Subjects were 12 boys (12–14 yrs old) who had previously been diagnosed for hyperactivity (clinical group) and 15 age‐matched normal controls. For the selective attention (SA) task vertex ERPs were recorded to dichotically presented tone pips, with differing frequencies to each ear. Each series contained randomly interspersed signals and subjects were instructed to count the signals to one ear (targets). Behavioral tasks consisted of responses to SA targets, a 10‐min vigilance series, and dichotic listening. No significant group differences were found to non‐attended channels for N and P amplitudes and latencies. N amplitude enhancements to the attended channels were significant for the controls (44%), but not for the clinical boys (14%). Also, P latencies and amplitudes to the target pips were significantly greater for the control than the clinical group. Behavioral responses showed significant deficits by the clinical boys for SA and vigilance, but not for dichotic listening. Correct behavioral SA responses correlated significantly with P target amplitudes, but not with N amplitude enhancements. These findings indicate severe dysfunctions by the clinical boys for selective attention, involving both stimulus and response sets.

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Clinical neurophysiologists use brainstem auditory evoked potentials (BAEPs) to monitor the auditory nerve during surgery in which there is a risk of postoperative hearing deficits. Over the last 25 years, monitoring these potentials has decreased operative morbidity by providing the operating team prompt feedback about the functional integrity of the auditory pathway. 1-4 Despite this fact, there are no uniformly accepted criteria for determining when an observed BAEP waveform change demands the attention of the surgeon. 5 Ethical considerations prevent studies specifically addressing what changes might indicate impending complications. Specific but divergent warning criteria have been proposed based on available data and clinical observations: 1) a wave V latency increase of 0.5 millisecond 6 ; 2) a complete loss of wave V 7,8 ; or 3) a wave V latency increase of 1.0 millisecond and a 50% reduction in amplitude. Although these third-alarm criteria correlate moderately well with clinical outcome, they were developed empirically and arbitrarily and have not been validated formally.In this issue of Neurology, James and Husain 9 review data from 156 adult patients undergoing surgery at or close to the cerebellopontine angle (CPA). They sought to determine if the current alarm criteria accurately predicted postoperative hearing deficits. Their findings demonstrate that strict reliance upon the commonly held criteria for sounding a warning in the operating room is not an absolute. Further, their data reveal that BAEP warning criteria should vary depending on whether the case is an acoustic neuroma or a different nearby problem. Patients undergoing surgery for acoustic neuromas were likely to have a hearing loss regardless of the extent of change observed in wave V. Thus, in this class of patients, the current criteria are not sensitive enough and may need to be revised to reflect more subtle alterations in the recorded waveform. In surgery for other processes in the vicinity of the CPA, the current criteria appear to be too conservative and may actually prolong surgery owing to false positives. Those patients undergoing non-CPA tumor procedures most likely to have a postoperative hearing deficit were those in whom wave V was irrevocably lost during surgery. Lesser changes in the BAEP waveform, including amplitude and latency measures currently thought to indicate an impending problem, were not necessarily associated with hearing impairment among such patients.Overall, interpretation criteria for BAEP in the operating room should vary depending on the type of case being monitored. Over reliance upon arbitrary warning criteria invites inaccuracy, which leads to increased patient risk. However, the concept of watching the BAEP waveform deteriorate until just prior to the disappearance of wave V in non-CPA tumor cases (or any case for that matter) before warning the surgeon does not seem acceptable. The single-alarm criterion may need to be replaced with a more complex sliding scale of change. Both clinical neurophysiolo...

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