Ryojo Akagami

Intraoperative facial motor evoked potential monitoring with transcranial electrical stimulation during skull base surgery

OBJECTIVE To address the limitations of standard electromyography (EMG) facial nerve monitoring techniques by exploring the novel application of multi-pulse transcranial electrical stimulation (mpTES) to myogenic facial motor evoked potential (MEP) monitoring. METHODS In 76 patients undergoing skull base surgery, mpTES was delivered through electrodes 1cm anterior to C1 and C2 (M1-M2), C3 and C4 (M3-M4) or C3 or C4 and Cz (M3/M4-Mz), with the anode contralateral to the operative side. Facial MEPs were monitored from the orbicularis oris muscle on the operative side. Distal facial nerve excitation was excluded by the absence of single pulse responses and by onset latency consistent with a central origin. RESULTS M3/M4-Mz mpTES (n=50) reliably produced facial MEPs while M1-M2 (n=18) or M3-M4 (n=8) stimulation produced 6 technical failures. Facial MEPs could be successfully monitored in 21 of 22 patients whose proximal facial nerves were inaccessible to direct stimulation. Using 50, 35 and 0% of baseline amplitude criteria, significant facial deficits were predicted with a sensitivity/specificity of 1.00/0.88, 0.91/0.97 and 0.64/1.00, respectively. CONCLUSIONS Facial MEPs can provide an ongoing surgeon-independent assessment of facial nerve function and predict facial nerve outcome with sufficiently useful accuracy. SIGNIFICANCE This method substantially improves facial nerve monitoring during skull base surgery.

Localized transcranial electrical motor evoked potentials for monitoring cranial nerves in cranial base surgery.

OBJECTIVE: To describe a novel monitoring technique that allows “functional” assessment of cranial nerve continuity during cranial base surgery. METHODS: Facial motor evoked potentials (MEP) in 71 consecutive patients were obtained by localized transcranial electrical stimulation in all patients requiring facial nerve monitoring during the period from November 2002 to August 2004. With transcranial electrical stimulation localized to the contralateral cortex, facial nerve MEPs are obtained through stimulation of more proximal intracranial structures. RESULTS: Logistic regression revealed that the final-to-baseline facial MEP ratio predicted satisfactory (House-Brackmann Grade 1 and 2 function) immediate postoperative facial function (0.005 > P > 0.0005). Contingency table analysis showed high correlation (&khgr;2, P ≤ 2 × 108) and acceptable test characteristics using a 50% final-to-baseline MEP ratio. CONCLUSION: Facial nerve MEPs recorded intraoperatively during cranial base surgery using the proposed technique predicts immediate postoperative facial nerve outcome. This technique can also be used to monitor other motor cranial nerves in cranial base surgery.

Prospective comparison of quality of life before and after observation, radiation, or surgery for vestibular schwannomas

OBJECT The best management strategy for small-to medium-sized vestibular schwannomas (VSs) remains controversial between observation, radiation, and microsurgical resection (surgery). The authors undertook a prospective observational cohort study comparing all 3 therapeutic modalities in patients with VSs, focusing on quality of life (QOL) outcomes. METHODS All patients in the study completed the 36-Item Short Form Health Survey at regular intervals, with a mean follow-up of 31.8 months. Two hundred five (77.7%) of 264 patients completed questionnaires, including 47 who underwent observation, 48 who received either linear accelerator radiosurgery or fractionated radiotherapy (radiation group), and 134 who underwent surgery (of whom 37 had tumors > 3 cm in diameter). Patients allocated to the observation group had smaller tumors than those in the other groups (mean 1.3 cm; p < 0.001). Patients who received radiation were older than patients in the other groups (mean 60.0 years; p < 0.001). RESULTS There were no baseline QOL differences between the observation, radiation, and surgery (tumors <or= 3 cm) groups. Quality of life remained unchanged for the observation and radiation groups throughout the follow-up period. In the surgery group with tumors <or= 3 cm, a significant improvement in total score and composite mental dimension was observed at 24 months. In the surgery group with tumors > 3 cm, there was an early improvement in composite mental dimension at 1.5 months, as well as at 24 months; total score and composite physical dimension were improved at 24 months in this group as well. CONCLUSIONS Based on the current management protocol, patients with VSs enjoy similar QOL throughout the follow-up period after undergoing observation, radiation therapy, or surgery.

