorded and compared between with and without image guidance. RESULTS: The system accuracy (root mean square), calculated by the computer automatically, showed a mean value of 0.28 +/- 0.06 mm. In some cases, there was a small discrepancy between the visible position of the pointer and its counterpart on the navigation system; we coined this actual visual accuracy. The average value was 1.53 +/- 0.49 mm. The maximum difference between the measurements from the navigation system and from their actual visual counterparts was less than 7%. With and without image guidance, in normal anatomical conditioning, there was no statistically significant difference between the duration of ostium sphenoidale exposure and sellar window creation; however, in anatomical variations, the surgical time was shown to be significantly shorter when navigation was used. CONCLUSION: We have demonstrated in this experimental setting that the electromagnetic tracking image guidance possesses a high accuracy at millimetric level and therefore provides precise localization and orientation in EPS. With the assistance of neuronavigation system, it is advantageous not only in saving operating time, but also, more importantly, in enhancing the orientation, thus, rendering surgeries safer and more efficient. During the in vivo pituitary surgery, EPS with image guidance can provide accurate and reliable stereoinformation to achieve better results with lesser risks, particularly in complex cases or in reoperations, even in the hands of experienced surgeons.

Vascular complications of vestibular schwannoma surgery: a comparison of the suboccipital retrosigmoid and translabyrinthine approaches.

OBJECT: Vascular complications of the surgery for vestibular schwannomas (VSs) can have devastating consequences; however, there is scant literature on the systematic analysis of the different types of complications. In this context, the authors of this study analyzed these complications, with particular interest in the role of surgical approach in their occurrence. METHODS: The charts of 391 patients who had undergone 413 procedures for VS during a 24-year period were reviewed retrospectively. A suboccipital retrosigmoid (RS) approach was used in 338 procedures, and the translabyrinthine (TL) route in 75. Postoperative hemorrhage or infarction was identified and stratified according to the complication type and surgical approach. Postoperative vascular complications were encountered in 11 procedures (2.7%), and their incidence was the same for both the RS and TL approaches. Of these complications, eight were hemorrhagic (two cerebellopontine angle, one intracerebellar, and five epidural hematomas) and three were ischemic in nature. Five patients (45.4%) had a complete recovery, and four patients (36.4%) a partial recovery; two patients (18.2%) died. The overall procedure-related mortality rate was 0.5% (two of 413 procedures): 0.3% (one of 338 procedures) for the RS approach and 1.3% (one of 75 procedures) for the TL approach (p > 0.05). CONCLUSIONS: In this study, the overall incidences of vascular complications in VS surgery were similar for the RS and TL approaches. Regardless of the preferred surgical route, this group of complications carries a significant risk of morbidity and therefore warrants special consideration in the management of VSs.

Endoscope-assisted image-guided approach to the pituitary gland: preliminary cadaveric study.

The microscopic transsphenoidal approach to the pituitary gland is the current standard technique used by neurosurgeons to operate the pituitary gland. The endoscopic transsphenoidal approach to the pituitary gland is a current trend because more neurosurgeons are becoming familiar with the use of endoscopes. The use of associated image-guided surgery (or surgical navigation technology; these names are equivalent and are used interchangeably) allows a precise approach that increases the safety and efficacy of a surgical procedure. The InstaTrack system (GE Medical Systems Navigation and Visualization, Inc., Lawrence, MA) is a frameless electromagnetic navigational system used in this study. The objectives of this preliminary and conceptual cadaveric study (three heads) are to get familiarized with the use of image guidance and the study of the endoscopic anatomy of this region and to investigate the technical requirements and benefits of possible future shifting from microscopic towards endoscopic image guidance.

Ligamentum flavum cysts causing incapacitating lumbar spinal stenosis.

BACKGROUND: Cysts of the ligamentum flavum are rare and unusual causes of spinal compression. METHODS: We report our experience of four cases of ligamentum flavum cysts occurring in the lumbar spine and discuss some of the possible etiologies and pathophysiologic mechanisms according to the available literature. CONCLUSION: This entity is clearly different from the synovial facet-joints or ganglion cysts.

Management of Rathke's cleft cysts.

BACKGROUND: Incidental diagnosis of Rathke's cleft cysts (RCCs) has increased due to the improvements in imaging techniques; however, symptomatic cases are rare and accurate preoperative diagnosis can be difficult. METHODS: Files and magnetic resonance imaging (MRI) of 10 surgically treated patients with RCC and 8 conservatively managed cases with a suspected diagnosis were reviewed retrospectively. Clinical, radiological, and histological features as well as intraoperative findings were scrutinized. RESULTS: In the surgical group, headache was present in 4 patients, hormonal abnormality in 4, visual deficits in 3, and otolaryngological symptoms in 2. Two of the nonsurgical cases had hyperprolactinemia, and the remaining were asymptomatic. The cyst had suprasellar extension (SSE) in 9 patients and was entirely suprasellar in 1 in the surgical group. It was purely intrasellar in 6 nonsurgical cases and had SSE in 2. The cyst content showed hyperintense MRI signal in the majority of T1 and T2 images in both groups. Transsphenoidal surgery was performed in 8 and transcranial surgery in 2 patients. Squamous metaplasia and inflammation was present in 3 cases each. Initial hormonal deficiencies did not improve postoperatively and new deficits were observed in 2 cases. There was no recurrence with an average follow-up of 32 months. CONCLUSIONS: Rathke's cleft cysts is a rare pathology with a wide spectrum of clinical and radiological features. Reactive inflammation of the normal pituitary gland may have a role in the pathogenesis of hormonal deficiency, in addition to compression. Preoperative recognition of the anteriorly displaced normal residual gland may be important in avoiding postoperative hormonal deficiency after transsphenoidal approach.

