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At least 73 records · Page 4Linked to original sources

PubMed1988

Effects of cerebellar retractions on the cochlear nerve: an experimental study on rhesus monkeys.

Cerebellar retractions were performed in the cerebellopontine (CP) angle of rhesus monkeys to study the relationship between changes in brainstem auditory evoked potentials (BAEP) and/or compound action potentials (CAP) from the cochlear nerve, and morphological changes in the cochlear nerve in order to investigate the nature of cochlear nerve injuries caused by this surgical procedure. The changes in the BAEP and/or CAP from the cochlear nerve that were seen during cerebellar retraction were similar to those seen in human patients during operation. After completion of each experiment the temporal bones were prepared for histological examination. Hemorrhages often developed at the fundus of the internal auditory canal as a direct result of cerebellar retraction. These hemorrhages were located at the area cribrosa, where the branches of the internal auditory artery penetrate the cribriform plate. As the hemorrhages appeared to be due to avulsion rupture of these branches, they were considered to be the probable cause of the sudden loss of all the components of the auditory responses. The cochlear nerve fibers, especially those at the basal turn of the cochlea, avulsed simultaneously at the area cribrosa in most cases.

Action Potentials↗

PubMed1988

[Cochlear nerve injuries caused by manipulations in cerebellopontine angle: Part II. An electrophysiological and morphological study in rhesus monkeys].

Cochlear nerve injuries caused by the manipulations in the cerebellopontine angle were electrophysiologically and morphologically investigated in rhesus monkeys. The brainstem auditory evoked potentials and/or the compound action potentials recorded from the intracranial portions of the cochlear nerve so often deteriorated due to cerebellar retractions. In these cases, the morphological changes were often verified at the most distal portions of the cochlear nerves at the fundus of the internal auditory canal (area cribrosa): the cochlear nerve fibers were pulled out from the bony foramina at the area cribrosa and the branches of the internal auditory artery were also avulsed and ruptured. Sudden loss of the auditory evoked potentials was occasionally experienced during cerebellar retractions in the monkeys as occurred in human CP angle surgery. In these cases, massive hemorrhages were found at the area cribrosa. This indicates that sudden loss of hearing function during CP angle manipulations is caused by vascular accident of the internal auditory artery. It was emphasized that the operative procedures should be done with the operative direction toward the cochlea and that the operative procedures away from the cochlea should be avoided, because they may effect traction force on the cochlear nerve.

Action Potentials↗

PubMed1988

Cochlear nerve topography and fiber spectrum in the pigmented mouse.

The topographical and cytological features of the pigmented mouse (CBA/CBA) cochlear nerve were analyzed. The cochlear nerve is very short and is approximately 0.2-0.3 mm in its length. The entire cochlear nerve and a portion of the ventral cochlear nucleus are located within the internal acoustic meatus, and are closely surrounded by bone. Approximately 10,000 nerve fibers are present, of which only about 3% are unmyelinated. The distribution of the axon diameters in the myelinated nerves is close to unimodal.

Animals↗

PubMed1992

Frequency thresholds of rat cochlear nerve fibers.

Activities of single cochlear nerve fibers of Wistar rats were recorded extracellularly. Best frequencies (BF) distributed from 0.50 to 62.6 kHz. The audiogram was made as the minimum boundary of the BF threshold distribution. The range of audible frequency was 0.54-63 kHz at 60 dB SPL and 0.15-67 kHz at 100 dB SPL. The lowest trough of the audiogram was 5 dB SPL at 41.2 kHz. There was the second trough of 10 dB SPL at 7.01 kHz leaving a notch between the two troughs. The shapes of the frequency-threshold curves (FTCs) of fibers were evaluated quantitatively and typical FTCs were shown as a function of BF.

Acoustic Stimulation↗

PubMed2003

C-Fos immunoreactivity mapping of the auditory system after electrical stimulation of the cochlear nerve in rats.

