Biomedical subjects

F G Fiorino

Publications and source records attributed to F G Fiorino.

At least 19 recordsLinked to original sources

PubMed2000

New approach for cochlear implantation: cochleostomy through the middle fossa.

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.

Adolescent↗

PubMed2000

The retrosigmoid approach for auditory brainstem implantation.

OBJECTIVE: To describe our experience with the retrosigmoid-transmeatal (RS-TM) approach in auditory brainstem implantation (ABI) as well as the anatomosurgical guidelines for this route. STUDY DESIGN: Retrospective case review. SETTING: Ear, Nose, and Throat Department of the University of Verona. PATIENTS: Five patients with neurofibromatosis type 2 (NF2) were operated on for vestibular schwannoma removal with ABI implantation from April 1997 to June 1999. The patients were four men and one woman, whose ages ranged from 22 to 37 years. The tumor sizes ranged from 12 to 30 mm. The records of a total of 179 patients operated on for vestibular schwannoma (VS) removal via the RS-TM approach from January 1990 to June 1999 were also evaluated. Their ages ranged from 18 to 88 years (average 54 years). The tumor sizes ranged from 4 to 50 mm. Five patients had a solitary VS in the only hearing ear. INTERVENTION: The classic RS-TM approach was used in all patients. After tumor excision, for ABI implantation, the landmarks (seventh, eighth, and ninth cranial nerves, choroid plexus) for the foramen of Luschka were carefully identified. The choroid plexus was then partially removed, and the tela choroidea was divided and bent back. 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 correctly positioned with the aid of electrically evoked auditory brainstem responses (EABRs). MAIN OUTCOME MEASURES: Intraoperative EABR and postoperative speech perception evaluation. RESULTS: Auditory sensations were induced in all patients with various numbers of electrodes. Different pitch sensations could be identified with different electrode stimulation. CONCLUSIONS: In the authors' experience, the RS-TM approach is the route of choice for patients who are candidates for ABI when there is a chance of hearing preservation during surgery. If auditory function is lost during surgery, anatomical preservation of the cochlear nerve may allow hearing restoration with a cochlear implant. Direct intraoperative recording of cochlear nerve action potentials (CNAPs) and round window electrical stimulation are mandatory for these purposes. In addition, decompression of the intrameatal portion of the vestibular schwannoma and planned partial tumor resection with hearing preservation are also possible with the RS-TM approach.

Acoustic Stimulation↗

PubMed1999

Malleus-to-footplate prosthetic interposition: experience with 265 patients.

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-foot-plate 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.

Adolescent↗

PubMed1999

Retrosigmoid-transmeatal en bloc removal of small to medium-sized acoustic neuromas.

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.

Action Potentials↗

PubMed1999

New window for cochlear implant insertion.

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.

Adult↗

PubMed1998

Advances in monitoring of seventh and eighth cranial nerve function during posterior fossa surgery.

OBJECTIVE: 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]). STUDY DESIGN: 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]). SETTING: The study was conducted at an Ear Nose and Throat Department, University of Verona, Verona, Italy. INTERVENTION: Intraoperative monitoring during cerebellopontine angle surgery was performed. RESULTS: 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. CONCLUSIONS: 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.

Adolescent↗

PubMed1998

Basal turn cochleostomy via the middle fossa route for cochlear implant insertion.

OBJECTIVE: 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. STUDY DESIGN: The study design was a case report and a description of surgical technique. SETTING: The study was conducted at an ENT Department, University of Verona, Verona, Italy. PATIENTS: 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. INTERVENTION: 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. MAIN OUTCOME MEASURES: 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. CONCLUSIONS: 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.

Aged↗

PubMed1997

Mechanisms of auditory impairment during acoustic neuroma surgery.

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.

Adolescent↗

PubMed1996

New perspectives in intraoperative facial nerve monitoring with antidromic potentials.

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.

Adult↗

PubMed1994

Click-evoked responses from the exposed intracranial portion of the eighth nerve during vestibular nerve section: bipolar and monopolar recordings.

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.

Acoustic Stimulation↗

PubMed1994

Neural conduction velocity of the human auditory nerve: bipolar recordings from the exposed intracranial portion of the eighth nerve during vestibular nerve section.

We measured the conduction velocity of the intracranial portion of the auditory nerve in 3 patients undergoing vestibular nerve section to treat Ménière'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).

Electroencephalography↗

PubMed1994

Stapedotomy with stapedius tendon preservation: technique and long-term results.

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.

Acoustic Impedance Tests↗

PubMed1994

Vulnerability of hearing function during acoustic neuroma surgery.

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.

Adult↗

PubMed1994

Bipolar recording of the cochlear nerve action potentials during cerebellopontine angle surgery.

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.

Adult↗

PubMed1993

Mechanics of the middle ear in otosclerosis and stapedoplasty.

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.

Acoustic Impedance Tests↗

PubMed1993

Electrophysiologic identification of the cochlear nerve fibers during cerebello-pontine angle surgery.

To facilitate identification and preservation of the auditory nerve during cerebello-pontine angle surgery, bipolar recording of cochlear nerve compound action potentials (CNAPs) was performed. Two silver wires insulated with teflon up to the exposed ends were utilized as electrodes. They were twisted together, the distance between the two tips being 1 mm or less. Rarefaction polarity clicks (31/s) ranging from the psychoacoustical threshold to 120 dB pe SPL were used as stimuli. The investigation was performed in three groups of patients. The first group consisted of 9 patients submitted to vestibular neurectomy and 4 patients operated on by microvascular decompression of the eighth nerve. The second group comprised 8 patients with acoustic tumors smaller than 2 mm and serviceable hearing. Postoperative audiometric results in the subjects in the second group were compared with those obtained in well-matched homogeneous controls consisting of patients with acoustic neuroma operated on without the aid of CNAP recording. Bipolar recording from the eighth nerve was extremely selective, a good response being obtained only when positioning the electrode on the cochlear portion of the eighth nerve. During removal of the acoustic neuroma, repeated bipolar probing of the tumor and eighth nerve facilitated the task of distinguishing the cochlear nerve from other nervous structures and from the tumor, and contributed to preserving hearing in most patients.

Action Potentials↗

PubMed1993

Investigations in electrophysiology and morphology of the VIII cranial nerve.

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.

Evoked Potentials, Auditory↗

PubMed1991

Reduced active protection to the cochlea during physical exercise.

The present investigation was designed to evaluate whether dynamic physical exercise is able to modify stapedius reflex (SR) activity and, as a consequence, to influence the amount of temporary threshold shift (TTS). Experimental subjects were 10 normal-hearing male volunteers, aged 27-34 years (mean 30.8). SR parameters in the time-domain were assessed before, during and after submaximal exercise test, performed for 10 min on an ergometer cycle at 50% of maximum work capacity. The same parameters were also investigated in the absence of exercise, at time-matched intervals. In addition, the combined effect of noise and exercise was studied. The outcome of the investigation indicates that dynamic physical exercise depresses the SR and potentiates noise-induced TTS. The mechanisms underlying the present findings are discussed.

Adult↗