Intracranial Phosphaturic Mesenchymal Tumors: A Systematic Literature Review of a Rare Entity.

BACKGROUND: Phosphaturic Mesenchymal Tumors (PMTs) are rare mesenchymal neoplasms known for producing Tumor-induced Osteomalacia (TIO). TIO is an uncommon paraneoplastic syndrome characterized by radiographic evidence of inadequate bone mineralization and analytical abnormalites. METHODS: We sought to present a case of TIO caused by skull base PMT with intracranial extension, manifesting with pain, progressive weakness, and multiple bone fractures. Furthermore, a systematic review was performed, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. A search was conducted in PubMed database with title/abstract keywords "Phosphaturic mesenchymal tumor" and "Osteomalacia." Search results were reviewed looking for intracranial or skull base tumors. RESULTS: Our systematic review included 29 reported cases of intracranial PMT. In the reviewed cases there was a significative female predominance with 22 cases (75,86%). Osteomalacia was presented in 25 cases (86,20%). Bone fractures were present in 10 cases (34,48%). The most common site of involvement was the anterior cranial fossa in 14 cases (48,27%). Surgery was performed in 27 cases (93,10%) with previous tumor embolization in 4 cases (13,79%). Total recovery of the presenting symptoms in the first year was achieved in 21 cases (72,41%). Recurrence of the disease was described in 6 cases (25%). CONCLUSIONS: Skull base PMTs with intracranial extension are extremely rare tumors. Most patients are middle-aged adults with a PMT predominantly located in anterior cranial fossa. Surgery is the current treatment of choice with optimal outcome at 1-year follow-up, although recurrence could be present in almost 25% of the cases.

Anticipating Facial Nerve Position Using Three-Dimensional Tractography During the Preoperative Assessment of Cerebellopontine Angle Tumors.

OBJECTIVE: We aim to evaluate the usefulness of preoperative facial nerve tractography in determining the facial nerve position in cerebellopontine angle tumor resection and its value in helping to preserve facial nerve function during surgery. METHODS: A prospective study was designed to include patients presenting with cerebellopontine angle tumors. Three-dimensional reconstruction of facial nerve tractography was performed and added to the usual preoperative testing in all patients. Facial nerve position was compared between tractography results and surgical findings. Moreover, facial nerve function was evaluated at baseline and during follow-up. RESULTS: Fifteen patients were included for analysis. Complete resection was obtained in 5 patients, near-total resection was achieved in 8 patients, and partial resection in 2 patients. We found a strong statistically significant concordance between the preoperative facial nerve tractography reconstruction and the intraoperative findings (complete concordance in 86.66% of all the cases; κ = 0.784; P < 0.0001). Facial nerve anatomic structure was preserved in all patients during surgery. At 6 months follow-up, 66.66% of patients had a facial nerve normal function or a mild dysfunction. CONCLUSIONS: Preoperative facial nerve tractography reconstruction showed a high correlation with intraoperative findings. Preoperative tractography information regarding facial nerve position and its cisternal course is valuable information and could help the surgeon in increasing the safety of the procedure during cerebellopontine angle tumor surgery.

Endovascular assisted vertebrobasilar junction aneurysm clipping in a hybrid operation room. Case report.

Introduction: We present a case of a 60-year-old female that underwent surgery for clipping a right vertebrobasilar junction aneurysm (VBJA) in a hybrid operation room. Research question: Does the retrograde suction technique with a proximal balloon is safe and effective as an adjuvant technique in surgery of VBJA? Material and methods: After an extended retrosigmoid approach was performed, a 6F Neuron catheter with an intermediate multipurpose catheter were navigated to the right vertebral artery (VA) through a 6-French sheath, which caused a severe catheter-induced vasospasm in the right VA. The aneurysm was then deflated and clipped. After the withdrawal of the catheter the vasospasm was resolved. Results: The patient had a good recovery, with VI cranial nerve palsy and mild dysphagia due to mild right vocal cord palsy, both improving at 1-month follow-up and fully recovered at 6-month follow-up. Discussion and conclusion: The combination of endovascular procedures and microsurgery at the same hybrid operation room in that case resulted in a safe and effective technique. It is an interesting tool that could help neurosurgeons deal with certain selected cases of VBJA. Intraoperative angiography offers the possibility to reposition a misplaced clip in the same surgery. Good collaboration between interventional neuroradiologists and vascular neurosurgeons helps in achieving good results in such difficult cases.

Inferior fronto-occipital fascicle displacement in temporoinsular gliomas using diffusion tensor imaging.

