Sixteen-and-a-half syndrome with metastatic pons tumor: A case report

RATIONALE

One-and-a-half syndrome (OAAH) is characterized as the combination of ipsilateral horizontal gaze palsy and internuclear ophthalmoplegia. OAAH syndrome accompanied with 7th and 8th cranial nerve palsy is called 16-and-a-half syndrome. We aimed to report the case of 16-and-a-half syndrome with metastatic pons tumor.

PATIENT CONCERNS

A 57-year-old male diagnosed with nonsmall-cell lung cancer (NSCLC) with brain metastasis occurring 15 months ago was referred to our clinic with the chief complaint of horizontal diplopia and right gaze palsy.

DIAGNOSIS

According to the patient symptom, ocular examination, and radiographic findings, he was diagnosed as 16-and-a-half syndrome which was caused by brain tumor metastasis from NSCLC.

INTERVENTIONS

We referred him to hemato-oncology department and he was treated with radiation and supportive therapy.

OUTCOMES

Unfortunately, the patient passed away 1 month later without improvement of ophthalmoplegia.

LESSONS

The clinical findings of our case indicate 16-and-a-half syndrome caused by brain tumor metastasis from NSCLC, which to our knowledge has not been previously reported. The case highlights a rare cause of OAAH spectrum disease and the importance of a systemic work-up including associated neurologic symptoms and brain imaging in patients with horizontal gaze palsy.

Large Jugular Bulb Diverticulum Invading the Internal Auditory Canal

Objectives:

We report, with neuro-otologic findings, a very rare case of a large jugular bulb diverticulum eroding the internal auditory canal (IAC).

Methods:

We present the imaging and functional studies of a 29-year-old woman in whom a large jugular bulb diverticulum on the left side was found incidentally.

Results:

Imaging studies revealed a normal external auditory canal, middle ear, and inner ear, but a large jugular bulb diverticulum extending superiorly on the left side had eroded the IAC from below and behind with destruction of the petrous bone. Caloric responses and facial movements were normal. Vestibular evoked myogenic potentials with bone conduction stimuli were absent on the left, indicating dysfunction of the left inferior vestibular system.

Conclusions:

This is the first report in the English-language literature of detailed imaging and functional findings in a very large diverticulum invading the IAC. Vestibular evoked myogenic potentials were useful in uncovering subclinical inferior vestibular system dysfunction in the jugular bulb diverticulum invading the IAC.

The middle ear muscle reflex in the diagnosis of cochlear neuropathy

Cochlear neuropathy, i.e. the loss of auditory nerve fibers (ANFs) without loss of hair cells, may cause hearing deficits without affecting threshold sensitivity, particularly if the subset of ANFs with high thresholds and low spontaneous rates (SRs) is preferentially lost, as appears to be the case in both aging and noise-damaged cochleas. Because low-SR fibers may also be important drivers of the medial olivocochlear reflex (MOCR) and middle-ear muscle reflex (MEMR), these reflexes might be sensitive metrics of cochlear neuropathy. To test this hypothesis, we measured reflex strength and reflex threshold in mice with noise-induced neuropathy, as documented by confocal analysis of immunostained cochlear whole-mounts. To assay the MOCR, we measured contra-noise modulation of ipsilateral distortion-product otoacoustic emissions (DPOAEs) before and after the administration of curare to block the MEMR or curare + strychnine to also block the MOCR. The modulation of DPOAEs was 1) dominated by the MEMR in anesthetized mice, with a smaller contribution from the MOCR, and 2) significantly attenuated in neuropathic mice, but only when the MEMR was intact. We then measured MEMR growth functions by monitoring contra-noise induced changes in the wideband reflectance of chirps presented to the ipsilateral ear. We found 1) that the changes in wideband reflectance were mediated by the MEMR alone, and 2) that MEMR threshold was elevated and its maximum amplitude was attenuated in neuropathic mice. These data suggest that the MEMR may be valuable in the early detection of cochlear neuropathy.

Saccular dysfunction in children with sensorineural hearing loss and auditory neuropathy/auditory dys-synchrony

CONCLUSION

There is a correlation between the AN/AD disorder and the saccular dysfunction in children with severe sensorineural hearing loss, which means that saccular dysfunction can be a concomitant sign of AN/AD. In conclusion, the term of audio-vestibular dys-synchrony (AVS) is a more suitable description for this condition.

OBJECTIVES

Patients with auditory neuropathy/auditory dys-synchrony (AN/AD) characteristically demonstrate poor neural responses from the vestibulocochlear nerve and brainstem while displaying evidence of intact outer hair cells function. Therefore, the objective of this study is studying of the relationship of the saccular dysfunction with AN/AD disorder in children with sensorineural hearing loss.

METHODS

In this cross-sectional study, 100 children with bilateral severe-to-profound sensorineural hearing losses underwent audiologic tests and cervical vestibular-evoked myogenic potentials (cVEMPs) at the Audiology Department of Hamadan University of Medical Sciences (Hamadan, Iran).

RESULTS

Eleven children with bilateral severe sensorineural hearing loss were given to unilateral AN/AD disorder (11 ears), and two children (4 ears) had bilateral AN/AD (total = 13 children). The ears with AN/AD took the form of unrepeatable or absent waves of ABR and presence of OAEs. The statistical analysis of an independent t-test between AN/AD ears as compared to non-AN/AD ears of these 13 children showed that the mean latencies of p13 and the mean latencies of n23 and the mean peak-to-peak amplitude had significant differences.