The aim of this study was to establish the use of c-Fos immunoreactivity as a marker for functional mapping in the auditory system in response to direct electrical stimulation of the cochlear nerve in the cerebellopontine angle. In rats the cochlear nerve was electrically stimulated with a biphasic current (120-250 microA, 5 Hz) for 30 min using a bipolar concentric Tungsten electrode. Bilateral cochlectomy was performed in a control group in order to investigate basal expression of c-Fos in the auditory brainstem nuclei. The response of auditory brainstem nuclei to electrical stimulation and the completeness of cochlear ablations were electrophysiologically verified. After the experiments, the animals were prepared for cryotomy and c-Fos immunohistochemistry. The results were morphologically analyzed and statistically compared among groups. In anesthetized animals with unilateral electrical stimulation of the cochlear nerve increased expression of c-Fos was detected in the ipsilateral ventral (VCN) and bilateral dorsal cochlear nucleus (DCN), whereas the VCN of the contralateral side revealed only few immunoreactive cells. In animals with bilateral cochlear ablation the number of c-Fos reactive cell nuclei representing basal expression was generally low in the VCN and DCN of both sides. Our data show that electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in the cochlear nucleus. It also confirms bilateral connections between the cochlear nuclei. These experimental results suggest that c-Fos immunoreactivity mapping provides a powerful tool for functional investigations on the cellular level after direct electrical stimulation of the cochlear nerve. Future functional studies analyzing the effect of electrical stimulation of the central auditory system as performed by auditory brainstem implants could be investigated in detail by mapping c-Fos expression on cellular level.

Animals↗

PubMed1988

[Cochlear nerve injuries caused by manipulations in cerebellopontine angle: Part I. Electrophysiological and morphological study in dogs].

Cochlear nerve injuries caused by manipulations in the cerebellopontine angle were electrophysiologically and morphologically investigated using dogs. Compression injuries were developed at the portions of the cochlear nerves that were directly retracted by a retractor. The blood vessels supplying the cochlear nerve trunk easily ruptured and the Schwann-glial junctions of the cochlear nerve were separated, due to traction force derived from the manipulations in the CP angle. From these results, some technical points to preserve hearing during CP angle surgery were discussed.

Action Potentials↗

PubMedDate not supplied

Electrically evoked compound action potential (ECAP) of the cochlear nerve in response to pulsatile electrical stimulation of the cochlea in the rat: effects of stimulation at high rates.

Some cochlear implant patients achieve better speech recognition with pulsatile electrical stimulation presented at high rates. The present study aimed to explore, in an animal model of cochlear implants, how the excitability of the cochlear nerve is affected by pulsatile electrical stimulation delivered at high rates, of up to 1,000-2,000 pulses per second (pps). Adult rats (n=23) were implanted with two or three stimulating electrodes in the left cochlea. In four of these rats, the left cochlea was deafened by local perfusion with 1 per cent or 4 per cent neomycin solutions prior to implantation. Pulsatile stimuli consisted of 20 micros electrical pulses, delivered in trains of 200 ms duration, separated by a pause of 200 ms. The pulse rates ranged from 100 to 2,000 pps (intra-train pulse rate). Electrically evoked compound action potentials (ECAPs) of the cochlear nerve were recorded either intracochlearly or from epidural electrodes (extra-cochlearly). With increasing pulse rates, the average ECAP amplitude decreased, whereas the average ECAP latency and its variability (SD) increased. For rates above 300 pps, the amplitude of the ECAP to the individual successive pulses delivered in the train progressively decreased during the initial part of the train, corresponding to a short-term adaptation of the cochlear nerve. This effect progressively increased for pulse rates ranging from 300 to 2,000 pps. In addition, there was a phenomenon of long-term adaptation, as indicated by a decrease in the amplitude of the ECAP to the first pulse of the train, indicating that the pause of 200 ms between each train was not long enough for full recovery of the cochlear nerve. This long-term adaptation was progressively more pronounced for increasing pulse rates. To characterize further the recovery in excitability of the cochlear nerve, forward masking experiments were conducted, showing a decrease of the ECAP amplitude when the interval between the first pulse (masker) and the second pulse (probe) was shorter than 2 ms. This ECAP decrease was slow for intervals between 2 and 1 ms and then abrupt for shorter intervals. The observations described above were similar for extra- and intra-cochlear recordings and were little, if at all, affected by treatment of the cochlea with neomycin.

Animals↗

PubMed2005

Electrical stimulation of the cochlear nerve in rats: analysis of c-Fos expression in auditory brainstem nuclei.

