Vestibular neuropathy accompanying auditory and peripheral neuropathies

OBJECTIVE

To define the incidence of measurable vestibular disorders in patients with auditory and peripheral neuropathies.

DESIGN

Descriptive study of the case features of auditory neuropathy in 14 patients, 8 of whom had concomitant peripheral neuropathies.

SETTING

University referral center.

PATIENTS

Fourteen patients aged from 10 to 75 years and diagnosed as having auditory neuropathy, 8 of whom had concomitant peripheral neuropathies.

MAIN OUTCOME MEASURES

Incidence of abnormal vestibular caloric test results and the relationship of such incidence to clinical variables including the ages of the subjects, the presence of a concomitant peripheral neuropathy, vestibular symptoms, and audiological findings.

RESULTS

Abnormal vestibular caloric test results occurred in 9 of the 14 patients. These 9 patients were on average older (35.6 years) than patients with normal caloric responses (17.8 years). Seven of the 9 patients with abnormal caloric responses had concomitant peripheral neuropathies compared with only 1 of the 5 patients with normal caloric responses. None of the 14 patients experienced symptoms of vestibular disorder.

CONCLUSIONS

Asymptomatic vestibular disorders are common in patients with auditory neuropathy when a peripheral neuropathy is also present. The reason for the abnormal vestibular test results is likely a neuropathy of the vestibular nerves. Arch Otolaryngol Head Neck Surg. 2000;126:1453-1456

Vestibular neurectomy

A brief history of the vestibular neurectomy is given. This treatment modality was introduced in Denmark by us, using the experiences obtained by the use of translabyrinthine treatment modality for vestibular schwannoma surgery. This paper presents our experiences with this type of surgery (translabyrinthine, retrolabyrinthine and retrosigmoid vestibular nerve section) from 1980 to 1996, including 43 operations in 42 patients. The patients had all been treated with conventional methods without success and were all severely handicapped by their attacks of vertigo. The mean age was 51 years, postoperative observation time between 2 and 15 years, with a mean of 6.4 years. The vertigo was controlled in 88% of the patients, while postoperative imbalance occurred in 14 patients, mainly due to the ablation of the vestibular labyrinth and not by episodic vertigo. A total of 39 patients indicated that they were satisfied with the operation. Six patients were deaf before surgery and 92% of the remaining patients retained their preoperative hearing. Postoperative complications were few, including two re-operations for CSF leaks, one patient with a slight transient facial nerve paresis and one transient VI nerve paresis. The results compare favorably with results from other authors. Retrosigmoid vestibular nerve section is an effective treatment modality to be offered to patients in whom other modalities have failed. Information about the efficacy and leniency of the treatment should be given to the patient's organization in order to diminish the fear of an intracranial intervention. Surgical experience is necessary in order obtain good results, the number of patients needing the operation is small and centralization of the treatment is mandatory.

[Auditory neuropathies in infants]

Auditory neuropathy is a sensorineural disorder characterized by absent or abnormal auditory evoked potentials, and normal cochlear outer hair cell function. It is believed that a variety of processes are involved in its pathophysiology and their influence on hearing can differ. We describe the diagnostic sequence and management of two new cases of auditory neuropathy in infants. The first case was a girl with no risk factors for hearing loss. Her absence of response to sounds was compared with her twin's reactions. Otoacoustic emissions were present but no auditory evoked potential response was detected. Her evolution was characteristic of deep sensorineural hearing loss without a hearing aid. At present she is awaiting a cochlear implant. The second case was a boy who underwent hearing loss screening for hyperbilirubinemia. Examinations were repeated three months later because the mother suspected hearing loss. Objective tests showed a pattern of auditory neuropathy. The boy's evolution was different: in spite of the presence of destructured auditory evoked potentials; it was evident that the boy conserved some hearing and had thresholds suggestive of moderate hearing loss.

How common are various causes of dizziness? A critical review

BACKGROUND

Although dizziness is a common symptom in both primary care and referral practices, the relative frequency of various causes has not been well delineated.

