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Patients with aplasia and hypoplasia of the cochlear nerve have no chance of having their hearing restored by stimulating the periphery of the auditory system using the traditional cochlear implant. A possible approach to auditory rehabilitation may be direct electrical stimulation of the cochlear nuclei with an auditory brainstem implant (ABI). Recently, two children, aged 4 and 3 years, respectively, with bilateral severe cochlear malformations and cochlear nerve aplasia received an ABI. The present paper reports the technique and the preliminary results of this experience. The classic retrosigmoid approach was used. The correct position of the electrodes was estimated with the aid of EABRs and neural response telemetry (NRT). No postoperative complications were observed. High-resolution CT scans with a bone algorithm reconstruction technique were taken postoperatively to evaluate electrode placement before discharge. The ABI was activated 30 days after implantation in both patients. To date 16 and 13 electrodes, respectively, have been activated in the two children. Three months after activation the first patient had achieved good environmental sound awareness, good speech detection and some speech discrimination. The second child, 1 month after activation, had achieved good environmental sound awareness and moderate speech detection. To the best of our knowledge this is the first report of patients with hypoplasia of the cochlea and aplasia of the cochlear nerve, aged below 5 years and treated with an ABI.

The present paper reports our experience with the surgical retrosigmoid-transmastoid (RS-TM) technique for implanting auditory brainstem implants (ABIs). From April 1997 to August 1998, four patients with neurofibromatosis type 2 (NF2) were operated on for vestibular schwannoma removal with ABI implantation. The subjects (three men and one women) ranged in age from 22 to 31 years. Tumour size ranged from 12 to 30 mm. A classical RS-TM approach was performed. After tumour excision, identification of landmarks (VIIth, VIIIth and IXth cranial nerves, choroid plexus) to the foramen of Luschka was carefully carried out. The choroid plexus was partially removed and the tela choroidea divided and deflected. The floor of the lateral recess of the fourth ventricle and the convolution of the dorsal cochlear nucleus became visible. The electrode array was then inserted into the lateral recess and placed in the correct position with the help of electrically-evoked auditory brain stem responses. Auditory sensations were induced in all patients with various numbers of electrodes. Different pitch sensations could be identified with different electrode stimulation. Details of the results are presented. In our series, the RS-TM approach represents the elective route for ABI insertion.

The middle fossa approach was used in 11 patients with profound bilateral hearing loss for insertion of a cochlear implant. Fibroadhesive otitis media (n = 1), bilateral cavity radical mastoidectomy (n = 1), autoimmune inner ear disease (n = 2), previous cranial trauma (n = 1), genetic prelingual deafness (n = 5), and otosclerosis (n = 1) were the causes of deafness. A cochleostomy was performed on the most superficial part of the basal turn, and the electrode array was inserted up to the cochlear apex. Speech perception tests (1-9 months after cochlear implant activation) yielded better results in these patients compared with a homogeneous group of postlingually deaf patients operated on through the traditional transmastoid route. Insertion of the implant through the middle fossa cochleostomy furnishes the possibility of stimulating areas of the cochlea (ie, the middle and apical turns) where a greater survival rate of spiral ganglion cells is known to occur, with improvement of information regarding the formants relevant for speech perception.

From April 1997 to December 1999, six patients (five men and one woman), ranging in age from 22 to 37 years with neurofibromatosis type 2 (NF2) were operated on via the classic retrosigmoid-transmental (RS-TM) approach for removal of a vestibular schwannoma (VS) (tumor size from 12 to 40 mm) and for auditory brain stem implantation (ABI). After tumor removal, the floor of the lateral recess of the fourth ventricle and the convolution of the dorsal cochlear nucleos were reached, and the ABI was inserted. More recently, an ABI was implanted via the retrosigmoid approach in a 4-year-old boy with a cochlear malformation (common cavity) associated with cochlear nerve aplasia. Electrically evoked auditory brain stem responses (EABRs) and neural response telemetry (NRT) were performed to verify the correct positioning of the inserted electrodes. No major complications related to ABI were observed. ABI has been activated to date in five of the NF2 patients. Auditory sensations with various numbers of electrodes were evoked in all patients. We consider the RS-TM approach the route of choice for ABI insertion in patients with NF2 and good hearing, offering a chance of hearing preservation, and in patients with complete cochlear ossification, severe head trauma and cochlear fracture, or nerve disruption, or a combination of these. A new indication for ABI implantation via the RS approach is presented by patients with bilateral cochlear nerve aplasia.

