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Purpose To evaluate whether the onset of pediatric refractory status epilepticus (rSE) is related to time of day. Method We analyzed the time of day for the onset of rSE in this prospective observational study performed from June 2011 to May 2019 in pediatric patients (1 month to 21 years of age). We evaluated the temporal distribution of pediatric rSE utilizing a cosinor analysis. We calculated the midline estimating statistic of rhythm (MESOR) and amplitude. MESOR is the estimated mean number of rSE episodes per hour if they were evenly distributed. Amplitude is the difference between MESOR and maximum rSE episodes/hour, or between MESOR and minimum rSE episodes/hour. We also evaluated the temporal distribution of time to treatment. Results We analyzed 368 patients (58% males) with a median (p25 – p75) age of 4.2 (1.3–9.7) years. The MESOR was 15.3 (95% CI: 13.9–16.8) and the amplitude was 3.2 (95% CI: 1.1–5.3), p = 0.0024, demonstrating that the distribution is not uniform, but better described as varying throughout the day with a peak in the morning (11am–12 pm) and trough at night (11 pm–12 am). The duration from rSE onset to application of the first non-benzodiazepine antiseizure medication peaked during the early morning (2am–3 am) with a minimum during the afternoon (2 pm–3 pm) (p = 0.0179). Conclusions The distribution of rSE onset is not uniform during the day. rSE onset shows a 24-h distribution with a peak in the mid-morning (11am–12 pm) and a trough at night (11 pm-12am).

Improved non-invasive localization of the epileptogenic foci prior to epilepsy surgery would improve surgical outcome in patients with partial seizure disorders. A critical component for the identification of the epileptogenic brain is the analysis of electrophysiological data obtained during ictal activity from prolonged intracranial recordings. The development of a noninvasive means to identify the seizure onset zone (SOZ) would thus play an important role in treating patients with intractable epilepsy. In the present study, we have investigated non-invasive imaging of epileptiform activity in patients with medically intractable epilepsy by means of a cortical potential imaging (CPI) technique. Eight pediatric patients (1M/7F, ages 4-14 years) with intractable partial epilepsy were studied. Each patient had multiple (6 to 14) interictal spikes (IIS) subjected to the CPI analysis. Realistic geometry boundary element head models were built using each individual's MRI in order to maximize the imaging precision. CPI analysis was performed on the IISs, and extrema in the estimated CPI images were compared with SOZs as determined from the ictal electrocorticogram (ECoG) recordings, as well as the resected areas in the patients and surgical outcomes. The distances between the maximum cortical activities of the IISs reflected by the estimated cortical potential distributions and the SOZs were determined to quantitatively evaluate the performance of the CPI in localizing the epileptogenic zone. Ictal ECoG recordings revealed that six patients exhibited a single epileptogenic focus while two patients had multiple foci. In each patient, the CPI results revealed an area of activity overlapping with the SOZs as identified by ictal ECoG. The distance from the extreme of the CPI images at the peak of IIS to the nearest intracranial electrode associated with the onset of the ictal activity was evaluated for each patient and the averaged distance was 4.6mm. In the group of patients studied, the CPI imaged epileptogenic foci were within the resected areas. According to the follow-up of the eight patients included, two were seizure free and six had substantial reduction in seizure frequency. These promising results demonstrate the potential for noninvasive localization of the epileptogenic focus from interictal scalp EEG recordings. Confirmation of our results may have a significant impact on the process of presurgical planning in pediatric patients with intractable epilepsy by dramatically reducing or potentially eliminating the use of intracranial recording.

