Identification Of Cranial Nerves Research Articles

The Extra-Extended Translabyrinthine Approach for Resection of Large Acoustic Neuroma: 2-Dimensional Operative Video.

The extended translabyrinthine approach to acoustic neuroma (AN) was created to allow improved visualization and access to larger tumors.1,2 The dural opening, however, remained confined to the presigmoid space. Other authors have introduced modifications to increase the dura exposure around the internal auditory canal (IAC).3-5 The extra-extended translabyrinthine approach was conceptualized by the senior author (CC) to maximize AN exposure and early cranial nerve identification. The tentorial peeling was added to allow extradural mobilization of the temporal lobe.6 This allows further safe bone removal around the IAC and petrous apex and consistent opening of the facial canal at IAC fundus. This modification creates 280-to-360-degree dura exposure at the IAC. The dural opening extends to the petrous apex superiorly and the prepontine arachnoid cistern inferiorly and includes resection of a tentorium dural flap created by the tentorial peeling.6 This exposure allows for near circumferential exposure of the tumor and early identification of the glossopharyngeal nerve in the cochlear aqueduct area, the trigeminal nerve at the porus trigeminal, and the facial nerve (FN) at IAC fundus. In addition, this ample exposure permits identification of the FN trajectory in the tumor capsule before any tumor dissection. We present a detailed video of extra-extended translabyrinthine approach technique in a patient with a large left AN (Hannover classification T4B).7 This video does not involve any human research projects not requiring Institutional Review Board/ethic committee approval. The patient consented to the procedure and to the publication of his image. Complete resection was obtained. The FN function was House-Brackman I/VI.

MRI sequence optimisation methods to identify cranial nerve course for radiotherapy planning.

Magnetic resonance imaging (MRI) is being increasingly used to improve radiation therapy planning by allowing visualisation of organs at risk that cannot be well-defined on computed tomography (CT). Diagnostic sequences are increasingly being adapted for radiation therapy planning, such as the use of heavily T2-weighted 3D SPACE (Sampling Perfection with Application optimised Contrasts using different flip angle Evolution) sequence for cranial nerve identification in head and neck tumour treatment planning. A 3D isotropic T2 SPACE sequence used for cranial nerve identification was adapted for radiation therapy purposes. Distortion was minimised using a spin-echo-based sequence, 3D distortion correction, isocentre scanning and an increased readout bandwidth. Radiation therapy positioning was accounted for by utilising two small flex, 4-channel coils. The protocol was validated for cranial nerve identification in clinical applications and distortion minimisation using an MRI QA phantom. Normal anatomy of the cranial nerves CI-CIX, were presented, along with a selection of clinical applications and abnormal anatomy. The usefulness of cranial nerve identification is discussed for several case studies, particularly in proximity to tumours extending into the base of skull region. In-house testing validated that higher bandwidths of 600 Hz resulted in minimal displacement well below 1 mm. The use of MRI for radiation therapy planning allows for greater individualisation and prediction of patient outcomes. Dose reduction to cranial nerves can decrease late side effects such as cranial neuropathy. In addition to current applications, future directions include further applications of this technology for radiation therapy treatments.

Trigger electromyography in endoscopic transnasal surgery of skull base tumors

Introduction . The development of minimally invasive technologies in recent decades has expanded the indications for the use of endoscopic transnasal transsphenoidal approaches in surgery of skull base tumors. It became possible to perform surgical interventions aimed at removing tumors of the base of the skull that spread to the area of the passage of cranial nerves (cavernous sinus, clival area, cerebello-pontine angle), which is associated with the risk of damage to certain cranial nerves. The study objective is to evaluate the effectiveness of trigger electromyography in providing anatomical and functional preservation of cranial nerves during endoscopic endonasal transsphenoidal removal of skull base tumors. Materials and methods . The study is based on statistical analysis and comparison of the results of surgical treatment of two groups of patients with various tumors of the base of the skull: the main group (30 patients with using trigger electromyography to identify cranial nerves intraoperatively) and the control group (43 patients without using this method). The effectiveness and safety of using the method of intraoperative identification of cranial nerves was evaluated based on a comparison of basic characteristics, treatment outcomes, and factors potentially affecting them. Results . Fifty-seven (57) cranial nerves were identified intraoperatively in the main group. The frequency of radical removal was 1.6 times higher in the main group (70 % vs 44.2 %, p = 0.03). When analyzing the dynamics of the state of motor cranial nerves after surgery in the main and control groups, it was shown that negative dynamics prevailed in the control group — 37.2 % vs 13.3 % (p = 0.03), and positive dynamics prevailed in the main group (37.3 % vs 13.9 %), 2.8 times (p = 0.08). Conclusion . The obtained data indicate that the use of the intraoperative identification method in endoscopic transnasal surgery of skull base tumors can positively affect the radical removal of tumors and the preservation of cranial nerve function in the postoperative period.