Nine patients with profound bilateral hearing loss received a cochlear implant via the middle fossa. Subjects presented with a bilateral radical mastoidectomy cavity, fibroadhesive otitis media, otosclerosis, autoimmune inner ear disease, previous cranial trauma and genetic prelingual deafness. A classic middle fossa approach was adopted. A small cochleostomy was performed on the most superficial part of the basal turn. A Nucleus CI24M cochlear implant system (Cochlear Corporation) was inserted in four patients, a Lauraflex implant (Philips Hearing Implants) in three patients and a Combi 40 + (Med-el) with double electrode array in two. The receiver-stimulator was positioned in a bone well drilled in the temporal squama and the electrode carrier was inserted in the fenestrated cochlea. Speech perception tests, performed over a period of time ranging from 1 to 6 months after cochlear implant activation, yielded better results than those obtained in postlingually deaf patients operated on via the traditional transmastoid route. Cochlear implant insertion via the middle fossa approach is a technique which is suitable for auditory rehabilitation of subjects with a bilateral radical mastoidectomy cavity, chronic middle ear disease, patients suffering from middle ear malformations, and patients with partial obliteration of the cochlea in the basal turn. However, the main advantage of middle fossa cochleostomy consists in the possibility of stimulating areas of the cochlea, i.e. middle and apical turns, where a greater survival rate of spiral ganglion cells is known to occur. This new approach led to major improvements in speech perception in all patients compared with patients operated on with the transmastoid approach and thus, given the present state of the art, it is the only approach which allows stimulation of the entire cochlea and enables the best auditory outcomes to be achieved in patients with a cochlear implant.

Absence of the long process of the incus with or without absence of the stapes head accounts for more than 80% of ossicular discontinuities. Total or partial replacement prostheses, made of various materials, are interposed to restore the transfer function of the middle ear. To simplify ossicular reconstruction, reduce operative times and costs, improve functional outcomes, and avoid the risk of infections, we have adopted, during the past 10 years, a technique that makes use of a personally designed alloplastic prosthetic device. The prosthesis connects the malleus to the footplate, even in the presence of the stapes superstructure. This malleus-to-footplate prosthesis consists in a plastipore-coated steel piston and hydroxyapatite head, complete with a groove. The groove is placed beneath the malleus neck after dissection of the tensor tympani tendon and the shaft of the piston on the footplate. Two hundred ninety primary ossiculoplasties with the malleus-to-footplate prostheses were performed in 265 patients from 1986 to 1995 in the ENT Department of the University of Verona. The average postoperative air-bone gap at 0.5 to 3 kHz was 11 dB at 1 year and 14 dB at 5 years. These outcomes are significantly better than those personally obtained previously with ossicular or alloplastic prostheses. No extrusions occurred. The structural characteristics of the malleus-to-footplate prosthesis endow the prosthesis with a high degree of biocompatibility and stability and optimal sound-transfer function. The rationale for this particular ossiculoplasty procedure is discussed. (Otolaryngol Head Neck Surg 1999;120:437-44.)

One hundred three subjects with acoustic neuroma (AN) underwent surgery—involving a retrosigmoid-transmeatal approach—between January 1990 and December 1995. All the intracanalar tumors ( n = 18) and 70 of the intra- and extracanalar neuromas with an extracanalar neuroma size less than 25 mm—a total of 88 patients—constituted the final study population. The first 48 patients were operated on with the use of classic procedures described in the literature, characterized by limited exposure of the internal auditory canal and removal of the tumor after debulking. Surgery in the next 40 subjects was conducted according to the technique of en bloc removal of the tumor. The main features of this technique are continuous direct recording of cochlear and facial-nerve action potentials, wide opening of the internal auditory canal with lateral extension to the fundus, and removal of the tumor following the capsular lining without debulking. Statistical analysis of the results of the en bloc removal, compared with the previously used debulking technique, showed improvement in postoperative outcome for both auditory and facial-nerve function. (Otolaryngol Head Neck Surg 1999;120:122-8.)

