Effect of vestibular nerve section on cytochrome oxidase activity in the vestibular ganglion cells of the squirrel monkey

Estimates of behavioral thresholds of infants are elevated relative to those of adults. Explanations for the differences include auditory sensory factors and non-sensory factors, but no direct estimates of the relative contributions of these two factors have been made. In this investigation, thresholds in quiet and in increasing levels of a masking noise for a 1 kHz tone, in infants 8 to 11 months old and in adults, were determined. The infant-adult differences in unmasked threshold was compared to the infant-adult difference in an estimate of the minimum masking level (MML) that was derived from the masking data. The intensity level of a masking noise at which masking begins is assumed to be independent of the non-sensory factors that impact on the threshold value itself. Therefore, it is reasoned that the infant-adult difference in MML reflects more closely differences in auditory sensory factors than does the infant-adult difference in unmasked threshold. In the region of 1 kHz, the infant-adult difference in behavioral threshold was 12 dB and the infant-adult difference in MML was 8 dB. Therefore, according to our assumptions, 8 dB of the infant-adult difference in unmasked threshold is accounted for by sensory factors and the remaining 4 dB must be attributable to non-sensory factors.     

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

We measured the conduction velocity of the intracranial portion of the auditory nerve in 3 patients undergoing vestibular nerve section to treat Ménière's disease. The conduction velocity varied from patient to patient, with an average value of 15.1 m/sec. The latency of peak III of the brain-stem auditory evoked potentials (BAEPs) increased by an average of 0.5 msec as a result of exposure of the eighth nerve, and if that increase is assumed to affect the entire length of the auditory nerve (2.6 cm) evenly, then the corrected estimate of conduction velocity would be 22.0 m/sec. Estimates of conduction velocity based on the interpeak latencies of peaks I and II of the BAEP, assuming that peak II is generated by the mid-portion of the intracranial segment of the auditory nerve, yielded similar values of conduction velocities (about 20 m/sec).     

Peripheral nerve revascularization: a current literature review

Gene therapy of human cancer is likely to be most effective when it is directed at targets that are expressed in cancer cells but are lacking from other cells. Human papillomaviruses can provide such targets, since these viruses are present in many cervical and oral cancers, and are likely to be etiological agents of the tumor. Continued expression of human papillomavirus genes is probably necessary for the growth of these cancers, and effective gene therapy could consist of antisense or ribozyme molecules directed against these genes. Some human papillomavirus gene products are antigenic, and immunotherapy based upon these antigens might prove clinically beneficial. Human papillomaviruses have specific promoters, are linked to toxin genes, the toxin may be selectively expressed by tumor cells where the virus genes are active. Thus, there are several approaches for the development of specific gene therapy for human cancers that contain human papillomaviruses.     

Vestibular nerve section: long-term follow-up

Vestibular nerve section is considered an effective modality in the treatment of refractory and incapacitating vertigo. Typically nerve section results are described on the basis of short-term follow-up. We have reviewed 41 cases of vestibular nerve section spanning an 18-year period. Although the majority of cases involved classic Meniere's disease, delayed endolymphatic hydrops, vestibular neuritis, and Meniere's syndrome secondary to head trauma were also included. Surgical approaches included translabyrinthine (20 cases), retrolabyrinthine (14 cases), retrosigmoid (six cases), and middle fossa (one case) procedures. Postoperative follow-up time averaged 102 months, with 46% of patients followed for a minimum of 9 years. Results are reported according to standards set forth by the American Academy of Otolaryngology--Head and Neck Surgery. Vertigo was cured or markedly improved in 88% of cases (90% in patients with Meniere's disease) at 18 to 24 months postoperatively. These vertigo results were sustained at the time of latest follow-up. Functional level was also preserved over time despite the development of bilateral symptoms in several cases. The rate of bilateral disease reached 22% of cases. Although vertigo results remained stable, long-term follow-up of successful hearing preservation cases demonstrated deterioration over time. Postoperative continuation of medical treatment is urged to optimize and sustain the vestibular neurectomy result.     

