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At least 415 records · Page 23Linked to original sources
PubMed1998

[Gadolinium and contrast medium MRI of the acoustic nerve in patients with meningeal neuritis and acoustico-facial syndrome].

Twelve cases of vestibular neuritis were investigated in gradient echo MRI with gadolinium. Only 3 severe cases associated with an acoustico facial syndrome (2 cases of herpes zoster oticus and one case after influenzae) demonstrated focal enhancement within the internal auditory canal on post contrast T1 weighted images. This enhancement involved at least 2 differents nerves. These 3 severe cases associating sensory neural hearing loss and facial palsy revealed a meningeal reaction after cerebrospinal fluid examination. The enhancement lasted a long time (up to 10 months) in one case of RAMSAY HUNT syndrome associated with a chronic lymphocytic leukemia. The MRI was able to confirm the anatomical reality of the vestibular neuritis and more precisely of the meningoneuritis and gave arguments for the theory of the polyneuropathy of Adour. Enhancement at MRI seems correlated with the severity of the affection (permanent vestibular areflexia in 3 cases and permanent hearing loss in 1 case).

Adult↗
PubMedDate not supplied

Involvement of cochlear nerve in acoustic tumours.

With conventional light and transmission electronmicroscopy we studied 10 cases of acoustic nerve tumour, 3 of which proved to be instances of von Recklinghausen neurofibroma and 7 of schwannoma. Schwannomas were not found to infiltrate the cochlear nerve. Hearing loss, if present in cases of schwannoma, could be related to non-specific lesions of the uninfiltrated cochlear nerve in the vicinity of the vestibular nerve tumour. Only neurofibromas were found to infiltrate the cochlear nerve. Distinction between tumour infiltration and non-specific lesion could be made by electron microscopy.

Adolescent↗
PubMed1976

[Surgery of vertebral aneurysms at the origin of PICA (author's transl)].

Thirteen cases of vertebral aneurysm at the origin of PICA (VA-PICA aneurysm) were operated on at the Department of Neurological Surgery of Kitano Hospital from March, 1970 through July, 1975. Those included 9 cases of saccular aneurysm and 5 cases of fusiform aneurysm (Table 1). The incidence of VA-PICA aneurysms among our whole series of intracranial aneurysms was 4.2%. Patients with subarachnoid hemorrhage were subjected to our routine 4 vessel angiography. For those with suspected vertebral aneurysm vertebral angiography was performed in a transoral projection. In this method, when the angle between the film and the horizontal plain of Frankfurt is fixed at 50 degrees, the origin of PICA is projected on the film between the upper and lower teeth line. Since X-ray beam falls vertically on the origin of PICA, the resultant vascular shadow is free from shortening, elongation and distortion, leading to precise demonstration of anatomical arrangement of the vessels. At surgery a lateral suboccipital incision was made. With the position of VA-PICA junction the surgical approach was slightly different. When the junction was located higher than the line between the lowest point of the occipital bone and the basion by 1 cm or more, the approach was made through the middle of the sigmoid sinus which was exposed by suboccipital osteoclastic craniectomy (mid-lateral cerebellar approach). When the VA-PICA junction was situated lower than the line by 1 cm or more, the operation was initiated at the upper limit of the lower one-third of the sigmoid sinus (lower-lateral cerebellar approach). Since VA-PICA junction is ventrally situated to the lower cranial nerves, surgical attack to the junction can be attained only through the space among the nerves. Two spaces are available for this direct attack. One is the space between the facial nerve, acoustic nerve and the group of vagal nerves. The other is between accessory nerve bundles or between the group of accessory nerves and the hypoglossal nerves. The former procedure is employed for reaching the aneurysm by mid-lateral cerebellar approach and the latter by lower-lateral cerebellar approach. In the patients in acute stage of ruptured VA-PICA aneurysm, hemisuboccipital craniectomy and laminectomy of the atlas were carried out for the purpose of decompression. Surgical procedures used included coating in 2 cases, trapping in 2, proximal ligation of the vertebral artery in 2 and neck clipping in 6. Two patients died due to grastrointestinal bleeding. Surgical complications noted were hypoglossal nerve palsy in 1 case mild sensory disturbance contralateral to the aneurysm in 3 cases. Those symptoms were thought to be caused either by direct injury to the lower cranial nerves or circulatory disturbance in the medullary branches of the vertebral artery. To eliminate those postoperative complications it is desirable to devise smaller aneurysm clips and smaller clip foreceps.

Adult↗
PubMed1995

Physiological identification of the auditory nerve during surgery for acoustic neuroma.

