Clinical Profile and Results Obtained in Patients Treated by Auditory Brainstem Implants

INTRODUCTION

Cochlear implants have been able to treat some types of hearing loss, but those related to cochlear nerve impairment made it necessary to find new ways to manage these deficits; leading to auditory brainstem implants (ABI).

AIM

Our objective is to present the clinical profile of patients treated through an ABI and the results obtained from 1997 to 2017.

MATERIAL AND METHODS

On the one hand, patients with statoacoustic nerve tumours (VIIIcranial nerve) were selected, and on the other hand, patients withoutVIII tumours with congenital malformations of the inner ear. Before and after the placement of the ABI, hearing was assessed through tonal audiometry, from which the PTA (Pure Tone Average) and the CAP (Categories of Auditory Performance) scale were obtained.

RESULTS

A total of 20 patients undergoing ABI surgery were included. Eight were of tumour cause (40%) and 12 non-tumour (60%). In 15 subjects (75%) a suboccipital approach was performed and in 5 (25%) translabyrinthine. The mean of active electrodes before the implantation of Cochlear® (Nucleus ABI24) was 13/21 (61.90%) versus 8.5/12 (70.83%) of the Med-el® (ABI Med-el). An improvement in the mean PTA of 118.49dB was found against 46.55dB at 2years. On the CAP scale, values of1 were obtained in the preimplantation and of 2.57 (1-5) in the 2-year revision.

CONCLUSION

The ABI is a safe option, and with good hearing results when the indication is made correctly.

Meningitis and Ramsay-Hunt syndrome in a 17-year old girl

INTRODUCTION

Ramsay Hunt syndrome (RHS) is a rare manifestation of varicella-zoster virus (VZV) reactivation in geniculate ganglion. It usually manifests with a characteristic triad of symptoms including ipsilateral ear pain, vesicles in the external auditory canal, and facial nerve palsy.

CASE

We present a case report showing RHS additionally manifested by meningitis and involvement of VIII cranial nerve. Clinical course was complicated by acute kidney injury induced by acyclovir therapy.

RESULTS

Despite the involvement of the geniculate ganglion and vestibulocochlear nerve in the course of herpes zoster, and the occurrence of acute kidney injury, the patient fully recovered.

CONCLUSIONS

A complete recovery of cranial nerves VII and VIII in the course of RHS can be achieved.

Acute vertigo and sensorineural hearing loss from infarction of the vestibulocochlear nerve: A case report

RATIONALE

Acute unilateral audiovestibulopathy is a common neurotological syndrome. Differential diagnoses of acute unilateral audiovestibulopathy include viral infection, vascular insults, and tumors. Regarding vascular causes, ischemic stroke in the anterior inferior cerebellar artery (AICA) territory is known to be the leading cause of acute audiovestibular loss. Previous reports of AICA infarction with audiovestibulopathy failed to demonstrate magnetic resonance imaging (MRI)-positive vestibulocochlear infarctions. Only 1 report demonstrated acute infarction involving the vestibulocochlear nerve on diffusion weighted imaging (DWI)-MRI.

PATIENT CONCERNS

A 67 year old man complained of sudden left hearing loss and vertigo. The patient showed left horizontal gaze-evoked nystagmus (GEN) and the head impulse test (HIT) was positive on the left side. Videonystagmography revealed spontaneous rebound nystagmus toward the right side; head-shaking nystagmus toward the right side. The patient presented with left caloric paresis (20.1%). Pure tone audiometry (PTA) revealed severe sensorineural hearing loss on the left side.

DIAGNOSIS

MRI of temporal bone showed multifocal acute infarctions in the left inferior cerebellum. Moreover, images revealed tiny infarctions along the left vestibulocochlear nerve and the cochlea, implying acute vestibulocochlear nerve and labyrinthine infarction. There was no evidence of steno-occlusion of major cerebral vessels on MR angiography.

INTERVENTIONS

Immediate stroke management was done.

OUTCOMES

Neurological symptoms gradually improved after 3 to 5 days.

LESSONS

We present a case illustrating a rare but significant finding of vestibulocochlear nerve infarction revealed by DWI-MRI. Prompt imaging protocol enabled the detection of significant findings in this patient with acute unilateral audiovestibulopathy. Clinicians should be aware of the vestibulocochlear nerve and labyrinth on MRI in patients with cerebellar stroke.

Acute Unilateral Vestibulopathy

Normal vestibular end organs generate an equal resting-firing frequency of the axons, which is the same on both sides under static conditions. An acute unilateral vestibulopathy leads to a vestibular tone imbalance. Acute unilateral vestibulopathy is defined by the patient history and the clinical examination and, in unclear cases, laboratory examinations. Key signs and symptoms are an acute onset of spinning vertigo, postural imbalance and nausea as well as a horizontal rotatory nystagmus beating towards the non-affected side, a pathological head-impulse test and no evidence for central vestibular or ocular motor dysfunction. The so-called big five allow a differentiation between a peripheral and central lesion by the bedside examination. The differential diagnosis of peripheral labyrinthine and vestibular nerve disorders mimicking acute unilateral vestibulopathy includes central vestibular disorders, in particular "vestibular pseudoneuritis" and other peripheral vestibular disorders, such as beginning Menière's disease. The management of acute unilateral vestibulopathy involves (1) symptomatic treatment with antivertiginous drugs, (2) causal treatment with corticosteroids, and (3) physical therapy.

[Tinnitus in patients with hemifacial spasm: a treatable combination?]

BACKGROUND

About 5-15% of people in the Western world will suffer from an extended period of tinnitus during their lifetime. This is often a non-treatable, disabling disorder. Tinnitus can be classified as pulsatile or non-pulsatile. Pulsatile tinnitus can be caused by a treatable neurovascular compression.