Inflammatory processes and antiinflammatory drugs in Alzheimer's disease: a current appraisal

The study of risk factors and protective influences can yield clues to the pathogenesis of Alzheimer's disease (AD). Intervention on such factors can effect disease prevention or treatment while etiology remains unknown. Most known AD risk factors offer no prospect of prevention, but 14 of 15 relevant publications since 1987 suggest that the symptoms of AD are prevented or attenuated by antiinflammatory treatments. These findings are supported by numerous circumstantial findings suggesting a role for cytokines and acute phase reactants in the pathogenesis of AD. In particular, activated microglia and/or reactive astrocytes, found within or near all AD lesions, are thought to kill target cells by using either free radicals or the classical complement pathway. These mechanisms should be suppressed by glucocorticoids, but the available data suggest that nonsteroidal antiinflammatory drugs (NSAIDs) exert a stronger protective influence than steriods. NSAIDs (but not steroids) suppress the action of cyclooxygenases (COX), which catalyze synthesis of prostaglandins. The latter are intermediaries in the postsynaptic signal transduction cascade of cells with NMDA-type glutamate receptors. They may also potentiate glutamatergic transmission by inhibiting astrocytic reuptake of glutamate. Both mechanisms can potentiate excitotoxic cell death. Further work is needed to clarify whether steroids, NSAIDs, or both prevent or attenuate the symptoms of AD.     

Sex roles and psychotherapy: A current appraisal.

Reviews the current status of research on the effects of sex-role stereotypes on mental health judgments. Studies in this area have addressed (a) whether there are different sex-role-related standards of mental health for men and women, (b) if violations of sex role norms result in adverse mental health judgments, and (c) if therapists set sex-role-related goals for their clients. It is concluded that sex-role stereotypes are strong mental health cues for nonprofessionals, with violations of sex-role norms leading to adverse mental health judgments, but that while professionals share the sex-role stereotypes of their lay contemporaries, the professionals are unaffected by them in making mental health judgments and in setting therapeutic goals. This discrepancy between stereotypes and behavior may be due to any of 3 factors: the methodological limitations of the studies, actual differences in mental health between men and women, or normal attitude–behavior discrepancies. (2 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Alternating episodes of vestibular nerve excitation and failure

Recurrent episodes of oscillopsia, rotational vertigo, and postural imbalance were elicited and modulated by changing the horizontal head positions of a patient with an arachnoid cyst in the right cerebellopontine angle that distorted the vestibulocochlear nerve. Oculomotor analysis revealed two different types of attacks depending on the particular head position: 1) episodes of vestibular hypofunction (minutes to several hours) with normal head position and 2) paroxysmal vestibular excitation (seconds) with head rotation to the left. The most likely cause is a transition from conduction block to ectopic discharges, which occurs when various peripheral nerves are compressed. One week after resection of the cyst and decompression of the eighth cranial nerve the patient was symptom free, and the electronystagmogram was normal.     

The vestibular nerve: its course to the anterior and lateral ampullae

In order to assess the health status and risk of various diseases in the population of Guangzhou, the surveillance data of death in 1983-1994 in Guangzhou was analyzed by indicesas: year of potential life lost (YPLL), work year of lost (WYPLL) and valued year of potential life lost (VYPLL). It was indicated that both Chinese standardized mortality rates (CSMR) and Chinese standardized rates (CSYPLLR) had been declined from 448.2 x 10(-5) and 53.16/1000 to 398.6 x 10(-5) and 42.29/1000 during 1983-1994, respectively. It was suggested that the health status of inhabitants in Guangzhou had been gradually improved. Cancer lesion and poisoning, cardiovascular diseases rank top in CSYPLLR, were the most important diseases affecting life span of the inhabitants. Lesion and poisoning, infectious disease, psychotic disease, ranked the first in Chinese tandardized WYPLL rates (CSWYPLLR) and Chinese standardized VYPLL rates (CSVYPLLR), were important factors that periled the society labor force and economic development. By comparison of sex, both CSMR and CSYPLLR were higher in male than in female (u = 14.76, P < 0.01; u = 27.05, P < 0.01, respectively). Although both values of CSWYPLLR and CSVYPLLR were negative, they were still higher in male than in female. The zero-age-group was far more higher than all the other age groups in CSPLLR, CSWYPLLR and CSVYPLLR.     

