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At least 91 records · Page 5Linked to original sources
PubMed1992

Changes in the acoustic nerve after hair cell regeneration.

Hair cells of the avian inner ear have been shown to regenerate following acoustic or ototoxic insult. The consequences of this regeneration on the acoustic nerve have yet to be defined. The purpose of the present study was to use TEM analysis following cochlear damage and hair cell regeneration to describe afferent and efferent neural terminals on hair cells in the newly repopulated sensory epithelium. Following acoustic overstimulation (12 h, 115 dB SPL, 1500 Hz) adult quail were sacrificed immediately (0 day), or at 2, 12, or 24 weeks. Serial thin sections were taken from the embedded papilla in a plane tangential to the basilar membrane in the area consistent with regenerative activity. Immediately following noise exposure very few hair cells could be seen within the epithelia; afferent terminals on remaining cells appeared normal. Two weeks later afferent terminals showed signs of degeneration; efferent terminals were rarely seen on tall hair cells but remained relatively normal on short hair cells. Three to six months later afferent terminals had regained a more normal appearance but were less numerous on tall hair cells; some return of efferent-like terminals was seen often contacting two tall hair cells. Large normal appearing, efferent terminals remained on short hair cells. These results suggest that regenerated hair cells are likely to receive neural innervation. It would appear that some degeneration of afferent terminals takes place prior to final innervation of new hair cells.

Acoustic Stimulation↗
PubMed1990

[The effects of mono- and bipolar stimulations of the acoustic nerve by a pulse current].

The amplitudes of the EPs during monopolar and bipolar stimulation of the acoustic nerve were analysed in the cat auditory cortex. Increasing number of trains of 0.2 and 0.5 msec duration of short (5 mu sec) electric pulses were delivered to the streptomycin-damaged cochlea. The comparison of the two types of stimulation revealed a larger dynamic range and a higher increase in the amplitude at the bipolar stimulation. The average value of the stimulation current was lower for the monopolar stimulation.

Animals↗
PubMedDate not supplied

[Computer tomography in the diagnosis of neurinomas of the acoustic nerve].

Computer-aided tomography (CT) was used in the examination of 259 patients with neurinoma of the acoustic nerve. Characteristic direct and indirect signs of the tumor and the degree of their manifestation depending on the size and predominant direction of the growth of the neurinoma were determined. In 46 patients the size of the tumour established by computer-aided tomography was compared with that revealed on operation. It was established that computer-aided tomography demonstrates exactly the true size of tumors whose compactness is greater than that of the brain matter. It is difficult to determine by CT the true size of tumors of low density and particularly those possessing isodensity; in some cases they are much larger than conceived from analysis of the computer-aided tomograms. Tumors less than 10 mm in diameter which cannot be recognized by ordinary CT can be diagnosed by CT and cisternography with amipak.

Adult↗
PubMed1984

[Surgery of large neurinomas of the acoustic nerve performed only by the translabyrinthine approach. Apropos of 50 cases].

A combined otoneurosurgical team has operated upon 68 patients with acoustic nerve neurinomas over a period of 13 months (Sept. 1982-Oct. 1983). Exploration and operation in this homogeneous series were carried out under the same conditions, and a CT scan was performed in each patient before and after surgery. The size of the neuroma was less than 2 cm in diameter in 18 cases, between 2 and 3 cm in 28 cases, between 3 and 4 cm in 10 and 4 cm or more in 12. This report relates to the 50 neurinomas over 2 cm in diameter, these requiring multidisciplinary co-operation during surgical removal. The translabyrinthine approach was used exclusively in 48 cases, and was combined with a retrosigmoid approach in the other 2 cases. Total tumoral excision was possible in 46 cases (92%) and partial removal in 4 patients (8%). Complications included one death (bilateral giant neurinomas), resolving purulent meningitis (2 cases), 3 patients with cerebrospinal fluid fistulae which healed after lumbar drainage, and 1 case of postoperative hematoma in the ponto-cerebellar angle requiring further surgery. The facial nerve was undamaged in 48 cases (96%). Postoperative facial palsy developed in 39 cases, and 15 have recovered subnormal motility. Follow up is insufficient in the other 17 patients. It is suggested that the translabyrinthine approach enables ablation of neurinomas of whatever size. This approach is reliable since it avoids injury to neighboring nerve structures. The facial nerve is detected immediately and can be protected throughout operation. The latter is, however, a long and difficult procedure, and otoneurosurgical collaboration is advisable.