We investigated functional activation of central auditory brainstem nuclei in response to direct electrical stimulation of the cochlear nerve using c-Fos immunoreactivity as a marker for functional mapping. The cochlear nerve was stimulated in the cerebellopontine angle of Lewis rats applying biphasic electrical pulses (120-250 muA, 5 Hz) for 30 min. In a control group, bilateral cochlectomy was performed in order to assess the basal expression of c-Fos in the auditory brainstem nuclei. The completeness of cochlear ablations and the response of auditory brainstem nuclei to electrical stimulation were electrophysiologically verified. C-Fos immunohistochemistry was performed using the free floating method. In anaesthetized animals with unilateral electrical stimulation of the cochlear nerve, increased expression of c-Fos was detected in the ipsilateral ventral cochlear nucleus (VCN), in the dorsal cochlear nucleus bilaterally (DCN), in the ipsilateral lateral superior olive (LSO) and in the contralateral inferior colliculus (IC). A bilateral slight increase of c-Fos expression in all subdivisions of the lateral lemniscus (LL) did not reach statistical significance. Contralateral inhibition of the nuclei of the trapezoid body (TB) was observed. Our data show that unilateral electrical stimulation of the cochlear nerve leads to increased expression of c-Fos in most auditory brainstem nuclei, similar to monaural auditory stimulation. They also confirm previous studies suggesting inhibitory connections between the cochlear nuclei. C-Fos immunoreactivity mapping is an efficient tool to detect functional changes following direct electrical stimulation of the cochlear nerve on the cellular level. This could be particularly helpful in studies of differential activation of the central auditory system by experimental cochlear and brainstem implants.

Animals↗

PubMed1995

Cochlear nerve section for intractable tinnitus.

Tinnitus is a common and often very disturbing symptom. The majority of patients can now be successfully treated either by conservative medical treatment or by specific surgery. Intractable subjective tinnitus originating within the cochlea or cochlear nerve can frequently be successfully treated by cochlear nerve section. The cochlear nerve must be severed medial to the spiral ganglion to obtain optimum results. One hundred fifty-one cases are reported. Complete relief of tinnitus was achieved in 101 patients, worthwhile improvement was obtained in 43 patients and 7 patients obtained no improvement. The indications for this surgery will be given. Careful examination, accurate diagnosis, and proper selection of patients with intractable tinnitus for cochlear nerve section offer a good chance for success.

Acoustic Impedance Tests↗

PubMed1987

Cochlear nerve injuries caused by cerebellopontine angle manipulations. An electrophysiological and morphological study in dogs.

Changes in the response from the cochlear nerve in dogs resulting from cerebellopontine angle (CPA) manipulations were correlated with histological changes in the nerve. The aim of this study was to determine the mechanisms underlying hearing deficits incurred as a result of manipulations in the CPA. Compound action potentials (CAP) were recorded from the cochlear nerve in response to click stimulation before, during, and after cerebellar and eighth nerve retractions were performed under anesthesia. The retractions were carried out to elicit different degrees of change in the latency and waveform of the CAP. About 30 minutes after completion of the manipulations, the dogs were perfused with a fixative and their cochlear nerves and brain stems were prepared for histological studies. The results showed that retraction of the eighth nerve caused a disintegration of the myelin sheath, and there were multiple and extensive foci of petechial hemorrhage and thromboses of the vasa nervorum of the cochlear nerve. In two dogs in which retraction was carried to a point at which the N2 peak of the CAP was abruptly obliterated, there was a separation of the central and peripheral myelin junction (Obersteiner-Redlich (OR) zone) and bleeding from the vasa nervorum at the OR zone. In the dogs in which the changes in the CAP had almost recovered before fixative perfusion, there were petechial hemorrhages within the cochlear nerve trunk, thus showing that improvement of electrophysiological responses may not always correlate with the absence of morphological changes.

Animals↗

PubMed2005

Temperature insensitivity of short-term adaptation in single-units of the chick cochlear nerve.

Short-term adaptation in acoustically stimulated chick cochlear nerve fibers has recently been shown to have similar kinetics as the readily-releasable vesicle pool in patch-clamped chick hair cells, suggesting that short-term adaptation depends on the dynamics of hair cell exocytosis. Our understanding of the relationship between these two phenomena has been hampered by differences in the temperatures at which the two types of data have been collected. In this report, the effect of temperature on short-term adaptation was studied in single-units of the chick cochlear nerve. Compared to units recorded at 38-41 degrees C, spontaneous and evoked firing rates were markedly decreased when the temperature was lowered to 28-32 degrees C, but the rate of short-term adaptation during 100 ms tone bursts was relatively unchanged, with a temperature Q(10), of approximately 1.2. The continued similarity of the adaptation time-constant of cooled units to vesicle depletion kinetics in chick hair cells measured at room temperature suggests that comparison of in vitro hair cell exocytosis and in vivo cochlear nerve firing properties may not be confounded by temperature differences between the two approaches.

