{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T09:41:07Z","timestamp":1789724467451,"version":"4.0.1"},"reference-count":40,"publisher":"Journal of Neurosurgery Publishing Group (JNSPG)","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2000,1]]},"abstract":"<jats:p content-type=\"fine-print\"><jats:italic>Object.<\/jats:italic> Great advances in neuroimaging, intraoperative cranial nerve monitoring, and microsurgical technique have shifted the focus of acoustic neuroma surgery from prolonging life to preserving cranial nerve function in patients. An appreciation of the vascular and cranial nerve microanatomy and the intimate relationship between neurovascular structures and the tumor is essential to achieve optimum results. In this paper the authors analyze the microanatomical variations in location of the facial and cochlear nerves in the cerebellopontine angle (CPA) associated with acoustic neuromas and, additionally, describe the frequency of involvement of surrounding neural and vascular structures with acoustic tumors of varying size. The authors base these findings on their experience with 1006 consecutive patients who underwent surgery via a retrosigmoid or translabyrinthine approach.<\/jats:p><jats:p content-type=\"fine-print\"><jats:italic>Methods.<\/jats:italic> Between July 1969 and January 1998, the senior author (D.M.L.) performed surgery in 1022 patients for acoustic neuroma: 705 (69%) via the retrosigmoid (suboccipital); 301 (29%) via the translabyrinthine; and 16 (2%) via the middle fossa approach. Patients undergoing the middle fossa approach were excluded from the study. The remaining 1006 patients were subdivided into three groups based on tumor size: Group I tumors (609 patients [61%]) were smaller than 2.5 cm; Group II tumors (244 patients [24%]) were between 2.5 and 4 cm; and Group III tumors (153 patients [15%]) were larger than 4 cm. The senior author's operative notes were analyzed for each patient. Relevant cranial nerve and vascular \u201cinvolvement\u201d as well as anatomical location with respect to the tumor in the CPA were noted. \u201cInvolvement\u201d was defined as adherence between neurovascular structure and tumor (or capsule), for which surgical dissection was required to free the structure. Seventh and eighth cranial nerve involvement was divided into anterior, posterior, and polar (around the upper or lower pole) locations. Anterior and posterior locations were further subdivided into upper, middle, or lower thirds of the tumor.<\/jats:p><jats:p content-type=\"fine-print\">The most common location of the seventh cranial nerve (facial) was the anterior middle third of the tumor for all groups, although a significant number were found on the anterior superior portion. The posterior location was exceedingly rare (&lt; 1%). Interestingly, patients with smaller tumors (Group I) had an incidence (3.4%) of the seventh cranial nerve passing through the tumor itself, equal to that of patients with larger tumors. The most common location of the eighth cranial nerve complex was the anterior inferior portion of the tumor. Not surprisingly, larger tumors (Group III) had a higher incidence of involvement of fourth cranial nerve (41%), fifth cranial nerve (100%), ninth\u201411th cranial nerve complex (99%), and 12th cranial nerve (31%), as well as superior cerebellar artery (79%), anterior inferior cerebellar artery (AICA) trunk (91.5%), AICA branches (100%), posterior inferior cerebellar artery (PICA) trunk (59.5%), PICA branches (79%), and the vertebral artery (VA) (93.5%). A small number of patients in Group III also had AICA (3.3%), PICA (3.3%), or VA (1.3%) vessels within the tumor itself.<\/jats:p><jats:p content-type=\"fine-print\"><jats:italic>Conclusions.<\/jats:italic> In this study, the authors show the great variation in anatomical location and involvement of neurovascular structures in the CPA. With this knowledge, they present certain technical lessons that may be useful in preserving nerve function during surgery and, in doing so, hope to provide neurosurgeons and neurootologists with valuable information that may help to achieve optimum outcomes in patients.<\/jats:p>","DOI":"10.3171\/jns.2000.92.1.0070","type":"journal-article","created":{"date-parts":[[2009,5,13]],"date-time":"2009-05-13T17:33:37Z","timestamp":1242236017000},"page":"70-78","source":"Crossref","is-referenced-by-count":107,"title":["Microanatomical variations in the cerebellopontine angle associated with vestibular schwannomas (acoustic neuromas): a retrospective study of 1006 consecutive cases"],"prefix":"10.3171","volume":"92","author":[{"given":"Prakash","family":"Sampath","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Rini","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donlin M.","family":"Long","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1754","reference":[{"key":"b1","series-title":"Otolaryngol Head Neck Surg","doi-asserted-by":"publisher","first-page":"220","DOI":"10.1177\/019459989310800303","article-title":"Predicting long-term facial nerve outcome after acoustic neuroma surgery.","volume":"108","author":"Arriaga","year":"1993"},{"key":"b2","series-title":"J Laryngol Otol","doi-asserted-by":"publisher","first-page":"463","DOI":"10.1017\/S0022215100112897","article-title":"Hearing conservation in acoustic neuroma surgery via the posterior fossa.","volume":"104","author":"Baldwin","year":"1990"},{"key":"b3","series-title":"Laryngoscope","first-page":"697","article-title":"Facial nerve monitoring during acoustic neuroma removal.","volume":"97","author":"Benecke","year":"1987"},{"key":"b4","series-title":"Tumors of the Nervus Acusticus and the Syndrome of the Cerebellopontine Angle.","author":"Cushing","year":"1917"},{"key":"b5","series-title":"Neurosurgery","doi-asserted-by":"publisher","first-page":"260","DOI":"10.1097\/00006123-199608000-00005","article-title":"Conservative management of acoustic neuroma: an outcome study.","volume":"39","author":"Deen","year":"1996"},{"key":"b6","series-title":"J Neurosurg","doi-asserted-by":"publisher","first-page":"901","DOI":"10.3171\/jns.1992.76.6.0901","article-title":"Current results of the retrosigmoid approach to acoustic neurinoma.","volume":"76","author":"Ebersold","year":"1992"},{"key":"b7","series-title":"J Neurosurg","doi-asserted-by":"publisher","first-page":"910","DOI":"10.3171\/jns.1992.76.6.0910","article-title":"Hearing preservation in acoustic neurinoma surgery.","volume":"76","author":"Fischer","year":"1992"},{"key":"b8","series-title":"Int J Radiat Oncol Biol Phys","doi-asserted-by":"publisher","first-page":"275","DOI":"10.1016\/S0360-3016(96)00335-5","article-title":"Evolution in technique for vestibular schwannoma radiosurgery and effect on outcome.","volume":"36","author":"Flickinger","year":"1996"},{"key":"b9","series-title":"Br J Neurosurg","doi-asserted-by":"publisher","first-page":"169","DOI":"10.1080\/02688699650040322","article-title":"Radiosurgery: a minimally interventional alternative to microsurgery in the management of acoustic neuroma.","volume":"10","author":"Forster","year":"1996"},{"key":"b10","series-title":"Am J Otol","first-page":"87","article-title":"Acoustic tumor management\u2014combined approach surgery with CO2 laser.","volume":"5","author":"Gardner","year":"1983"},{"key":"b11","series-title":"Laryngoscope","first-page":"1405","article-title":"The argon laser in acoustic tumor surgery.","volume":"91","author":"Glasscock","year":"1981"},{"key":"b12","series-title":"J Neurosurg","doi-asserted-by":"publisher","first-page":"864","DOI":"10.3171\/jns.1993.78.6.0864","article-title":"Preservation of hearing in surgery for acoustic neuromas.","volume":"78","author":"Glasscock","year":"1993"},{"key":"b13","series-title":"Acoustic Tumors. 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