Preservation of hearing in patients undergoing microsurgery for vestibular schwannoma: degree of meatal filling.

OBJECT: Preservation of hearing has become a standard goal in selected patients undergoing surgery for a vestibular schwannoma (VS). This study was aimed at analyzing the role played by filling of the internal auditory canal (IAC) as well as those played by preoperative hearing quality, and tumor size in the postoperative preservation of serviceable hearing (SH). METHODS: Three hundred eighty-six patients with VS were treated. Hearing preservation was attempted in 128 cases (33.2%) by using intraoperative monitoring and following a retrosigmoid approach. The maximal extrameatal size of the tumor, its extension within the IAC, and pre- and postoperative hearing quality, according to the Gardner-Robertson classification, were evaluated. Preservation of SH was achieved in 24.2% of the 128 patients. With respect to tumor size, SH was preserved in 39% of 77 patients harboring a tumor 15 mm wide or smaller and in 2% of 51 patients with lesions 16 mm wide or larger (p < 0.001). With regard to filling of the IAC, among 63 patients harboring a tumor 15 mm or smaller, in whom magnetic resonance images were available, SH was preserved in 52.8% of 36 patients with partial filling and in 25.9% of 27 patients with complete filling (p = 0.032). Concerning preoperative hearing quality, in the patients with tumors 15 mm or smaller, SH was preserved in 46.5% of 43 patients with Gardner-Robertson Class I hearing and 29.4% of 34 patients with Class II hearing (p = 0.126). Both tumor size and the extent of IAC filling proved statistically significant in a multivariable analysis (p < 0.001 and p = 0.026, respectively). CONCLUSIONS: Incomplete filling of the IAC and a tumor size of 15 mm or smaller are independent favorable factors in SH preservation. Excellent preoperative hearing appears to have a positive impact but does not have statistical significance. Intraoperative monitoring is useful in guiding the dissection; however, the surgeon's knowledge of topographical landmarks and meticulous surgical technique remain the essential factors of success.

Distortion of normal pituitary structures in sellar pathologies on MRI.

OBJECTIVE: This study was undertaken to assess the displacement patterns and shifts of the normal pituitary gland in sellar pathologies on MRI and to determine if the position of the bright spot (BS) represents a predicting factor for the position of the residual adenohypophysis (RAH) in pathological conditions. METHODS: In a control group of 102 patients without any pituitary pathology, the presence of the BS was evaluated. In 100 patients with intra- or suprasellar pathologies, presence and respective topography of BS and RAH were scrutinized on MRI, according to lesion type, size, endocrine status and intra-operative findings in the surgical group. RESULTS: The BS was visible in 91.2% of 102 cases in the control group, as compared to 75 of the 100 patients with sellar lesions. Location of RAH was identified in 58% of the patients, and RAH enhanced more than the lesion in all cases after contrast infusion. The RAH was identified in 65.3% of the 75 "BS positive" patients, as compared to 36% of the 25 "BS negative". The normal residual gland was visualized intra-operatively in 63.5% of the 52 operated patients: in 37 "BS positive" patients, it was visualized intra-operatively in 81.1% and in 28 "RAH positive" patients, it was identified in 82.1%. CONCLUSIONS: The BS can be identified in the majority and RAH in more than half of the cases with pituitary lesions on MRI. Positions of both the BS and RAH help predict the location of the normal residual gland during surgery and, therefore, may contribute to preserving the pituitary function.

Metastatic hemangiopericytoma presenting as an epidural spinal cord lesion.

OBJECTIVE: Hemangiopericytoma is an aggressive vascular tumour that rarely affects the central nervous system and is even more rarely spinal in presentation. The clinical features of a patient with a recurrent extraspinal hemangiopericytoma presenting with an epidural spinal cord compression by local invasion are described, including a review of the literature on metastatic hemangiopericytoma to the spine. METHODS: A case of a 53-year-old male, with a recurrent extraspinal hemangiopericytoma which metastasized to the thoracic spine five years after detection of the primary tumour is presented. A chart review was conducted where all pertinent history, physical, laboratory, and radiological data were collected. A Pub-Med search using the keyword "hemangiopericytoma" identified all reported cases documenting clinical features, treatment, recurrence and outcome with respect to metastatic hemangiopericytoma to the spine. RESULTS: Nine patients have been reported to have metastatic hemangiopericytoma to the spine. The median patient age was 47 years and there was a slight male preference. An unusual feature of the hemangiopericytoma is the prolonged period, up to 16 years, between the diagnosis of the primary hemangiopericytoma and the metastases to the spine. All patients were treated with a combination of radiation and surgery. CONCLUSIONS: Hemangiopericytomas show a slow clinical evolution with a strong propensity to relapse long after previous treatment and thus, once identified, prolonged follow-up for recurrence is indicated. A close follow-up of these patients is required because of frequent recurrences and delayed metastases even if the primary lesion was well-controlled. Although overall uncommon, hemangiopericytoma should be kept in mind in the differential diagnosis of vascular epidural spinal cord tumours.

