Intracranial schwannomas account for 6\u00e2\u20ac\u201c8\u00c2\u00a0% of all primary brain tumors as a kind of
\n benign tumor 1], 3]. They most commonly arise from the vestibular cranial nerves followed by the trigeminal
\n nerve, facial nerve, and lower cranial nerves; they rarely affect pure motor CN (3rd,
\n 4th, 6th) 1]. Schwannomas of the 6th cranial nerve are exceptionally rare. In the English literature,
\n 22 cases have been reported of intracranial schwannomas of the 6th cranial nerve pathologically
\n confirmed 4]\u00e2\u20ac\u201c23] (Table\u00c2\u00a01), except 4 cases reported by Hayashi et al. 24] who performed only stereotactic radiosurgery. We report a patient with a small schwannoma
\n of the abducens nerve performed by surgical treatment based on a review of the literature.<\/p>\n
Table 1.<\/strong> Cases of intracranial 6th nerve schwannomas published in the literature\n <\/p>\n According to the site where the schwannoma arises and its predominant location along It reveals an average age of 43.41\u00c2\u00a0years old, from 10 to 68\u00c2\u00a0years old. Eighteen out Almost all cases of abducens nerve schwannoma were misdiagnosed preoperatively. It Histological images of our case revealed a cellular schwannoma with spindle cells Based on the location of the tumor, most cases are treated by a suboccipital 4], 12]\u00e2\u20ac\u201c14], 17], 20], 22], 23] approach, then subtemporal 5], 15], 16] (present case) and frontotemporal 8]\u00e2\u20ac\u201c10] approaches, and anterior transpetrosal 18], 21], orbitozygomatic 19], and transcondylar 11] approaches for a few patients. Schwannomas located partially or entirely in the cavernous Table 2.<\/strong> Result of resection of the 6th schwannoma in different locations\n <\/p>\n Because of the frangible nature, the 6th nerve function seldom completely recovered Regarding an alternative or adjuvant therapy, stereotactic radiosurgery has been reported Intracranial schwannomas account for 6\u00e2\u20ac\u201c8\u00c2\u00a0% of all primary brain tumors as a kind of benign tumor 1], 3]. They most commonly arise from the vestibular cranial nerves followed by the trigeminal nerve, facial nerve, and lower cranial nerves; they rarely affect pure motor CN (3rd, 4th, 6th) 1]. Schwannomas of the 6th cranial nerve are […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-26357","post","type-post","status-publish","format-standard","hentry"],"_links":{"self":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/posts\/26357","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/comments?post=26357"}],"version-history":[{"count":0,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/posts\/26357\/revisions"}],"wp:attachment":[{"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/media?parent=26357"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/categories?post=26357"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/healthmedicinet.com\/news\/wp-json\/wp\/v2\/tags?post=26357"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Classification<\/h4>\n
\n the course of the 6th nerve, Tung 8] and Celli 25] have proposed two kinds of classification. Celli 25] divided the tumor into three types concerned for the 3rd to the 5th nerve: type I
\n (cisternal, CI), 8 cases 4], 11]\u00e2\u20ac\u201c14], 17], 21] (present case) out of 22; type II (cavernous, CA), 5 cases 9], 10], 15], 18], 19] out of 22; and type III (cisternocavernous, CI-CA), 8 cases 5]\u00e2\u20ac\u201c8], 16], 20], 22], 23] out of 22. Tung 8] classified them into only two types: type I, schwannoma arises from the cavernous
\n sinus, including the symptoms of the 6th nerve palsy and with or without mild headache;
\n and type II, the tumor located in the prepontine area and perhaps accompanied by obstructive
\n hydrocephalus, raised intracranial pressure, the 6th nerve palsy, and with or without
\n other cranial nerve palsy. By contrast, Celli\u00e2\u20ac\u2122s classification which emphasizes on
\n the anatomical position, without symptomatology, is more accurate and simple. But
\n Tung\u00e2\u20ac\u2122s classification seems to be more comprehensive and stresses on symptomatology.
\n The big tumors belonging to the CI-CA type of Celli\u00e2\u20ac\u2122s classification are difficult
\n to be labeled using Tung\u00e2\u20ac\u2122s classification. Maybe it is only classified on the basis
\n of the principal part or origination of the tumor using Tung\u00e2\u20ac\u2122s system.\n <\/p>\nClinical presentation<\/h4>\n
\n of 22 cases were over 30\u00c2\u00a0years old (82\u00c2\u00a0%) and only 2 cases 5] (present case) were under 14\u00c2\u00a0years old (0.09\u00c2\u00a0%). The male\/female ratio is about 1:1.