CASE DESCRIPTION

Here we describe two patients, a 68-year old woman and 40-year old man suffering from pulsatile tinnitus and hemifacial spams due to neurovascular compression of the facial and acoustic nerve in the anterior cranial fossa. After microvascular decompression using the Jannetta procedure, in which a sponge was placed between the blood vessel and the nerve, the tinnitus and hemifacial spasm disappeared.

CONCLUSION

Recognition of hemifacial spasm in patients with tinnitus is important because the symptoms are treatable when it is due to neurovascular compression. Because hemifacial spasm can manifest in subtle forms - for instance unilateral blinking - this important symptom can easily be overlooked.

A purely intracanalicular cochlear schwannoma presenting with progressive hearing loss

Schwannomas arising from the cochlear nerve and confined to the internal auditory canal are rare. Clinically, a cochlear schwannoma can cause a progressive hearing loss. We report the case of a 56-year-old woman with a cochlear schwannoma that manifested as a slowly progressive hearing loss. The lesion was diagnosed by gadolinium-enhanced 3-Tesla magnetic resonance imaging.

Unilateral auditory neuropathy spectrum disorder

CONCLUSIONS

The majority of the patients with unilateral auditory neuropathy spectrum disorder (UANSD) were pediatric and mostly showed a great degree of hearing loss when diagnosed. Abnormal auditory brainstem response (ABR) and preserved otoacoustic emissions (OAEs) and/or cochlear microphonics (CM) were important features to differentiate it from common sensorineural deafness and central nerve hearing loss.

OBJECTIVE

To identify the clinical characteristics of patients with UANSD.

METHODS

This was a retrospective study involving 14 patients diagnosed as having UANSD between 2004 and 2010 in the Chinese PLA Hospital.

RESULTS

In all, 50% of the cases were males (1:1 sex ratio) and the average age of onset was 4.1 years. Of the 14 affected ears with UANSD in these cases, 6 were left-sided, while 8 were right-sided. Of the 14 contralateral ears, 4 presented with sensorineural hearing loss, while the other 10 showed normal hearing. The degree of hearing loss in the 14 affected ears varied, including moderate in 1, moderately severe in 4, severe in 5, and profound in 4. ABRs were absent in the 14 affected ears, while the OAEs, and/or CM were present.

Epstein-Barr virus-associated meningitis presenting with hearing impairment

A 42-year-old man presented with fever, headache and liver dysfunction, and was diagnosed as having aseptic meningitis by lumbar puncture. The PCR detected Epstein-Barr virus (EBV)-DNA in the peripheral blood and cerebrospinal fluid. About 20 days after onset, the patient presented with hearing impairment in the right ear, which was confirmed by a pure tone audiogram. The hearing acuity improved after the initiation of hydrocortisone sodium phosphate. We presume that the hearing impairment was due to auditory nerve neuritis related to extension of inflammation of the meninges. This is the first reported case of EBV-associated meningitis showing hearing impairment.

Clinical significance of a hearing and imaging workup in a child with cochlear nerve aplasia and a normal internal auditory canal

Modern magnetic resonance imaging has significantly improved the diagnosis of cochlear nerve deficiencies. A careful assessment of all clinical, imaging, and auditory data is of utmost importance in such cases in order to properly establish the site of the abnormality. We report the case of a 3-year-old girl with unilateral cochlear nerve aplasia, normal middle and inner ear anatomy, and an absence of otoacoustic emissions, all of which erroneously suggested cochlear damage. We also briefly review the embryogenesis of the inner ear and auditory pathway. A patient with similar findings in the setting of a bilateral hearing loss and insufficient imaging would be at risk of inappropriate cochlear implantation.

A 47-year old male with a cerebellopontine angle tumor

A 47-year old man presented with a five-year history of fluctuating hearing impairment in the left ear. There was no tinnitus or vertigo. Imaging studies demonstrated a contrast-enhancing cerebellopontine angle mass in the left internal auditory canal. Surgically the lesion was attached to the cochlear nerve. Pathological evaluation revealed what is best described as an angiolipomatous hamartoma of the cochlear nerve. Similar lesions have only rarely been described.

Microvascular decompression of cochlear nerve for tinnitus incapacity: pre-surgical data, surgical analyses and long-term follow-up of 15 patients

The level of success of neurovascular decompression in ponto-cerebellar angle for hemifacial spasm and trigeminal neuralgia has already established the reality of the pathology to explain such symptoms. However, cochlear nerve compression syndrome by vascular loop is still a controversial topic. We have performed a retrospective cases review with long-term follow-up (5-7 years) concerning the results of microvascular decompression surgery of the cochlear nerve via an endoscopy assisted retrosigmoid approach on 15 patients suffering from unilateral incapacitating tinnitus with abnormal auditory brainstem response and an offending vessel on magnetic resonance imaging. During the surgery, a vascular compression was found on every patient. In a long-term follow-up, 53.3% (8 cases) of our tinnitus cases improved and 20% (3 cases) of them were completely cured. The ABR returned to normal in all patients who had good clinical results (diminished or disappeared tinnitus). When a vertebral artery loop (5 cases) was concerned we obtained 80% of good clinical results. No one showed amelioration or sudden aggravation of their hearing. Three cases required surgical correction of cerebrospinal fluid leak and one case developed spontaneously regressive swallowing problems. Such microvascular decompression surgery of the cochlear nerve appears to be successful in treating incapaciting tinnitus in particular when a vertebral artery loop is observed. Therefore, in such a case, one might recommend neurovascular decompression surgery, keeping in mind that the complications of this surgery should be minimized by a careful closure of the retrosigmoid approach. In order to ensure a better selection of patient more accurate cochlear nerve monitoring and functional MRI should be a promising assessment.