Ophthalmic artery originating from basilar artery: a rare variant.

The basilar artery as the origin of the ophthalmic artery is extremely rare. A 48-year-old patient had undergone angiography for suspicion of a right middle cerebral artery aneurysm. No aneurysm was detected. Vertebral artery injections demonstrated the left ophthalmic artery originating from the basilar trunk. Current embryologic theories fall short in explaining this entity. Awareness of neuroanatomic variations is of paramount importance in diagnosis and treatment of vascular lesions of the brain.

Intrasellar aneurysm and a growth hormone-secreting pituitary macroadenoma. Case report.

An aneurysm completely included within a pituitary adenoma that lies inside the sella turcica is rare and challenging from both a diagnostic and treatment viewpoint. A 39-year-old woman presented with symptoms and signs of acromegaly. Magnetic resonance imaging revealed a pituitary macroadenoma, which was associated with an intrasellar aneurysm. Digital subtraction angiography confirmed the presence of the cavernous carotid artery aneurysm. Complete endovascular obliteration of the aneurysm was achieved using Guglielmi Detachable Coils and the patency of the internal carotid artery was maintained. The pituitary adenoma was resected subtotally via a transsphenoidal microsurgical approach 8 months later. Preoperative detection of a coexisting intrasellar aneurysm in a patient with a pituitary adenoma is mandatory to avoid life-threatening hemorrhagic complications. Endovascular coil placement is an effective treatment option when performed before the transsphenoidal removal of the adenoma.

Distal mycotic aneurysm of the AICA mimicking intracanalicular acoustic neuroma.

BACKGROUND: Among cases of cerebellopontine angle lesions, vascular lesions involving the internal auditory canal are extremely rare. We report a distal fusiform mycotic pseudoaneurysm of the anterior inferior cerebellar artery (AICA) that simulated an acoustic neuroma on presentation. METHODS: A 60-year-old woman was investigated for recent onset of acute dizziness. Laboratory and radiographic investigations are presented, as well as the surgical management of the patient and pathological examination of the aneurysm. CONCLUSIONS: An exceptionally rare case of distal mycotic intracanalicular pseudoaneurysm of the AICA with intraluminal thrombus and fusiform anatomy is described. In our review of the literature (1966-present), only five other intracanalicular AICA-aneurysms were encountered, none of which were infectious in etiology. The possible pathophysiologic mechanisms of distal AICA-aneurysms are discussed along with the currently available literature.

Enhancing alkylating agent resistance through ERCC2 gene transfection in human glioma cell line.

OBJECTIVE: To confirm the enhancing effect of excision repair cross complementing rodent repair deficiency gene 2 (ERCC2) on alkylating agents resistance. METHODS: The authors constructed a pcDNA3-ERCC2 plasmid. The pcDNA3-ERCC2 was transfected into a selected ERCC2 negative human glioma cell line, SKMG-4, using liposome-mediated transfection. After G418 selection, a stable transfected cell line was obtained and tested for cytotoxicity of several alkylating agents. RESULTS: The stable transfectant was obtained and confirmed by RT-PCR as well as Western blot analysis to be strongly expressing ERCC2 at both mRNA and protein levels. The IC(90) ( micro mol/L) of two alkylating agents, cisplatin and melphalan, increased from 1.0 to 1.75 (75%) and 5.6 to 9.0 (61%), respectively, compared with control cell line. CONCLUSION: The present data provided evidences and confirmed the authors' previous results that ERCC2 contributes, at least partially, to alkylating agent resistance in human glioma cell line.

Role of computed tomographic cisternography in the management of cerebrospinal fluid rhinorrhea.

In a retrospective review of 13 patients, computed tomographic cisternography (CTC) was the primary imaging modality used for the detection of cerebrospinal fluid (CSF) leaks. In five of the cases, the diagnosis of CSF rhinorrhea was confirmed by the beta2-transferrin test. In the remaining cases, it was corroborated through endoscopic visualization, clinical history, and nuclear scanning. This study analyzes the efficacy of CTC in the detection of CSF leaks and discusses the different methods of computerized manipulation and reconstruction of the images for effective site localization. The study demonstrates that computerized reconstruction of images should be considered an integral part of CTC because it appears to be an inexpensive and simple diagnostic tool that improves on the accuracy of detection. Although T2-weighted magnetic resonance imaging may be helpful, this study emphasizes the efficacy of CTC in the diagnosis of CSF leaks. Using the techniques of image reconstruction improves on diagnostic precision with relatively little increase in cost, time, and labour. This study also introduces a diagnostic algorithm for otolaryngologists dealing with the challenge of identifying and locating CSF leaks.