The current article describes the surgical technique and the very preliminary results of insertion of a cochlear implant, via the middle fossa (MF), in patients with middle ear disease.The study design was a case report and a description of surgical technique.The study was conducted at an ENT Department, University of Verona, Verona, Italy.Two subjects with profound bilateral hearing loss, the first one presenting a bilateral radical mastoidectomy cavity and the second one with fibroadhesive otitis media, were operated on via the current technique.After adequate exposure of the MF floor, a triangular bony area between the greater superficial petrous nerve and the projection of the labyrinthine portion of the facial nerve was drilled out. The basal cochlear turn facing the middle cranial fossa floor was easily encountered, a small cochleostomy measuring 1 1/2 mm in diameter was performed on the most superficial part of the basal turn, and the electrode carrier was inserted into the fenestrated cochlea. The receiver-stimulator was positioned on a bone well drilled previously in the temporal squama.The activity of the inserted electrodes was tested by means of telemetry and intraoperative recording of the electrically evoked auditory responses. Speech perception tests, performed 15 and 30 days after cochlear implant activation, showed a remarkable improvement in the outcomes versus the preoperative values that are provided for comparison.This new surgical approach to cochlear implant insertion via the MF route allows stimulation of part of the basal and the middle and apical areas of the cochlea, where greater survival rates of spiral ganglion cells are observed. Cochlear implant insertion via the MF approach represents a promising technique for auditory rehabilitation of subjects with a bilateral radical mastoidectomy cavity, patients suffering from middle ear malformations or chronic middle ear disease due to eustachian tube dysfunction, or subjects with doubtful responses to promontory stimulation.

This study aimed to illustrate some recent advances in intraoperative monitoring of the seventh and eighth cranial nerves (i.e., direct recording of cochlear nerve action potentials [CNAPs] and facial nerve action potentials [FNAPs]).Reports of representative cases and average postoperative results obtained in subjects submitted to cerebellopontine angle surgical procedures are examined. Results obtained in patients with direct recording techniques are compared with those obtained with the classical monitoring techniques (auditory brain stem response [ABR], electrocochleography [ECoG], facial electromyography [EMG]).The study was conducted at an Ear Nose and Throat Department, University of Verona, Verona, Italy.Intraoperative monitoring during cerebellopontine angle surgery was performed.Patients monitored with direct audiomonitoring techniques presented better postoperative auditory functions compared to patients monitored with ABR. The FNAP and EMG groups showed FN outcome that did not differ significantly.Intraoperative monitoring of cranial nerves furnishes a valid tool for identification of neural structures, prevention of damage, understanding of the pathophysiology of damage, and prediction of postoperative function. The fundamental prerequisite for obtaining optimal benefits from monitoring is the use of techniques of direct and continuous electrophysiologic recording with instantaneous feedback to the surgeon, such as CNAPs and FNAPs.

Surgery of acoustic neuroma (AN) has significantly refined over the past years due to a series of advances in diagnostics and surgical technique. Electrophysiologic investigation performed during surgery has greatly contributed to this progress, increasing the surgeon's understanding of the mechanism of damage and suggesting various changes in his or her surgical strategy. In this context, the advantages of the retrosigmoid “en-bloc” removal of small to medium size ANs have been examined in the present study. At the ENT Department of the University of Verona, 103 subjects with AN were operated on, from January 1990 to December 1995, with a retrosigmoid-transmeatal approach. Eighteen subjects (17.4%) presented pure a intracanalar (IC) tumor and 85 (82.6%) had both IC and extracanalar (EC) involvement. All the IC tumors (n = 18) and 70 of the IC-EC neuromas with an EC size less than 25 mm are reported in this paper for a total of 88 patients. The first 48 patients were operated on via the classic procedures described in the literature, characterized by removal of the tumor after “debulking” and limited exposure of the internal auditory canal (IAC). The following 40 subjects were operated on according to the technique of “en-bloc” removal of the tumor and wide exposure of the IAC. In the “en-bloc” group the tumor was first detached from the cerebellar flocculus and the pons, when necessary. The tumor was not debulked to preserve the anatomic relationship with the nerves and to facilitate identification, cleavage and dissection of the tumor from the neural structures. Thereafter, the posterior wall of the IAC was drilled out and opened in a circumferential range from 180 to 270°. The IAC dura was subsequently opened, and the distal end of the AN along with the vestibular nerves were identified. The vestibular nerves were sectioned in the distal portion of the IAC and dissected with the tumor from the underlying facial and cochlear nerves. Dissection continued medially to the IAC porus. The AN was progressively dissected from the cochlear and facial nerves in the cerebellopontine angle (CPA) with multiple direction maneuvers, as required by the characteristics and degree of adherence to the neural structures. The anatomic and functional results obtained with this new procedure (“en-bloc” removal) were compared with the classic “debulking” technique. The statistical analysis shows an improvement in postoperative outcome for both auditory and facial nerve function. The “en-bloc” removal procedure along with the wide exposure of the content of the IAC and electrophysiologic monitoring of the seventh and eighth cranial nerves are, in our experience, the recommended strategies for improving outcomes in small to medium size ANs.