Does Packing the Eustachian Tube Impact Cerebrospin al Fluid Rhinorrhea Rates in Translabyrinthine Vestibular Schwannoma Resections?

OBJECTIVE

To calculate cerebrospinal fluid (CSF) leak rates for translabyrinthine (TL), middle cranial fossa (MCF), and retrosigmoid/suboccipital (SO) craniotomies performed for removal of vestibular schwannoma (VS) and analyze whether packing the eustachian tube (ET) in TL VS resections impacts CSF rhinorrhea rates.

STUDY DESIGN

Retrospective.

SETTING

Tertiary care center.

METHODS

Chart review.

RESULTS

Three hundred fifty-nine VS resections were reviewed in 356 patients ranging from 10 to 86 years of age. Two hundred thirty-one TL, 70 MCF, 53 SO, and 5 combined TL/SO procedures were analyzed. Total CSF leak rates (incisional, otorrhea, and rhinorrhea) were 14.2% for TL, 11.4% for MCF, and 13.2% for SO approaches. Differences in overall CSF leak rates were not statistically significant. For those who underwent TL craniotomies, 2 groups of patients were identified based on whether their ETs were packed during surgery. In 1 group, the incus was removed, the aditus enlarged, the ET packed, and the middle ear filled with muscle. In the second group, the aditus, epitympanum and middle ear were packed without removing the incus, and the ET was not packed. Of 148 patients who had their ET packed, 12 developed CSF rhinorrhea (8.1%). The CSF rhinorrhea rate for patients who did not have ET packing was 5.9% (3 of 51 patients). This difference was not statistically significant (p = 0.80). When Proplast was used to pack the ET (121 patients), the CSF rhinorrhea rate was 5.8%. Unfortunately, this material extruded in 4 of 121 patients (3.3%) and presented clinically as delayed purulent otorrhea.

CONCLUSION

Cerebrospinal fluid leak rates were similar in patients undergoing TL, SO, and MCF approaches, and CSF rhinorrhea was not decreased by ET packing. Patients whose ETs are packed with Proplast are at risk for extrusion and otorrhea years after their initial VS resection.

Diagnosis and Management of Intracochlear Schwannomas

OBJECTIVE

To describe and analyze a series of intracochlear schwannomas.

METHODS

From 1987 to 2005, 19 patients with schwannomas involving the cochlea were included in this series. Clinical, audiovestibular, and imaging data concerning initial and follow-up visits were collected.

RESULTS

The mean age was 54 years (range, 25-71 yr). The series comprised 10 women and 9 men, 18 solitary tumors and 1 neurofibromatosis Type 2 patient. The mean diagnosis delay was 11 years (range, 1-31 yr). At diagnosis, a total or profound hearing loss (Class D of American Academy of Otolaryngology-Head and Neck Surgery classification) was noted in 17 patients (89%), and a severe loss (Class C) was reported in 2 patients (11%). Facial paresis was reported in 2 patients (11%; Grades 2 and 4 of House and Brackmann classification). Magnetic resonance imaging showed an involvement of the posterior labyrinth in 8 patients (37%), an extension of the schwannoma to the internal auditory meatus in 8 patients (37%), and a cerebellopontine angle extension in 7 patients (32%). In 11 patients (58%), the schwannoma was removed through a transotic route. In the 8 remaining patients, a watch-and-rescan policy was decided. The postoperative course was uneventful. Postoperative follow-up period was 27 months (range, 6-88 mo). Postoperative facial function was assessed as Grade 1 in 7 patients, as Grade 2 in 4, and as Grade 4 in 1 patient.

CONCLUSION

The diagnosis of intracochlear schwannomas can be difficult on magnetic resonance imaging. The diagnosis should be considered in all unilateral hearing losses.

[Prevalence of auditory neuropathy: prospective study in a tertiary-care center]

OBJECTIVE

The primary goal of this study is to determine the frequency of onset of this disorder in our infant population. Its clinical importance is due, among other reasons, to the fact that idiopathic cases constitute false negatives in the auditory screening programmes based on the performance of otoacoustic emissions to all newborn children and brainstem auditory evoked response only to those presenting these risk factors, for which reason another goal is to establish the prevalence of these pure cases and the diagnostic delay they cause.

PATIENTS AND METHOD

Prospective study of all newborn children at the Virgen de la Arrixaca Mother and Child Hospital (Murcia, Spain) in the period between June 1, 2000 and June 30, 2006.

RESULTS

Our screening programme, with a coverage of 95.68 %, detected 114 patients with unilateral or bilateral sensorineural hearing loss, with 6 presenting hearing loss attributable to auditory neuropathy.

CONCLUSIONS

The estimated prevalence of auditory neuropathy in our infant population turned out to be 1406 for every 10 000 children, ie 5.26 % of all sensorineural hearing loss diagnosed. Another significant finding was the delay in diagnosis, since the mean age at the moment of diagnosis was of 11.5 months, mainly due to idiopathic cases not detected during neonatal screening. Two clear conclusions can be inferred from these data: a) auditory neuropathy does not constitute an extraordinarily rare disorder, and b) idiopathic cases constitute false negatives in the universal auditory screening programmes based on the performance of otoacoustic emissions, which habitually leads to a delay in diagnosis and treatment.

Is microvascular compression of the vestibulocochlear nerve a cause of unilateral hearing loss?

OBJECTIVES

We sought to confirm earlier findings in the literature that microvascular compression of the vestibulocochlear nerve might cause unilateral sensorineural hearing loss. We measured the length and width of the internal auditory canal (IAC) to investigate a possible association between a narrow porus, the presence of an anterior inferior cerebellar artery (AICA) loop, and the development of a microvascular compression syndrome.