Adult↗
PubMed2000

Epithelioid schwannomas of the acoustic nerve.

Epithelioid schwannomas occur predominantly in relation to peripheral nerves and are associated with histological and clinical malignancy. However, a variant of the epithelioid schwannoma involving cranial nerves is extremely rare. In this study we report three cases of epithelioid schwannomas originating from the acoustic nerves and located in the cerebello-pontine angles. In the first case, the tumor was histopathologically entirely solid and demonstrated biphasic pattern with both spindle-shaped cells and a population of round or polygonal epithelioid cells. The second one consisted of the smaller part exhibiting typical Antoni B and A tissue and large areas containing clusters and bundles of epithelioid cells. Purely epithelioid schwannoma composed predominantly of cords or nests of round and polygonal epithelioid cells were observed in the third case. All schwannomas revealed marked polymorphism and nuclear hyperchromasia. Immunohistochemical studies showed a diffuse, strong positivity for S-100 protein in the cytoplasm of the spindle and epithelioid tumor cells. These two populations of cells were positively stained for vimentin, but were negative for EMA, cytokeratin and HMB45. Patchy GFAP-immunoreactivity was also noticed at the peripheral parts of the tumors. The authors discuss differential diagnosis of this unusual variant of schwannoma in relation to malignant transformation of the epithelioid component.

Adult↗
PubMedDate not supplied

[A comparative assessment of the results of plastic surgery on the facial nerve following total removal of neurinomas of the acoustic nerve].

The study was conducted in 3 patients following the application of intracranial facial nerve anastomoses, in 25 patients with the facial nerve anastomosed with the accessory nerve, and in 17 patients with facial-hypoglossal nerve anastomoses. Apart from the clinical observations of the facial muscle contractions, the comparative evaluation of the plastic operations was conducted with the aid of electromyography, electrogustometry and salivary glands secretion studies. The authors concluded that the intracranial anastomosis results in better restoration of the motor function of the facial muscles, the gustation being also partially restored on the side on the intervention. Among the anastomoses of the VII nerve with the XII and XI that with the XII is preferred.

Adult↗
PubMed1997

Ganglionic hamartoma of the intracanalicular acoustic nerve causing sensorineural hearing loss.

OBJECTIVE: This article highlights the clinical presentation and treatment issues of ganglionic hamartoma of the internal auditory canal and emphasizes the similarity of this lesion to acoustic neuroma regarding its audiologic and radiographic characteristics. STUDY DESIGN: This article is composed of case reports and a literature review. SETTING: The study was performed at a university hospital/tertiary referral center. PATIENT: A patient with biopsy-proven ganglionic hamartoma of the acoustic nerve was studied. INTERVENTION: Intervention consisted of surgical therapy. MAIN OUTCOME MEASURE: The main outcome measure was clinical evaluation. RESULTS: The result was successful removal of lesions with facial nerve preservation. CONCLUSIONS: An intracanalicular ganglionic hamartoma resulted in progressive sensorineural hearing loss and magnetic resonance imaging findings suggestive of small acoustic neuroma. This lesion, composed of an admixture of ganglion cells, fibroadipose-tissue, and normal myelinated axons, although rare, should be added to the differential diagnosis of internal auditory canal lesions.

Adult↗
PubMedDate not supplied

[Subarachnoid hemorrhage as the 1st clinical manifestation of neurinoma of the acoustic nerve].

The association of sub-arachnoidal hemorrhage and benignant tumors of the pontocerebellar angle represent a rare event. The authors describe a case of neurinoma of the acoustic nerve which revealed itself with a sub-arachnoidal hemorrhage. After recalling the other only observation reported in literature, the authors discuss both its clinic and etiopathogenesis.

Cerebral Angiography↗
PubMed1976

[The relationship between the clinical picture and course of acoustic nerve tumors and the direction of their growth in the cerebellopontine angle].