BACKGROUND AND PURPOSE: Brain tumors can result in displacement or destruction of important white matter tracts such as the inferior fronto-occipital fascicle (IFOF). Diffusion tensor imaging (DTI) can assess the extent of this effect and potentially provide neurosurgeons with an accurate map to guide tumor resection; analyze IFOF displacement patterns in temporoinsular gliomas based on tumor grading and topography in the temporal lobe; and assess whether these patterns follow a predictable pattern, to assist in maximal tumor resection while preserving IFOF function. METHODS: Thirty-four patients with temporal gliomas and available presurgical MRI were recruited. Twenty-two had insula infiltration. DTI deterministic region of interest (ROI)-based tractography was performed using commercial software. Tumor topographic imaging characteristics analyzed were as follows: location in the temporal lobe and extent of extratemporal involvement. Qualitative tractographic data obtained from directional DTI color maps included type of involvement (displaced/edematous-infiltrated/destroyed) and displacement direction. Quantitative tractographic data of ipsi- and contralateral IFOF included whole tract volume, fractional anisotropy, and fractional anisotropy of a 2-dimensional coronal ROI on the tract at the point of maximum tumor involvement. RESULTS: The most common tract involvement pattern was edematous/infiltrative displacement. Displacement patterns depended on main tumor location in the temporal lobe and presence of insular involvement. All tumors showed superior displacement pattern. In lateral tumors, displacement tendency was medial. In medial tumors, displacement tendency was lateral. When we add insular involvement, the tendency was more medial displacement. A qualitative and quantitative assessment supported these results. CONCLUSIONS: IFOF displacement patterns are reproducible and suitable for temporoinsular gliomas presurgical planning.

Endoscopic Transanterior Middle Temporal Approach to the Atrium-An Anatomical Feasibility Study.

OBJECTIVE: The atrium is the most common location for masses in the lateral ventricle. However, access to this area is limited owing to its deep location and adjacent eloquent neurovascular structures, such as the choroidal arteries, perisylvian white matter (WM) tracts, and optic radiations. We investigated the feasibility and safety of an endoscopic approach to the atrium via the anterior middle temporal gyrus (MTG). METHODS: Radiological assessment of a minimally invasive surgical trajectory to the atrium was achieved in 10 patients. Surgical simulation to assess the feasibility of our endoscopic approach was performed on 24 cadaveric specimens using a transzygomatic corridor and temporal craniotomy. Preoperative computed tomography was performed to confirm the surgical trajectory using neuronavigation. Using Klinger's method, 5 hemispheres were dissected to assess the relationship of our approach to the WM tracts. RESULTS: The optimal entry angle to reach the atrium through the anterior MTG was related to the temporal horn in the axial plane and to the Sylvian fissure in the sagittal plane. Our entry point in the anterior MTG was 19 ± 1.92 mm from the temporal pole. The transparenchymal distance to atrium was 24.55 ± 4.3 mm. The WM dissections confirmed that our approach did not violate the optic radiations, uncinate fasciculus, inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, or superior longitudinal fasciculus. CONCLUSION: Our findings have confirmed the feasibility of an anterior endoscopic approach to the atrium through the anterior MTG, with preservation of the functional integrity of the eloquent cortex and WM tracts.

Treatment of cavernous malformations in supratentorial eloquent areas: experience after 10 years of patient-tailored surgical protocol.

BACKGROUND: Eloquent area surgery has become safer with the development of intraoperative neurophysiological monitoring and brain mapping techniques. However, the usefulness of intraoperative electric brain stimulation techniques applied to the management and surgical treatment of cavernous malformations in supratentorial eloquent areas is still not proven. With this study, we aim to describe our experience with the use of a tailored functional approach to treat cavernous malformations in supratentorial eloquent areas. METHODS: Twenty patients harboring cavernous malformations located in supratentorial eloquent areas were surgically treated. Individualized functional approach, using intraoperative brain mapping and/or neurophysiological monitoring, was utilized in each case. Eleven patients underwent surgery under awake conditions; meanwhile, nine patients underwent asleep surgery. RESULTS: Total resection was achieved in 19 cases (95%). In one patient, the resection was not possible due to high motor functional parenchyma surrounding the lesion tested by direct cortical stimulation. Ten (50%) patients presented transient neurological worsening. All of them achieved total neurological recovery within the first year of follow-up. Among the patients who presented seizures, 85% achieved seizure-free status during follow-up. No major complications occurred. CONCLUSIONS: Intraoperative electric brain stimulation techniques applied by a trained multidisciplinary team provide a valuable aid for the treatment of certain cavernous malformations. Our results suggest that tailored functional approach could help surgeons in adapting surgical strategies to prevent patients' permanent neurological damage.

Radiologic Predictors for Extent of Resection in Pituitary Adenoma Surgery. A Single-Center Study.