METHODS

We performed a prospective blinded analysis of 167 magnetic resonance imaging scans of the cerebellopontine angle. The presence of an AICA loop was scored. We analyzed these 167 patients for unilateral sensorineural hearing loss, which was defined as an interaural difference of 20 dB at 1 frequency or 10 dB at 2 or more frequencies. Furthermore, the width and length of the IAC on magnetic resonance imaging were measured.

RESULTS

An AICA loop was identified in 94% of the 167 patients. There were 196 type I loops, 106 type II loops, and 14 type III loops. Sixty-six patients had unexplained unilateral hearing loss. There was no association between type II and III vascular loops, the width of the IAC, and unilateral hearing loss (p > .05).

CONCLUSIONS

In this study we found no association between the depth of extension of the AICA loop into the IAC and the presence of unilateral hearing loss.

Internal Auditory Canal Morphology in Children with Cochlear Nerve Deficiency

OBJECTIVE

To describe the internal auditory canal (IAC) and inner ear morphologic characteristics of children with cochlear nerve (CN) deficiency.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution magnetic resonance imaging (MRI).

INTERVENTIONS

MRI of the brain. Clinical evaluation.

MAIN OUTCOME MEASURES

Review of medical records, audiological testing results, and imaging studies. Images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs and inner ears. Audiometric thresholds were evaluated in all subjects.

METHODS

Fourteen children with small or absent (deficient) CNs have been identified by means of high-resolution MRI. A review of the medical records, audiologic testing results, and imaging studies was undertaken. The images were evaluated for the structure of the cochlear, vestibular and facial nerves, IACs, and inner ears. The audiometric thresholds were evaluated in all subjects.

RESULTS

Among the 14 patients, 5 had known syndromes. MRI allowed an exact specification of the nervous structures within all ears with normal-size IACs. Precise characterization of the nerves in ears with small IACs was more difficult, requiring a consideration of both imaging findings and functional parameters. Five children had bilateral deficient CNs, whereas the remaining 9 subjects were affected unilaterally. Thus, 19 ears had CN deficiency (absent CN, 16; small CN, 3). Eleven ears had normal-size IACs and deficient CNs. Of the 9 ears with small IACs, 8 had deficient CNs (absent, 7; small, 1) on the basis of both MRI and functional assessments. Two ears with small IACs had clear morphologic and/or functional evidence for the presence of a CN: one had a small-size CN on MRI, whereas another had a single nerve in a small IAC with present facial and auditory functions.

CONCLUSION

The findings of this study suggest that CN deficiency is not an uncommon cause of congenital hearing loss. The findings that most ears with CN deficiency had normal IAC morphology and that two ears with small IACs had CNs present indicate that IAC morphology is an unreliable surrogate marker of CN integrity. On the basis of these findings, we think that high-resolution MRI, rather than CT imaging, should be performed in all cases of pediatric hearing loss, especially in those cases where profound hearing loss has been documented. For ears with small IACs, the resolution of MRI currently remains limiting. In these cases, the determination of CN status frequently requires a variety of anatomic (CT and MRI) and functional tests (auditory brainstem response, otoacoustic emissions, behavioral audiometry, and physical examination).

Connexin 26 variants and auditory neuropathy/dys-synchrony among children in schools for the deaf

Genetic and auditory studies of 731 children with severe-to-profound hearing loss in US schools for the deaf and 46 additional children receiving clinical services for hearing loss ranging from moderate to profound demonstrated that mutations in the connexin 26 (GJB2) and connexin 30 (GJB6) genes explain at least 12% of those with nonsyndromic sensorineural deafness. Otoacoustic emissions (OAEs) testing to detect functional outer hair cells indicated that 76 of the children had emissions and therefore may have (as yet unconfirmed) auditory neuropathy/dys-synchrony (AN/AD). Five of these children with OAEs were GJB2 homozygotes or compound heterozygotes with the genotypes 35delG/35delG, W77X/W77X, 35delG/360delGAG, 35delG/V95M, and V84M/M34T. In particular, unilateral AN/AD was confirmed in a child with moderate hearing loss and the 35delG/V95M genotype. Detecting OAEs in individuals with GJB2 mutations suggests that lack of functional gap junctions as a result of GJB2 mutations does not necessarily destroy all outer hair cell function.

Speech perception in individuals with auditory neuropathy

PURPOSE

Speech perception in participants with auditory neuropathy (AN) was systematically studied to answer the following 2 questions: Does noise present a particular problem for people with AN? Can clear speech and cochlear implants alleviate this problem?

METHOD

The researchers evaluated the advantage in intelligibility of clear speech over conversational speech in 13 participants with AN. Of these participants, 7 had received a cochlear implant. Eight sentence-recognition experiments were conducted to examine the clear speech advantage in 2 listening conditions (quiet and noise) using 4 stimulation modes (monaural acoustic, diotic acoustic, monaural electric, and binaurally combined acoustic and electric stimulation).

RESULTS

Participants with AN performed more poorly in speech recognition in noise than did the normal-hearing, cochlear-impaired, and cochlear implant controls. A significant clear speech advantage was observed, ranging from 9 to 23 percentage points in intelligibility for all listening conditions and stimulation modes. Electric stimulation via a cochlear implant produced significantly higher intelligibility than acoustic stimulation in both quiet and in noise. Binaural hearing with either diotic acoustic stimulation or combined acoustic and electric stimulation produced significantly higher intelligibility than monaural stimulation in quiet but not in noise.

CONCLUSIONS

Participants with AN most likely derive the clear speech advantage from enhanced temporal properties in clear speech and improved neural synchrony with electric stimulation. Although the present result supports cochlear implantation as one treatment choice for people with AN, it suggests that the use of innovative hearing aids may be another viable option to improve speech perception in noise.