Vestibular and cochlear neuritis in patients with Ramsay Hunt syndrome: a Gd-enhanced MRI study

CONCLUSION

It is suggested that vertigo in patients with Ramsay Hunt syndrome is mostly induced by superior vestibular neuritis consecutive to the reactivation of varicella-zoster virus (VZV) infection from the geniculate ganglion through the faciovestibular anastomosis. Refractory hearing loss in patients with Ramsay Hunt syndrome may be due to cochlear neuritis following the spread of VZV.

OBJECTIVES

An attempt was made to selectively identify vestibulocochlear nerves in the internal auditory canal (IAC) on gadolinium (Gd)-enhanced MRI in patients with Ramsay Hunt syndrome.

METHODS

Fourteen patients with Ramsay Hunt syndrome presenting with facial palsy, herpes zoster oticus, vertigo, and/or sensorineural hearing loss were scanned on 1.5 T MRI enhanced with Gd. Perpendicular section images of the IAC were reconstructed to identify the facial, superior, and inferior vestibular nerves and the cochlear nerves separately.

RESULTS

All except one of the patients with Ramsay Hunt syndrome with vertigo showed both canal paresis on the caloric test and Gd enhancement of the superior vestibular nerve in the IAC on MRI. Among 10 patients with hearing loss, 3 patients with severe to moderate sensorineural hearing loss showed Gd enhancement of the cochlear nerve in the IAC on MRI.

Audiovestibular loss in anterior inferior cerebellar artery territory infarction: a window to early detection?

Acute audiovestibular loss is a common neurotological condition that is characterized by sudden onset of severe prolonged (lasting days) vertigo and hearing loss and is diagnosed by the presence of canal paresis to caloric stimulation and sensorineural hearing loss on pure tone audiogram. Before 2000, papers on anterior inferior cerebellar artery (AICA) territory infarction focused mostly on associated brainstem and cerebellar findings, without a detailed description of neurotological findings. Since 2000, several reports have demonstrated that acute audiovestibular loss is an important sign for the diagnosis of AICA territory infarction. To date, at least eight subgroups of AICA infarction have been identified according to the pattern of neurotological presentations, among which the most common pattern of audiovestibular dysfunction is the combined loss of auditory and vestibular functions. Because audiovestibular loss may occur in isolation before ponto-cerebellar infarction involving AICA distribution, audiovestibular loss may serve as a window to prevent the progression of acute audiovestibular loss into more widespread areas of infarction in posterior circulation (mainly in the AICA territory). Clinician should keep in mind that acute audiovestibular loss may herald impending AICA territory infarction, especially when patients had basilar artery occlusive disease presumably close to the origin of the AICA on brain MRA, even if other central signs are absent and MRI does not demonstrate acute infarction.

[Cochlear-vestibular disorders in the patients presenting with chronic purulent otitis media]

The author presents statistical information concerning the prevalence of chronic purulent otitis media. Characteristics of typical complaints are described with special reference to cochlear-vestibular disorders in patients presenting with epitympanitis. The results of detailed analysis of the causes of cochlear-vestibular disorders in the patients with chronic purulent otitis media during the preoperative and postoperatve periods are reported.

Adding insult to injury: cochlear nerve degeneration after "temporary" noise-induced hearing loss

Overexposure to intense sound can cause temporary or permanent hearing loss. Postexposure recovery of threshold sensitivity has been assumed to indicate reversal of damage to delicate mechano-sensory and neural structures of the inner ear and no persistent or delayed consequences for auditory function. Here, we show, using cochlear functional assays and confocal imaging of the inner ear in mouse, that acoustic overexposures causing moderate, but completely reversible, threshold elevation leave cochlear sensory cells intact, but cause acute loss of afferent nerve terminals and delayed degeneration of the cochlear nerve. Results suggest that noise-induced damage to the ear has progressive consequences that are considerably more widespread than are revealed by conventional threshold testing. This primary neurodegeneration should add to difficulties hearing in noisy environments, and could contribute to tinnitus, hyperacusis, and other perceptual anomalies commonly associated with inner ear damage.

Investigation of auditory dysfunction in Leber hereditary optic neuropathy

PURPOSE

To investigate the possibility of auditory dysfunction in patients with Leber hereditary optic neuropathy (LHON).

METHODS

We prospectively recruited 10 affected patients from the north-east of England harbouring one of the three primary mitochondrial LHON mutations (3460G>A n = 3, 11778G>A n = 5 and 14484T>C n = 2). A detailed auditory history was taken and they were asked to complete a validated hearing questionnaire. Each patient then underwent a comprehensive topographic neuroauditory assessment to evaluate both middle- and inner-ear functions and the integrity of the brainstem auditory pathways.

RESULTS

We found no evidence of cochlear nerve dysfunction or abnormalities of the central brainstem auditory pathways in our LHON cohort and five patients had completely normal hearing tests. The remainder had mild conductive hearing loss from childhood ear infections and/or high-frequency sensorineural hearing loss from previous noise injury.

CONCLUSION

Although further studies are required to confirm our findings, auditory dysfunction as a result of a primary LHON mutation is probably uncommon.