Transthecal digital nerve block. An anatomical appraisal

Amantadine is an antiviral agent that was unexpectedly found to cause symptomatic improvement in patients with Parkinsonism, although its mechanism of action remains to be elucidated. Aromatic L-amino acid decarboxylase (AADC) is a regulated enzyme that catalyzes the decarboxylation of 3,4-dihydroxyphenylalanine (L-Dopa). It may be especially important during L-Dopa therapy in Parkinsonism, during which it may be rate-limiting for the production of dopamine. This study reports the effects of amantadine on the gene expression of AADC in PC12 cells. It shows that amantadine induces AADC gene expression at concentrations of 10 and 100 microM after 24 hr of incubation. The results suggest that the stimulation of AADC mRNA by amantadine may be one of its effects on dopamine metabolism that may have relevance for potentiation of L-Dopa therapy in Parkinsonism.     

Imaging of the labyrinth and vestibular nerve. Clinical significance for differential diagnosis of vestibular diseases

High resolution magnetic resonance imaging (HR-MRI) and computed tomography (HR-CT) of the inner ear are becoming more important for the diagnosis of peripheral vestibular lesions. Modern HR-MRI techniques allow visualization of detailed anatomic features of the vestibulo-cochlear regions as well as pathologic findings in the inner ear such as, neoplastic lesions (e.g., small intracanalicular acoustic neuromas), anomalies causing vertigo and hearing loss (e.g. Mondini's-malformation, perilymph fistula, vestibular paroxysmia), and inflammatory diseases (e.g., Cogan's syndrome, labyrinthitis, zoster neuritis). HR-CT is still the first examination that should be performed in patients with middle ear diseases (e.g., tumor, infection), trauma (e.g. temporal bone fractures), or fibro-osseous diseases. Although the imaging of the vestibulo-cochlear system has dramatically improved, there are still several peripheral vestibular disorders that cannot be visualized so far, e.g., benign paroxysmal positioning vertigo, idopathic vestibular neuritis or Menière's disease.     

Prediction of facial nerve displacement in extra large vestibular schwannoma

The primary objective in the surgery of extra large vestibular schwannoma is the total removal of the tumour mass while preserving the facial nerve. Preservation of the facial nerve in extra large tumours is reported as being notoriously difficult in the majority of cases. This study was undertaken to evaluate the accuracy in predicting displacement of the facial nerve by preoperative radiological imaging studies in 19 cases of extra large vestibular schwannoma. The direction of displacement of the facial nerve was predicted with preoperative axial and coronal MRI scans and verified intraoperatively. We achieved total removal of tumours in 84.2%, facial nerve displacement was predicted in 80% and we accomplished anatomical preservation in 80%. Prediction of displacement was difficult in tumours with little or no intracanalicular components or with severe bony destruction of the internal acoustic meatus. The preoperative prediction of facial nerve displacement in extra large tumours allows safe internal decompression of the tumour and careful dissection near the predicted area of the facial nerve during the operation. Consequently, a high rate of anatomical preservation of the facial nerve can be achieved.     

Response of the hypothalamic neurons to stimulation of the vestibular nerve and lateral vestibular nucleus in rabbits

Effects of single, double, and rhythmic stimulation upon hypothalamic neurons responding to the 1st excitatory phase of lateral vestibular nucleus stimulation, were studied. The data obtained show that activation of some hypothalamic neurons following stimulation of the lateral vestibular nucleus has a monosynaptic character. The findings suggest that ascending afferents from the lateral vestibular nucleus to the hypothalamus pass via oligo- as well as polysynaptic pathways.     

Intraoperative facial nerve monitoring (IFNM) predicts facial nerve outcome after resection of vestibular schwannoma

