Ryuzo Shiobara

Anterior transpetrosal-transtentorial approach for sphenopetroclival meningiomas: surgical method and results in 10 patients.

This report presents a new surgical method and the results in 10 patients with petroclival meningiomas extending into the parasellar region (sphenopetroclival meningiomas). Minimal but effective extradural resection of the anterior petrous bone via a middle fossa craniotomy offered a direct view of the clival area with preservation of the temporal bridging veins and cochlear organs. The dural incision was extended anteriorly to Meckels cave, and in cases with invasion of the cavernous sinus, Parkinsons triangle was enlarged by mobilization of the trigeminal nerve. This approach offered an excellent view from the mid-clivus to the cavernous sinus. Extra-as well as intradural tumor masses and dural attachments could be cleared under direct view of the pontine surface. The risk of injury to the lower cranial nerve and of retraction damage to the temporal lobe and brain stem were kept minimal by this approach. Total tumor resection was achieved in 7 patients, with no resultant mortality. Eight patients had a satisfactory postsurgical course, extraocular paresis being their main complaint. The extent of tumor resection depended on the degree of tumor adhesion to the carotid artery, and operative morbidity on the degree of tumor invasion of the brain stem. Of the 3 patients in whom subtotal tumor removal was achieved, only one experienced regrowth of the tumor and underwent a second operation during the follow-up period (6 months-6 years).

The Growth Rate of Acoustic Neuromas

Growth rate of acoustic neuromas (AN) was studied in 43 patients. The growth rate was analyzed using tumor increasing size (IS) and tumor volume doubling time (VDT). The growth rate of unilateral AN was lower than that of bilateral AN associated with neurofibromatosis2 (NF2). The growth rate of recurrent tumors was higher than that of non-operative tumors. The relationships between growth rate and age and tumor size were also analyzed. The younger the patient or the greater the tumor size, the higher the growth rate. Several factors, i.e. age and sex of patients, tumor pathology and tumor size, should be considered together for predicting the growth rate on AN.

Surgical approaches for vertebro-basilar trunk aneurysms located in the midline

SummaryFourteen cases of midline vertebro-basilar trunk aneurysms were operated on by four routes of surgical approach: middle fossa anterior transpetrosal approach (ATP), presigmoid transpetrosal approach (PTP), conventional lateral suboccipital approach (LSO) or suboccipital transcondylar approach (STC). There was no mortality, but the morbitity was different depending on the surgical approach. In basilar trunk aneurysms located higher than the internal auditory canal, excellent results were obtainable by ATP, especially in the case of posteriorly projecting aneurysms. For midline vertebral aneurysms located lower than the internal auditory canal, STC resulted in less surgical complications than LSO. Extradural resection of the jugular tubercle was necessary for aneurysms located on the distal vertebral artery at or close to the vertebro-basilar junction. For vertebro-basilar junction aneurysms located at the level of the internal auditory canal, hearing was preserved by STC, but not by ATP or PTP. However, choice of the surgical approach may depend on the direction of the aneurysm and the technical accessibility of the skull base. All these skull base approaches reduced surgical complications of retraction damage to the cranial nerves and the brain stem. This holds true for all aneurysms arising from the midline vertebro-basilar trunk.

Hearing Preservation in Acoustic Neuroma Surgery and Postoperative Audiological Findings

One hundred fifty-three cases of acoustic neuroma were treated surgically by the middle cranial fossa approach or extended middle cranial fossa approach. Attempts to preserve hearing were made in 30 cases with tumours extending 2.0 cm or less into the posterior fossa; successful hearing preservation was achieved in 12 cases. Among the 15 patients with preoperative hearing levels (HL) of 50 dB or lower and speech discrimination scores (SDS) of 50% or higher, hearing was preserved in 9 (60%) patients. A similar rate of hearing preservation was achieved among the patients with normal or near-normal hearing. Compared with those patients in whom hearing could not be preserved, those with hearing preservation had better HL, higher SDS, and less abnormal ABR findings preoperatively. Postoperatively, the HL and SDS deteriorated slightly. In addition, there was a marked prolongation of the IT5, and the incidence of absence of the stapedius reflex increased. Compared with the preoperative HL, the postoperative HL was unchanged in 5 cases; deteriorated temporarily and then improved in 5 cases; and deteriorated, though with hearing preserved, in 2 cases. Intraoperative monitoring was conducted by recording the ABR and VIII nerve compound action potentials and by electrocochleography. However, postoperative hearing could not always be predicted from the findings obtained at the end of the operation.