Acoustic Stimulation↗

PubMed2004

Acoustic neuroma ingrowth in the cochlear nerve: does it influence the clinical presentation?

We examined the clinical presentation in patients with a histologically proven ingrowth of the cochlear nerve by acoustic neuroma to see whether this differs from what is known from large acoustic neuroma series. In total, 85 acoustic neuromas had an en bloc dissection to study histologically the relation between the cochlear nerve and the acoustic neuroma. In 21 of these 85 specimens, there was histologic proof of invasion of the cochlear nerve by the tumor. For 13 of these 21 tumors, sufficient clinical data could be retrieved to describe the clinical presentation in these patients. We collected clinical data such as age, sex, presenting symptoms, duration of symptoms, tone audiograms, tumor size measurements and volumetric calculations, and latency interval data I-V of brain stem evoked response audiometry and calculated whether there was any correlation among those data. We also compared these clinical data with the data from some large acoustic neuroma series. No clear difference could be shown between the clinical presentation of acoustic neuroma patients with cochlear nerve ingrowth and the clinical presentations in large acoustic neuroma series. This outcome favors the theory that the hearing impairment in acoustic neuroma patients is mainly the result of compression on the vessels of the cochlea and/or on the cochlear nerve.

Adolescent↗

PubMed1987

[Do 2d-order neurons exist in the cat cochlear nerve?].

There are not any neurons along the course of the cat cochlear nerve fibers. This corroborates the data of other investigations, that some rodents have intercalated neurons between the cochlear nerve fibers, but they do not occur in cats. Thus, the possibility to registrate activity of neurons of the first and second order within the cat cochlear nerve, the possibility that is still discussing in the electrophysiological literature, is denied.

Animals↗

PubMed1988

Frequency dependence of synchronization of cochlear nerve fibers in the alligator lizard: evidence for a cochlear origin of timing and non-timing neural pathways.

The dependence of synchronization of spike discharges on tone frequency was measured in cochlear nerve fibers of anesthetized alligator lizards at 21 degrees C. Synchronization measures were based on the fundamental component of a Fourier analysis of the instantaneous discharge rate in response to tone bursts. Measurements were obtained from fibers innervating hair cells in both the region of the cochlea that contains a tectorial membrane (tectorial fibers) and the region where hair-cell stereocilia are free-standing in scala media (free-standing fibers). Both rate and synchronization tuning-curves were measured automatically as a function of tone frequency. For tectorial fibers, the shapes of synchronization tuning-curves are roughly similar to the shapes of rate tuning-curves: the characteristic frequencies (CF's) of both curves are approximately equal. For free-standing fibers, the shape of synchronization tuning-curves differ markedly from those of rate tuning-curves. The CF's of synchronization and rate tuning-curves differ - the ranges are 0.2-0.6 kHz and 1-4 kHz, respectively - and the two CF's are uncorrelated. Synchronization filter-functions, which are contours of synchronization index at constant average discharge rate, were measured as a function of tone frequency for both tectorial and free-standing fibers. These synchronization filter-functions have the shapes of lowpass filters. For the populations of tectorial fibers and of free-standing fibers taken separately, these functions are independent of CF. The corner frequency of these functions is 0.50 +/- 0.038 kHz for tectorial fibers and 0.37 +/- 0.037 kHz for free-standing fibers. We conclude that these populations are characterized by different synchronization filters. For free-standing fibers, synchronization filter-functions measured at average driven discharge rates of about 20 and 40 spikes/s do not differ appreciably, and the high-frequency slope is -80 to -115 dB/decade. The results show that tectorial fibers encode timing information for low-level stimuli, whereas free-standing fibers do not. It is proposed that in the alligator lizard, neural pathways that encode timing information originate in the tectorial region and those that encode non-timing information originate in the free-standing region.

Acoustic Stimulation↗

PubMed2005

Diameter of the cochlear nerve in endolymphatic hydrops: implications for the etiology of hearing loss in Ménière's disease.