Hearing loss during removal of acoustic neuroma (AN) may be due to labyrinthine and/or neural and/or vascular damage. Surgical maneuvers relating to perioperative and postoperative hearing may give rise to mechanisms of auditory impairment. Recording action potentials from the intracranial portion of the cochlear nerve (CN) has proven particularly useful for identifying the mechanisms of iatrogenic auditory injury. In this paper intraoperative and postoperative auditory impairments are investigated in relation to surgical steps in a group of 47 subjects with AN (size ranging from 5 to 25 mm) undergoing removal by a retrosigmoid-transmeatal approach. Drilling of the internal auditory canal (IAC), removal of the AN from the IAC fundus, coagulation close to the CN, lateral to medial tumor traction, separation of the CN from the facial nerve, and stretching of the CN have proven to be the most critical surgical steps in hearing preservation. On the other hand, maneuvers such as intracapsular tumor removal, vestibular neurectomy, suction close to the AN, and closure of the IAC defect did not correlate with changes in auditory potentials. Predisposing factors to postoperative hearing deterioration were IAC enlargement greater than 3 mm, IAC tumor size greater than 7 mm, extracanalar tumor size greater than 20 mm, labyrinth medial to the IAC fundus, severe involvement of the CN in the IAC, preoperative abnormal auditory brainstem responses, and normal vestibular reflectivity. Age and preoperative hearing did not prove to be statistically related to postoperative hearing. The variations in morphology and latency of CNAPs are discussed in relation to the mechanisms of iatrogenic injury. (Otolaryngol Head Neck Surg 1997;117:596-605.)

Electromyographic (EMG) activity recorded from the facial muscles in response to electrical and mechanical stimulation is the most popular method for continuous monitoring of the facial nerve during cerebellopontine-angle surgery. EMG recording is, however, extremely sensitive to the administration of neuromuscular blockers. An alternative technique for the continuous monitoring of the facial nerve [i.e., monopolar recording of facial nerve antidromic potentials (FNAPs)], is described. Ten subjects undergoing retrosigmoid vestibular neurectomy for Meniere's disease and 11 subjects operated on with acoustic neuroma surgery via a retrosigmoid approach (tumor size range, 12-28 mm) participated in the investigation. Bipolar electrical stimulation of the marginalis mandibulae was performed to elicit FNAPs. Stimulus intensity ranged from 0 to 10 mA with a delivery rate of 7/s. Antidromic potentials were recorded with a silver-wire monopolar electrode positioned intracranially on the proximal portion (root entry zone) of the acoustic-facial bundle. Bipolar recordings with two silver electrodes were also performed from the trigeminal and facial nerves in the cerebellopontine angle to define the specific origin of the action potentials. FNAP amplitude increased as a function of stimulus intensity. The average latency was 3.35 ms (range, 3.0-3.7 ms). Action potentials recorded intracranially during electrical stimulation of the marginal nerve originated specifically from the facial nerve. Changes in latency and amplitude of FNAPs were analyzed as a function of the main surgical steps in patients operated on for acoustic neuroma. FNAP monitoring provided quantitative real-time information about damaging maneuvers performed on the nerve and postoperative facial function.

An alternative technique for the continuous monitoring of the facial nerve, monopolar recording of facial nerve antidromic potentials (FNAPs), on 10 subjects undergoing retrosigmoid vestibular neurectomy for Meniere's disease is described. To elicit FNAPs bipolar electrical stimulation of the marginalis mandibulae was performed. Stimulus intensity ranged from 0 to 10 mA with a delivery rate of 7/second. Antidromic potentials were recorded with a silver wire monopolar electrode positioned intracranially on the proximal portion (root entry zone) of the acoustic-facial bundle. Bipolar recordings with two silver electrodes were also performed from different nerves in the cerebellopontine angle to define the specific origin of the action potentials. FNAP. amplitude increased as a function of stimulus intensity. The average latency was 3.35 milliseconds (range 3.0 to 3.7 ms). Action potentials recorded intracranially during electrical stimulation of the marginal nerve originated specifically from the facial nerve. FNAP recording is therefore a promising technique for the continuous intraoperative monitoring of the facial nerve during cerebellopontine angle surgery.

