Neuronavigated Ultrasound in Neuro-Oncology: A True Real-Time Intraoperative Image.

OBJECTIVE: Ultrasound is considered a real-time imaging method in neuro-oncology because of its highly rapid image acquisition time. However, to our knowledge, there are no studies that analyze the additional surgical time that it requires. METHODS: A prospective study of 100 patients who underwent intra-axial brain tumor resection with navigated intraoperative ultrasound. The primary outcomes were lesion visibility grade on ultrasound and concordance with preoperative magnetic resonance imaging (MRI) scan, intraoperative ultrasound usage time, and percentage of tumor resection on ultrasound and comparison with postoperative MRI scan. RESULTS: The breakdown of patients included the following: 53 high-grade gliomas, 26 metastases, 14 low-grade gliomas, and 7 others. Ninety-six percent of lesions were clearly visualized. The tumor border was clearly delimited in 71%. Concordance with preoperative MRI scan was 78% (P < 0.001). The mean time ± SD for sterile covering of the probe was 2.16 ± 0.5 minutes, and the mean image acquisition time was 2.49 ± 1.26 minutes. Insular tumor location, low-grade glioma, awake surgery, and recurrent tumor were statistically associated with an increased ultrasound usage time. Ultrasound had a sensitivity of 94.4% and a specificity of 100% for residual tumor detection. CONCLUSIONS: Neuronavigated ultrasound can be considered a truly real-time intraoperative imaging method because it does not increase surgical time significantly and provides optimal visualization of intra-axial brain lesions and residual tumor.

Middle Cranial Fossa Approach: Anatomical Study on Skull Base Triangles as a Landmark for a Safe Anterior Petrosectomy.

Objective The Kawase approach provides access to the petroclival and posterior cavernous sinus regions, cerebellopontine angle, and upper basilar artery territory. Nevertheless, it remains one of the most challenging approach for neurosurgeons, due to the considerable related morbidity and mortality. The goal of this study was to evaluate the relationship between anatomical landmarks and their possible variations, and to measure the extension of the Kawase space, to define the reliability of these landmarks while performing an anterior petrosectomy. Design Using eight cadaveric specimens (15 sides), an anatomical dissections and extradural exposure of the Kawase area were performed. Settings A two-step analysis of the distances between the mandibular branch of the trigeminal nerve (V3) and the structures at risk of iatrogenic damage was performed. Main outcome measures We measured the distance between V3 and the basal turn of the cochlea, and between V3 and the internal acoustic canal (IAC), analyzing the limits of bone resection without causing hearing damage. Results We analyzed eight cadaveric (15 sides) formalin-fixed heads injected with colored silicone: four males and four females of Caucasian race (mean age: 73.83 years). We found a mean distance of 10.46 ± 1.13 mm between the great superficial petrous nerve (GSPN) intersection with V3 and the basal turn of the cochlea, and of 11.92 ± 1.71 mm between the origin point of V3 from the Gasserian ganglion and the fundus of the IAC. Conclusion The knowledge of the safe distance between the most applicable anatomic landmarks and the hearing structures is a practical and useful method to perform this approach reducing related comorbidity.

Artery of Percheron and Endoscopic Endonasal Surgery: Case Report and Review of the Literature.

Artery of Percheron (AOP) is a rare anatomical variant in which a single perforating artery arising from the P1 segment of the posterior cerebral artery supplies paramedian thalami and rostral midbrain. The occlusion of AOP produces bilateral thalamic ischemia and may be a rare complication in relation to an extended endoscopic endonasal approach. We report the case of a patient who developed AOP damage during endoscopic endonasal surgery (EES); to our knowledge, this complication has been previously reported only in one case, in relation to a second surgery. We also review the anatomical variants in thalamic vascularization and the factors that may be involved in this complication. A 52-year-old female underwent an extended endoscopic endonasal approach with intraoperative neurophysiological monitoring. In the postoperative period, she presented with a decreased level of consciousness and bilateral mydriasis. Magnetic resonance imaging showed rostral midbrain and paramedian thalami ischemia congruent with AOP infarction. AOP infarction may be associated with extended EES when treating lesions with retrosellar extension. Every effort should be made to preserve the small perforating arteries. Intraoperative neurophysiological monitoring of the motor and sensory pathways may not detect damage to the AOP.

Intraoperative Use and Benefits of Tractography in Awake Surgery Patients.

OBJECTIVE: The present study analyzed the benefits of the use of tractography in the preoperative and intraoperative scenarios. METHODS: We present a prospective cohort study with 2 groups of patients who had undergone awake surgery for brain tumor resection. A control group for which no intraoperative navigated diffusion tensor imaging (DTI) was used (non-DTI group) and the case group (DTI group). The operative time, complete tumor resection, and neurological postoperative deficits were measured as primary outcomes. A secondary analysis was performed to determine the power of preoperative DTI to predict for complete tumor resection. RESULTS: A total of 37 patients were included, 18 in the non-DTI group and 19 in the DTI group. No differences were found between the 2 groups for sex, mean age, tumor histological findings, and preoperative mean tumor volume. The awake surgical time in the non-DTI group was 119.8 ± 31.1 minutes and 93.6 ± 12.2 minutes in the DTI group (P = 0.007). A trend was found toward complete tumor resection in the DTI group (P = 0.09). The sensitivity and specificity for predicting complete tumor resection were 88% and 62.5% for the non-DTI group and 100% and 80% for the DTI group, respectively. The area under the receiver operating characteristic curve was 0.720 in the non-DTI group and 0.966 in the DTI group (P = 0.041). CONCLUSIONS: Intraoperative navigated tractography shortened the time of awake neuro-oncological surgery and might provide help in performing complete tumor resection. Also, tractography used in the preoperative planning could be a useful tool for better prediction of complete tumor resection.