METHODS

A MEDLINE search identified 12 articles containing original data on the etiology of dizziness in consecutive patients. Study sites included primary care offices (n = 2), emergency room (n = 4), and referral clinics (n = 6). Each study's strength of design was graded using nine quality criteria.

RESULTS

Dizziness was attributed to a peripheral vestibulopathy in 44% of patients, a central vestibulopathy in 11%, psychiatric causes in 16%, other conditions in 26%, and an unknown cause in 13%. Certain serious causes were relatively uncommon, including cerebrovascular disease (6%), cardiac arrhythmia (1.5%), and brain tumor (<1%).

CONCLUSIONS

Dizziness is due to vestibular or psychiatric causes in more than 70% of cases. Since serious treatable causes appear uncommon, diagnostic testing can probably be reserved for a small subset of patients.

[Management of the acoustic tumor in an only/better hearing ear]

Because profound bilateral hearing impairment is a catastrophic event, the management and care of an individual with an 8th nerve lesion in an only/better hearing ear remains a significant challenge for both patient and physician. Current options regarding the treatment of the acoustic tumor in an only/better hearing ear include: observation, attempted hearing preservation surgery and stereotactically guided radiation therapy. In this article, we present 3 cases of acoustic tumor within the internal auditory canal in an only/better hearing ear diagnosed by gadolinium-enhanced MRI and discuss the recommendations, especially observation, available in the care of these cases. In one patient, hearing disturbance caused by the tumor in a better hearing ear made the patient quite depressive and desperate. One of the most important consideration is for the physician to provide the patient with adequate informed consent regarding the possibility of profound bilateral hearing loss caused by either the natural growth or surgical removal of the tumor in the future, and alternative methods of communication with others such as: hearing aid and lip reading, cochlear implant and brainstem implant.

Fractionated stereotactic radiation therapy and single high-dose radiosurgery for acoustic neuroma: early results of a prospective clinical study

PURPOSE

To prospectively assess the local control and toxicity rate in acoustic neuroma patients treated with linear accelerator-based radiosurgery and fractionated stereotactic radiation therapy.

METHODS AND MATERIALS

We evaluated 37 consecutive patients treated with stereotactic radiation therapy for acoustic neuroma. All patients had progressive tumors, progressive symptoms, or both. Mean tumor diameter was 2.3 cm (range 0.8-3.3) on magnetic resonance (MR) scan. Dentate patients were given a dose of 5x4 Gy or 5x5 Gy and edentate patients were given a dose of 1x10 Gy or 1x12.50 Gy prescribed to the 80% isodose. All patients were treated with a single isocenter.

RESULTS

With a mean follow-up period of 25 months (range 12-61), the actuarial local control rate at 5 years was 91% (only 1 patient failed). The actuarial rate of hearing preservation at 5 years was 66% in previously-hearing patients. The actuarial rate of freedom from trigeminal nerve toxicity was 97% at 5 years. No patient developed facial nerve toxicity or other complications.

CONCLUSION

In this unselected series, fractionated stereotactic radiation therapy and linear accelerator-based radiosurgery give excellent local control in acoustic neuroma. It combines a high rate of preservation of hearing with a very low rate of other toxicity, although follow-up is relatively short.

Profound hearing loss attributable to cochlear nerve disease: diagnosis with combination of otoacoustic emission and magnetic resonance imaging

OBJECTIVE

To detect the causes of deafness based on the combined findings of auditory brainstem response (ABR), distortion product otoacoustic emissions (DPOAEs), and three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) magnetic resonance imaging (MRI).

STUDY DESIGN

Retrospective review of the medical records of 13 patients with unilateral profound hearing loss since childhood.

METHODS

Subjects were tested with pure-tone audiometry, ABR, DPOAEs, and 3DFT-CISS imaging.