Haemorrhagic venous infarction following the posterior petrosal approach for acoustic neurinoma surgery: a report of two cases

Abstract The authors report two surgical cases with acoustic neurinoma in which haemorrhagic infarction occurred via a compromise in cerebral deep venous outflow. In both cases, surgery was performed via the posterior petrosal approach, and the neurinomas were completely removed. In the first case, the haemorrhagic infarction was considered to have resulted from transection of the tentorial sinus, the presence of which had not been predictable by preoperative angiography. In the second case, the haemorrhagic infarction was caused by a coagulation of the petrosal vein, which was firmly adherent to a tumour. With the posterior petrosal approach, meticulous care is necessary to preserve the deep anastomotic veins into and around the cerebellar tentorium. Thereby, catastrophic morbidity related to compromised deep cerebral venous outflow can be avoided.

Acoustic neuroma surgery

ZusammenfassungZur operativen Entfernung von Akustikustumoren vereinigten wir die Methode von Morrison und King mit der von Bochenek und Kukwa. Das modifizierte Verfahren erfordert ein otologisch-neurochirurgisches Team. Seine jeweilige Ausdehnung ist abhängig von der Tumorgröße. So wird bei Tumoren, die nur wenig über den inneren Gehörgang hinaus in die hintere Schädelgrube vordringen, nur der angrenzende Knochen entfernt. Für größere Geschwülste kommen Labyrinthektomie und Mastoidektomie mit Durchtrennung der Sinus petrosus superior, des Tentoriums und der Dura der hinteren Schädelgrube zur Anwendung. Im Gegensatz zu der Methode von Morrison führen wir zunächst die Labyrinthektomie und Mastoidektomie durch und eröffnen den inneren Gehörgang anschließend.In den letzten 3,5 Jahren wurden 35 Akustikustumoren und andere Kleinhirnbrückenwinkeltumoren operiert. Bei 23 von ihnen kam die angegebene Methode zur Anwendung. Sie hat den Vorteil, daß selten schwere postoperative Komplikationen auftreten.SummaryIn our approach for acoustic tumors, the method of Morrison and King and that of Bochenek and Kukwa have been modified into one method. This modified method is basically a neuro-otological-neurosurgical team approach, extending the operative field by drilling the temporal bone and cutting the superior petrosal sinus, tentorium, and posterior fossa dura according to the size of the tumor. Therefore, for tumors slightly protruding into the posterior fossa from the prous of the internal auditory canal, only the bone adjacent to it is removed (Bochenek et al’s method). For lager tumors, labyrinthectomy and mastoidectomy with the separation of the superior petrosal sinus and the tentorium and posterior fossa dura are also performed. In Morrison et al.’s method, the translabyrinthine approach is done first and the middle cranial fossa approach is performed thereafter. In contrast, in the modified method, drilling the bone from the middle cranial fossa to the tip of the mastoid — labyrinthectomy and mastoidectomy — is the first thing done after elevating the temporal lobe and revealing the middle cranial fossa, and the internal auditory canal is opened thereafter.Thirty-five cases of acoustic tumors and other cerebello-pontine angle tumors were operated on during the past 3.5 years through the middle cranial fossa. Among 30 cases of acoustic tumors, eight cases in which the tumors were confined to the internal auditory canal were operated on through the middle cranial fossa. In four cases, Bochenek et al’s method was performed in which bones adjacent to the internal auditory canal and a part of the labyrinth are removed without cutting the superior petrosal sinus. In 23 cases including five cerebellopontine angle tumors, the modified translabyrinthine-transtentorial approach through the middle cranial fossa was done. This modification has the advantage that severe postoperative complications are less frequent. The surgical technique and the results are discussed.