Триггерная электромиография в эндоскопической трансназальной хирургии опухолей основания черепа

Preserving anatomical integrity and functions of cranial nerves when removing skull base tumors is one of the significant problems of endoscopic endonasal surgery. For this purpose, it is possible to use intraoperative mapping and cranial nerves identification. The aim of the study was to evaluatе the effectiveness of trigger electromyography (T-EMG) used to prevent iatrogenic damage to the cranial nerves intraoperatively. Twenty-one patients with different skull base tumors were included in the study. Mapping and identification of cranial nerves were carried out during tumor excision, using endoscopic endonasal access. Surgeries were performed on large skull-based chordomas, neuromas of the trigeminal nerve in the cavernous sinus region, pituitary adenomas, meningiomas in the clivus and a skull-based cholesteatoma. Mapping and identification of cranial nerves were carried out using electromyography in trigger mode using bipolar and monopolar electrodes. Functional activity of cranial nerves was evaluated both before and after the operation. The effectiveness of the technique was compared with that of the control group (41 patients). In the course of surgical interventions using T-EMG in the main group of patients, 40 nerves were analyzed. In the course of the study, III, V, VI, VII, XII cranial nerves were identified intraoperatively. In 4 patients in the main group and in 13 patients in the control group, a postoperative deficit of cranial nerves was observed. We did not receive statistically reliable data that the intraoperative identification of cranial nerves using T-EMG reduces the frequency of postoperative complications in the form of a deficiency of cranial nerves (p=0.11), but the ratio of chances (0.26) testifies in favor of rarely occurring complications in main group. Trigger electromyography allows us to estimate the functional state of the cranial nerves during endoscopic endonasal operations. The method of using T-EMG is promising and requires further research.

Cranial nerve monitoring in endoscopic endonasal surgery of skull base tumors (observing of 23 cases)

BackgroundPreservation of anatomic integrity and function of the cranial nerves during the removal of skull base tumors is one of the most challenging procedures in endoscopic endonasal surgery. It is possible to use intraoperative mapping and identification of the cranial nerves in order to facilitate their preservation.The purpose of this study was to evaluate the effectiveness of intraoperative trigger electromyography in prevention of iatrogenic damage to the cranial nerves.MethodsTwenty three patients with various skull base tumors (chordomas, neuromas, pituitary adenomas, meningiomas, cholesteatomas) underwent mapping and identification of cranial nerves during tumor removal using the endoscopic endonasal approach in Department of Neurooncology of Federal State Autonomous Institution “N.N. Burdenko National Medical Research Center of Neurosurgery” of the Ministry of Health of the Russian Federation from 2013 to 2018. During the surgical interventions, mapping and identification of the cranial nerves were carried out using electromyography in triggered mode. The effectiveness of the method was evaluated based on a comparison with a control group (41 patients).ResultsIn the main group of patients, 44 nerves were examined during surgery using triggered electromyography. During the study, the III, V, VI, VII, and XII cranial nerves were identified intraoperatively. Postoperative cranial nerve deficiency was observed in 5 patients in the study group and in 13 patients in the control group. The average length of hospitalization was 9 days.ConclusionWe did not receive statistically significant data supporting the fact that intraoperative identification of cranial nerves using trigger electromyography reduces the incidence of postoperative complications in the form of cranial nerve deficits (p = 0.56), but the odds ratio (0.6) suggests a less frequent occurrence of complications in the study group.Based on our experience, the trigger electromyography methodology appears quite promising and requires further research.