RESULTS

No significant components of ABR were observable in any of the deaf ears. In 10 cases, the cochlear nerves of the deaf ears were found to be as normal as the healthy sides by 3DFT-CISS imaging, and no significant levels of DPOAEs were recorded. In the other three cases, no apparent cochlear nerves were identified by 3DFT-CISS imaging. Although no significant levels of DPOAEs were observable in two cases with cochlear nerves invisible by the MRI study, almost the same level of DPOAEs as that in the healthy side was recorded in the last case.

CONCLUSIONS

In the last particular case, the cochlear nerve seemed to be mainly responsible for the profound deafness. 3DFT-CISS imaging in combination with preexisting audiological measures may provide direct evidence for the cochlear nerve disease. steady state, internal auditory canal, cochlear nerve disease.

Decision tree induction in the diagnosis of otoneurological diseases

Expert systems have been applied in medicine as diagnostic aids and education tools. The construction of a knowledge base for an expert system may be a difficult task; to automate this task several machine learning methods have been developed. These methods can be also used in the refinement of knowledge bases for removing inconsistencies and redundancies, and for simplifying decision rules. In this study, decision tree induction was employed to acquire diagnostic knowledge for otoneurological diseases and to extract relevant parameters from the database of an otoneurological expert system ONE. The records of patients with benign positional vertigo, Meniere's disease, sudden deafness, traumatic vertigo, vestibular neuritis and vestibular schwannoma were retrieved from the database of ONE, and for each disease, decision trees were constructed. The study shows that decision tree induction is a useful technique for acquiring diagnostic knowledge for otoneurological diseases and for extracting relevant parameters from a large set of parameters.

Expert opinion on the diagnosis of acoustic tumors

Ideally, clinicians recommend diagnostic tests when the patient's risk of disease is sufficient to justify putting numerous similar patients through the morbidity required to diagnose disease in one patient. In the case of acoustic tumor diagnosis, there are few published data available to the clinician to help assess risk in an individual patient. The purpose of this study was to obtain information by an opinion poll of a group of experts. We used the Delphi method to poll clinicians trained at the House Ear Clinic. We asked these experts 20 questions related to acoustic tumor diagnosis. Some of the expert opinion presented herein is the only data related to acoustic tumor diagnosis available to clinicians. These data are a first step in elevation of decision-making for tumor diagnosis above the level of speculation. However, the experts' responses displayed a pattern of inaccuracy that limits the clinical application of their opinion. Exposing this pattern was instructive for identifying desirable features of protocols for diagnosing tumors. We recommend that protocols not depend on clinicians estimating probability of tumor. Instead, protocols may list specific findings, such as unilateral distortion on the telephone, to indicate, when present, that the risk of tumor is sufficient to order a diagnostic test.

Ganglionic hamartoma of the intracanalicular acoustic nerve causing sensorineural hearing loss

OBJECTIVE

This article highlights the clinical presentation and treatment issues of ganglionic hamartoma of the internal auditory canal and emphasizes the similarity of this lesion to acoustic neuroma regarding its audiologic and radiographic characteristics.

STUDY DESIGN

This article is composed of case reports and a literature review.

SETTING

The study was performed at a university hospital/tertiary referral center.

PATIENT

A patient with biopsy-proven ganglionic hamartoma of the acoustic nerve was studied.

INTERVENTION

Intervention consisted of surgical therapy.

MAIN OUTCOME MEASURE

The main outcome measure was clinical evaluation.

RESULTS

The result was successful removal of lesions with facial nerve preservation.

CONCLUSIONS

An intracanalicular ganglionic hamartoma resulted in progressive sensorineural hearing loss and magnetic resonance imaging findings suggestive of small acoustic neuroma. This lesion, composed of an admixture of ganglion cells, fibroadipose-tissue, and normal myelinated axons, although rare, should be added to the differential diagnosis of internal auditory canal lesions.