Long-Term Outcomes of Fractionated Stereotactic Radiation Therapy for Pituitary Adenomas at the BC Cancer Agency

PURPOSE To assess the long-term disease control and toxicity outcomes of fractionated stereotactic radiation therapy (FSRT) in patients with pituitary adenomas treated at the BC Cancer Agency. METHODS AND MATERIALS To ensure a minimum of 5 years of clinical follow-up, this study identified a cohort of 76 patients treated consecutively with FSRT between 1998 and 2007 for pituitary adenomas: 71% (54/76) had nonfunctioning and 29% (22/76) had functioning adenomas (15 adrenocorticotrophic hormone-secreting, 5 growth hormone-secreting, and 2 prolactin-secreting). Surgery was used before FSRT in 96% (73/76) of patients. A median isocenter dose of 50.4 Gy was delivered in 28 fractions, with 100% of the planning target volume covered by the 90% isodose. Patients were followed up clinically by endocrinologists, ophthalmologists, and radiation oncologists. Serial magnetic resonance imaging was used to assess tumor response. RESULTS With a median follow-up time of 6.8 years (range, 0.6 - 13.1 years), the 7-year progression-free survival was 97.1% and disease-specific survival was 100%. Of the 2 patients with tumor progression, both had disease control after salvage surgery. Of the 22 patients with functioning adenomas, 50% (11/22) had complete and 9% (2/22) had partial responses after FSRT. Of the patients with normal pituitary function at baseline, 48% (14/29) experienced 1 or more hormone deficiencies after FSRT. Although 79% (60/76) of optic chiasms were at least partially within the planning target volumes, no patient experienced radiation-induced optic neuropathy. No patient experienced radionecrosis. No secondary malignancy occurred during follow-up. CONCLUSION In this study of long-term follow-up of patients treated for pituitary adenomas, FSRT was safe and effective.

Hearing preservation after microsurgical resection of large vestibular schwannomas.

BACKGROUND:Hearing, which is often still clinically useful at presentation even with larger tumors, is a major determinant of quality of life in vestibular schwannoma (VS) patients. OBJECTIVE:To present the hearing preservation rate after surgery in patients with large (≥3 cm) VSs and identify clinical or radiologic predictors of hearing preservation. METHODS:From April 2003 to March 2009, 192 patients underwent resection of a VS, including 46 large (≥3 cm) tumors, of whom 28 had serviceable hearing preoperatively. Six of 28 patients (21.4%) had preserved hearing postoperatively. RESULTS:Mean tumor diameter was 3.6 cm (range, 3.0-5.0 cm) and tumor volume was 17.2 mL (range, 6.9-45.2 mL). For patients with grade A Sanna-Fukushima hearing, the hearing preservation rate was 4 of 11 (36.4%). Complete resection was achieved in 6 of 6 cases with hearing preservation (41/47 for all patients). Six of 6 patients with preserved hearing had a cerebrospinal fluid cleft in the internal auditory canal (IAC) compared with 9 of 16 patients without preoperative hearing and 9 of 20 for patients with serviceable hearing that was lost postoperatively (P = .045). Six of 6 patients with preserved hearing had less than 35% of the tumor anterior to the longitudinal axis of the IAC compared with 13 of 20 in the serviceable hearing that was lost group (P = .036). CONCLUSION:Our series demonstrates hearing preservation is possible for patients with large VSs and should be attempted in all patients with preoperative hearing. The quality of preoperative hearing, a cerebrospinal fluid cleft at the apex of the IAC, and a smaller proportion of tumor anterior to the IAC were positively associated with hearing preservation.