Cochlear implantation in 3 adults with auditory neuropathy/auditory dys-synchrony

We describe 3 adult patients with auditory neuropathy/auditory dys-synchrony (AN/AD) who underwent cochlear implantation. All patients had absent or poorly formed auditory brainstem responses (ABRs) in combination with preserved otoacoustic emissions (OAEs). They exhibited various aetiologies and a large variation in clinical features known to be consistent with AN/AD. Cochlear implantation was successful in 2 out of 3 cases. We conclude that AN/AD implantee candidates should be counselled with care.

[Looking for the auditory and vestibular pathology in celiac disease]

The aim of the study was looking for the vestibular or/and auditory pathology in patients with celiac disease. The group of 30 cases aged 6-18 (mean: 9,2) were tested. The results were compared with 30 healthy persons aged 6-18. The tonal audiometry, distorsion product otoacoustic emission, brain stem auditory evoked potentials, electronystagmography and vestibular evoked myogenic potentials were performed. There were no pathological findings on the base of audiological tests (till upper brain stem) in celiac disease. In electronystagmography gaze nystagmus, disordered eye-tracking test and optokinetic nystagmus were observed the most frequently. Gluten-free diet and time of the disease did not influence the results. The electrical conduction through the auditory and vestibular pathways were analyzed as well. No disturbances were noted in celiac disease. The results confirm the hypothesis that neurological signs--vestibular in our study--appeared early, were connected with the histopathological changes of jejunum and remained despite of correct treatment of the disease.

The Influence of Prophylactic Vasoactive Treatment on Cochlear and Facial Nerve Functions after Vestibular Schwannoma Surgery

OBJECTIVE

Facial nerve paresis and hearing loss are common complications after vestibular schwannoma surgery. Experiments with facial nerves of the rat and retrospectively analyzed clinical studies showed a beneficial effect of vasoactive treatment on the preservation of facial and cochlear nerve functions. This prospective and open-label randomized pilot study is the first study of a prophylactic vasoactive treatment in vestibular schwannoma surgery.

METHODS

Thirty patients were randomized before surgery. One group (n = 14) received a vasoactive prophylaxis consisting of nimodipine and hydroxyethylstarch which was started the day before surgery and was continued until the seventh postoperative day. The other group (n = 16) did not receive preoperative medication. Intraoperative monitoring, including acoustic evoked potentials and continuous facial electromyelograms, was applied to all patients. However, when electrophysiological signs of a deterioration of facial or cochlear nerve function were detected in the group of patients without medication, vasoactive treatment was started immediately. Cochlear and facial nerve function were documented preoperatively, during the first 7 days postoperatively, and again after long-term observation.

RESULTS

Despite the limited number of patients, our results were significant using the Fisher's exact test (small no. of patients) for a better outcome after vestibular schwannoma surgery for both hearing (P = 0.041) and facial nerve (P = 0.045) preservation in the group of patients who received a prophylactic vasoactive treatment.

CONCLUSION

Prophylactic vasoactive treatment consisting of nimodipine and hydroxyethylstarch shows significantly better results concerning preservation of the facial and cochlear nerve function in vestibular schwannoma surgery. The prophylactic use is also superior to intraoperative vasoactive treatment.

Acute peripheral vestibular syndrome of a vascular cause

BACKGROUND

Acute peripheral vestibular syndrome (APVS) is an idiopathic peripheral vestibulopathy characterized by prolonged vertigo (over 24 h), nausea, vomiting, and postural instability. There has been no previous report of APVS presumably of a vascular cause.

OBJECTIVES

To describe APVS presumably resulting from a vascular disturbance with embolic cerebral infarction.

PATIENT

A 67-year-old woman developed sudden onset of severe isolated vertigo, nausea, and vomiting, which lasted for 3 days. Ten days earlier, she had had 4 episodes of transient vertigo lasting a few minutes. She had a spontaneous right-beating horizontal nystagmus with a torsional component, in the primary position and on gaze to the right or left. Caloric test showed a decreased response on the left side. Diffusion-weighted brain MRI showed 2 tiny acute infarcts in the left hippocampus and basal ganglia. Magnetic resonance angiogram showed no abnormalities. Continuous electrocardiographic monitoring for 24 h showed paroxysmal atrial fibrillation.

CONCLUSION

In this patient, clinical and laboratory findings were consistent with APVS. Considering the simultaneous onset of acute silent infarcts on brain MRI, the definite cardioembolic source with atrial fibrillation, and the episodic transient vertigo attacks before APVS, we speculate that small emboli arising from the heart may have lodged selectively in the anterior vestibular artery, producing APVS.

Microvascular decompression for hemifacial spasm: postoperative neurologic follow-up and evaluation of life quality

Microvascular decompression (MVD) is an effective and safe treatment in hemifacial spasm (HFS). Postoperative evaluations are usually made by neurosurgeons. Follow-up studies performed by neurologists and postoperative quality of life (QoL) investigations are lacking. All 25 HFS patients operated with MVD in our centre between 2000 and 2004 were evaluated with the recently validated HFS-7 scheme, extended with the item 'sleep disturbance due to HFS' (HFS-8). The patients underwent a careful neurological examination median 3 years after the operation. The evaluation focused on clinical aspects, changes in blood pressure and time until observable effect of MVD. The evaluation of HFS-7 questionnaire and the extended form (HFS-8) showed significant improvement in QoL after MVD. Neurological outcome was in almost all cases excellent or good. Eleven (44%) patients had no neurological deficits at all. Only one patient had serious complications with ipsilateral facial palsy, deafness, balance problems and vertigo. The other patients had minor neurological findings or symptoms. Eighteen (72%) patients experienced early effect within 3 months after MVD; seven (28%) patients had late effect between 6 and 14 months. Median age of the patients with late effect (62.6 years) was significantly higher than in those with early effect (52.7 years).