3D analysis of nystagmus in peripheral vertigo

Three-dimensional analysis of nystagmus was carried out in patients with peripheral vestibular diseases using a computerized image recognition technique developed by us. In the present study, we analyzed data from patients with Meniere's disease and vestibular neuritis with the central premise of localizing the pathology in the peripheral vestibular organs. In Meniere's disease, the recordings of all subjects showed two components of eye movements, namely the horizontal and torsional components. On the other hand, most of the patients with vestibular neuritis exhibited all three components of spontaneous nystagmus. The horizontal and vertical components of nystagmus in patients with vestibular neuritis were directed towards the contralateral side of the lesion and upwards. Based on these results and with reference to animal experiments that have related the eye movements with each labyrinthine end organ, it can be speculated that in Meniere's disease the pathological changes may involve all semicircular canals, whereas the main site of lesion in vestibular neuritis could be localized to the superior vestibular nerve.

Histopathology of idiopathic chronic recurrent vertigo

Vestibular neuritis is a degenerative neuropathy of the peripheral vestibular system. The etiology of this condition is uncertain, although it is generally believed to be viral. A small percentage of patients with vestibular neuritis have chronic recurrent episodes of vertigo. Detailed cytologic descriptions of acute or chronic vestibular neuritis are lacking, and no previous studies have reported evidence of chronic inflammation in human temporal bone specimens. The authors of this study examined temporal bone specimens from three patients with a history of chronic recurrent vertigo of unknown cause. Varying degrees of inflammation and destruction were seen in the vestibular system, and mild involvement of the cochlear system was noted. These findings are consistent with postinfectious inflammatory changes of the cochlear-vestibular system analogous to a postinfectious syndrome involving the central nervous system.

Absent vestibular evoked myogenic potentials in vestibular neurolabyrinthitis. An indicator of inferior vestibular nerve involvement?

BACKGROUND

Benign paroxysmal positioning vertigo (BPPV) is generally thought to be caused by canalolithiasis in the posterior semicircular canal, an organ that is innervated by the inferior vestibular nerve. We hypothesized that absent vestibular evoked myogenic potentials (VEMPs) would indicate involvement of the inferior vestibular nerve and that posterior semicircular canal-type BPPV could not develop after vestibular neurolabyrinthitis (VNL) in patients with absent VEMPs.

OBJECTIVE

To find out if VEMPs could be helpful in evaluating involvement of the inferior vestibular nerve in acute VNL.

DESIGN

We reviewed the VEMP findings in 47 patients (34 men and 13 women) with acute VNL, 10 of whom had then developed posterior semicircular canal-type BPPV.

RESULTS

While p13-n23, the first positive-negative peak of the VEMP, was ipsilaterally present on stimulation of the unaffected side in all patients, it was absent on the affected side in 16 patients (34%). The absence or presence of p13-n23 was independent of the results of caloric tests, pure tone audiometry, and auditory brain-stem responses. Typical posterior semicircular canal BPPV developed in 10 of the 47 patients after the acute attack of VNL, always on the same side as the neurolabyrinthitis. The p13-n23 potentials were preserved on stimulation of the affected ear in all 10 patients with BPPV.

CONCLUSIONS

These results suggest that if VEMPs are absent from an ear that has suffered acute VNL, then posterior semicircular canal BPPV is unlikely to develop as a consequence of the VNL. The reason for this appears to be that the absence of VEMPs is due to involvement of the inferior vestibular nerve or involvement of the structures that it innervates.

Hearing loss in multiple sclerosis: localization of the auditory pathway lesion according to electrocochleographic findings

Multiple sclerosis is known to affect the myelin of the auditory pathway resulting in acute hearing loss. Two cases of sudden deafness due to multiple sclerosis have been evaluated by conventional audiometry, brainstem auditory evoked response audiometry and transtympanic electrocochleography. The abnormalities of the compound action potential in both patients (enhanced latency, abnormal adaptation using fast stimulus rate) and the normal receptor potentials (cochlear microphonic, summating potential), as well as the absence of brainstem responses suggest a disturbance of synchronization at the level of the first auditory neurone. The electrocochleography provides valuable information for the topodiagnosis of this and other neural hearing losses, especially in the absence of reliable brainstem responses.