Suboccipital Lateral Approach for Resection of Cerebellopontine Angle Meningioma: Operative Video and Technical Nuances.

We present the case of a 34-year-old woman, who presented to our department with a 4 months history of dizziness, hearing loss, and tinnitus on the right side. MRI (magnetic resonance imaging) scan demonstrated a large extra-axial lesion, suggestive of a meningioma, with dural attachments to the petrosal bone surface and tentorium, closely related with the trigeminal, abducens, facial, vestibulocochlear, and lower cranial nerves in the right side. Treatment options were discussed with the patient, and surgical resection was selected to remove the lesion, and decompress the cranial nerves and brainstem. The surgery was performed with a patient in a semi-seated position with head placed in a flexed, nonrotated position. A right lateral suboccipital approach was performed, exposing the right transverse and sigmoid sinuses. After dura opening, microsurgical dissection was used to open the cisterna magna, and obtain cerebellum relaxation. That was followed by identification of cranial nerves VII–XII and then identification of the tumor itself. Tumor debulking was then performed with use of suction and ultrasonic aspirator. After extensive resection, the tumor margins were dissected away from brainstem, cerebellum, and cranial nerves. Finally, the tumor attachment to the tentorium was coagulated and cut and the tumor was completely removed. Postoperative MRI confirmed complete resection of the tumor. The patient was discharged on the 1st week after surgery, with no additional postoperative deficits or complications. The link to the video can be found at: https://youtu.be/aZ3jhZTAeAA .

Neurophysiological Identification of Cranial Nerves During Endoscopic Endonasal Surgery of Skull Base Tumors: Pilot Study Technical Report

Intraoperative identification of cranial nerves is crucial for safe surgery of skull base tumors. Currently, only a small number of published papers describe the technique of trigger electromyography (t-EMG) in endoscopic endonasal removal of such tumors. To assess the effectiveness of t-EMG in preventing intraoperative cranial nerve damage in endoscopic endonasal surgery of skull base tumors. Nine patients were operated on using the endoscopic endonasal approach within a 1-year period. The tumors included large skull base chordomas and trigeminal neurinomas localized in the cavernous sinus. During the surgical process, cranial nerve identification was carried out using monopolar and bipolar t-EMG methods. Assessment of cranial nerve functional activity was conducted both before and after tumor removal. We mapped 17 nerves in 9 patients. Third, fifth, and sixth cranial nerves were identified intraoperatively. There were no cases of postoperative functional impairment of the mapped cranial nerves. In one case we were unable to get an intraoperative response from the fourth cranial nerve and observed its postoperative transient plegia (the function was normal before surgery). t-EMG allows surgeons to control the safety of cranial nerves both during and after skull base tumor removal.

Neurophysiological Identification of Cranial Nerves during Endoscopic Endonasal Surgery of Skull Base Tumors

Objective: Prevention of iatrogenic injuries of cranial nerves without reduction of extent of surgical removal of skull base tumors.

Identification of cranial nerves around trigeminal schwannomas using diffusion tensor tractography: a technical note and report of 3 cases

There are no large series studies identifying the locations of cranial nerves (CNs) around trigeminal schwannomas (TSs); however, surgically induced cranial neuropathies are commonly observed after surgeries to remove TSs. In this study, we preoperatively identified the location of CNs near TSs using diffusion tensor tractography (DTT). An observational study of the DTT results and intraoperative findings was performed. We preoperatively completed tractography from images of patients with TSs who received surgical therapy. The result was later validated during tumorectomy. A total of three consecutive patients were involved in this study. The locations of CNs V-VIII in relation to the tumor was clearly revealed in all cases, except for CN VI in case 3.The predicted fiber tracts were in agreement with intraoperative observations. In this study, preoperative DTT accurately predicted the location of the majority of the nerves of interest. This technique can be applied by surgeons to preoperatively visualize nerve arrangements.

Identification of cranial nerves near large vestibular schwannomas using superselective diffusion tensor tractography: experience with 23 cases.

