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At least 541 records · Page 30Linked to original sources
PubMed2003

[Intraoperative monitoring of the facial nerve: anesthesia and neurophysiology considerations].

Intraoperative monitoring of the motor component of the 7th cranial pair or any other nerve should be routine during any surgical procedure involving risk of neural damage, whether or not the skull is opened. This paper discusses the main indications for monitoring facial and acoustic nerves during ear and neurosurgery involving the pontocerebellar angle (for acoustic neuroma or in surgery on the 8th cranial pair). Intraoperative electromyographic monitoring of the facial nerve should be used routinely in acoustic neuroma surgery to reduce the degree of postoperative neurological impairment and avoid possible malpractice suits. Although such monitoring requires that the muscle remain unblocked, intraoperative neuromuscular relaxants can be used if doses are administered along with appropriate monitoring of the level of peripheral neuromuscular block.

Anesthesia↗
PubMed1997

Facial nerve injury in acoustic neuroma (vestibular schwannoma) surgery: etiology and prevention.

Facial nerve injury associated with acoustic neuroma surgery has declined in incidence but remains a clinical concern. A retrospective analysis of 611 patients surgically treated for acoustic neuroma between 1973 and 1994 was undertaken to understand patterns of facial nerve injury more clearly and to identify factors that influence facial nerve outcome. Anatomical preservation of the facial nerve was achieved in 596 patients (97.5%). In the immediate postoperative period, 62.1% of patients displayed normal or near-normal facial nerve function (House-Brackmann Grade 1 or 2). This number rose to 85.3% of patients at 6 months after surgery and by 1 year, 89.7% of patients who had undergone acoustic neuroma surgery demonstrated normal or near-normal facial nerve function. The surgical approach appeared to have no effect on the incidence of facial nerve injury. Poor facial nerve outcome (House-Brackmann Grade 5 or 6) was seen in 1.58% of patients treated via the suboccipital approach and in 2.6% of patients treated via the translabyrinthine approach. When facial nerve outcome was examined with respect to tumor size, there clearly was an increased incidence of facial nerve palsy seen in the immediate postoperative period in cases of larger tumors: 60.8% of patients with tumors smaller than 2.5 cm had normal facial nerve function, whereas only 37.5% of patients with tumors larger than 4 cm had normal function. This difference was less pronounced, however, 6 months after surgery, when 92.1% of patients with tumors smaller than 2.5 cm had normal or near normal facial function, versus 75% of patients with tumors larger than 4 cm. The etiology of facial nerve injury is discussed with emphasis on the pathophysiology of facial nerve palsy. In addition, on the basis of the authors' experience with these complex tumors, techniques of preventing facial nerve injury are discussed.

Adolescent↗
PubMed1993

Assessment of central, peripheral, and autonomic nervous system functions in vibrating tool operators: neuroelectrophysiological studies.

To evaluate the effects of vibrating tool operation (i.e., combined stressors of local vibration, noise, cold climate, and heavy work) on the central, peripheral, and autonomic nervous systems, the short-latency somatosensory and brain stem auditory evoked potentials (SSEP and BAEP), the distribution of sensory median nerve conduction velocities (DCV), conventional median nerve conduction velocities (NCV), and the electrocardiographic R-R interval variability (CVRR) were measured in three groups of male vibrating tool operators and age-matched male healthy adults. Two components of the CVRR reflecting parasympathetic activity (C-CVRSA) and sympathetic activity (C-CVMWSA) were also examined. In the first group of vibrating tool operators (15 chain saw operators), all parameters of DCV (V10-V90 velocities) and sensory and motor nerve conduction velocities of NCV were significantly slowed. All peak latencies of SSEP were significantly prolonged, while no significant differences were found in the interpeak latencies of SSEP. The N9 peak latency of SSEP was significantly related to total working days. In the second group of the operators (12 chain saw and 8 brush saw operators), the I-V interpeak and V peak latencies of BAEP were significantly prolonged in the 12 chain saw operators; the I-V interpeak latency of BAEP was significantly correlated with the working years in the 8 brush saw operators. In the third group of vibrating tool operators, i.e., 13 operators with a history of vibration-induced white finger (VWF group) and 11 operators without VWF (non-VWF group), both the CVRR and C-CVRSA were significantly reduced in the VWF group; only the CVRR was significantly reduced in the non-VWF group. Similarly, the faster velocities of DCV (V70, V80, and V90 velocities) were significantly slowed in both the VWF and non-VWF groups. In conclusion, it is suggested that vibrating tool operation affects the faster sensory and motor nerve fibers, the parasympathetic activity, and the auditory pathway from the acoustic nerve to the brain stem.