BACKGROUND: Preoperative radiologic evaluation of pituitary adenomas is essential. Despite the efforts made to determine the achieved resection grade after pituitary adenoma surgery, there is a high level of disagreement among all the available classifications and measurement methods used. Our study aimed to determine pituitary adenoma imaging features, easily obtained from preoperative magnetic resonance, which could be used as resection predictor variables. Second, we analyzed the usefulness of the ellipsoid method in pituitary adenoma volume determination. METHODS: Two-hundred and ninety-four pituitary adenomas, which were surgically treated in our department, were retrospectively analyzed. Age, gender, surgical approach, hormonal status, greater tumor diameter, volume, cavernous sinus invasion, and extent of resection were evaluated. RESULTS: One-hundred and forty-eight surgical procedures were conducted with a microsurgical transsphenoidal approach whereas 146 were conducted with an endoscopic endonasal approach. Gross total resection was achieved in 54.08% of cases. There were no significant differences in the extent of resection regarding the approach used, age, gender, or hormonal production by the tumor. Only Knosp grade (P < 0.001) and tumor volume (P < 0.05) had a statistically and independent significant relationship with the extent of resection. Furthermore, we found a high correlation between the calculated volume, using the ellipsoid method, and the volume measurement obtained with complex planimetry methods. CONCLUSIONS: Pituitary adenoma volume and cavernous sinus invasion, graded with the Knosp scale, are 2 pituitary tumor features that, when used in combination, predict the complexity of the surgery and the difficulty of achieving gross total resection in pituitary adenoma surgery.

Functional approach using intraoperative brain mapping and neurophysiological monitoring for the surgical treatment of brain metastases in the central region.

OBJECTIVE Brain metastases are the most frequent intracranial malignant tumor in adults. Surgical intervention for metastases in eloquent areas remains controversial and challenging. Even when metastases are not infiltrating intra-parenchymal tumors, eloquent areas can be affected. Therefore, this study aimed to describe the role of a functional guided approach for the resection of brain metastases in the central region. METHODS Thirty-three patients (19 men and 14 women) with perirolandic metastases who were treated at the authors' institution were reviewed. All participants underwent resection using a functional guided approach, which consisted of using intraoperative brain mapping and/or neurophysiological monitoring to aid in the resection, depending on the functionality of the brain parenchyma surrounding each metastasis. Motor and sensory functions were monitored in all patients, and supplementary motor and language area functions were assessed in 5 and 4 patients, respectively. Clinical data were analyzed at presentation, discharge, and the 6-month follow-up. RESULTS The most frequent presenting symptom was seizure, followed by paresis. Gross-total removal of the metastasis was achieved in 31 patients (93.9%). There were 6 deaths during the follow-up period. After the removal of the metastasis, 6 patients (18.2%) presented with transient neurological worsening, of whom 4 had worsening of motor function impairment and 2 had acquired new sensory disturbances. Total recovery was achieved before the 3rd month of follow-up in all cases. Excluding those patients who died due to the progression of systemic illness, 88.9% of patients had a Karnofsky Performance Scale score greater than 80% at the 6-month follow-up. The mean survival time was 24.4 months after surgery. CONCLUSIONS The implementation of intraoperative electrical brain stimulation techniques in the resection of central region metastases may improve surgical planning and resection and may spare eloquent areas. This approach also facilitates maximal resection in these and other critical functional areas, thereby helping to avoid new postoperative neurological deficits. Avoiding permanent neurological deficits is critical for a good quality of life, especially in patients with a life expectancy of over a year.

Assessment of the Endoscopic Endonasal Transclival Approach for Surgical Clipping of Anterior Pontine Anterior-Inferior Cerebellar Artery Aneurysms.

OBJECTIVE: Aneurysms of the anterior pontine segment of the anterior-inferior cerebellar artery (AICA) are uncommon. Their treatment is challenging because critical neurovascular structures are adjacent to it and the available surgical corridors are narrow and deep. Although endoscopic endonasal approaches are accepted for treating midline skull base lesions, their role in the treatment vascular lesions remains undefined. The present study is aimed to assess the anatomic feasibility of the endoscopic endonasal transclival (EET) approach for treating anterior pontine AICA aneurysms and compare it with the subtemporal anterior transpetrosal (SAT) approach. METHODS: Twelve cadaveric specimens were prepared for surgical simulation. The AICAs were exposed using both EET and SAT approaches. Surgical window area and the length of the exposed artery were measured. The distance from the origin of the artery to the clip applied for proximal control was measured. The number of AICA perforators exposed and the anatomic features of each AICA were recorded. RESULTS: The EET approach provided a wider surgical window area compared with the SAT (P < 0.001). More AICA perforators were visualized using the EET approach (P < 0.05). To obtain proximal control of the AICA, an aneurysm clip could be applied closer to the origin of AICA using EET (0.2 ± 0.42 mm) compared with SAT (6.26 ± 3.4 mm) (P < 0.001). CONCLUSION: Clipping anterior pontine AICA aneurysms using the EET approach is feasible. Compared with SAT, the EET approach provides advantages in surgical window area, ensuring proximal control before aneurysm dissection, visualization of perforating branches, and better proximal control.