The preservation of the facial nerve (FN) and acoustic function in large vestibular schwannoma (VS) surgery is challenging because of nerve course uncertainties and morphological deviations. Preoperative diffusion tensor tractography (DTT) has been proposed to predict the FN location. This study was conducted to evaluate the effectiveness of this technique for identifying the FN, cochlear nerve (CN) and trigeminal nerve (TN) in large VSs. The study included 23 consecutive patients with VS of Hannover classification T3b to T4b from November 2013 through May 2014. Diffusion tensor images and anatomical images were acquired. The DTT images of the cranial nerves were extracted before surgery for each patient to determine the relationships of these nerves with the tumor. The results were then validated during the tumorectomy. In 21 (91.30%) patients, the location of the FN on the DTT images agreed with the intraoperative findings, including in 2 patients in whom the FN passed through the interface between the parenchyma and the cystic changes and in 3 patients with a membranoid FN. The CN or fibers of unclear function were observed on DTT images in four patients with functional hearing. One penetrating fiber of unknown function was effectively constructed. The TN was accurately detected on the DTT images for all patients. DTT effectively revealed the location of the FN, including cases in which the FN was membranoid or passed through the interface between an area exhibiting cystic changes and the tumor nodule. Fibers aside from the FN and the TN were revealed by DTT in patients who retained functional hearing. Penetrating fibers were also found using DTT. This technique can be useful during VS resection.

Comparison and Clinical Application of CT and MRI for Evaluation of the Equine Cranial Nerves

Reasons for performing studyAdvanced imaging modalities enable assessment of the equine skull and brain. Horses are susceptible to neurological dysfunction of the cranial nerves; however, our understanding of these structures’ imaging anatomy is limited.HypothesisMagnetic resonance imaging (MRI) will be superior to computed tomography (CT) for the identification of cranial nerves, but optimal assessment may depend on both modalities.ObjectivesIdentify cranial nerves and compare and contrast the utility of MRI and CT images of cadaver and clinical material. Interpret images from both modalities and determine the cranial nerve imaging anatomy.Study designProspective cadaver anatomical study combined with retrospective clinical case study.MethodsThe head of a neurologically normal 9‐year‐old Thoroughbred gelding was scanned immediately following euthanasia (performed for reasons unrelated to this study). High resolution MRI (1.5 Tesla) and CT examinations were conducted over a 12 h interval following euthanasia. Images obtained were compared with selected clinical cases which were scanned during anaesthesia (MRI; approximately 30–60 min) or standing sedation (CT; approximately 30 s).ResultsOn a high resolution MRI scan of a cadaver equine skull, each of the 12 cranial nerves and their topographic location was readily appreciated. Cranial nerves 1, 2, 3, 5, 7 and 8 were more easily identified in clinically relevant MRI scans. CT allowed visualisation of the stylomastoid foramen, the inner and middle ear and cranial nerves 2, 3, 5 and 7.ConclusionsHigh field MRI allows for excellent visualisation of equine cranial nerves. CT allows for detailed visualisation of the osseous canals and foramina. This study advances anatomical knowledge of the normal equine cranial nerves to aid interpretation in horses that display neurological dysfunction localising to the brain and brainstem.Ethical animal research: Horse owners gave their consent for their animals to be included in the study. Sources of funding: Institutional. Competing interests: None.

Skull Base Meningiomas and Cranial Nerves Contrast Using Sodium Fluorescein: A New Application of an Old Tool.

Objective The identification of cranial nerves is one of the most challenging goals in the dissection of skull base meningiomas. The authors present an application of sodium fluorescein (SF) in skull base meningiomas with the purpose of improving the identification of cranial nerves. Design A prospective study within-subjects design. Setting Hospital Ernesto Dornelles, Porto Alegre, Brazil. Participants Patients with skull base meningiomas. Main Outcomes Measures Cranial nerve identification. Results The group of nine meningiomas was composed of one cavernous sinus, three petroclival, one tuberculum sellae, two sphenoid wing, one olfactory groove, and one temporal floor meningioma. The SF enhancement in all tumors was strong, and the contrast with cranial nerves clearly evident. There were one definite olfactory nerve deficit, one transient abducens deficit, and one definite hemiparesis. All lesions were resected (Simpson grades 1 and 2). The analysis of the difference of the delta SF wavelength between the meningiomas and cranial nerve contrast was performed by the Wilcoxon signed rank test and showed p = 0.011. Conclusions The contrast between the enhanced meningiomas and cranial nerves was evident and assisted in the visualization and microsurgical dissection of these structures. The anatomical preservation of these structures was improved using the contrast.