Neuro-otological emergencies

PURPOSE OF THE REVIEW

Physicians find acute vertigo a diagnostic challenge. This article review recent evidence outlining the clinical presentation of acute central and peripheral dizzy syndromes and suggest when clinicians may consider acute neuro-imaging.

RECENT FINDINGS

Recent evidence highlights the difficulty that acute vertigo may sometimes pose to the clinician. For example, migrainous vertigo may have oculomotor abnormalities suggestive of either central neurological or peripheral vestibular dysfunction. Furthermore, vertebrobasilar stroke syndromes may mimic peripheral disorders such as vestibular neuritis, or when there is hearing involvement may be misdiagnosed as Meniere's disease. In addition to the need for identifying serious conditions in acute vertigo, recent evidence suggests that early steroid treatment in vestibular neuritis may improve long term outcome. Further trials regarding symptomatic outcome are required, however, before routine use of steroids can be recommended in this condition.

SUMMARY

Recent findings have not made the assessment of acute vertigo any easier for the nonspecialist. Although the commonest vertigo syndromes are benign, serious conditions such as stroke may masquerade as a peripheral labyrinthine disorder and conversely benign conditions such as migrainous vertigo may have clinical characteristics of central disorders. These findings re-emphasize the need for a thorough clinical evaluation of the acutely dizzy patient.

Superficial siderosis causing retrolabyrinthine involvement in both cochlear and vestibular branches of the eighth cranial nerve

Although superficial siderosis (SS) has been clinically characterized as a combination of sensorineural hearing impairment, cerebellar ataxia and pyramidal signs, precise evaluation of the function of the eighth cranial nerve has rarely been reported. The purpose of this study was to evaluate the audiological and vestibular function. We present a patient with complaints of progressive bilateral hearing loss and gait difficulty. We evaluated the audiological and vestibular functions with auditory brainstem responses and vestibular evoked myogenic potentials (VEMPs) by clicks and galvanic stimuli. The patient showed linear hypointensities surrounding the brainstem, cerebellum and the eighth cranial nerve on T2-weighted MRI images, which is characteristic of SS. Auditory brainstem response showed only wave I in the right ear and no response in the left ear. Click VEMPs and galvanic VEMPs showed no response on either side. The results of a neuro-otological examination suggested that both audiological and vestibular dysfunction in the patient with SS is of retrolabyrinthine origin.

Parallel auditory vestibular evoked neurogenic and myogenic potential results in a case of peripheral vestibular dysfunction, showing that the former originates from the vestibular system

PURPOSE

Vestibular evoked myogenic potentials (VEMPs) uses high intensity clicks with recording from the tonically active sternocleidomastoid muscle, taking advantage of the close proximity of the saccule to the oval window. Our group has used the same stimulus to record Vestibular Evoked Neurogenic Potentials (VENPs) directly from the brain. VEMPs are now regarded the electrophysiological gold standard in peripheral vestibular system examination. We present a case of peripheral vestibular dysfunction to show that both VEMPs and VENPs provide similar results during recovery.

METHODS

A case of Meniere's Disease in recovery is examined. VEMPs were recorded using a 105 dB nHL click stimulus from the ipsilateral sternocleidomastoid muscle. VENPs were recorded using an ipsilateral parietal to Fpz montage and a 1 kHz tone-pip stimulus. Standard BAEPs and threshold latency series (TLS) were performed.

RESULTS

VEMP and VENP were unobtainable from the left side at initial presentation in a patient with Meniere's Disease, with normal BAEP and TLS bilaterally. After one month of therapy both the VEMP and VENP normalized.

CONCLUSIONS

As VEMPs are known to originate from the vestibular system, the parallel VENP result suggests the same for the latter VENP may prove to be useful and complement VEMP in determining vestibular dysfunction.

[Observation of auditory brainstem response and distortion product otoacoustic emission on the animal model of autoimmune auditory neuropathy]

OBJECTIVE

To set up an animal model of autoimmune auditory neuropathy and to observe the auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) in guinea pigs.

METHODS

The spiral ganglion and the cochlear nerve were obtained and purified by electrophoresis from 250 normal guinea pigs. The purified cochlear nerve antigen was mixed with an equal volume of complete Freunds adjuvant for immunization. Seventy guinea pigs were divided into three groups: experiment group (50 guinea pigs), control group (10 guinea pigs), normal group (10 guinea pigs). ABR, DPOAE, serum IgG levels, and morphological changes of spiral ganglion cells and the cochlear nucleus were observed. The protein expressions of the antigen were examined by immunohistochemistry and the super-structure of the auditory nerve were observed.