VIIIth cranial nerve involvement in sarcoidosis

Hearing loss and vertigo are uncommon but well-recognized complications of neurosarcoidosis. Until recently the site of the lesion has been debatable and the efficacy of steroids commonly prescribed for this type of hearing loss has been said to be doubtful. A case is presented of sarcoidosis-induced hearing loss in which bilateral VIIIth nerve lesions were demonstrable by MRI with gadolinium enhancement. Treatment with high-dose steroids and azathioprine produced a symptomatic improvement and virtual resolution of the lesions.

[Vestibular neuritis: a frequently unrecognized cause of diplopia]

The vestibular function plays an essential role in the stabilization of the image on the retina. In addition, when the head is tilted, it contributes to maintain horizontally the plane of the gaze. Vestibular changes can result in oscillopsia and/or diplopia. The latter is related to occurrence of a skew deviation. The authors emphasize the frequent occurrence of diplopia following disorders of the vestibular nerve, specially after vestibular neuritis. In clinical practice, the causal relationship between vestibular neuritis and diplopia is often unrecognized.

Skew deviation after vestibular neuritis

We treated five patients with vestibular neuritis who had strabismus. Three of them spontaneously noted vertical diplopia. During the following weeks and months, strabismus progressively resolved, indicating the recently acquired nature of the oculomotor condition. In three of these individuals, a change in visual vertical and cyclo-torsion of the globes suggested that strabismus was a form of skew deviation that occurred as a part of an ocular tilt reaction resulting from the peripheral vestibular lesion. Strabismus appears to occur frequently in this common vestibular condition.

[Reeducation of patients with vertigo]

The use of physical therapy in the treatment of vertigo is based on the plasticity and the restoration and adaptive qualities of the vestibular apparatus. Indications for physical therapy and the choice of techniques are based on the location of the lesions: exercises aimed at habituation in positional vertigo, with use of the rocking manoeuvre in the case of cupulolithiasis, and stimulation of spinal, labyrinth, visual or extraocular muscle proprioceptors in the case of unilateral lesions of the first neuron or in ototoxic destruction. These techniques give lasting effects and avoid prolonged treatment by anti-vertigo drugs which, by impairing the development of compensation, often lead to persisting functional disorders.

Acoustic neuroma presented as repeated hearing loss

Up to 15% of patients with acoustic neuroma may have a history of sudden hearing loss. Recovery from sudden hearing loss with acoustic neuroma is rare. In this paper, a case of bilateral acoustic neuromas presented as repeated sudden hearing loss with recovery on the left side after removal of right-sided tumor were reported. She experienced three episodes of sudden hearing loss, showing various types of audiograms and ABR on the left side. There was no relationship between the type of audiograms and ABR findings. Factor influencing ABR might be different from the cause of hearing impairment. Acoustic neuromas can be reliably identified by performing MRI properly. However, MRI showed negative scan and ABR finding was abnormal in the first episode of our case. ABR continues to be a sensitive diagnostic back-up test to MRI for the detection of acoustic neuromas. Even if the patient, who showed abnormal ABR findings suggesting retrocochlear pathology, showed normal MRI, acoustic neurinoma should not be ruled out and both ABR and MRI must be re-examined at regular intervals.

Surgery for non-Menière's vertigo

Neurootologists are fortunate in having a considerable number of surgical options available to them for the treatment of patients with disabling vertigo. Most surgery for vertigo is performed on patients suffering from the ravages of Meniere's disease. In addition, other forms of disabling peripheral vertigo may also be surgically managed. Over a 3 year period, the author performed surgery on 14 patients suffering from disabling non-Meniere's vertigo. During the same period, 60 patients with Meniere's disease underwent surgical treatment. There were three non-Meniere's conditions for which surgery was performed: chronic vestibular neuronitis, delayed onset vertigo (after sensorineural hearing loss), and labyrinthine injury following temporal bone fracture. Two surgical operations were utilized: transmastoid labyrinthectomy and selective vestibular neurectomy. At 1 year follow-up all of the patients involved in this study enjoyed either total relief of symptoms or marked improvement, demonstrating that satisfactory surgical results can be obtained for non-Meniere's vertigo. However, surgeons must exercise extreme caution in selecting non-Meniere's patients for surgery. Moreover, proper patient selection, accurate diagnosis and the exclusion of central disease are crucial in obtaining good surgical results.