Adult↗
PubMed1984

[A case of paroxysmal tinnitus and nystagmus accompanied by facial spasm].

Trigeminal neuralgia and facial spasm are usually caused by cross vascular compression of the trigeminal root entry zone and facial nerve exit zone. A similar mechanism is believed to affect the acoustic nerve as well, giving rise to tinnitus and nystagmus. We present one case of paroxysmal tinnitus and nystagmus, accompanied by facial spasm, and discuss the mechanism and the significance of the neurotological examination.

Arteries↗
PubMedDate not supplied

[Spontaneous and experimental vestibular activity following total removal of neurinomas of the auditory nerve].

Spontaneous and experimental vestibular activity in 84 patients after total resection of neurinomas of the acoustic nerve is analysed. In the immediate postoperative period the frequency of marked manifestations of spontaneous vestibular activity reduced sharply, but spontaneous nystagmus persisted in 97.5% of patients. In some patients spontaneous nystagmus to the side from which the tumor had been removed become more conspicuous. In the remote postoperative period spontaneous nystagmus was unilateral in 45.5% of patients, bilateral in 40.3%, and not recorded at all in 14.2% of patients. In the early postoperative period vestibular hyperreflexia was recorded in 93.7% of cases, in the remote period it was found in 76.6% of cases. Data obtained by comparing the results of caloric tests with cold and hot water in these patients are also analysed.

Adolescent↗
PubMedDate not supplied

Electrophysiologic study in acute lead poisoning.

A 2-month-old girl with acute lead poisoning demonstrated electrophysiologic evidence of neurotoxicity. Motor nerve conduction studies of the median, ulnar, peroneal, and posterior tibial nerves revealed both axonal and demyelinating neuropathy. Somatosensory evoked potential studies of median and posterior tibial nerves demonstrated evidence of cortical involvement. Brainstem auditory evoked potential study disclosed the possibility of acoustic nerve involvement but no evidence of a brainstem lesion. Postmortem examination revealed cerebral edema and focal segmental demyelination of the median nerve.

Acoustic Stimulation↗
PubMed2001

Management of benign cranial nonacoustic schwannomas by fractionated stereotactic radiotherapy.

Schwannomas are the most common tumors of cranial nerves. Nonacoustic schwannomas are very rare tumors, accounting for approximately 10% of intracranial schwannomas. Standard treatment is complete surgical resection if possible. The role of fractionated stereotactic radiotherapy remains to be defined. Thirteen patients with cranial nonacoustic schwannomas underwent fractionated stereotactic radiotherapy. Seven patients had trigeminal schwannomas, three schwannomas of the lower cranial nerves, and three located in the cerebellopontine angle without involvement of the acoustic nerve. Treatment included primary or adjuvant radiotherapy in progressive disease. Tumor volume ranged from 4.5 to 76.0 cc (median 19.8 cc). Median dose was 57.6 Gy with 1.8 Gy/fraction. Median follow-up was 33 months (range 13-70 months). Local tumor control rate was 100% (13/13). Tumor size remained stable in nine patients and decreased in four. Improvement of preexisting neurological deficits was seen in four cases. No patient developed new cranial nerve or brain stem deficits. No patient showed clinically significant complications of irradiation. Fractionated stereotactic radiotherapy is an effective and well-tolerated noninvasive treatment for cranial nonacoustic schwannomas with excellent tumor control rates. It is an option for patients at higher risk for microsurgical resection or in residual and recurrent tumors.

Adult↗
PubMed1976

Neurotoxic effects of dichloroacetylene.

