The majority of the evidence reviewed was poorly reported and there is therefore an inherent risk of bias. Given the recent improvement in resolution and reduction in cost of MR imaging, ABR can no longer be considered appropriate as the primary test used to screen for acoustic neuroma. T2W or T2*W sequences enable accurate evaluation of the VIIIth and VIIth cranial nerves within the cerebellopontine angle and internal auditory canal as well as evaluation of the cochlea and labyrinth, and inclusion of GdT1W sequences is unlikely to contribute information that would alter patient management in the screening population. The quality of the imaging chain and experience of the reporting radiologist are key factors determining the efficacy of a non-contrast screening strategy. Based on a cost-effectiveness model developed to reflect UK practice it was concluded that a diagnostic algorithm that deploys non-contrast MR imaging as an initial imaging screen in the investigation of acoustic neuroma is less costly than and likely to be as effective as available contrast MR imaging.
This study suggests that cortical electric response audiometry has a performance that is as good as or better than the auditory brain stem response for threshold estimation in adults and that sophisticated stimulation techniques do not appear to be required. An efficient test protocol that automates many laborious tasks reduces the test time to less than half that previously reported in the literature for this response.
This article introduces the cortical auditory evoked potential (CAEP) and describes the use of the N1-P2 response complex as an objective predictor of hearing threshold in adults and older children. The generators of the CAEP are discussed together with issues of maturation, subject factors, and stimuli and recording parameters for use in the clinic. The basic methods for response identification are outlined and suggestions are made for determining the CAEP threshold. Clinical applications are introduced and the accuracy of the CAEP as an estimator of hearing threshold is given. Finally, a case study provides an example of the technique in the context of medicolegal assessment.
It is anticipated that there could be significant reductions in test time for the same signal to noise ratio by using NB CE-Chirps when testing newborns. This effect may vary in practice and is likely to be most beneficial for babies with low amplitude ABR responses. We propose that the ABR nHL threshold to eHL correction for NB CE-Chirps should be approximately 5 dB less than the corrections for tone pips at 4 and 1 kHz.
When appropriate criteria are used, the warm monothermal caloric test offers a performance that is acceptable for routine clinical use, sparing a considerable proportion of patients from unnecessary tests at the cool temperature. We believe that the warm/cool monothermal test difference is probably a consequence of the interrelationship between canal paresis and directional preponderance.
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