Intraoperative facial nerve monitoring (IFNM) is a suitable technique for intraoperative facial nerve identification and dissection, especially in large vestibular schwannomas (VS) (acoustic neuroma). To evaluate its feasibility for estimating functional nerve outcome after VS resection 60 patients underwent surgery using IFNM. Out of this group the last 40 patients were included in a prospective study evaluating the prognostic value of various IFNM parameters (proximal and distal absolute EMG amplitude, stimulation threshold, and proximal-to-distal amplitude ratio) for prediction of initial postoperative facial nerve function and recovery of function. Stimulation threshold and absolute EMG amplitude proximally at the brain stem were both predictive for postoperative nerve function. Good initial facial nerve outcome (modified House Brackmann grading, mHB degree I and degree II) was found in 15/16 patients with a proximal EMG amplitude greater than 800 microV and in 19/22 patients with proximal stimulation threshold less than 0.3 mA. Sixteen of 16 patients with proximal stimulation threshold equal to or greater than 0.3 mA had moderate-to-severe facial palsy (mHB degree III or worse). Six of six patients without evokable proximal amplitude initially had insufficient nerve function (mHB degree IV). Intraoperative decrease of the proximal amplitude was associated with an unfavourable outcome, whereas distal amplitudes usually stayed unchanged. Mean distal EMG amplitudes were also found to be decreased with poor nerve function, which may mean that the tumour had already affected the nerve. A proximal amplitude of 300 microV or less and a proximal-to-distal amplitude ratio below 1:3 were found in the absence of functional recovery in 6/8 (75%) and 5/6 (83%) patients with initial mHB degree IV, respectively. Two patients with initial mHB degree IV improved to mHB degree III despite intraoperative evidence of missing functional nerve integrity. Therefore, functional recovery cannot be predicted by IFNM in all cases of anatomical nerve preservation. We conclude that a minimum follow-up period of 1 year may still be advisable even in certain patients without evidence of intraoperative functional nerve integrity.     

Clinical appraisal of current nuclear and other noninvasive cardiac diagnostic techniques

At a time of rapid increases in the cost of medical care and the application of complex invasive procedures to cardiovascular diagnosis, the use of noninvasive methods has aroused interest. This report discusses the usefulness and limitations of various noninvasive diagnostic methods including nuclear medicine techniques, echocardiography, exercise electrocardiography and determination of systolic time intervals. Emphasis is placed on the applicability of these methods to specific disease processes (such as ischemic heart disease, cardiac valve disease, pulmonary embolic disease), their relative merits, future potential and present shortcomings.     

Selective vestibular neurectomy: a comparison of techniques

Viral chronic hepatitis often occurs in heart transplant recipients receiving cyclosporin. This essential immunosuppressive drug may induce cholestasis. We investigated the effect of treatment with cyclosporin on serum conjugated bile acids in patients with chronic hepatitis developing after heart transplantation. Fifty-nine patients were studied: 17 with chronic hepatitis, 15 heart transplant patients with normal alanine aminotransferase activity, and 27 heart transplant patients with chronic hepatitis, the last two groups receiving cyclosporin. Hepatic biochemical tests and total bile acid concentration were determined on fasting blood samples. The individual glyco- and tauroconjugated bile acids were quantified by high-performance liquid chromatography and direct spectrometry. In patients taking cyclosporin the bilirubin concentration and the alkaline phosphatase activity were increased only when hepatitis was present, in association with a slight increase in cholic acid level (5.13 microM vs. 0.68 microM; P < 0.01). Conjugated lithocholate concentration was dramatically higher when hepatitis and immunosuppression with cyclosporin were associated (1.17 microM vs. 0.03 and 0.04 microM; P < 0.01). Chenodeoxycholate was the main circulating bile acid only in the heart transplant patients treated with cyclosporin but without hepatitis. These results suggest that the mechanisms which explain the cyclosporin-associated modifications of the bile acid pool are different according to the presence or absence of hepatitis. The occurrence of hepatitis in patients on cyclosporin led to an increase in serum lithocholate and primary bile acid concentrations. Further studies are required to assess the effect of ursodeoxycholic acid for this cholestasis.     

Age effects and health appraisal: a meta-analysis

OBJECTIVE: The purpose was to clarify the effects of methodological variables in the research on age differences in self-rated health and specifically the effects of: (a) the item type used to solicit the appraisal, (b) the approach to sampling, and (c) the criteria for assembling the age groups for study. METHODS: Studies differing on these dimensions were compared using meta-analytic techniques. Seventeen usable samples were grouped according to the age comparisons--seven compared "young" and "old" samples while ten compared "young-old" and "old-old" groups. RESULTS: The results failed to support the frequently reported health optimism of old-old samples when compared with young-old. Further, the findings suggest that the item type used in eliciting the rating of health may be instrumental in the respondent's appraisal process. For instance, use of the age-comparative item tends to favor "old" groups when compared to young, whereas the global health item has an effect in the other direction. Effect size was also related to a study's sampling procedure and to the method used in assembling groups (i.e., age ranges used to represent young and old). DISCUSSION: Practical implications and areas of needed research are discussed.     