In inhalation tests involving lethal as well as sublethal doses of dias examined in rabbits by means ofhistologic and neurofunctional methods. Histologic examination revealed chromatolysis, disintegration of Nissl bodies, and cell shrinkage in proportion to the doses employed in the nuclei of the unpaired brain stem, in the sensory cortical regions and especially in the sensory cranial nerve nuclei. The sensory trigeminal nucleus was involved most severely, followed in decreasing intensity 0y the facial and oculomotor nerves and the motor trigeminal nucleus; the least changes were observed in the acoustic nerve. By testing the protopathic sensitivity of the facial skin it was possible for the first time to produce evidence of a sensory loss in the distribution of the trigeminal nerve by animal experimentation. The neuropathological and functional deficits observed may explain the cranial nerve lesions in human DCA intoxication; however, these lesions seem to be less distinct in experimental animals.

Acetylene↗
PubMed1978

[Surgical treatment of hemifacial spasm associated with tortuous vertebrobasilar system (author's transl)].

Surgical treatment of hemifacial spasm associated with tortuous vertebrobasilar system was reported. A patient was 63-year-old female, who first experienced mild and intermittent muscle twitching around her left eye twenty years prior to admission. Five years later, the twitching extended to all the facial muscles on the left side. She was treated with facial nerve block, which resulted in facial palsy for about one year. Because of recurrence of the hemifacial spasm, she was admitted to the Neurosurgical Department of Bokuto Municipal Hospital on October 12, 1977. Neurological examination revealed no abnormalities except for left hemifacial spasm with slight muscular weakness. Electromyogram showed severe twitching and synkinesis of all the muscles of facial expression. Vertebral angiogram on the left side disclosed pronounced elongation of the vertebral and basilar arteries, which extended into the left cerebellopontine angle. Compression of the facial nerve root exit zone at the brainstem by the vertebral artery was considered to be the cause of the hemifacial spasm. Suboccipital craniectomy was carried out on November 29, 1977. The vertebral artery extended into the cerebellopontine angle, and adhered to the facial nerve. After mobilization of the vertebral artery from the facial nerve, a small prosthesis of non-absorbable spongy material (Teflon felt) was interposed between the vertebral artery and brainstem. Postoperatively, the hemifacial spasm disappeared, but the facial palsy, which had been observed preoperatively probably due to previous facial nerve block and long-standing hemifacial spasm, remained. The function of the acoustic nerve was preserved. Recently vascular compression of the facial nerve root exit zone has been reported as a major cause of hemifacial spasm, but such abnormal vessels are rarely demonstrated angiographically.

Basilar Artery↗
PubMed1982

Neurinoma of the oculomotor nerve. Case report.

A 15-year-old boy with a recurrent third nerve palsy who was found to have a neurinoma of the third nerve is described. Unusual features of his presentation and review of the literature relative to this rare tumor are discussed. Tumors derived from Schwann cells, which wrap around the axons of peripheral nerves, are called neurinomas, neurofibromas, plexiform neurofibromas, neurilemomas, and schwannomas. Neurinomas are usually localized in the peripheral nerves. The most frequent site of occurrence of an intracranial schwannoma is the acoustic nerve; however, the tumor may occur along the second, fifth, seventh, 11th, and 12th cranial nerves. Neurinomas of the oculomotor nerves are extremely rare. In the literature, there are only four reported cases clinically manifested and pathologically verified as neurinomas of the third nerve.

Adolescent↗
PubMed1987

Indirect injury to cranial nerves after surgery with Cavitron ultrasonic surgical aspirator (CUSA). Case report.

The Cavitron ultrasonic surgical aspirator (CUSA) was used in a patient with an acoustic nerve tumour. After surgery she presented unilateral palsies of several cranial nerves. The nerve injuries were most likely induced by ultrasonic energy transmitted from the CUSA via the petrous bone. We suggest that when the CUSA is used in such operations care should be taken to avoid contact between the vibrating probe of the CUSA and the petrous bone.

Aged↗
PubMedDate not supplied

[A study of damaged acoustic biopotentials in guinea pigs following exposure to white noise].