Length of tumor-cochlear nerve contact and hearing outcome after surgery for vestibular schwannoma

OBJECTIVES Tumor size is likely to be a major determinant of hearing preservation after surgery for vestibular schwannoma. Findings in some large case series have not supported this concept, possibly due to variation in the technique used for tumor measurement. The authors sought to determine if the length of tumor-cochlear nerve contact was predictive of hearing outcome in adults undergoing resection of a vestibular schwannoma. METHODS Patients who underwent a hearing-preserving approach for resection of a vestibular schwannoma at one institution by a neurosurgeon/neurotologist team between 2001 and 2005 were screened. Patients with American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Class A or B hearing preoperatively were included. Magnetic resonance images were reviewed and used to calculate the length of tumor-cochlear nerve contact. Tumors were also measured according to AAO-HNS guidelines. RESULTS Thirty-one patients were included, 8 (26%) of whom had hearing preservation. Univariate analysis revealed that extracanalicular length of tumor-cochlear nerve contact (p = 0.0365), preoperative hearing class (p = 0.028), I-V interpeak latency of the brainstem auditory evoked potential (p = 0.021), and the interaural I-V interpeak latency difference (p = 0.018) were predictive of hearing outcome. Multivariate analysis confirmed the predictive value of extra-canalicular length of contact and preoperative hearing class (p = 0.041 and p = 0.0235, respectively). CONCLUSIONS Vestibular schwannomas with greater lengths of tumor-cochlear nerve contact increase a patients risk for hearing loss after surgery with attempted hearing preservation. Involvement of the internal auditory canal produces a constant risk of hearing loss. Data from the experience of a single surgical team can be used to estimate the probability of good hearing outcome for any given patient with serviceable hearing and a vestibular schwannoma.

Use of Tranexamic Acid Is Associated with Reduced Blood Product Transfusion in Complex Skull Base Neurosurgical Procedures: A Retrospective Cohort Study.

BACKGROUND:Compared with other procedures, complex skull base neurosurgery has the potential for increased intraoperative blood loss yet coagulation near eloquent cranial structures should be minimized. The safety and efficacy of the antifibrinolytic, tranexamic acid in elective neurosurgical procedures is not known. Our primary objective was to determine the relationship between the use of tranexamic acid and transfusion at our institution. Our secondary objective was to determine the incidence of adverse events associated with the use of tranexamic acid. METHODS:In this retrospective cohort study, we included all patients who underwent complex skull base neurosurgical procedures at our institution between 2001 and 2013. Tranexamic acid was introduced during these procedures in 2006. Patient and surgical variables, transfusion data, and adverse events in the perioperative period were abstracted from the medical record. The rates of transfusion and adverse events were compared between patients who did and did not receive tranexamic acid. Multivariate regression was used to identify independent predictors of perioperative transfusion. RESULTS:We compared 245 patients who received tranexamic acid with 274 patients who did not receive the drug during the study period. The 2 groups were similar, with the exception that patients who received tranexamic acid had larger tumors (mean, 3.5 vs 2.9 cm; P < 0.001) and longer procedures (mean, 7.2 vs 6.2 hours, P < 0.001). The rate of perioperative transfusion in patients who received tranexamic acid was lower (7% vs 13%, P = 0.04). After adjusting for preoperative hemoglobin, tumor diameter, and surgical procedure category, the use of tranexamic acid was independently predictive of perioperative transfusion (adjusted odds ratio, 0.32; 95% confidence interval, 0.15–0.65, P = 0.002). The rates of thromboembolic events and seizure were similar between the 2 groups. CONCLUSIONS:Our results demonstrate that tranexamic acid use is associated with reduced transfusion rates in our study population, with no apparent increase in seizure or thrombotic complications. Our data support the need for further randomized clinical trials to evaluate the efficacy and safety of tranexamic acid on perioperative blood loss during complex skull base neurosurgery.