Continuous electromyographical (EMG) monitoring of the facial nerve is widely used during acoustic tumor surgery. Mechanical stimulation of the facial nerve is capable of eliciting synchronous and asynchronous EMG responses alerting the surgeon to damaging maneuvers performed on the nerve. Mechanical stimulation, however, elicits EMG responses only when the nerve has been injured by the underlying pathology or previous surgical maneuvers, and the technique is sensitive to administration of muscular blockers. In addition, EMG is unable to furnish quantitative information about the damage. The present paper illustrates an alternative technique for intraoperative facial nerve monitoring, that is, the recording of facial nerve antidromic potentials (FNAPs).Eleven subjects operated on by acoustic neuroma surgery via a retrosigmoid approach (tumor sizes ranging from 12 to 28 mm) participated in the investigation. Bipolar electrical stimulation of the marginalis mandibulae was performed to elicit FNAPs. Stimulus intensity ranged from 2 to 6 mA with a delivery rate of 7/second. A silver-wire electrode positioned on the proximal portion of the acoustic-facial bundle was used to record action potentials. Changes in latency and amplitude of FNAPs were analyzed as a function of the main surgical steps. FNAP monitoring provided quantitative real-time information about damaging maneuvers performed on the nerve and allowed prediction of postoperative facial function.

A technique of bipolar recording of the cochlear nerve compound action potentials (CAPs) to make identification and preservation of the cochlear nerve easier during cerebellopontine angle surgery is described. Four patients, aged 32 to 65 years, with acoustic tumors smaller than 2 mm and serviceable hearing, participated in the study. To investigate the resolution power of bipolar CAP recordings, a pilot study had been performed in a group of four patients submitted to vestibular neurectomy. Two silver electrodes insulated by Teflon up to the exposed ends were utilized for bipolar recording of the CAPs. They were twisted with each other and the distance between the two electrode tips could be varied from 0.3 to 0.7 mm. Rarefying polarity clicks (31/s) at 100 to 125 dB SPL were utilized as stimuli. Bipolar recording from the eight nerve was extremely selective: a good response was obtained only when the electrode was positioned on the cochlear portion of the eighth nerve. No response was present when the electrode was placed on the vestibular nerve and on the tumor. Frequent probing of tumor and eighth nerve with the bipolar recording electrode during acoustic neuroma removal facilitated the task of identifying the cochlear nerve and allowed its preservation in all patients.

From 1975 to 1992, a total of 1459 primary stapedoplasty operations (i.e., stapedectomy, stapedotomy with tendon section, and stapedotomy with tendon preservation) were performed in 1323 subjects at the Ear, Nose, and Throat Department of the University of Verona. Pure-tone audiometry was carried out in all subjects who were operated on and who underwent 6-month and 10-year follow-ups. To evaluate the influence of stapedius tendon preservation on functional outcome, we randomly selected subgroups of patients using the three different stapedioplasty techniques and tested them by multiple-frequency tympanometry, psychoacoustic tuning curves, and speech discrimination in noise. Finally, to assess the effect of prosthesis diameter on middle ear transfer function, we used the electrocochleographic technique and examined the threshold and latency of cochlear nerve compound action potentials recorded during surgery from the round window. The results of this study show that the best auditory performance in otosclerotic subjects is achieved by performing a stapedotomy of 0.7 mm diameter, using a 0.6 wire-Teflon piston, and preserving the stapedius tendon.

We measured the conduction velocity of the intracranial portion of the auditory nerve in 3 patients undergoing vestibular nerve section to treat Meniere's disease. The conduction velocity varied from patient to patient, with an average value of 15.1 m/sec. The latency of peak III of the brain-stem auditory evoked potentials (BAEPs) increased by an average of 0.5 msec as a result of exposure of the eighth nerve, and if that increase is assumed to affect the entire length of the auditory nerve (2.6 cm) evenly, then the corrected estimate of conduction velocity would be 22.0 m/sec. Estimates of conduction velocity based on the interpeak latencies of peaks I and II of the BAEP, assuming that peak II is generated by the mid-portion of the intracranial segment of the auditory nerve, yielded similar values of conduction velocities (about 20 m/sec).

Intraoperative monitoring of auditory evoked potentials reveals possible correlations between surgical maneuvers and the function of auditory structures and pathways in cerebellopontine angle surgery. Direct cochlear nerve action potentials (CNAPS) furnish realtime information on the function of the cochlea and cochlear nerve and were utilized in 14 patients undergoing removal of small (12-18 mm) unilateral acoustic tumors. The latency of the first negative component (N1) of the CNAPs proved extremely sensitive in detecting intraoperative auditory damage and was a good predictive index of postoperative auditory outcome. Evaluation of temporal and morphological CNAP patterns allowed identification of coagulation close to the cochlear nerve, drilling of the internal auditory canal and removal of the intrameatal portion of the tumor as the most critical steps in hearing preservation.