RESULTS

The threshold of ABR response increased ranged from 10 to 25 dB in 32% (32/100 ears) of the guinea pigs. The peak latencies of waves I , III and the interpeak latency I approximately III were prolonged in the hearing loss group of guinea pigs. Prolonged peak latency of wave III was noted in hearing loss group at 2 and 3 weeks post immunization and slowly decreased to normal peak latency. The amplitude of DPOAE was no difference in the guinea pigs. The levels of serum IgG increased significantly compared with those of the control group. Inflammatory cell infiltration was observed in the cochlear nerve and the number of spiral ganglion cells detected. On the contrary, inflammatory cell infiltration was not observed in the cochlear nucleus. The cell densities and the across-sectional areas of neurons in anteroventral cochlear nucleus and posteroventral cochlear nucleus were no difference in the guinea pigs. The antigen protein distributed strictly in cochlear nerve and the spiral ganglion. Some demyelinated areas in cochlear nerve was observed in this group. The threshold of ABR response in 68% guinea pigs (68/100 ears) did not increase. The data of DPOAE and the serum IgG levels show no difference compared with the control group. There were not pathological observation in spiral ganglion cells, cochlear nucleus and cochlear nerve.

CONCLUSION

An animal model of autoimmune auditory neuropathy has been set up successfully and the character of the ABR and DPOAE was observed.

Die vestibulär evozierten Muskelpotenziale in Abhängigkeit vom nervalen Ursprung und der Lage eines Akustikusneurinoms

INTRODUCTION

Most acoustic neuromas (AN) originate from the inferior vestibular nerve (IVN). Vestibular evoked myogenic potentials (VEMP) are accepted as the only unilateral test for the function of the sacculus and the IVN.

METHODS

The influence of the origin from the IVN and superior vestibular nerve (SVN), and the position of the AN in relation to the internal auditory canal on VEMPs was investigated. A total of 39 patients (aged: 30-67 years, mean: 53 years) were examined. The VEMPs were recorded on the activated sternocleidomastoid muscle and averaged over 200 stimuli. Tone bursts (95 dB nHL; 500 Hz; stimulation rate 5 Hz) were used to generate the VEMPs.

RESULTS

The exact origin of the AN from the SVN or the IVN could be determined intraoperatively and correlated using VEMP in 28 patients.

CONCLUSION

The origin of the AN has only a marginal influence on the results of VEMP measurements. The position of the AN in relation to the internal auditory canal seems to have more influence than the origin.

Stereotactic radiosurgery for recurrent pleomorphic adenoma invading the skull base--case report--

A 38-year-old man presented with a recurrent pleomorphic adenoma in the parapharyngeal space invading the skull base 19 years after the first operation for a parotid gland tumor. Stereotactic radiotherapy was performed to control the tumor growth using a marginal dose of 8 Gy and maximum dose of 18 Gy with care taken to minimize the dose to nearby structures. The symptoms were reduced within a few months. Magnetic resonance imaging over 5 years showed that the tumor was controlled with no regrowth. Stereotactic radiotherapy is a therapeutic option for the treatment of pleomorphic adenomas.

Hemorrhagic acoustic schwannoma: radiological and histopathological findings

A 49-year-old man on anticoagulation treatment with phenprocoumon presented with acute right sided 7th and 8th cranial nerve palsy, acute hearing loss, headache, vertigo, and vomiting. CT and MRI revealed a cerebellopontine angle tumor 15mm in diameter and acute intratumoral hematoma. A cellular schwannoma composed predominantly of Antoni A tissue with dilated thin-walled vessels, surrounded by old hemorrhage with hemosiderin-laden macrophages was found histologically.

A case of isolated nodulus infarction presenting as a vestibular neuritis

We reported a patient with cerebellar infarction who presented with purely isolated vertigo, ipsilesional spontaneous nystagmus, and contralesional axial lateropulsion without usual symptoms or signs of cerebellar dysfunction. An MRI of the brain showed a small left cerebellar infarct selectively involving the nodulus. A pure vestibular syndrome in our patient may be explained by ipsilateral involvement of nodulo-vestibular inhibitory projection to vestibular nucleus. Clinicians should be aware of the possibility of a nodulus infarction in patient with acute vestibular syndrome, even if the pattern of nystagmus and lateropulsion is typical of a vestibular neuritis.

Auditory neuropathy in Friedreich ataxia. A report of two cases

Friedreich ataxia (FA) is a hereditary neurodegenerative disease with autosomical recessive inheritance. The purpose of this paper is to present two cases of FA with auditory neuropathy, demonstrated by Otoacoustic emissions (OAE) and brainstem auditory evoked potentials (BAEP). The patients were two adolescent girls. Both patients underwent behavioral pure-tone audiometry, BAEP, OAE, motor nerve conduction measurement, and magnetic resonance image studies. Both girls showed at least five of nine clinical criteria for FA. They also showed abnormal BAEP and normal OAE indicating auditory neuropathy. One patient showed normal thresholds on behavioral pure-tone audiometry, whereas the other patient showed a mild sensorineural hearing loss. In one case there was absence of peripheral caloric vestibular response, and electronystagmographic abnormalities compatible with cerebellar dysfunction. Cochlear function as assessed by OAE had not been reported previously in cases of FA. We conclude that auditory neuropathy should be considered in patients diagnosed as FA. Furthermore, BAEP and OAE should be included in the diagnostic routine in these patients.