Counseling psychology from 1971 to 1986: Perspective on and appraisal of current training emphases.

Observers have speculated about changes in counseling psychology over the past decade. In this investigation we compared the perspectives of 1971 and 1986 directors of American Psychological Association-approved counseling programs on emphases given to various components of training and found no changes over the 15-year interval. The 1986 directors perceived current training as emphasizing applied and theoretical aspects of social-emotional and education-vocational counseling, group work, and research skills. Although 1986 directors felt that their training programs' strengths rested on more traditional aspects of the counseling specialty, they perceived counseling students' interests as focused on other areas (e.g., marriage counseling). Implications for the identity of counseling psychology and training in the specialty are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Uncrossed disynaptic inhibition of second-order vestibular neurons and its interaction with monosynaptic excitation from vestibular nerve afferent fibers in the frog

1. Eighth nerve evoked responses in central vestibular neurons (n = 146) were studied in the isolated brain stem of frogs. Ninety percent of these neurons responded with a monosynaptic excitatory postsynaptic potential (EPSP) after electrical stimulation of the ipsilateral VIIIth nerve. In 5% of these neurons, the EPSP was truncated by a disynaptic inhibitory postsynaptic potential (IPSP), and in 5% of these neurons a pure disynaptic IPSP was evoked. 2. Disynaptic IPSPs superimposed upon apparently pure EPSPs were revealed by bath application of the glycine receptor antagonist strychnine (0.5-5 microM) or of the gamma-aminobutyric acid-A (GABAA) receptor antagonist bicuculline (0.5-2 microM). The evoked EPSP increased in most central vestibular neurons (strychnine: 15 out of 16 neurons; bicuculline 26 out of 29 neurons). At higher stimulus intensities, the evoked spike discharge increased from 2 to 3 spikes before up to 8-10 spikes per electrical pulse during the application of blocking agents. The unmasked disynaptic inhibitory component increased with stimulus intensity to a different extent in different neurons. 3. Lesion studies demonstrated that these inhibitory components were generated ipsilaterally with respect to the recording side. The disynaptic strychnine-sensitive inhibition was mediated by neurons located either in the ventral vestibular nuclear complex (VNC) or in the adjacent reticular formation. The spatial distribution of the disynaptic inhibition was investigated by simultaneous recordings of VIIIth nerve-evoked field potentials at different rostrocaudal locations of the VNC. A significant strychnine-sensitive component was detected in the middle and caudal parts but not in the rostral part of the VNC. A bicuculline-sensitive component was detected in the rostral and in the caudal parts but not in the middle part of the VNC. In view of a similar rostrocaudal distribution of glycineor GABA-immunoreactive neurons in the VNC of frogs, our results suggest that part of the disynaptic inhibition is mediated by local interneurons with a spatially restricted projection area. 4. The monosynaptic EPSP of second-order vestibular neurons was mediated in part by N-methyl-D-aspartate (NMDA) and in part by non-NMDA receptors. The relative contribution of the NMDA receptor-mediated component of the EPSP decreased with stronger stimuli. This negative correlation could have resulted from a preferential activation of NMDA receptors via thick vestibular nerve afferent fibers. Alternatively, the activation of NMDA receptors became disfacilitated at higher stimulus intensities due to the recruitment of disynaptic inhibitory inputs. Comparison of data obtained in the presence and in the absence of these glycine and GABAA receptor blockers indicates a preferential activation of NMDA receptors via larger-diameter vestibular nerve afferent fibers. 5. The kinetics of NMDA receptors (delay, rise time) activated by afferent nerve inputs were relatively fast. These fast kinetics were independent of superimposed IPSPs. The association of these receptors with large-diameter vestibular nerve afferent fibers suggests that fast NMDA receptor kinetics might be matched to the more phasic response dynamics of the large diameter vestibular afferent neurons to natural head accelerations.