Typewriter tinnitus: a carbamazepine-responsive syndrome related to auditory nerve vascular compression

Six subjects with similar unilateral tinnitus that was fully suppressed by carbamazepine have been identified. Their ages at the time of the sudden onset of their tinnitus ranged from 39 to 87 years (mean 67). The 3 men had right ear tinnitus. Two of the 3 women had left ear tinnitus. All 6 described a staccato quality of their intermittent tinnitus ('like a typewriter in the background, pop corn, Morse code'). Five of the 6 subjects had no other hearing or vestibular complaints; their audiograms were symmetric and consistent with their ages. Vascular compression of the auditory nerve ipsilateral to the tinnitus was detected in 4 of the 5 subjects imaged. The similarities between typewriter tinnitus and other cranial nerve syndromes associated with vascular compression (trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia) suggest that surgical decompression of the auditory nerve can relieve medication-refractive cases of typewriter tinnitus.

The jaundiced gunn rat model of auditory neuropathy/dyssynchrony

OBJECTIVE

High levels of bilirubin are neurotoxic and may result in deafness or auditory neuropathy/auditory dyssynchrony (AN/AD). The jaundiced (jj) Gunn rat animal model of kernicterus has electrophysiologic and neuroanatomic abnormalities of brainstem auditory nuclei with normal cochlear microphonic recordings. We examined morphologic changes in the cochlea, spiral ganglion, and auditory nerve and relate these findings to current understanding of AN/AD.

METHODS

At 15 days of age, jj and nonjaundiced (Nj) littermates were injected with sulfadimethoxine (sulfa) and killed 3 days later by transcardial perfusion. Sections were cut through decalcified temporal bones, cochlear nerves, and auditory brainstem and processed for light and electron microscopy and immunohistochemical localization of calbindin-D and parvalbumin.

RESULTS

Spiral ganglion neurons were severely degenerated with a paucity of myelinated axons in jj animals. Electron microscopy of the intramodilar auditory nerve revealed a lack of large caliber axons in jj-sulfa versus Nj-sulfa controls. Large diameter degenerating axons were characterized by an electron-dense atrophied axis cylinder resembling an axonopathy.

CONCLUSIONS

Our findings of abnormal spiral ganglion cells and selective loss of large, myelinated auditory nerve fibers with no abnormalities in cochlear hair cells, support the sulfa-treated jj Gunn rat as a model for bilirubin induced AN/AD. The paucity of large caliber neurons undermines temporal coding of auditory information and neural synchrony and demonstrates that in addition to brainstem auditory nuclei, spiral ganglion neurons are selectively vulnerable to bilirubin toxicity.

[The role of neurovisualization methods in diagnosis and verification of vertigo etiology]

Roentgen computed tomography (RCT) and MR-imaging (MRI) were used in investigation of vertigo etiology and affection of the cochleovestibular analyzer in 130 patients aged 28 to 74 years with recurrent systemic rotatory vertigo or its other symptoms. All the patients have undergone comprehensive otoneurological examination, RCT and MRI which showed that peripheral cochleovestibular syndromes (PCVS) caused by arterial hypertension (AH), atherosclerosis (AS), vascular dystonia (VD) are rarely characterized by focal alterations in the brain. PCVS comparison with blood flow in the vertebral arteries (VA) detected most frequently anomalies and asymmetries of the diameters. MR-angiography plays an important role in verification of pathology of intracranial VA. In central cochleovestibular syndrome (CCVS) with AH, AS, VD, principal pathological changes were registered in the brain trunk and cerebellum by MRI. Vestibulometry and otoneurological method detect not only vascular cochleovestibular peripheral and central syndromes but also to make differential diagnosis. RCT and MRI verify cochleovestibular syndromes in patients with multiple encephalomyelitis, VIII nerve neurinoma and tumors of the posterior cranial fossa.

Auditory brainstem implant (ABI): new frontiers in adults and children

Previous studies have considered only patients with neurofibromatosis type 2 (NF2) older than 12 years as candidates for an auditory brainstem implant (ABI). Our study expands the potential criteria to include both children and adult subjects with other cochlear or cochlear nerve malfunctions who either would not benefit at all from a cochlear implant (eg, cochlear nerve aplasia or avulsion) or whose benefit was or would be severely compromised (eg, cochlear ossification, cochlear fracture).

STUDY DESIGN

In our department, over the period from April 1997 to September 2002, 29 patients, 20 adults and 9 children, were fitted with ABIs. Their ages ranged from 14 months to 70 years. Thirteen subjects had tumors, 10 NF2 and 3 solitary vestibular schwannoma, and 16 patients had a variety of nontumor (NT) cochlear or cochlear nerve diseases. A retrosigmoid-transmeatal approach was used in T and a retrosigmoid approach in NT patients. The electrode array was inserted into the lateral recess of the fourth ventricle and correct electrode positioning was monitored with the aid of electrically evoked auditory brainstem responses (EABRs).

RESULTS

Correct implantation was achieved in all patients. No complications were observed due to implantation surgery or related to ABI activation or long-term use. Auditory sensations were induced in all patients with various numbers of electrodes (from 5 to 15). Different pitch sensations were identifiable with different electrode stimulation. Closed-set word recognition, open-set sentence recognition, and speech tracking scores achieved by the patients are reported in detail. The auditory performance of the patients showed significantly better outcomes than controls (Multicentric European clinical investigations on ABI with NF2).

CONCLUSION

We have shown that the indications for the ABI can be extended to include NT patients with severe cochlear and/or cochlear nerve abnormalities. The degree of auditory benefit varies as a function of the underlying pathological conditions, with NT subjects exhibiting significantly better outcomes than the T patients.