Vascular decompression surgery for severe tinnitus: selection criteria and results

Seventy-four patients were operated on within a period of 10 years to treat incapacitating tinnitus; 72 underwent microvascular decompression (MVD) of the intracranial portion of the auditory nerve, and 2 underwent section of the eighth nerve close to the brain stem. Of those who underwent MVD, 2 had no change in symptoms and later also underwent section of the eighth nerve near the brain stem. Two patients did not return for follow-up. Of the 72 remaining patients, 13 (18.1%) experienced total relief from tinnitus, 16 (22.2%) showed marked improvement, 8 (11.1%) showed slight improvement, 33 (45.8%) had no improvement, and 2 (2.8%) became worse. The patients who experienced total relief and those who showed marked improvement had experienced their tinnitus for an average of 2.9 years and 2.7 years, respectively; those who showed slight improvement and those who had no improvement had experienced their tinnitus for a longer time before the operation (mean, 5.2 and 7.9 years, respectively). Of the 72 patients who were operated on and followed, 32 were women. Of these, 54.8% experienced total relief from tinnitus or marked improvement, while only 29.3% of the men showed such relief or improvement. Selection of the patients for operation was mainly based on patient history and, to some extent, on auditory test results (brainstem auditory evoked potentials [BAEP], acoustic middle ear reflexes, and audiometric data).

Sudden hearing loss induced by acoustic neuroma: significance of small tumors

In our series of 111 patients operated on for acoustic neuroma from 1972 to 1990, 21 (18.9%) had sudden hearing loss. The 21 tumors involved were comprised of 9 small, 5 medium, and 7 large tumors. Emphasis is placed on the fact that even a small tumor has the potential to produce sudden hearing loss (SHL) and that the possibility of seeing patients with SHL is increasing thanks to advances in imaging diagnosis. Recognition of SHL as an initial symptom of acoustic tumor is considered essential to detect small acoustic neuroma.

[A case of Tolosa-Hunt syndrome accompanied by facial and vestibular nerve damage]

A 37-year old man, who had repeatedly suffered from transient ophthalmoplegia in his left eye at the age of 29 and 36, developed left painful ophthalmoplegia accompanied by ipsilateral facial nerve palsy in August, 1991. Neurological examination revealed involvement of the left oculomotor, trochlear, ophthalmic division of the trigeminal, abducens, facial and vestibular nerves. Gadolinium-enhanced MRI which was taken at the acute phase of the illness demonstrated markedly enhanced left cavernous sinus and adjacent thickened dura mater in the middle cranial fossa. At the remission phase after starting corticosteroid therapy, these enhanced lesions were no longer observed even in enhanced MRI studies. We diagnosed him as suffering from Tolosa-Hunt syndrome presently accompanied by facial and vestibular nerve damage because of his history of illness, confined lesion in the left cavernous sinus and steroid-induced remission. We concluded that Tolosa-Hunt syndrome may be accompanied by damage of other cranial nerves in its course and that repeated gadolinium-enhanced MRIs are necessary for diagnosis and observation of the patients.

Surgical therapy of the eyelids in patients with facial paralysis

Patients with facial paralysis have a degree of lagophthalmos and paralytic ectropion. We present our experience in the surgical management of 25 consecutive patients treated for these problems. Paralytic lagophthalmos was corrected using gold weights inserted into the upper eyelid. The advantages and disadvantages of this surgical technique are reviewed. Medial canthoplasty and lateral canthoplasty were performed to rectify paralytic ectropion. Ancillary procedures included browpexy, upper-lid blepharoplasty, and temporalis sling. The results were excellent in 23 of 25 patients and good in the remaining two. After a minimum of 6 months' follow-up, there were no complications. The authors believe that the above procedures will yield consistently excellent cosmetic and functional results in patients with paralysis of the eyelids.