Identificación prequirúrgica de pares craneales en tumores de la base del cráneo mediante la técnica de tensor de difusión

ObjectiveThe objective of this work is to demonstrate the usefulness of high density diffusion tensor imaging techniques (HD-DTI 32 directions), to visualize the course of the cranial nerves prior to surgery in patients with skull base tumor disease. Materials and methodsTwenty-six patients with skull base tumor disease were studied with sequences of high density diffusion tensor imaging. The imaging results were correlated with the intra-operative findings. ResultsPre-surgical identification of the course of the nerves affected by the injuries of the skull base was possible in all the studied patients, with the imaging results correlating with the intraoperative findings. ConclusionThe visualization of the course of the cranial nerves with high density diffusion tensor imaging was shown to be safe and reproducible for the identification of cranial nerves and their course.

Impact of an Oral Health Assessment Training Program for Israeli Registered Dietitians on Knowledge of Nutrition Focused Physical Assessment of the Head, Neck and Oral Cavity

Objective: To determine the impact of an Oral Health Assessment Training Program for Israeli Registered Dietitians (IRDs) working in geriatrics on their knowledge of nutrition focused physical assessment (NFPA) components of the head/neck and oral cavity. Design/Subjects: A pre-posttest designwas used to assess change in knowledge of IRDsworking inMinistry of Health Long-Term-Care facilities in Israel. A convenience sample of 30 IRDs completed a knowledge pretest (translated intoHebrew) twoweeks prior to a 11⁄2-day training program on NFPA of the head/neck and oral cavity followed by completion of a posttest after the training program. Statistics: Descriptive statistics were used to describe the sample and knowledge scores; paired t testwas used to assess change in knowledge. Results:Of the 30 participants, 100% were female with a mean age of 37.2 / 8.5 years and 9.2 / 5.8 years of practice. Sixty-three percent (n 19, 63.3%) had a bachelors degree as their highest degree. Out of a possible 29 points, the mean pretest score was 14.9 / 3.9 and the mean posttest score was 23.5 / 2.9. Knowledge increased significantly from pre to posttest (t 9.773, p 0.001); the mean increase was 8.6 / 4.8 points. Pretest knowledge deficits included anatomical structures of the oral cavity, cranial nerve identification and function, swallowing phases, and oral manifestations of vitamin deficiencies. Knowledge in all these areas significantly improved on the posttest. Conclusions/Implications for Practice: The results demonstrate that IRDs participating in an Oral Health Assessment Training Program increased their knowledge significantly following training. Future studies should explore retention of knowledge over time.

Intraoperative monitoring of lower cranial nerves in surgery of the skull base

Intraoperative electromyographic monitoring of the facial nerve is now recognized as a beneficial adjunct to facial nerve preservation in surgery for vestibular schwannomas. With advances in surgical treatment of lesions involving the posterolateral skull base, monitoring of other lower cranial nerves has rapidly evolved. Electromyographic data assist in cranial nerve identification, preservation, and estimation of nerve outcome. Implementation of procedures and protocol should be established by surgical team members. Technology currently provides the ability to monitor real-time electromyographic responses both visually and audibly. Monitoring and stimulation methods for facial and lower cranial nerves are presented. Intraoperative electromyographic monitoring of the facial nerve is now recognized as a beneficial adjunct to facial nerve preservation in surgery for vestibular schwannomas. With advances in surgical treatment of lesions involving the posterolateral skull base, monitoring of other lower cranial nerves has rapidly evolved. Electromyographic data assist in cranial nerve identification, preservation, and estimation of nerve outcome. Implementation of procedures and protocol should be established by surgical team members. Technology currently provides the ability to monitor real-time electromyographic responses both visually and audibly. Monitoring and stimulation methods for facial and lower cranial nerves are presented.