Using auditory-visual speech to probe the basis of noise-impaired consonant-vowel perception in dyslexia and auditory neuropathy

Both dyslexics and auditory neuropathy (AN) subjects show inferior consonant-vowel (CV) perception in noise, relative to controls. To better understand these impairments, natural acoustic speech stimuli that were masked in speech-shaped noise at various intensities were presented to dyslexic, AN, and control subjects either in isolation or accompanied by visual articulatory cues. AN subjects were expected to benefit from the pairing of visual articulatory cues and auditory CV stimuli, provided that their speech perception impairment reflects a relatively peripheral auditory disorder. Assuming that dyslexia reflects a general impairment of speech processing rather than a disorder of audition, dyslexics were not expected to similarly benefit from an introduction of visual articulatory cues. The results revealed an increased effect of noise masking on the perception of isolated acoustic stimuli by both dyslexic and AN subjects. More importantly, dyslexics showed less effective use of visual articulatory cues in identifying masked speech stimuli and lower visual baseline performance relative to AN subjects and controls. Last, a significant positive correlation was found between reading ability and the ameliorating effect of visual articulatory cues on speech perception in noise. These results suggest that some reading impairments may stem from a central deficit of speech processing.

Sacculo-collic pathway dysfunction accompanying auditory neuropathy

CONCLUSIONS

In a patient with bilateral auditory neuropathy (AN), the vestibular-evoked myogenic potential (VEMP) was probably absent because of a neuropathy involving the inferior vestibular nerve and/or its end organ, the saccule. Our result can therefore be interpreted as a concomitant unilateral sacculo-collic neuropathy. We suggest the use of more precise terms to characterize AN patients with involvement of different parts of the inner ear and its innervations. We encourage detailed vestibular assessment in patients with AN in order to assess the co-existence of any symptomatic or asymptomatic vestibular disorder. Information such as that provided in this report will be valuable for clinicians caring for this group of patients.

OBJECTIVE

AN is a disorder characterized by the absence or severe impairment of auditory brainstem responses in the presence of normal cochlear outer hair cell function as revealed by otoacoustic emissions (OAEs) and/or electrocochleography (ECoG). A variety of processes and etiologies are thought to be involved in its pathophysiology. In most literature reports the auditory profile of patients with AN is discussed. However, the extent of vestibular involvement, especially that involving the saccule, is not known. We performed vestibular tests to assess the status of the saccule in a patient with AN.

MATERIAL AND METHODS

One patient with AN was studied. The patient was a right-handed 21-year-old female with chief complaints of hearing loss and speech perception difficulty.

RESULTS

The auditory test results were consistent with the diagnosis of AN, i.e. absent auditory brainstem responses, moderate hearing loss, an inappropriately profound speech discrimination score and the presence of OAEs and measurable cochlear microphonics on ECoG. On neurological examination, gait and balance tests were normal. Ice-water caloric testing induced a sensation of dizziness in both ears. Short tone-burst VEMPs showed no response on left-ear stimulation and a biphasic response with normal latency and amplitude on right-ear stimulation.

Syndrome de Cogan révélé par une diarrhée glairo-sanglante

INTRODUCTION

Cogan's syndrome is defined by the combination of non syphilitic interstitial keratitis and inner ear dysfunction, similar to Meniere's disease.

OBSERVATION

Cogan's syndrome was revealed by haemorrhagic glaireous diarrhoea in a 21 year-old woman whose medical history included Hirschsprung's disease. Cerebral MRI revealed viral-like bilateral neuritis of the eighth cranial nerve, never described in the literature before. The auditory and visual disorders regressed after treatment with corticosteroids.

CONCLUSION

The early diagnosis of Cogan's syndrome permits the cure of the visual and auditory and notably inner ear symptoms with corticosteroid therapy.

Vascular malformation (so-called hemangioma) of Scarpa's ganglion

Vascular malformations of the cerebello-pontine angle (CPA) arising from the capillary plexus surrounding Scarpa's ganglion are rare tumors. We report a case of so-called "hemangioma" of the CPA which was operated on via a trans-labyrinthine approach based on a preoperative diagnosis of vestibular schwannoma. Although there are some differences between these tumors in terms of the clinical, biological and especially MRI findings, surgery is usually performed based on an assumption of vestibular schwannoma. Surgery is the treatment of choice for these lesions as early intervention ensures better postoperative facial function. It is important to make the differential diagnosis if conservative management of vestibular schwannoma is adopted.

Syphilis in the HIV era

The incidence of syphilis has consistently increased from 2000 to 2002. We report a case of acquired syphilis with symptoms of Tullio phenomenon in a patient concurrently diagnosed with HIV infection. The resurgence of syphilis in HIV-positive groups at high risk has public health implications for prevention of both diseases.

Optico-cochleo-dentate degeneration associated with severe peripheral neuropathy and caused by peroxisomal D-bifunctional protein deficiency

The clinical, neuroradiological, neuropathological and biochemical findings in a patient with optico-cochleo-dentate degeneration (OCDD; OMIM 258700) are presented in a severe case succumbing at the age of 4 years. The electron microscopic and biochemical data showed for the first time that OCDD may occur as the phenotypic expression of D-bifunctional protein deficiency, i.e., a peroxisomal disorder. The boy was born as the first child of healthy, consanguineous parents of Turkish origin. No other family members were affected. The main clinical symptoms consisted of muscle hypotonia ("floppy infant"), generalized epileptic fits, hypacusis, rotatory nystagmus, insufficient pupillary reactions, and mental retardation. Fibroblast cultures revealed D-bifunctional protein deficiency. Neuropathological examination displayed moderate frontoparietal and insular microgyria, and atrophy of the cerebellum. Loss of neurons was severe in the granular layer, the Purkinje cell band of the cerebellum, and rather complete in the dentate nucleus. A corresponding loss of myelinated fibers associated with characteristic periodic acid-Schiff-positive macrophages was most prominent in the white matter of the cerebellum. There was additional severe loss of myelinated fibers in the central portions of the optic nerve, reduction of the nerve fiber density in the cochlear nerve, and reduction of myelinated nerve fibers by about 80-90% in the sural nerve, which has not been studied in previous cases. At the electron microscopic level, characteristic inclusions mainly in perivascular macrophages and astrocytes were the most prominent finding. The inclusions usually showed a bilaminar structure, whereas trilaminar structures, typically seen in adrenoleukodystrophy, and multilaminar structures were less frequently seen.