Nimodipine ameliorates trauma-induced cochlear neuronal death

Excessive entry of Ca2+ into injured cochlear neurons activates various Ca(2+)-activated enzymes and subsequent spiral ganglion cell death. Therefore, preventing intracellular calcium overload by using Ca2+ channel antagonists may become an important countermeasure to spiral ganglion cell death. We experimentally investigated whether an L-type Ca2+ channel blocker (nimodipine) can rescue traumatized cochlear neurons from degeneration. A group of rats (n = 6) was pre-operatively treated with nimodipine for one week and compression injury was applied to the cerebellopontine angle portion of the cochlear nerve in a highly quantitative fashion. The rats from the compression with nimodipine treatment groups were post-operatively treated with nimodipine for 10 days and killed for histological examination. The histological analysis of the temporal bones revealed that the spiral ganglion cells in the basal turn of the cochlea where the magnitude of traumatic impact had been the least in our experimental condition were rescued in a statistically significant fashion in the compression with nimodipine treatment group. The results of the present study indicate that nimodipine may become an intra- and post-operative important adjunct to raise the rate of hearing preservation in vestibular schwannoma excision or other cerebellopontine angle surgical interventions.

Osteoma of the internal auditory canal

Osteomas of the internal auditory canal, inaccesible to clinical examination, are rare lesions. There are only 14 cases of osteomas and exostoses of the internal auditory canal reported in the international medical literature. A patient with an osteoma of the internal auditory canal is presented, along with differential diagnosis and possible etiologic factors for the lesion. The auditory brainsteam evoked response testing showed increased absolute latencies of 1 wave and discrepancy of the wave morphology due to bony compression of the eight nerve in the internal auditory canal. Computed tomography showed a bony growth in the internal auditory canal. Magnetic response showed no abnormalities. No surgery was performed since the symptoms improved by conservative therapy.

Seventh nerve palsies may be the only clinical sign of small pontine infarctions in diabetic and hypertensive patients

BACKGROUND

Small brainstem infarctions are increasingly recognized as a cause of isolated ocular motor and vestibular nerve palsies in diabetic and/or hypertensive patients. This raises the question whether there are also isolated 7(th) nerve palsies due to pontine infarctions in patients with such risk factors for the development of cerebrovascular diseases.

METHODS

Over an 11-year-period, we retrospectively identified 10 diabetic and/or hypertensive patients with isolated 7(th) nerve palsies and electrophysiological abnormalities indicating pontine dysfunction. All patients had examinations of masseter and blink reflexes, brainstem auditory evoked potentials, direct current electro-oculography including bithermal caloric testing, and T1- and T2-weighted MRI (slice thickness: 4-7 mm).

RESULTS

Electrophysiological abnormalities on the side of the 7(th) nerve palsy included delayed masseter reflex latencies (4 patients), slowed abduction saccades (4 patients), vestibular paresis (2 patients), and abnormal following eye movements (2 patients). Electrophysiological abnormalities were always improved or normalized at re-examination, which was always associated with clinical improvement. MRI revealed an ipsilateral pontine infarction in 2 patients. Another 2 had bilateral hyperintense intrapontine lesions, and one an ipsilateral cerebellar infarction.

CONCLUSIONS

Simultaneous improvement or recovery of abnormal clinical and electrophysiological findings strongly indicated that both were caused by the same actual pontine lesions. A 7(th) nerve palsy may be the only clinical sign of a pontine infarction in diabetic and/or hypertensive patients. Such mechanism may be underestimated if based on MRI only.

Temporal pattern of cochlear nerve degeneration following compression injury: a quantitative experimental observation

OBJECT

It has been empirically recognized that the cochlear nerve is highly vulnerable to traumatic stress resulting from surgical procedures; therefore, careful manipulation of the cochlear nerve is mandatory in preventing trauma-induced hearing loss during cerebellopontine angle (CPA) surgery. There is, however, no precise knowledge about the temporal pattern of cochlear nerve degeneration following trauma. This study was performed to determine the temporal pattern of injury that occurs after cochlear nerve trauma, knowledge of which is indispensable not only to neurosurgeons but also to all those who manage lesions involving the cochlear nerve.

METHODS

Right suboccipital craniectomies were performed in groups of rats with the aid of a surgical microscope, and the seventh and eighth cranial nerve trunks were identified at the internal auditory meatus. The cochlear nerve was quantifiably compressed while compound action potentials of the cochlear nerve were monitored and recorded. Following injury, one group of rats was killed for histological examination at the end of each week for 4 weeks. Data from this study disclosed that the degeneration of the compressed cochlear nerve progressed in a relatively rapid manner and was complete within 1 week after the insult. The main pathophysiological mechanisms responsible for cochlear neuronal death in this experimental setting appeared to be necrosis, and an apoptotic mechanism seemed to play a subsidiary role.

CONCLUSIONS

Accurate knowledge about the temporal profile of trauma-induced cochlear nerve degeneration is closely linked with the problem of the therapeutic time window. The results of the present study indicated that any measures to ameliorate cochlear nerve degeneration following trauma should be started as early as possible (within 1 week) after an injury.