Vestibular neurectomy (VN) results in a high success rate in the control of vertigo in Meniere's disease, although the subsequent fate of auditory function is fairly unpredictable. The present investigation reports the postoperative results obtained in a group of 30 subjects with a clinical diagnosis of Meniere's disease and vascular cross-compression of cranial nerve VIII. All subjects underwent VN using a retrosigmoid approach, and in half of them microvascular decompression (MVD) of the cochlear nerve with interposition of autogenous muscle was performed at the same time. All patients had complete relief from vertigo. Hearing was significantly improved in the VN-MVD group (46.7% of subjects). In this group tinnitus and aural fullness also improved significantly, with values of 62.6% and 66.6%, respectively.

We compare the click-evoked compound action potentials from the exposed intracranial portion of the eighth nerve using bipolar and monopolar recording electrodes in patients undergoing vestibular nerve section. It is assumed that a bipolar recording electrode will only record propagated neural activity in the auditory nerve, whereas a monopolar recording electrode may in addition record electrical activity that is conducted passively to the recording site. The results of the present study confirm that the earliest detectable propagated neural activity in the intracranial portion of the auditory nerve occurs with a latency that is close to that of peak II of the brain-stem auditory evoked potentials, and the results also confirm that the late components in the click-evoked compound action potentials that have been demonstrated previously using the monopolar recording technique represent propagated neural activity in the auditory nerve. The results also indicate that the responses that are recorded by a bipolar recording electrode, when the small tips of which are placed on the eighth nerve when it is relatively dry, represent only small populations of nerve fibers. Even when an attempt is made to align the two tips of a bipolar electrode with the course of the auditory nerve, this type of electrode may record from different populations of nerve fibers.

Seventy-three otosclerotic patients, 138 subjects who had undergone stapes surgery (50 total stapedectomies, 43 stapedotomies with stapedius tendon section and 45 stapedotomies with stapedius tendon preservation) and 70 normal controls were investigated by susceptance multiple frequency tympanometry. The aims were to evaluate the efficiency of this procedure in diagnosing otosclerosis and to assess the resonance properties of middle ears undergoing different types of stapedectomy. Tympanometry was performed using sweep frequencies ranging from 226 to 2,000 Hz for each pressure step of 12.5 daPa (pressure range from -500 to 400 daPa). The resonance frequency of the system was evaluated by identifying the "W" morphology of susceptance tympanograms. The results of the present investigation indicate that stapes surgery abnormally reduces the stiffness of the tympano-ossicular system. This phenomenon is limited by preservation of the stapedius tendon, which confers a significant degree of stiffness on the conductive system.

The morphological and functional changes of the eighth nerve in patients undergoing cerebello-pontine angle (CPA) surgery are under investigation in the ENT Department of the University of Verona. The main aspects of the research are: ultrastructural examination of the eighth nerve in normals and subjects operated on for vestibular or cochleo-vestibular neurectomy and for acoustic neuroma; monitoring cochlear nerve function during CPA surgery by monopolar and bipolar recording of cochlear nerve action potential (CNAPs). The specific aims of this research are: to acquire information on the pathophysiology of a number of peripheral cochleo-vestibular disorders; to evaluate the role of intraoperative recording of the eighth nerve in preserving hearing.

The present investigation evaluates the effectiveness of NaF treatment in modifying the natural course of subclinical otosclerosis, as monitored by the stapedius reflex. The study was carried out on 128 relatives of patients suffering from surgically confirmed footplate otosclerosis. The diagnosis of subclinical otosclerosis was made on the basis of presence of the on-off effect. One group of subjects was treated with NaF in doses ranging from 6 to 16 mg according to age. The treatment lasted 2 years. A second group served as a control. Changes in stapedius reflex morphology were evaluated at 1, 2, and 5 years from the onset of treatment. The investigation demonstrated that NaF has a stabilizing effect on early otosclerosis. This drug, in fact, arrests the disease process in more than 60 percent of ears at the 2-year follow-up and in more than 50 percent at 5 years. A program of secondary prevention of otosclerosis by NaF is suggested.

The present paper investigates the hearing function in chronic otitis media vs. tympanoplasty in 41 patients with bilateral chronic otitis media, operated on unilaterally. the auditory evaluation was performed immediately before surgery and at a follow-up time varying from 1 to 14 years (mean = 5 years). Results were expressed in terms of relative gain (in respect to preoperative hearing levels) and total gain (in comparison with the contralateral ear). a progressive reduction of the hearing threshold as a function of time was observed both in non-operated and operated ears. the comparison of the threshold shifts between the two ears indicated that the long-term functional results of tympanoplasty can be considered quite satisfactory.