62 guinea-pigs were treated twice exposed to white noise, 105 dB SPL, 20 to 20 000 cps for 40 minutes with a break of 24 hours in between. The cochlear microphonics (CM), the compound action potentials of the acoustic nerve (NAP) and the slow evoked potentials (SEP) were recorded. There were different degrees of damage to be seen in the acoustic biopotentials. The CM showed little damages only whereas the compound action potentials of the hearing nerve showed significant impairments in excitation and in adaptation. In the SEP excitation was decreased. From this, we may conclude that the CM must not be the only criterion for judging damages in the acoustic system after acoustic trauma. Furthermore we see that the central acoustic pathway is capable to compensate peripheric hearing damages within a short time. An additional exposure to noise does not necessarily add or cumulate the degrees of damage.

Action Potentials↗
PubMed1989

[Recording of electric evoked responses from the distal field of the vestibular part of the VIII nerve. Preliminary report].

The authors described the results of distant field registration of evoked responses from the vestibular part of acoustic nerve. The investigations were carried out as a preliminary pilot study and were successful in obtaining the repeatable responses in guinea pigs. The detailed informations about the stimulation, reception and average technique equipment were enumerated. The variant proposition of the extraction of side motor disturbances was done.

Animals↗
PubMed1984

Neurovascular decompression for hemifacial spasm.

Results of 23 cases of facial spasm operated on by posterior fossa exploration were reviewed. In all cases, but one, vessels were found to impinge on the facial nerve root exit zone from the brain stem. All cases in which the facial nerve had been liberated from the vessel had satisfactory results and there was no recurrence of spasm. Significant sensorineural hearing loss occurred postoperatively in 11 cases. The hearing loss greatly improved within a month and persisted as permanent loss greater than 10 dB in 6 cases (26.0%). The complication has been lessened by approaching to the nerve from caudal direction and by retracting the cerebellum to oblique direction to the acoustic nerve. Microvascular decompression is the best procedure available for hemifacial spasm.

Adult↗
PubMed1985

[Implantation technics for long-term recording of the compound action potentials in the guinea pig, Cavia porcellus. A comparison of methods].

Long-term recordings of the compound action potential of the acoustic nerve of young, pigmented guinea pigs were carried out by two different techniques of implantation. The electrodes were inserted either by way of the mastoid process into the bony recess above the round window or they were introduced into the facial canal via the stylomastoid foramen. Before and after each implantation, special tests (Preyer-reflex, otoscopy, impedance audiometry) were performed for preliminary selection of the animals and to discover postoperative induced disturbances of sound conduction in the middle ear. These tests showed that the proportion of operatively induced middle ear inflammations was reduced from 24 to 10%, if electrodes were implanted into the facial canal.

Acoustic Impedance Tests↗
PubMed2005

Schwannoma of the palatine tonsil.

Schwannoma is a solitary, benign tumour arising from the neural sheath Schwann cells of the peripheral, cranial or autonomic nerves. In the head and neck region, it occurs most commonly in association with the acoustic nerve within the skull and is rarely found in oral structures. When it is found in oral structures, the tongue is reported to be the favoured site. Schwannoma of the tonsil is extremely rare, with only two cases reported in the literature. We report what is, to our knowledge, the third case of schwannoma of the tonsil, diagnosed by histopathology.

Adult↗
PubMed1990

[Electrophysiologic studies in patients with cochlear implants].

The insertion of reliable extracochlear single-canal cochlear implants in cophotic and subcophotic patients allows the electrical stimulation of the acoustic nerve for rehabilitation, as well as audiovestibular explorations that are no longer possible in the acoustic mode. The authors therefore aim at replacing all these examinations with their Electrical equivalent: --early evoked potentials (E-BERA), --medium-latency evoked potentials (E-MLR), --Event-related evoked potentials (E-P300), for which, to our knowledge, theses are the first recordings, --electrical stapedial reflex, --vestibular stimulations. The method, results and clinical and physiological applications of each method are given, as well as its prospects.

Acoustic Stimulation↗