MRI findings of vestibulocochlear hemorrhage in a leukemic patient with sensorineural hearing loss

This case report presents a patient with M4 leukemia with signs and symptoms of acute sensorineural hearing loss. The patient's MRI demonstrated high signal on unenhanced T1-weighted images within the left vestibulocochlear complex that was consistent with subacute hemorrhage. Follow-up MRI showed clearing of the previously seen high T1-weighted signal from the left vestibulocochlear complex. This case report documents for the first time the MRI findings of vestibulocochlear complex hemorrhage in a leukemic patient.

[Room tilt illusion: Report of two cases and terminological review]

The room tilt illusion is a transient misperception of the visual image as tilted on its side or even upside down; in this case it has been termed acute upside down reversal of vision. We report on two cases of room tilt illusion as manifestation of VIII nerve neuritis (herpes-zoster infection) and cerebellar hemorrhage. Room tilt illusion has been reported in association with vertebrobasilar stroke, migraine, multiple sclerosis, epilepsy and labyrinthine disorders. The pathophysiology of this rare visual illusion has been related to a lesion of the visual or vestibulo-otolith pathways. In animals the neurones of the parieto-insular vestibular cortex areas are multisensory. So, they can respond to somatosensory, optokinetic and visual stimuli. In humans the knowledge about vestibular cortex function and localization is less precise than in animals. However, we propose a disorder of multisensorial vestibular cortex, resulting from a lession of vestibular pathways or association cortex, as mechanism of this phenomenon.

Intraosseous dural arteriovenous fistula of the skull base associated with hearing loss. Case report

The most common clinical presentations of dural arteriovenous fistulas (DAVFs) are bruit, headache, increased intracranial pressure, and intracranial hemorrhage. In particular locations, such as the cavernous sinus or middle cranial fossa, cranial nerve involvement due to dural arterial steal or venous occlusion may develop. A case in which a DAVF is associated with hearing loss, however, has not previously been reported. The authors report a case in which an intraosseous DAVF and associated hearing loss probably resulted from cochlear nerve or vascular compression caused by the draining vein or nidus of the DAVF.

[Brainstem lesions: clinicoradiological electrophysiological correlation when chronic]

INTRODUCTION

The brainstem is a vital structure. Imaging and electrophysiological studies are important aids to clinical diagnosis.

OBJECTIVE

To define the clinical, imaging and electrophysiological correlation in 28 patients with chronic brainstem lesions.

PATIENTS AND METHODS

We analyzed the results of physical examination, imaging studies (CAT and MR) and brainstem auditory evoked potentials (BEAP) in each patient.

RESULTS

There was a predominance of males in the group studied. The commonest age groups were between 25 34 and 35 44 years old. Involvement of the cranial nerves was the commonest neurological finding, and the XII cranial nerve was the one most commonly involved. The condition had persisted for 1 to 4 years in 60.8% of the patients. There was a predominance of lesions of the pons in 28.6%. In five patients classical syndromes were seen. The commonest aetiology was ischaemic cerebrovascular disease in 53.6% of the patients. The lesions were detected on MR in 86.6% of the cases and on CAT scans in only 27.3%. The BEAP was abnormal in 75% of the patients. There was close correlation between the clinical topography and results of MR (p<0.05) but little correlation with the CAT scans or PEATC.

CONCLUSION

We consider that MR is the investigation of choice in these patients.

Differential vulnerability of inner and outer hair cell systems to chronic mild hypoxia and glutamate ototoxicity: insights into the cause of auditory neuropathy

OBJECTIVE

To describe the effects of long-term mild hypoxia and of glutamate poisoning on the functional properties of the cochlea.

METHODS

Outer hair cell activity was monitored using otoacoustic emissions and cochlear microphonics, and inner hair cell/cochlear afferent function was measured using neural responses (cochlear action potentials or auditory brainstem responses [ABRs]).

RESULTS

In contrast to the effects of acute anoxia, in which all aspects of cochlear function are simultaneously lost, mild, long-term hypoxia results in a clear differential effect on outer versus inner hair cell systems. During a 2-hour period of mild hypoxia, ABR amplitude and threshold deteriorate significantly, whereas outer hair cell function, as reflected by otoacoustic emissions, shows little or no change. A similar dissociation between inner and outer hair cell function is observed during instillation of glutamate (1-10 mM), where the cochlear microphonic and the otoacoustic emissions are unchanged, whereas cochlear action potential amplitudes are reduced.

CONCLUSION

These studies demonstrate a difference in vulnerability of inner and outer hair cell systems. The inner hair cell/cochlear afferent system is vulnerable to long-term, mild hypoxia; this may be an etiologic factor in hearing loss of cochlear origin, particularly in high-risk birth infants with auditory neuropathy.

The varieties of auditory neuropathy

Auditory neuropathy (AN) was initially described as impairment of auditory neural function, with preserved cochlear hair cell function. In this report, 67 patients with audiological and neurophysiological criteria for hearing loss due to auditory neuropathy are described. Reviewing this large body of patients, AN appears to consist of a number of varieties, with different etiologies and sites affected. All varieties share a relatively spared receptor function, and an impaired neural response, with diminished ability to follow fast temporal changes in the stimulus, but different varieties in this general scheme can be distinguished. Analyses of the clinical features indicate that auditory neuropathies vary in several measures including age of onset, presence of peripheral neuropathy, etiology, and behavioral and physiological measures of auditory function. The sites affected along the peripheral auditory pathway may include dysfunction of the outer hair cells, the synapse between hair cell and auditory nerve, and the auditory nerve fibers, with myelin as well as axonal impairments contributing to the disorder.