The recent audiological literature has put forward the hypothesis that children with unilateral hearing loss (UHL) show delays in educational achievement and academic progress and some behavioural difficulties. This motivated us to investigate the long-term effects of monaural auditory deprivation in a group of adults who had suffered from UHL since childhood. A group of subjects, ranging in age from 30 to 55 years, suffering from sensorineural UHL since early childhood, has been examined for psychosocial and psychoacoustical effects and statistically compared with a control group matched for age and sex. We prepared a questionnaire directed to provide some objective and subjective indices of psychosocial disability and handicap. Some questions were directed towards specific aspects of auditory function; others assessed the degree of education and the type of working performed. The results of the investigation confirmed the superiority of binaural v. monaural hearing. This was clearly demonstrated in psycho-acoustical performance in sound localisation, speech recognition in noise, together with the appreciation of music. On the other hand, the parameters concerned with educational, social and employment achievement did not support the existence of any significant difference between binaurally and monaurally hearing subjects. The data obtained in the present study thus do not support the existence of non-auditory, long-term effects of monaural hearing loss.

We are all aware of the damaging action of noise on the auditory system; however, loud noises have also been thought to affect other organ systems. Among these, the cardiovascular system is considered the most involved and therefore has been given the most attention in animals and in humans. The cardiovascular system is a “stress strain” apparatus which can respond to a wide range of environmental conditions such as temperature and exercise. From a clinical point of view, it is well known that cardiovascular diseases are the major causes of death [1], As shown in Table 1, 48.5% of the total mortality rate involves cardiovascular diseases. Among these, ischemic cardiopathies are the most prevalent cause of death, with a figure of 34.9%. Table 2 details the possible risk factors of ischemic cardiopathy. Among these hypercholesterolemia, smoking and arterial hypertension are statistically confirmed causes of miocardial ischemia. Other associated factors are sedentary occupations and psychological or environmental stress. In spite of the large number of risk factors, it may be noted that noise is not included. This may be due to the lack of attention given to the problem or to the negligible effects of this physical agent.

Chemical cochleovestibular deafferentation was performed on 21 individuals suffering from disabling vertigo caused by unilateral Meniere's disease. Patients ranged in age from 31 to 60 years, with a mean age of 47.4. The duration of the disease spanned 3 to 14 years, mean duration being 5.8 years. Subjects displayed pure-tone thresholds higher than 50 dB HL in the affected ear and better than 25 dB HL in the contralateral ear. The frequency of vertigo, evaluated during the 6 months before surgery, ranged from 1 crisis a month to 2 a week; mean duration of crises was 1 to 6 hours. Medical treatment had failed in all cases. The surgical procedure consisted of stapedectomy, deposition of several crystals of NaCl in the vestibule, and sealing of the oval window with a vein graft. Postoperative recovery was rapid, allowing patients to be discharged 4 to 6 days after surgery. All subjects reported complete relief of vertigo. Tinnitus disappeared in 47.6% of the subjects, was reduced in 33.3% and unchanged in 19.1%. Most patients complaining of aural fullness preoperatively reported relief of this symptom after surgery. The outcomes of the present study indicate that NaCl deposition into the vestibule is a simple, safe, and effective technique of cochleovestibular deafferentation.

Stapedectomy and stapedotomy are presently the techniques utilized in the surgical treatment of otosclerosis. The technique of choice at the ENT Department of the University of Verona has changed from stapedectomy to stapedotomy with and without stapedius tendon preservation. From January 1975 to December 1985, 805 ears were operated on for otosclerosis at our department. A statistical analysis has been performed on three groups of patients (stapedectomy, stapedotomy without and with stapedius tendon preservation) at short and long term. The results suggest that stapedotomy with stapedius tendon preservation should be the preferred surgery in the treatment of otosclerosis.

The present study deals with 832 ossicular chain reconstruction procedures performed in 655 patients from January 1975 to December 1985. Homograft and autograft ossicles, intraoperatively minisculptured according to personal or traditional techniques, were used in 626 ears (75.2%). In the remaining 206 ears Plastipore or Proplast total or partial ossicular replacement prostheses were employed. The functional hearing results are evaluated as a function of length of follow-up, techniques used, and preoperative diagnosis. Short-term hearing gain is satisfactory and very similar for both ossicles and implants. Long-term observation however, shows, a progressive and systematic reduction of the postoperative hearing gain for both treatments. The long-term deterioration of hearing levels in ears receiving implants is more evident and dramatic than that observed in ears with ossicles. The difference is statistically significant. The causes of failure are evaluated based on both clinical data and findings at revision surgery.

