Endoscopic Approach to Remove Intra-extracranial Tumors in Various Skull Base Regions: 10-year Experience of a Single Center.

BACKGROUND: Some problems have been found in the usually adopted combined approach for the removal of intra-extracranial tumors in skull base. Herein, we described a pure endoscopic transnasal or transoral approach (ETA) for the removal of intra-extracranial tumors in various skull base regions. METHODS: Retrospectively, clinical data, major surgical complications, pre- and postoperative images, and follow-up information of a series of 85 patients with intra-extracranial tumors in various skull base regions who were treated by surgery via ETA in our skull base center during the past 10 years were reviewed and analyzed. RESULTS: Gross total tumor removal was achieved in 80/85 cases (94.1%) in this study. All 37 cases with tumors in anterior skull base and all 14 cases with tumors in jugular foramen received total tumor removal. Thirteen and three cases with tumors in clivus received total and subtotal tumor removal, respectively. Total and subtotal tumor removal was performed for 16 cases and 2 cases in lateral skull base, respectively. The complications in this study included: cerebrospinal fluid leakage (n = 3), meningitis (n = 3), and new cranial nerve deficits (n = 3; recovered in 3 months after surgery). In the follow-up period of 40-151 months (median: 77 months), seven patients (8.8%) out of the 80 cases of total tumor removal experienced recurrence. CONCLUSIONS: Complete resection of intra-extracranial growing tumors in various skull base regions can be achieved via the pure ETA in one stage in selected cases. Surgical procedure for radical removal of tumors is feasible and safe.

Usefulness of intraoperative electromyographic monitoring of oculomotor and abducens nerves during skull base surgery.

BACKGROUND: Intraoperative neurophysiologic monitoring of the extraocular cranial nerve (EOCN) is not commonly performed because of technical difficulty and risk, reliability of the result and predictability of the postoperative function of the EOCN. METHODS: We performed oculomotor nerve (CN III) and abducens nerve (CN VI) intraoperative monitoring in patients with skull base surgery by recording the spontaneous muscle activity (SMA) and compound muscle action potential (CMAP). Two types of needle electrodes of different length were percutaneously inserted into the extraocular muscles with the free-hand technique. We studied the relationships between the SMA and CMAP and postoperative function of CN III and CN VI. RESULTS: A total of 23 patients were included. Nineteen oculomotor nerves and 22 abducens nerves were monitored during surgery, respectively. Neurotonic discharge had a positive predictive value of less than 50% and negative predictive value of more than 80% for postoperative CN III and CN VI dysfunction. The latency of patients with postoperative CN III dysfunction was 2.79 ± 0.13 ms, longer than that with intact CN III function (1.73 ± 0.11 ms). One patient had transient CN VI dysfunction, whose CMAP latency (2.54 ms) was longer than that of intact CN VI function (2.11 ± 0.38 ms). There was no statistically significant difference between patients with paresis and with intact function. CONCLUSIONS: The method of intraoperative monitoring of EOCNs described here is safe and useful to record responses of SMA and CMAP. Neurotonic discharge seems to have limited value in predicting the postoperative function of CN III and CN VI. The onset latency of CMAP longer than 2.5 ms after tumor removal is probably relevant to postoperative CN III and CN VI dysfunction. However, a definite quantitative relationship has not been found between the amplitude and stimulation intensity of CMAP and the postoperative outcome of CN III and CN VI.

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

BACKGROUND: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Early experience of resection of meningiomas in anterior skull base with intra-extracranial extension via a pure endoscopic endonasal approach].

OBJECTIVE: The early experience of treating anterior skull base meningiomas with intra-extracranial extension via pure endoscopic endonasal approach (EEA) was presented, the safety, feasibility and preliminary treatment outcomes were investigated. METHODS: Eight patients with intra-extradural meningiomas who were admitted from October 2006 to October 2010 were operated on via EEA in one stage in Xuanwu hospital. In this study, the operative technique was described, the degree of resection, complications and the early clinical outcomes were discussed. RESULTS: The complete resection of meningiomas with intra-extracranial extension was achieved in all patients using EEA in one stage. Preoperative visual symptoms were improved or resolved in all cases who presented with preoperative visual complaints. No patient in our series experienced a new neurological deficit after surgery or recurrence and death related meningiomas in the follow-up period (33-75 months). One patient experienced postoperative cerebrospinal fluid leak, delayed meningitis and secondary hydrocephalus which responded to therapy. After treatment, the patient was cure. CONCLUSION: Our limited experience indicates that EEA is feasible and safe for the complete resection of anterior skull base meningiomas with intra- and extracranial extension in one stage in selected cases.