[Vascular origin of cerebellopontine angle syndrome]

INTRODUCTION

The seventh and eighth cranial nerves course toward the internal auditory canal within the cerebellopontine angle. Lesions in this region are usually related to malfunctions of these cranial nerves. Although an acoustic schwannoma is one of the main etiologies of cerebellopontine angle pathology, various inflammatory processes and vascular anomalies even though rare must be considered.

PATIENTS/METHODS

We describe 5 cases with vascular loops of the basilar or vertebral arteries as a possible cause for hearing loss, vertigo and pulsatile tinnitus. In two cases the vascular lesion was confirmed at surgery, in which a decompression procedure was performed. The work-up for each patient included an auditory test battery and electronystagmography. Imaging studies included MRI and angiography in two cases.

RESULTS/CONCLUSIONS

Our experiences show that while the cerebellopontine angle syndrome is mostly caused by benign tumors an abnormal vascular loop has to be considered in any differential diagnosis.

Neurovascular compression syndrome of the eighth cranial nerve. Can the site of compression explain the symptoms?

Considerable skepticism still exists concerning the concept of neurovascular compression (NVC) syndromes of the eighth cranial nerve (8th N). If such syndromes exist, the sites of compression of the nerve must explain the symptoms encountered. We recorded compound action potentials of the cochlear nerve (CCAPs) during neurovascular decompression (NVD) to examine the topography of the three components of the 8th N. The sites of compression of the 8th N in cases of NVC syndrome confirmed at surgery were superimposed on the topography of the CN and vestibular nerve (VN) in order to determine the relationship between the sites of compression and the symptoms. CCAPs were clearly and consistently recorded on the caudal surface of the 8th N along the midline. In patients with vertigo and tinnitus there was vascular compression of the rostroventral (VN) and caudal surface (CN) of the nerve, respectively. In patients with both vertigo and tinnitus, there was compression of both VN and CN. Our findings clearly demonstrate that the symptoms of NVC of the 8th N depend on the part of the nerve that is compressed by blood vessels, and they support the concept of NVC syndrome of the 8th N.

Stenosis of the internal auditory canal with VIIth and VIIIth cranial nerve dysfunctions

We report the case of a 37-year-old woman with a history of long-standing right-sided sensorineural hearing loss who presented with an acute onset of vertigo and ipsilateral facial palsy. A computed tomographic scan study showed a stenosis of the right internal auditory canal (IAC). Neither generalized skeletal disease nor bony tumors, which may cause the IAC stenosis, were evident. The IAC stenosis found in this patient may be due to congenital malformation. Inflammation, compression or ischemia in the stenosed IAC may have resulted in the vertigo and facial palsy. This is the only case that we are aware of in which IAC stenosis is accompanied by vertigo and facial palsy.

[Otolaryngologic symptoms from tumors of the posterior cranial fossa]

The aim of the paper was the estimation of the otolaryngological signs in the patients with the tumor of posterior cranial cavity. Each one was underwent the otoneurological diagnosis inclusive of electronystagmography. The most frequent symptoms we noticed were headache, vertigo together with cerebellar signs and disorder of the VII, VIII and IX-th cranial nerves, The ENG seemed to be a useful method in a localizing process of intracranial damages.

[Hearing function of workers of "noisy" occupations at the Podolsk machinery plant and effectiveness of therapeutic measures]

In recent years noise and vibration have become dominant hazards influencing workers' health. A significant share of the resulting disease in covered by occupational deafness. The article demonstrates data of hearing examination among 262 workers exposed to intermittent noise of 95-100 dB A. Slow progress of occupational deafness and bilateral cochlear neuritis with over 15 years of service appeared to be characteristic for the examinees. Helium neon laser applied on mastoid process and general improving treatment appeared to be effective.

Dose and diameter relationships for facial, trigeminal, and acoustic neuropathies following acoustic neuroma radiosurgery

PURPOSE AND OBJECTIVE

To define the relationships between dose and tumor diameter for the risks of developing trigeminal, facial, and acoustic neuropathies after acoustic neuroma radiosurgery, a large single-institution experience was analyzed.

MATERIALS AND METHODS

Two hundred and thirty-eight patients with unilateral acoustic neuromas who underwent Gamma knife radiosurgery between 1987-1994 with 6-91 months of follow-up (median 30 months) were studied. Minimum tumor doses were 12-20 Gy (median 15 Gy). Transverse tumor diameter varied from 0.3-5.5 cm (median 2.1 cm). The relationships of dose and diameter to the development of cranial neuropathies were delineated by multivariate logistic regression.

RESULTS

The development of post-radiosurgery neuropathies affecting cranial nerves V, VII, and VIII were correlated with minimum tumor dose and transverse tumor diameter (P < 0.01 for all except Dmin for VIII where P = 0.10). A comparison of the dose-diameter response curves showed the acoustic nerve to be the most sensitive to doses of 12-16 Gy and the facial nerve to be the least sensitive.

CONCLUSION

The risks of developing trigeminal, facial, and acoustic neuropathies following acoustic neuroma radiosurgery can be predicted from the transverse tumor diameter and the minimum tumor dose using models constructed from data presently available.