\n A typical 6th nerve palsy was present in all except 3 of the reported patients 17], 21], 23]. Six cases 6], 8], 16], 22] (present case) presented isolated 6th nerve palsy. This indicates that a patient
\n presenting an isolated 6th nerve palsy, with a specific mass in CI or CA found in
\n neuroimaging, could be likely to diagnose a schwannoma of the 6th cranial nerve preliminarily.
\n Twelve cases included signs of other cranial nerves, 9 cases 5], 7], 9]\u00e2\u20ac\u201c14], 18] involved trigeminal nerves, 3 cases 9], 10], 15] involved oculomotor nerves, and 7 cases 7], 12], 14], 17], 19], 21], 23] involved vestibulocochlear and facial nerves. Headaches were present in 11 cases.
\n Hydrocephalus was present in 4 cases 4], 5], 7], 12]. About the present patient, 3 preoperative pictures at 10, 12, and 14\u00c2\u00a0years old descript
\n the symptoms and course of the 6th nerve palsy accurately.\n <\/p>\nDiagnosis<\/h4>\n
\n is high possibility that the tumors were initially misdiagnosed as trigeminal or vestibular
\n schwannomas. The trigeminal schwannomas could show isolated 6th nerve palsy, and the
\n 6th nerve schwannoma could present without any 6th nerve palsy. In addition, the low
\n incidence is the significant cause for most surgeons. The location and the attachment
\n to the 6th nerve is the key for diagnosis. Some cases 5], 7], 10], 11] were not revealed during surgery that it comes from the 6th nerve. Therefore, the
\n 6th nerve schwannoma diagnosis could only come from the pre- and postoperative neurological
\n deficit. In the present case, the definite diagnosis of the 6th nerve schwannoma was
\n established from intraoperative observation of the tumor location and the attachment
\n to the 6th nerve, as well as from the neuroimaging and the obvious isolated 6th nerve
\n palsy pre- and postoperatively. It should be emphasized that ampliative Dorello\u00e2\u20ac\u2122s
\n canal demonstrated the tumor origination from the 6th nerve, for only the 6th nerve
\n enters the cavernous sinus through Dorello\u00e2\u20ac\u2122s canal, which is located between the petrosphenoidal
\n ligament and petrous apex.\n <\/p>\n
\n in a collagenous background (Fig.\u00c2\u00a04a, b). Cellular schwannomas are a variant of standard schwannomas. They show a benign
\n clinical behavior relative to standard schwannomas, but they are more likely to local
\n recurrence 2].\n <\/p>\nOperation<\/h4>\n
\n sinus are a completely special surgical group. Frontotemporal 8]\u00e2\u20ac\u201c10] or subtemporal 5], 15] approaches or their variations 18] are used. One-half cases of the CI types and one-half cases of the CI-CA type schwannomas
\n obtain a radical resection, respectively. Tumor residue was left on the brainstem
\n 5] (present case) or the 6th nerve 13]. In our present case, the tumor was adherent to the prepontine cisternal part of
\n the pons and the basilar artery. Comparatively speaking, 2 10], 18] out of 5 cases belonging to CA types obtain total resection (Table\u00c2\u00a02). Most of this type was not totally removed because of invasion of the cavernous
\n sinus or firm adherence to the nerves.<\/p>\n
\n postoperatively. A complete recovery was obtained in only 4 cases 17], 18], 21], 22]. The case of CA type presented by Nakagawa 18] is out of the ordinary. It showed transient diplopia preoperatively and complete
\n recovery of the 6th nerve function postoperatively. Reference 22] is the second case whom there was diplopia preoperatively and complete postoperative
\n recovery of the 6th nerve palsy. The tumor was cystic and located in the CI-CA. An
\n anastomosis was performed following total resection of the tumor. The other two cases
\n reported by Nakamura 17] and Vachata and Sames 21] are both belonging to CI type and showed no diplopia preoperatively and complete
\n recovery of the 6th nerve function postoperatively. These may be due to tumor growth
\n that has been functionally compensated by the rest of intact nerve fibers. Above all,
\n it seems easier to recover the function of the 6th nerve in cases of schwannomas in
\n the CI-type group. The prognosis for the 6th nerve function was not in a good status
\n in the present case, perhaps because the tumor had invaded into the cavernous sinus
\n through Dorello\u00e2\u20ac\u2122s canal and was adherent to the 6th nerve, the pons, and the basilar
\n artery.\n <\/p>\nStereotactic radiosurgery<\/h4>\n
\n 26], 27] for controlling nonvestibular schwannomas. In 2010, Hayashi et al. 24] performed stereotactic radiosurgery in 4 intracavernous 6th nerve schwannomas. The
\n tumors are small in size and controlled to grow without acute complications or adverse
\n effect. It could be an alternative measure for a small one. All in all, the direction
\n of further research is to improve the diagnosis and therapy for the 6th schwannomas
\n to have better postoperative recovery.\n <\/p>\n","protected":false},"excerpt":{"rendered":"