[Surgery for jugular foramen schwannomas via a pure endoscopic transoral approach].

OBJECTIVE: To report a new approach, endoscopic transoral approach for the resection of jugular foramen schwannoma. METHODS: Nine patients with jugular foramen schwannoma (three males and six females, ranging in age from 15 to 61 years old) were treated by direct surgery via a pure endoscopic transoral approach to the jugular foramen. Eight patients complained of hypoglossal nerve palsy with hemiatrophy of the tongue; six cases complained of vagus nerve palsy. Three cases complained of glossopharyngeal nerve palsy, one case complained of facial nerve palsy and hearing loss. RESULTS: The nerves in this area were preserved and radical intracapsular removal of the tumor was performed via endoscopic transoral approach in the nine cases. Tumor removal, as assessed by intraoperative endoscopic inspection, postoperative magnetic resonance imaging and clinical evaluation, revealed all tumors were completely removed. One patient suffered from temporary swallowing difficulties and temporary right vagus palsy 1 day after surgery. There were no others intraoperative and postoperative complications. All patients were followed up for 4 - 29 months, no recurrences were occurred in all these patients and the muscle bulk, motor and the pre-postoperative swallowing function, the vagus palsy, the facial nerve palsy and hearing loss had improved in these patients. CONCLUSION: The endoscopic transoral approach and intracapsular removal of the tumor provided for successful minimally invasive surgery in the jugular foramen schwannomas.

[Endoscopic endonasal surgery of trigeminal schwannoma extending into the infratemporal fossa].

OBJECTIVE: To investigate the feasibility of removing extracranial trigeminal schwannomas located in the infratemporal fossa by using a purely endoscopic endonasal approach. METHODS: From November 2004 to July 2009, 8 patients with extracranial trigeminal schwannomas located in the infratemporal fossa (4 male patients and 4 female patients, age ranged 31 - 62 years) were surgically treated by using a purely endoscopic endonasal approach. RESULTS: The maximum diameters of the tumors ranged from 3 to 7 cm. All tumors were completely removed. The operation time was 40 to 120 min, blood loss was 300 to 1500 ml. The clinical symptoms of some patients were relieved or improved. There were no intraoperative and postoperative complications, no deaths in this series. No relapse happened during the follow-up. CONCLUSIONS: The purely endoscopic endonasal approach may provide a minimally invasive and safe approach to remove extracranial trigeminal schwannomas extending into the infratemporal fossa. Radical resection is associated with an excellent long-term outcome in this series.

[Nasal endoscopic resection of extended intradural clival chordoma].

OBJECTIVE: Clival chordoma with intradural extension is very difficult to manage mont. Primary experience of nasal endoscopic surgery for the extra-intra clival chordomas was reported. METHODS: Between 2007 and 2009, 7 patients (4 males and 3 females, ages ranging from 8 to 62 years) with clival extra-intra dural chordoma underwent nasal endoscopic surgeries, 4 of them with combined transoral approach. Charts were reviewed for clinical characteristics, previous therapies, tumor extent, management modalities, complications, and outcome. RESULTS: Total resection of tumor was obtained in 6 cases and subtotal resection in one case. Postoperative follow-up period ranged from 3 to 25 months, median 22 months. One of 6 cases with total resection was recurrent and alive with disease. The patient with subtotal resection died secondary to progression of disease 10 months after the surgery. There was no intraoperative complication. Expect for one case of transient cerebral spinal fluid leakage, no postoperative complication was encountered. CONCLUSIONS: Nasal endoscopic approach may provide a less invasive surgery for clival chordoma with intradural extension. It is safe and effective when it is performed by the surgeons with adequate experience and skills and perioperative managements were taken.