The present investigation was performed to study coronary blood flow along with other indices of cardiac activity in subjects exposed to short-term noise. The study was carried out on 10 normal-hearing individuals suffering from Variant Angina of Prinzmetal. The acoustic stimuli consisted of 100 dB (A) broad-band noise, lasting 30 s. The following parameters were examined: ECG (D1, D2 and D3) and heart-rate by means of electrocardiographic recording, left ventricular systolic pressure (LVSP), left ventricular end diastolic pressure (LVEDP) and dP/dT max by means of arterial catheterization, and coronary blood flow by means of the thermodilution method. The results, statistically evaluated by means of multiple comparison test and t-test, did not reveal any significant modifications in the ECG traces, LVEDP, or dP/dT max. The transitory and moderate variations of LVSP and heart rate were not reflected in coronary blood flow, which remained unchanged during and after noise exposure.

Thirteen individuals with unilateral Menière's disease were chosen for experimental chemical labyrinthectomy. All subjects suffered from frequent attacks of disabling vertigo and had mean pure-tone thresholds greater than 50 dB in the affected ear. The surgical procedure was similar to stapedectomy; after removal of the stapes, several crystals of NaCl were placed in the vestibule which was then covered with a vein graft. Postoperative recovery was rapid, allowing patients to be discharged 4-6 days after surgery. Of the 13 subjects, all reported complete relief from vertigo. Tinnitus was cured in 7 subjects, greatly improved in 4 and unchanged in 2. Most patients complaining of aural fullness preoperatively reported relief from this symptom following surgery. To date (up to 4 years post-surgery) none of the subjects has shown any significant alteration in audiologic or vestibular function in the contralateral ear. The ease and safety of this procedure make it an attractive method when cochleovestibular deafferentation is indicated.

Stapedius reflex testing was utilized to monitor the progression of subclinical otosclerosis and evaluate the efficacy of NaF treatment in stabilizing the disease process. The investigation was performed on 93 relatives of patients suffering with surgically confirmed otosclerosis. Subjects were divided into two groups. The first group was treated with NaF in doses ranging from 6 to 16 mg in relation to age. The treatment lasted two years. The second group served as control subjects. Before entering the research, all subjects presented reflex abnormalities represented by a partial or complete on-off effect in one or both ears. Changes in stapedius reflex morphology (from partial to complete on-off and from complete on-off to absence of the reflex) were evaluated at 1 and 2 years. The groups had not developed significant differences at 1 year. At 2 years, the incidence of stable stapedius reflex findings was 91.5% in the treated ears and 77% in the control group. The difference is significant (p less than 0.05) and indicates a stabilizing effect of NaF on the disease process.

The present article reports on our experience with hearing preservation during 158 acoustic neuroma (AN) operations via the retrosigmoid-transmeatal (RS-TM) approach with the aid of intraoperative auditory monitoring. Several auditory monitoring methods are described. Of these, the bipolar cochlear nerve action potential (CNAP) was found to be the most helpful in preserving hearing. Of 106 patients with useful hearing preoperatively, more than 50% had useful hearing after surgery. Electrical auditory brainstem responses were useful in the placement of an auditory brain stem implant (ABI) in 4 patients with neurofibromatosis type 2 (NF2). All 4 reported speech perception benefit and use their ABIs regularly in their lives. It is our firm belief that intraoperative auditory monitoring has a pivotal role in the preservation and restoration of hearing in AN surgery.

Isolated or combined labyrinthine, neural, and vascular damage account for failure to preserve hearing during removal of acoustic neuromas. However, the specific mechanisms of auditory impairment remain unclear unless surgical maneuvers can be related to peri- and postoperative hearing on the basis of intraoperative monitoring of auditory function.Among the different auditory monitoring techniques, recording of cochlear nerve action potentials (CNAPs) from the intracranial portion of the nerve has proven particularly useful for identifying the mechanisms of iatrogenic auditory injury.The present investigation analyzes intra- and postoperative auditory impairment in relation to surgical steps in a group of 38 subjects with acoustic neuroma (size ranging from 5 to 24 mm) undergoing removal via a retrosigmoid approach.Coagulation close to the cochlear nerve, drilling of the internal auditory canal, and removal of the intrameatal portion of the acoustic neuroma have prove to be the most critical surgical steps in hearing preservation.Changes were correlated with intra- and extrameatal tumor size, the relationship between the internal auditory canal and vestibule, and internal auditory canal enlargement, anatomic involvement of the cochlear nerve, preoperative auditory level, and ABR and ENG test findings.Changes in CNAP morphology and latency are detailed, and mechanisms of injury are analyzed and discussed as a function of these variables.