The data of clinical, surgical and post-mortem studies in 95 patients with neurinomas of the acoustic nerve permitted to eliminate 3 variants in the growth of neoplastical process into the ponto-cerebellar angle: 1) subtentorial (the upper variant) -- 27 cases; 2) the middle line of the brain stem (middle variant) -- 15 cases; 3) the lower parts of the angle (lower variant)--52 cases. Depending upon the direction of the growth into this space and upon the stage of the disease there were differences in the succession, frequency and expressiveness of focal and general brain symptoms. The development of the disease also differed.

Adult↗
PubMedDate not supplied

[Dynamics of the otoneurologic symptoms after complete and partial removal of a tumor of the acoustic nerve at different stages of its development].

The peculiarities of the dynamics of the entire complex of otoneurologic symptoms were studied in 60 patients with a tumor of the acoustic nerve in stages II and III of the disease after total (in 38) and partial (in 22) resection of the neoplasm. The data obtained bore evidence that the dynamics of the otoneurologic symptoms depended on the developmental stage of the tumor, its relation to the brain stem, and the character of the operation (total or partial removal of the tumor). Total resection of the tumor in stage II proved most effective: in the residual period both stem vestibular disorders and statokinetic and coordination disturbances were minimum or absent. In total removal of the tumor in stage III of the disease the regression of the symptoms was delayed and much less apparent. In subtotal removal of the tumor during stage II the symptoms regressed slightly or not at all. Symptomatology remained gross, irreversible or even frequently became more severe after subtotal removal of the tumor in stage III of the disease.

Audiometry↗
PubMedDate not supplied

[CLinico-morphologic correlations in cases of fatal outcome following removal of acoustic nerve neuromas].

The clinical findings were compared with the results of morphological examination of the brain in 32 patients who had died in different periods after surgery for removal of neurinoma of the acoustic nerve. In all cases vessels supplying the brain stem were injured during removal of the tumor. In 5 cases all three groups of arteries of the pons varolii were injured, which led to the development of infarction of half of the pons. The short circumflex pons arteries and the anterior inferior cerebellar artery were injured in 18 patients, which caused the formation of an infarct in the lateral part of pons varolii. The distal segment of the anterior inferior cerebellar artery was injured in 9 patients, as a result of which a small focus of infarction formed in the dorsolateral parts of the pons.

Arteries↗
PubMed1989

[Neurinoma of the acoustic nerve diagnosed at the otoneurologic laboratory of the Regional Hospital with Polyclinic in Ostrava].

In 1977-1987 at the otoneurological laboratories of the Regional Hospital with Policlinic in Ostrava 41 neurinomas of the acoustic nerve were diagnosed. The incidence of the disease in the catchment area was 1:125,555 per year. Women were affected more frequently than men, the mean ratio being 5:3. 12% of the tumours were under 1 cm in size and 30% under 2 cm. In women and youth as a rule larger tumours were found than in men. Women had also on average a shorter case-history--by 1.5 years. Acute unilateral hypacusia, as the initial symptom of the disease was recorded in 17% of the patients, again more frequently in women (23%) than in men (6.5%). In the majority of patients the diagnosis was late through the fault of the attending physician who for long considered the patient's complaints trivial and did not indicate an adequate examination. The thus lost time reduces the patient's chances. Even the most perfectly equipped otoneurological laboratory with optimal diagnostics cannot reverse the patient's sad fate.

Adolescent↗
PubMed1977

Observations on the etiology of trigeminal neuralgia, hemifacial spasm, acoustic nerve dysfunction and glossopharyngeal neuralgia. Definitive microsurgical treatment and results in 117 patients.

Microsurgical observations have been made of the cranial nerve root entry or exit zones 117 patients operated upon for the treatment of hyperactive-hypoactive dysfunction syndromes (trigeminal neuralgia, hemifacial spasm, acoustic nerve dysfunction, and glossopharyngeal neuralgia). Cross-compression or distortion of the appropriate nerve root at its entry or exit zone was noted in all patients. This compression or distortion was usually caused by normal or arteriosclerotic, elongated arterial loops, it was usually relieved by decompressive microsurgical techniques. A small percentage of patients were found to have compression of the nerve root at the entry-exit zone by a tumor, a vein, or some other structural abnormality; they were relieved by tumor excision or other measures as described. Relief was gradual postoperatively if the treated nerve was not stroked or manipulated at operation but it was immediate if the nerve was manipulated. Preoperative evidence of decreased nerve function improved postoperatively.

Adult↗