Does It Leak In or Does It Leak Out

Accessible online at: http://BioMedNet.com/karger Dear Sir, Adel Moussa Malek et al. report an interesting case of a 17-month-old child with a ‘rapid’ resolution of an epidural hematoma associated with an overlying skull fracture. They review the literature about this rare phenomenon and propose an novel explanation. They state that unlike classical epidural hematoma, this entity may be caused by an increase in epicranial/subcutaneous pressure after focal head trauma which leaks serosanginous fluid into the epidural space through an underlying skull fracture. When the epicranial tissue pressure subsides, the fluid leaks back out through the fracture into the epicranial space. We would like to report a similar case. A 31⁄2-year-old male fell a height of 1.5 m off a bunk bed. He cried immediately and vomited; there was no loss of consciousness. On exam, there was a left cephalohematoma, he aroused to voice, and there were no focal findings. The first computed tomography (CT) scan was done at 65 min after the time of injury, showing a 1.5-cm left temporal epidural hematoma of heterogeneous density with an overlying fracture (fig. 1, 2). He was observed closely in the intensive care unit

Clinical and Radiographic Factors Predicting Hearing Preservation Rates in Large Vestibular Schwannomas.

Objectives Postoperative hearing preservation rates for patients with large vestibular schwannomas range from 0 to 43%. The clinical and radiographic factors predicting hearing preservation in smaller vestibular schwannomas are well described; however, their importance in larger tumors is unclear. We investigated factors predicting hearing preservation in large vestibular schwannomas. Design Retrospective review. Setting Quaternary care academic center. Participants A total of 85 patients with unilateral vestibular schwannomas > 3 cm underwent retrosigmoid resections. Main Outcomes Measures Preoperative and postoperative serviceable hearing rates. Methods Clinical and radiographic data including preoperative and postoperative audiograms, preoperative symptoms, magnetic resonance imaging features, and postoperative facial weakness were analyzed. Results Hearing was preserved in 41% of patients (17 of 42) with preoperative serviceable hearing. Hypertension and diabetes increased the likelihood of preoperative hearing loss. Preoperative tinnitus predicted a lower likelihood of hearing preservation. No radiographic factors predicted hearing preservation; however, larger tumor size, smaller fourth ventricular width, and the presence of a cerebrospinal fluid cleft surrounding the tumor predicted postoperative facial weakness. Conclusion Systemic comorbidities may influence hearing loss preoperatively in patients with large vestibular schwannomas. The absence of tinnitus may reflect hearing reserve and propensity for hearing preservation. Preoperative radiographic features did not predict hearing preservation despite some associations with postoperative facial weakness.

Adult Craniopharyngioma: Case Series, Systematic Review, and Meta-Analysis

BACKGROUND The optimal therapeutic approach for adult craniopharyngioma remains controversial. Some advocate for gross total resection (GTR), while others advocate for subtotal resection followed by adjuvant radiotherapy (STR + XRT). OBJECTIVE To conduct a systematic review and meta-analysis assessing the rate of recurrence in the follow-up of 3 yr in adult craniopharyngioma stratified by extent of resection and presence of adjuvant radiotherapy. METHODS MEDLINE (1946-July 1, 2016) and EMBASE (1980-June 30, 2016) were systematically reviewed. From1975 to 2013, 33 patients were treated with initial surgical resection for adult onset craniopharyngioma at our center and were reviewed for inclusion in this study. RESULTS Data from 22 patients were available for inclusion as a case series in the systematic review. Eligible studies (n = 21) were identified from the literature in addition to a case series of our institutional experience. Three groups were available for analysis: GTR, STR + XRT, and STR. The rates of recurrence were 17%, 27%, and 45%, respectively. The risk of developing recurrence was significant for GTR vs STR (odds ratio [OR]: 0.24, 95% confidence interval [CI]: 0.15-0.38) and STR + XRT vs STR (OR: 0.20, 95% CI: 0.10-0.41). Risk of recurrence after GTR vs STR + XRT did not reach significance (OR: 0.63, 95% CI: 0.33-1.24, P = .18). CONCLUSION This is the first and largest systematic review focusing on the rate of recurrence in adult craniopharyngioma. Although the rates of recurrence are favoring GTR, difference in risk of recurrence did not reach significance. This study provides guidance to clinicians and directions for future research with the need to stratify outcomes per treatment modalities.