We report the design and clinical use of an electrode which can locate the acoustic nerve fibres in the normal eighth nerve and also in eighth nerves deformed by acoustic neuromas. The improvement in facial nerve preservation during acoustic neuroma surgery is partly due to the use of a facial nerve stimulator to anatomically locate the fibres. Our new acoustic nerve detector has the capability of anatomical location of cochlear fibres which may help to improve hearing preservation in selected cases of acoustic neuroma. The device functions by detecting the compound action potential evoked by no frequency auditory simulation at 500 Hz. The 500 Hz compound action potential is detected with a bipolar probe and then amplified and filtered. This results in a 500 Hz tone when the probe contacts the auditory nerve. Detection is virtually instantaneous. The acoustic nerve detector (AND) is demonstrated in a normal eighth nerve complex and its use is then described in the total removal of an acoustic neuroma with a 1 cm extracanalicular extension in which useful hearing was saved post-operatively. The present prototype may not be sensitive enough to detect the very low signals that may result when cochlear fibres are widely distorted around a large tumour or in cases where slight contusion of the nerve occurs during dissection. In all other cases the real time anatomical information is extremely helpful in guiding acoustic nerve dissection and also in monitoring the effects of petrous bone drilling.

Amplifiers, Electronic↗
PubMed1992

[Functional results of preservation of cranial nerves in removal of acoustic neurinoma].

Seventeen patients with acoustic neurinoma were reviewed on the basis of postoperative preservation of facial and acoustic nerve functions. The sizes of tumors were intracanalicular in 5 cases, smaller than 20mm in diameter in 2 cases, smaller than 30mm in 5 cases, and larger than 30mm in 5 cases. In all cases, the facial nerve was anatomically preserved at operation. Functional recoveries of the facial nerve in follow-up were excellent in 7 cases out of 17 (41%), good in 5 (29%) and poor in 5 (29%). Although the functional preservation for the facial nerve was related to the size of the tumor, it was favorable in cases of cystic tumor even with a size larger than 20mm. By pure tone audiogram, hearing was found to be preserved in 12 cases before operation. At operation, the acoustic nerve was anatomically preserved in 4 cases. Postoperative hearing was maintained in two cases, one of which showed a successful preservation of serviceable hearing. In this case, tumor resection was performed with intraoperative monitoring of auditory brain stem reactions (ABRs). Discussion was made concerning a possible surgical candidates for the hearing preservation, and it was proposed that every effort should be made to preserve the cochlear nerve if following conditions were verified in the case: 1) normal or nearly normal hearing (less than 40-50dB hearing loss), 2) the size of tumor is intracanalicular or smaller than 2cm in diameter, 3) there is no deterioration of intraoperative ABR.

Adult↗
PubMed1984

Reconstruction of the facial nerve in acoustic neurinoma surgery. Juxtapontine-intratemporal nerve graft.

Five cases of large acoustic neurinomas (diameter 2.5 cm) with involvement of the facial nerve in the tumour capsule are presented. The preoperative function of the facial nerve was normal. During surgery, in order to achieve a radical tumour removal, the facial nerve was severed juxtapontine. Reconstruction was performed at the same procedure using a 5-6 cm long sural nerve graft. Thus the central juxtapontine stump was joined to the peripheral stump in the facial nerve canal of the petrous bone. After six months, all five patients exhibited a well functioning mimic and a good eyelid function. At the one year control four patients had normal nerve function clinically and one patient still showed asymmetrical mimic.

Adult↗
PubMed1978

Eighth nerve in acoustic neuromas. Special reference to superior vestibular nerve function and histopathology.

Eighth nerve specimens were removed during acoustic neuroma surgery, and findings were related to cochlear and especially to superior vestibular nerve function as studied by conventional caloric testing in 21 cases. The origin of the tumor was in eight cases the inferior and in two cases the superior vestibular nerve, and in eight cases the vestibular nerve without more specific localization. In three advanced cases the exact site of origin could not be determined. Leaving age-related changes out of account, the utricle and horizontal canal ampulla appeared normal in all ears except one in which the ampulla was replaced by tumor tissue. In 11 ears the superior vestibular nerve was histologically intact and three of these ears also showed normal caloric responses. In seven ears there was a canal paresis, and in three no reaction was obtained. The ten ears with partial or total nerve invasion by tumor either showed a weak reaction or no response at all. It is likely that an early conduction block arises in both cochlear and vestibular nerves, and reduced reactions to appropriate stimuli do not warrant conclusions that the numbers of anatomically intact nerve fibers possibly are reduced.

Adult↗
PubMedDate not supplied

[Brain stem evoked potentials to acoustic stimulation in patients with neurinomas of the 8th cranial nerve].