OBJECTIVE/HYPOTHESIS: Endolymphatic hydrops (ELH) is an important histopathological hallmark of Ménière's disease. Experimental data from human temporal bones as well as animal models of the disorder have generally failed to determine the mechanism by which ELH or related pathology causes hearing loss. Hair cell and spiral ganglion cell counts in both human and animal case studies have not, for the most part, shown severe enough deterioration to explain associated severe sensorineural hearing loss. However a limited number of detailed ultrastructural studies have demonstrated significant reductions in dendritic innervation densities, raising the possibility that neurotoxicity plays an important role in the pathology of Ménière's disease (MD) as well as experimental endolymphatic hydrops (ELH). This study tests the hypothesis that neurotoxicity is an important primary mediator of injury to the hydropic ear and is reflected in measurable deterioration of the cochlear nerve in the animal model of ELH. This study also explores the previously presented hypothesis that cochlear injury in ELH is mediated through the actions of nitric oxide (NO) by evaluating whether hearing loss or various measures of cochlear damage can be ameliorated by administration of an agent that limits excess production of NO. STUDY DESIGN: Part one of the project involves the surgical induction of endolymphatic hydrops and correlation of long term hearing loss with histological parameters of ELH severity as well as cochlear nerve and eighth cranial nerve diameter measurements. In part two, aminoguanidine is administered orally to a separate set of hydropic animals in an attempt to limit cochlear injury presumably mediated by NO. METHODS: Guinea pigs are subjected to surgical induction of unilateral endolymphatic hydrops after establishing baseline ABR thresholds at 2, 4, 8, 16, and 32 kHz. Threshold shifts are established prior to sacrifice at 4 to 6 months and temporal bones processed for light microscopy. Measurements of cochlear nerve and eighth cranial nerve maximal diameters as well as average maximal diameters are carried out and correlated to hearing loss and a semi-quantitative measure of hydrops severity. The identical experiments are carried out in animals treated with aminoguanidine, an inhibitor of inducible nitric oxide synthase. RESULTS: : The mean maximal diameter (n = 14) of the hydropic cochlear nerve was significantly reduced (432.14 +/- 43.18 vs. 479.28 +/- 49.22 microns, P = .0025) as compared to the control nerve. This was also seen in measures of the eighth cranial nerve (855.71 +/- 108.82 vs. 929 +/- 81.53 microns, P = 0.0003). Correlation studies failed to show correlation between hydrops severity and a cochlear nerve deterioration index (r = -0.0614, P = .8348). Similarly, hearing loss severity failed to correlate with cochlear nerve deterioration (r = 0.1300, P = .6577). There was a significant correlation between hearing loss and hydrops severity (r = 0.6148, P = .0193). Aminoguanidine treated animals (n = 5) also sustained nerve deterioration to the same degree as non-treated animals and there appeared to be no protective effect (at the dosage administered) against ELH related hearing loss, hydrops formation, or nerve deterioration. CONCLUSION: ELH results in significant deterioration of cochlear nerve and eighth cranial nerve maximal diameters in the guinea pig model. These findings are in accord with previous studies which detected ultrastructural evidence of dendritic damage and indicate that neural injury is of sufficient severity to result in light microscopic evidence of cochlear nerve and eighth cranial nerve deterioration. These data support the concept that the principle pathological insult in ELH is a form of neurotoxicity, especially in light of previous studies which indicate relative preservation of hair cells at similar points in time. The lack of correlation between the severity of hydrops and nerve deterioration suggests that nerve deterioration is independent of hydrops severity.

Animals↗

PubMed2002

Dimensions of the cochlear nerve canal: a radioanatomic investigation.

The purpose of this study was to determine the normal variations of cochlear nerve canal dimensions, which is useful information to have when assessing congenital malformations, i.e. during the preoperative evaluation of cochlear implant candidates. The length and diameter of the cochlear nerve canal were measured in 117 casts from randomly selected temporal bone specimens obtained from the Uppsala Temporal Bone Laboratory. In 16 of the casts the dimensions were correlated with those obtained from CT scans of the same temporal bone. Measurements were also made from CT examinations of the temporal bone of 50 patients referred for evaluation of cholesteatoma or chronic otitis media. The mean length and diameter in the axiopetrosal plane measured in casts were 1.17 and 2.58 mm, respectively. The mean diameter in the axial plane was 2.59 mm. The mean length and diameter determined from CT scans of the specimens were 1.19 and 1.98 mm, respectively. The mean length and diameter determined from CT examinations of patients were 1.08 and 1.91 mm, respectively. In conclusion, the cochlear nerve canal is short, with a circular cross-section. If the diameter of the canal is < 1.4 mm then the possibility of cochlear nerve abnormality should be considered; if it is > 3.0 mm then other anomalies may coexist.