Accidentally detected brain tumors: clinical analysis of a series of 110 patients

The clinical records of 1,155 patients with 1,159 brain tumors who drained on Keio University Hospital between 1983 and 1994 were reviewed. Apparently asymptomatic patients and those whose complaints or neurological deficits were not caused by the brain tumors were defined as accidental cases. For example, patients with a headache which was considered to be unrelated to the presence of a tumor were included in this series. One hundred and ten (9.5%) of the 1,155 cases were found to be accidental. Since three accidental cases had multiple meningiomas, there were 113 accidental brain tumors which involved 63 meningiomas, 22 pituitary adenomas, 9 gliomas, 7 metastatic carcinomas. 5 acoustic neurinomas and 7 miscellaneous. Meningiomas occurred significantly more frequent than other types of accidentally identified tumors. Convexity meningiomas and falx meningiomas accounted for 53.9% of the accidental meningiomas, whereas parasagittal meningiomas were less frequent. It is of note that three out of four cases with multiple meningiomas were accidental. Comparison between the present results and the previously reported incidence of asymptomatic brain tumors in postmortem studies suggest that a substantial number of pituitary adenomas, acoustic neurinomas and small parasagittal meningiomas without suggestive symptoms are likely to be missed by routine neuroradiological examinations.

Classification of the Extended Middle Cranial Fossa Approach

There are several possible operative approaches to acoustic neuroma surgery. Ideally, there should be no need to select among approaches according to tumor size or indications for hearing preservation. The ideal approach should also allow otologists and neurosurgeons to work as a team using the same operative field and achieve functional preservation (facial nerve function and hearing) in a high percentage of cases. In 1977, the authors first reported on the extended middle cranial fossa (EMCF) approach for AN surgery. Based on our 15-year experiences of this approach, we have classified it into 3 types and describe their indications and techniques in the present paper. In addition, we examine the advantages and disadvantages and emphasize its excellent applicability as a team approach for otologists and neurosurgeons.

Intracranial Reconstruction of the Facial Nerve Clinical observation

Nine cases of intracranial facial nerve reconstruction are reviewed in this paper. All patients underwent this procedure for severe injury or disruption of the facial nerve during surgery for acoustic neruroma through the modified extended middle cranial fossa approach (1). Satisfactory recovery of facial function was obtained in 4 patients. Three patients underwent hypoglossal-facial nerve anastomosis 1.3-1.5 years later for no or poor recovery of the facial function. One patient refused any further surgical treatment despite unsatisfactory recovery. The remaining 1 patient, during a telephone interview, stated that facial function had not returned at all 1 year and 5 months postoperatively. Although some degree of associated movement or mass movement was unavoidable, facial movement and mimetic facial expression were better in the patients with satisfactory recovery, as compared with those after hypoglossal-facial nerve anastomosis (2). Fibrin glue, which we used in the latest 3 cases instead of suture, seemed to possibly solve the technical difficulty in placing a suture. Facial function after intracranial reconstruction with fibrin glue was as good or better than that after repair by suturing.

Long-Term Prognosis of Profound Facial Nerve Paralysis Secondary to Acoustic Neuroma Resection

The long-term prognosis of profound facial nerve paralysis was reviewed in 107 patients who, despite preserved nerve continuity, showed no facial movement after acoustic neuroma resection. Spontaneous recovery occurred in 77 patients. However, there was no apparent recovery in 30 patients. Twenty-two of these patients underwent hypoglossal-facial nerve anastomosis 7–33 months after tumor resection. When spontaneous recovery occurred, the first sign of remission was observed between 3 and 4 months after surgery in nearly half of the patients. Such a sign did not appear after 12 months. The recovery of facial movement deteriorated depending on how long remission onset was delayed. However, the quality of facial movement in patients with such delayed remission was still identical or better than that in those after hypoglossal-facial nerve anastomosis. These results showed that hypoglossal-facial nerve anastomosis should be performed approximately 1 year after tumor resection if no sign of remission has been observed by then.