Distortion-product otoacoustic emissions and glycerol on the guinea pig hydropic ear.

OBJECTIVE: The aim of the present work was to investigate the therapeutic effects of glycerol on the distortion-product otoacoustic emissions in guinea pigs in which experimental endolymphatic hydrops had been surgically induced. METHODS: Thirty albino guinea pigs were used. The experimental protocol considered three groups of guinea pigs (10 animals each). Group 1 received no drug treatment, while group 2 and 3 were given glycerol orally 0.75 and 0.50 g/kg of body weight once a day for 24 days. RESULTS: The animals treated with glycerol showed an improvement of the distortion-product emission responses in the middle frequencies. This effect was not observed in the higher frequency region. This effect was evident 7 days after glycerol administration in the guinea pigs treated with a dose of 0.75 g/kg. The 0.50 g/kg dosage gave evidence of ameliorating effects 14 days after treatment. CONCLUSION: Glycerol given orally resulted in an improvement of distortion-product otoacoustic emissions in the guinea pig. Further studies are necessary before the effect of such a treatment can be assessed in humans.

Acute mastoiditis in pediatric age.

The object of the present paper is to review 39 cases of acute mastoiditis treated surgically at the 2nd and 4th ENT Clinics of the University of Rome 'La Sapienza'. The aetiological factors were investigated observing an association of the acute mastoid abscess with cholesteatoma. Moreover 5 patients developed mastoiditis after previous mastoid surgery. The rationale of surgical management is discussed.

Facial nerve monitoring in skull base surgery.

The purpose of this work was to compare pre- and post-operative facial nerve function between unmonitored and monitored cases of skull base lesions. The study involved 32 patients suffering from lateral skull base tumours (10 unmonitored and 22 monitored). Facial nerve function was monitored intraoperatively by an acoustic facial electromyographic system (NIM-2). Post-operative facial function was graded according to the House-Brackmann scale. In the group of monitored cases, facial nerve function was normal (Grade 1 or 2) in 79 per cent of the patients, while the unmonitored patients showed normal function in only 50 per cent of the cases. These results confirm previous observations that audible evoked electromyographic monitoring significantly reduces permanent facial nerve dysfunction.

Experimental endolymphatic hydrops and glycerol. Electrophysiologic study.

The object of the present study was to evaluate electrophysiologically the therapeutic effect of glycerol on the cochlear function of guinea pigs in which experimental hydrops had been surgically induced. Fifteen albino guinea pigs were used. Each animal was chronically implanted to follow the evolution of hearing. The experimental protocol considered 3 groups of guinea pigs (5 animals each). Group 1 received no drug treatment, while groups 2 and 3 were given glycerol orally at 0.75 and 0.50 g/kg of body weight once a day for 4 months. The audiograms of the animals treated with glycerol showed a statistically significant hearing improvement compared with the control group. Clinically, our results seem to support the view of those who favor the use of glycerol for the medical treatment of Meniere's disease at an early stage.

The contralateral ear after surgery in different otoneurosurgical or neurosurgical pathologies.

The present study was specifically designed to ascertain the effect that otoneurosurgical or neurosurgical approaches may have on the contralateral ear. 18 patients suffering from different histologic lesions were examined. Pure-tone audiometry was performed before and after surgery each postoperative day up to the fourteenth day. The audiograms were abnormal after surgery in all but one of the patients tested. This hearing loss was transitory and the recovery occurred completely within 3 months. These outcomes suggest that the hearing loss was linked to a loss of cerebrospinal fluid.

Primary adenoid cystic carcinoma of the middle ear and mastoid.

Two primary adenoid cystic carcinomas of the middle ear and mastoid are presented. This pathologic condition is uncommon and no large series exist in the literature. Adenoid cystic carcinoma could arise from ectopic salivary gland tissue located in the wall of the jugular bulb in proximity to the hypotympanum. These tumors demonstrate much invasion of bone and soft tissue. The surgical rationale in the management of this rare tumor is discussed.

[Experimental perilymphatic fistula: the electrocochleographic findings]. / Fistola perilinfatica sperimentale: rilievi elettrococleografici.

The aim of the present study was to evaluate the effect of experimental perilymphatic fistula on cochlear electrophysiological responses. Six albino guinea pigs, in which recording electrodes were implanted in order to record the electrocochleogram, were used. Experimental protocol investigated cochlear responses before the induction of the fistula in the round window membrane perforation and then two month later. Compound action potential thresholds increased immediately after perforation of the round window membrane. The thresholds rapidly recovered. This phenomenon was accompanied by clear-Out reduction in amplitude upon suprathreshold stimulation. This latter observation associated with a decrease in the amplitude of the threshold seems to be a specific audiologic sign of the fistula. The clinical implication are discussed.

Vestibular neurectomy by the infralabyrinthine approach.

There are a variety of approaches for treating vertigo with selective vestibular neurectomy but each has definite limitations proving that no ideal technique is yet available. An original posterior-inferior approach to the internal auditory canal (infralabyrinthine approach) has been recently proposed. It attempts to overcome the limitations and to combine the advantages of the previous procedures. This report presents our preliminary results using this particular technique in the management of vestibular symptoms of Menière's disease.

Reconstruction of old radical cavities.

Various techniques and materials have been proposed to deal with problems connected with radical cavities including recurrence of inflammatory processes, requirement of regular medication, social inconvenience (i.e., inability to practice any water sport, work in adverse environment, etc.). The present paper details the results of revalidation of old radical cavities using as filling a mixture of tricalcium phosphate and hydroxyapatite granules. Three techniques were used in reconstruction of the posterior canal wall. In the first procedure, the material was incorporated with fibrin adhesive to fill the cavity. In the other two methods the ceramic granules were covered respectively with a sheet of bone pate-fibrin sealant or with septal cartilage homografts. Twenty-four patients with chronic discharging old radical cavities were operated with anatomic results of 91.7 percent successful graft taken. The functional results showed an air-bone gap less than 30 dB in 72.7 percent of the cases after 6 months. After 2 years hearing gain was satisfactory in 63.6 percent of the patients. The different methods of reconstruction of posterior canal wall did not influence these findings.

The effect of glycerol on the guinea-pig hydropic ear.

The aim of this paper was to investigate the effect of glycerol on experimental endolymphatic hydrops in guinea-pigs. The right endolymphatic sac and duct were obliterated through an extradural posterior fossa approach. Some animals received a 3 g/kg dose of glycerol for a period of 7 days, whereas others received the same dose for 30 days. The activity of glycerol was studied by investigating the volumetric changes in the scala media determined with a computerized planimeter. Glycerol induced a significant reduction of the hydrops showing its effectiveness and suggesting a strial metabolic response.