Subclinical vestibulocerebellar dysfunction in migraine with and without aura

OBJECTIVE

In patients with migraine, neurotologic symptoms and signs occur commonly. The authors' aim was to determine whether neurotologic findings are in accordance with the type of migraine and whether test findings differ from those of healthy controls.

METHODS

The authors examined 36 patients with various types of migraine classified by International Headache Society criteria. Comprehensive neurotologic tests were performed between attacks: video-oculography (VOG), electronystagmography, static posturography, and audiometry on 12 patients with migraine with aura (MA) and 24 patients with migraine without aura (MO). Results were compared to those of test-specific nonmigrainous control groups. Only eight migraineurs (six with MA and two with MO) had vertigo or dizziness.

RESULTS

Despite the absence of clinical neurotologic symptoms, most of the patients with migraine (83%) showed abnormalities in at least one of these tests. Both migraine types differed significantly from the control group (in VOG, in saccadic accuracy, and in static posturography). Vestibular findings tended to be more severe in MA than in MO.

CONCLUSIONS

These data suggest that interictal neurotologic dysfunction in MA and MO share similar features and that the defective oculomotor function is mostly of vestibulocerebellar origin.

Cochlear implantation in patients with auditory neuropathy of varied etiologies

OBJECTIVES/HYPOTHESIS

Auditory neuropathy is a relatively recently described pattern of hearing loss characterized by preservation of outer hair cell function despite absent brainstem auditory evoked responses. Intact outer hair cell function is demonstrated by the presence of otoacoustic emissions and/or a measurable cochlear microphonic on electrocochleography, whereas no synchronous neural activity (absent action potentials) is seen on acoustically evoked brainstem auditory evoked response testing. The study reviews the authors' experience with six patients diagnosed with auditory neuropathy, four of whom have undergone cochlear implantation.

MATERIALS AND METHODS

A retrospective review of all medical and audiological charts at the University of Virginia Hospitals (Charlottesville, VA) was performed to identify patients who have undergone cochlear implantation or have been diagnosed with auditory neuropathy, or both.

RESULTS

Six patients with hearing loss attributable to auditory neuropathy were identified, four of whom have undergone cochlear implantation. Causes varied, including congenital, infectious, and idiopathic origins. Adults demonstrated subjective auditory perception on promontory stimulation, whereas no repeatable brainstem auditory evoked response waveforms could be demonstrated on pediatric promontory stimulation testing. Patients with implants demonstrated implant-evoked brainstem auditory evoked responses and improved audiological performance.

CONCLUSIONS

The six cases presented in the study represent varied causes and, probably, varied sites of lesions of auditory neuropathy. Promontory stimulation has been valuable, particularly in adults. Cochlear implantation allows the opportunity to provide a supraphysiological electrical stimulation to the auditory nerve, with the hope of reintroducing synchronous neural activity. Greater confidence and enthusiasm for cochlear implantation in appropriately selected patients with auditory neuropathy are gained through experience with such diverse cases.

Incidence of cochlear involvement in hyperbilirubinemic deafness

Neonatal hyperbilirubinemia remains an important cause of childhood deafness, especially in developing countries. After neonatal hyperbilirubinemia, the auditory neural pathways, cochlea, or both may be affected. In this study, we aimed to determine the incidence of cochlear impairment and the appropriate means of hearing screening in hyperbilirubinemic neonates. A retrospective review of 1,032 pediatric patients with hearing loss revealed 67 cases (6.5%) of severe hyperbilirubinemia in the neonatal period. Thirty of these patients had neonatal hyperbilirubinemia as the single identifiable risk factor for hearing loss. In 26 of 30 cases (87%), otoacoustic emissions (OAEs) were absent, whereas in the remaining 4 cases (13%), robust emissions were detected despite an absent auditory brain stem response (ABR). Auditory screening of newborns with jaundice by OAEs possesses a significant risk of undiagnosed deafness. On the other hand, if the ABR is used as the single means of screening, auditory neuropathic conditions will probably be underlooked. Therefore, we recommend dual screening of hearing by ABR and OAEs in hyperbilirubinemic newborns.

Electrical stimulation of the auditory nerve via cochlear implants in patients with auditory neuropathy

Auditory neuropathy (AN) is a term used to describe an auditory disorder in which there is evidence of normal outer hair cell function (otoacoustic emissions and/or cochlear microphonics) and poor function of the auditory nerve (absent or highly distorted auditory brain stem response starting with wave I). Many of these patients have evidence of generalized peripheral nerve disease, leading to an assumption that the peripheral portion of the auditory nerve is the most likely site of lesion. A small group of these patients has received cochlear implants, and the majority of them achieve average to above-average performance. Although this outcome may seem incongruous with neural disease, average performance by patients with AN may be a result of the reintroduction of neural synchrony by electrical stimulation and/or the fact that most deaf patients have poor nerve survival. Although cochlear implants are promising for deaf patients with AN, more study of the disorder is needed.