Aged↗

PubMed1972

The frequency response and other properties of single fibres in the guinea-pig cochlear nerve.

1. Micro-electrode recordings were obtained from over 100 single fibres in the cochlear nerve of the pentobarbitone or urethane anaesthetized guinea-pig. The acoustic system was calibrated at the tympanic membrane and threshold sound level measurements so corrected.2. The minimum thresholds of the fibres approached with 10-20 dB of the behavioural thresholds reported in the literature. Exceptions to this were fibres from preparations where there was evidence of malfunction of the cochlea either from abnormally low perfusion or local damage, and a few high frequency fibres. With these high threshold fibres excepted, the range of thresholds at a given frequency in any one animal was less than 20 dB.3. The slopes of the low and high frequency cut-offs of the frequency-threshold curves (;tuning curves') within 25 dB of minimum threshold, ranged from 10 to 60 and from 20 to 125 dB/octave respectively for fibres with characteristic frequencies below 2 kHz, increasing to 90-180 and 200-600 dB/octave respectively for fibres with characteristic frequencies at about 8 kHz. These slopes represent the minimum values for the high-frequency cut-offs, which increase towards 1000 dB per octave in some cases at higher levels above threshold. At 30-50 dB above threshold, the low frequency cut-offs become suddenly less steep and approximate to 5 dB per octave.4. The relative sharpness of the frequency-threshold curves, measured as the ;Q(10 dB)', i.e. the ratio of characteristic frequency to the band width at 10 dB above minimum threshold, ranged from 1 to 4 for fibres with characteristic frequencies below 2 kHz, to 3-15 for fibres with characteristic frequencies near 10 kHz.5. The slopes and ;Q(10 dB)' measures of the frequency-threshold curves of most of the abnormally high threshold fibres approximated to, or were lower than those of analogous measurements of the guinea-pig basilar membrane vibration patterns.6. Four fifths of the cochlear nerve fibres had spontaneous discharge rates greater than 1/sec. No consistent relationship was observed between the rate of this activity and response properties, with the exception that nearly half of the high threshold fibres were silent. In these and other respects the response properties to tonal and click stimuli resembled those of cochlear nerve fibres in the cat. In no case was inhibition of the spontaneous discharge by single tones observed.7. It is concluded that, contrary to earlier reports, the cochlear nerve fibres of the guinea-pig are substantially more frequency selective than the existing measurements of the guinea-pig basilar membrane displacement. In terms of band width, this discrepancy approaches a factor of ten. The finding of a considerable range of band widths within optimal preparations, and frequency-threshold curves approximating to the mechanical functions in fibres from pathological cochleas, provides circumstantial evidence for a physiologically vulnerable sharpening mechanism occurring within the cochlea subsequent to the displacement pattern of the basilar membrane.

Acoustic Stimulation↗

PubMed2000

Hypoplasia of the bony canal for the cochlear nerve in patients with congenital sensorineural hearing loss: initial observations.

PURPOSE: To evaluate the length and width of the bony canal of the cochlear nerve in patients with congenital sensorineural hearing loss (SNHL) who have "normal" findings at thin-section computed tomography (CT) of the temporal bone. MATERIALS AND METHODS: The authors retrospectively evaluated the length and width of the bony canal for the cochlear nerve in two groups of patients. The first group was composed of 33 patients with profound SNHL and no demonstrable abnormality at thin-section CT. The control group was composed of 50 patients who underwent temporal bone CT for causes unrelated to SNHL. The mean value +/- SD was calculated for both cohorts. Statistical analysis consisted of the nonparametric Wilcoxon rank sum test with the NPAR1WAY program. RESULTS: The length and width of the bony canal for the cochlear nerve were significantly smaller in patients with SNHL than in the control group (P <.05) CONCLUSION: The hypoplastic bony canal for the cochlear nerve in patients with SNHL may be indicative of a previously unrecognized embryologic malformation of the cochlear nerve.

Adolescent↗