Acoustic stimulation evoked stem potentials (ESP) were studied in 30 patients in different developmental stages (stages II and III) of neurinoma of the 8th nerve and after operation for removal of the tumor. The different character of changes of the ESP allows the effect of the tumor on the brain stem to be judged. Besides, dynamic follow-up of the ESP changes in the postoperative period as well as in later periods (3, 6, 12 months and later) is necessary for detecting the consequences of brain stem ischemia caused by compression by the tumor and for restoring the stem functions. Study of the ESP potentials is therefore an adequate method for the dynamic control of restoration of the brain stem functions after compression ischemia.

Adult↗
PubMed1998

Decompression of the labyrinthine segment of the facial nerve in acoustic neuroma surgery: a consideration for minimizing postoperative delayed facial nerve dysfunction.

Delayed facial nerve palsy, a condition characterized by spontaneous deterioration of facial nerve function in patients who had otherwise normal or near-normal facial function in the immediate postoperative period, has been reported in 15 to 29% of patients undergoing microsurgical resection of vestibular schwannomas. One putative mechanism for its occurrence suggests that edematous entrapment of the facial nerve in the meatal foramen (the narrowest segment of the internal auditory canal) may lead to nerve ischemia or necrosis and subsequent facial nerve dysfunction. To assess whether meatal decompression may help reduce the incidence of delayed facial nerve palsy during microsurgical resection of acoustic tumors, we compared 25 patients undergoing translabyrinthine removal of acoustic neuromas who received prophylactic decompression of the labyrinthine segment of the facial nerve (Group 1) with 40 patients who did not receive facial nerve decompression (Group 2). No patients in Group 1 had a delayed progressive facial paralysis with degeneration. In contrast, when Group 2 patients with larger, average-sized tumors were reviewed, eight patients (20%) developed delayed degeneration. These findings suggest that decompression of the labyrinthine segment may be of value in acoustic tumor surgery in reducing delayed facial nerve dysfunction. Further study is indicated in this important area.

Journal Article↗
PubMed1992

F response and somatosensory and brainstem auditory evoked potential studies in HMSN type I and II.

To evaluate conduction along the proximal and distal segments of motor and sensory long limb nerves, as well as along the very short acoustic nerve, F response and somatosensory and brainstem auditory evoked potential were studied in a series of patients with hereditary motor and sensory neuropathy (HMSN) types I and II. A diffuse and comparable slowing of conduction in proximal and distal nerve segments, as well as along the acoustic nerve, seems to favour a primary myelin defect in HMSN I. F response and motor conduction velocity showed a similar derangement in both proximal and distal motor segments. Latencies of somatosensory evoked potentials were symmetrically prolonged and correlated with motor nerve impairment. Central conduction times were normal. Studies of brainstem auditory evoked potentials showed a high incidence of acoustic nerve involvement, the most evident abnormality being a statistically significant increase in the latency of the I wave. Our data seem to support the presence of primary myelinopathic damage in HMSN I.

Adolescent↗
PubMed1989

[The facial nerve in acoustic tumor surgery].

The results of facial nerve function in twenty-four cases of acoustic neuroma removal using translabyrinthine approach from 1982 to 1987 were reported. Facial nerve had been paralysed in one case preoperatively. The facial nerve function were preserved in 21 out of 23 cases (91.3%). The appearance of facial nerve during surgery was as follows: normally located in 9 cases, displaced and deformed in 12 cases and invaded by the tumor in 3 cases. The size and location of the tumor determine the chance of preservation of facial nerve function. The procedures of manipulating the facial nerve and preventing the injury to the facial nerve during surgery were discussed in detail.

Adolescent↗
PubMed1993

Repair of facial nerve after removal of cerebellopontine angle tumors: a comparative study.

The results of repair of 18 facial nerves were examined by means of a modified House-Brackmann grading system. Six were repaired by end-to-end anastomosis and 12 by nerve graft. The reliability of the simplified House-Brackmann grading system was also assessed, using the kappa statistic to analyze the agreement between pairs of observers who examined the function of 40 nerves in 37 patients. Facial nerves studied had been either preserved, repaired or grafted, or divided and treated by faciohypoglossal nerve anastomosis. One nerve was not treated. The grading system proved to be somewhat unreliable, with complete agreement between observers in only 25% of cases. Facial nerve repair produced a fair return of function in just under two-thirds of the cases. The ability of an examiner ignorant of the patient's history to assess from the end result how the nerve had been managed was also estimated. Observers showed little ability to decide correctly on the previous treatment of the nerve when the patient showed moderate dysfunction postoperatively. The implications of these findings for grading systems and for management of the facial nerve in acoustic nerve tumor surgery are discussed.

Adolescent↗