Under-rated neuro-otological symptoms: Hoffman and Brookler 1978 revisited

In 1978, Hoffman and Brookler published an article in The Laryngoscope to challenge prevailing views on the lack of diagnostic power of certain symptoms often reported by patients to neuro-otologists. Some of these 'under-rated neuro-otological symptoms' include complaints of non-rotational dizziness, blurred and double vision, and the development of visual motion hypersensitivity in patients with balance disorders. In this review, I revisit these visual symptoms in the light of new findings from our laboratory. Double vision due to skew eye deviation can indeed occur in peripheral vestibular disease when there is a large, acute peripheral imbalance of vestibular function. It is more frequent and severe in brain stem disease. In both cases, it is explained by disruption of the torsional vestibular ocular reflex. It is usually assumed that damage to the otolith underlies the emergence of skew diplopia, but recent evidence shows that the vertical canal system is likely to be partly responsible as well. The other 'under-rated symptom' revisited here is what patients describe as dizziness when watching moving objects or whilst walking in visually busy surroundings such as supermarkets. Recent work has shown that this 'visual vertigo' emerges in patients who, in addition to suffering from a vestibular disorder, have increased visual dependence. Visual dependence denotes subjects who preferentially use vision, as opposed to vestibular or proprioceptive input, for spatial orientation and postural control. We do not know as yet what makes some vestibular patients become extremely visually dependent. However, we have provided evidence for Hoffman and Brookler's impression that visually triggered complaints should not be summarily dismissed, as they often point to an underlying vestibular disorder.

Malignant melanoma presenting as sudden onset of complete hearing loss

The authors describe a rare case of rapidly progressive bilateral hearing loss associated with carcinomatous meningitis secondary to a primary malignant melanoma of the lower limb 6 years previously. Carcinomatous meningitis is a relatively rare diagnosis, with the involvement of the eighth cranial nerve being present in only a small proportion of patients. Diagnosis relies on clinical suspicion (when multiple cranial nerve lesions occur), magnetic resonance imaging, and cerebrospinal fluid cytology.

Hearing habilitation with auditory brainstem implantation in two children with cochlear nerve aplasia

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.

Childhood vertigo: a case report and review of the literature

Vertigo is a relatively uncommon pediatric complaint, with correct diagnosis made even more challenging by the patient's inherent difficulty in describing his or her symptoms. Confusion may exist among vertigo, dizziness, dysequilibrium, ataxia, pre-syncope or syncope, and seizure activity by both the pediatric patient and his or her family. A complete history and physical examination, as well as appropriate ancillary studies, may assist in clarifying the diagnosis. This paper attempts, via case report and literature review, to discuss the various etiologies of acute vertigo in the pediatric population, provide diagnostic clues, and evaluate some of the available diagnostic modalities.

An isolated and sporadic auditory neuropathy (auditory nerve disease): report of five patients

Five patients of various ages with difficulty in speech discrimination were evaluated. All showed evidence of abnormal auditory brainstem responses (ABRs) beginning with the VIIIth cranial nerve. Broad summating potentials were evoked on their electrocochleograms (EcochGs) and they all exhibited almost normal cochlear outer hair cell function by otoacoustic emissions (OAEs) recordings. Behavioural audiometric testing revealed a mild to moderate elevation of pure-tone threshold in all patients. The shape of their pure-tone losses varied, being predominantly low-frequency in four patients (rising slope pattern) and flat across all frequencies in one patient. Speech intelligibility scores of all patients were poor and out of proportion to what would have been expected if threshold elevation of pure-tone was of cochlear origin (i.e. markedly poor scores on the speech audiogram with good scores on the auditory comprehension test). Patients were neurologically normal when the hearing impairment was first manifested. We suggest that this type of hearing impairment is due to an isolated and sporadic disorder of auditory nerve function. It occurs in isolation and does not seem to be part of a generalized neuropathological process.

[Vascular compression syndrome of the vestibulocochlear nerve--otolaryngologic and radiologic diagnosis]

Vascular compression syndrome is the term used to classify a group of conditions though to be caused by the compression of cranial nerve by vessel. In the most cases the contact of vascular loop formed by the anterior inferior cerebellar artery (AICA) with the eight and facial nerve correlated with unilateral auditory symptoms or hemifacial spasms. The vascular compression syndrome of vestibulocochlear nerve in 8 patients treated in I ENT Clinic of Silesian Academy and MRI Department in Katowice was observed. All patients were otologic findings such as a tone audiometry, ENG, ABR and radiological diagnostics included MRI and angio MRI. The prospective analysis was performed. The results suggest that the unilateral sensorineural hearing loss, tinnitus, vestibular disorders and positive findings on magnetic resonance imaging are the most reliable evidence for the presence neurovascular compression syndrome of the eight cranial nerve. The MRI and otologic studies provided quite detailed information about topography of relationship between the blood vessels and cranial nerves in the crebellopontine cistern.

Evaluation of the vestibular aqueduct in vestibulocochlear disorders by magnetic resonance imaging

The visibility of the vestibular aqueduct (VA) was examined using magnetic resonance imaging (MRI) in 95 patients: 15 patients with Meniere's disease, 4 with vestibular Meniere's disease, 4 with cochlear Meniere's disease and 72 patients with other vestibular and/or cochlear disorders. In order to visualize the VA, the T2-weighted image (T2WI) and the proton-density weighted image (PDWI) were obtained in the sagittal plane with a head coil. The visibility of the VA was classified into 4 grades, i.e. grade 0 (not visible), grade 1 (partially visible with PDWI), grade 2 (partially visible with T2WI) and grade 3 (clearly visible with T2WI). The visibility of the VA was significantly lower bilaterally in Meniere's disease, vestibular Meniere's disease, cochlear Meniere's disease and idiopathic bilateral sensorineural hearing loss (IBSNHL) than in the other diseases. The differences among Meniere's disease, vestibular Meniere's disease and cochlear Meniere's disease were not significant. The significance of decreased visibility in IBSNHL is unknown so far. The VA studies using MRI strongly suggest that the pathogenesis of Meniere's disease, vestibular Meniere's disease, cochlear Meniere's disease and IBSNHL is, at least in part, related to the findings of the VA.