The antiepileptic drug felbamate has demonstrated efficacy against a variety of seizure types in the pediatric population, particularly seizures associated with Lennox-Gastaut syndrome. Postmarketing experience, however, revealed serious idiosyncratic adverse effects not observed during clinical trials, including aplastic anemia and liver failure. As a result, many physicians have been hesitant to prescribe felbamate. This retrospective study evaluated the efficacy of felbamate in a pediatric population with intractable epilepsy. Of 38 patients, 22 had Lennox-Gastaut syndrome (58%); 6 had myoclonic-astatic epilepsy of Doose (16%); 5 had symptomatic generalized epilepsy, not otherwise specified (13%); and 5 had symptomatic localization-related epilepsy (13%). Most patients had multiple seizure types and had been tried on a variety of antiepileptic medications. With felbamate treatment, 6 patients (16%) became seizure free, including 4 of the 6 patients with myoclonic-astatic epilepsy of Doose; 24 patients (63%) had a greater than 50% reduction in seizure frequency. In this population felbamate appeared to be safe, with minimal adverse effects. The study is limited by the small number of patients and by its retrospective nature, but nonetheless adds to the evidence that felbamate is an important antiepileptic drug for medically refractory epilepsy in children and is well tolerated with few adverse effects.

In the present study, we have validated the cortical potential imaging (CPI) technique for estimating cortical potentials from scalp EEG using simultaneously recorded electrocorticogram (ECoG) in the presence of strong local inhomogeneity, i.e. Silastic ECoG grid(s). The finite element method (FEM) was used to model the realistic post-operative head volume conductor, which includes the scalp, skull, cerebrospinal fluid (CSF) and brain, as well as the Silastic ECoG grid(s) implanted during the surgical evaluation in epilepsy patients, from the co-registered magnetic resonance (MR) and computer tomography (CT) images. A series of computer simulations were conducted to evaluate the present FEM-based CPI technique, and to assess the effect of the Silastic ECoG grid on the scalp EEG forward solutions. The present simulation results show that the Silastic ECoG grid has substantial influence on the scalp potential forward solution due to the distortion of current pathways in the presence of the extremely low conductivity materials. On the other hand, its influence on the estimated cortical potential distribution is much less than that on the scalp potential distribution. With appropriate numerical modeling and inverse estimation techniques, we have demonstrated the feasibility of estimating the cortical potentials from the scalp EEG with the implanted Silastic ECoG gird(s), in both computer simulations and in human experimentation. In an epilepsy patient undergoing surgical evaluation, the cortical potentials were reconstructed from the simultaneously recorded scalp EEG, in which main features of spatial patterns during interictal spike were preserved and over 0.75 correlation coefficient value was obtained between the recorded and estimated cortical potentials. The FEM-based CPI technique provides a means of connecting the simultaneous recorded ECoG and the scalp EEG, and promises to become an effective tool to evaluate and validate CPI techniques using clinic data.

Objective The present study aims to accurately estimate the in vivo brain-to-skull conductivity ratio by means of cortical imaging technique. Simultaneous extra- and intra-cranial potential recordings induced by subdural current stimulation were analyzed to get the estimation. Methods The effective brain-to-skull conductivity ratio was estimated in vivo for 5 epilepsy patients. The estimation was performed using multi-channel simultaneously recorded scalp and cortical electrical potentials during subdural electrical stimulation. The cortical imaging technique was used to compute the inverse cortical potential distribution from the scalp recorded potentials using a 3-shell head volume conductor model. The brain-to-skull conductivity ratio, which leads to the most consistent cortical potential estimates with respect to the direct intra-cranial measurements, is considered to be the effective brain-to-skull conductivity ratio. Results The present estimation provided consistent results in 5 human subjects studied. The in vivo effective brain-to-skull conductivity ratio ranged from 18 to 34 in the 5 epilepsy patients. Conclusions The effective brain-to-skull conductivity ratio can be estimated from simultaneous intra- and extra-cranial potential recordings and the averaged value/standard deviation is 25±7. Significance The present results provide important experimental data on the brain-to-skull conductivity ratio, which is of significance for accurate brain source localization using piece-wise homogeneous head models.

Background: It is of clinical importance to localize pathologic brain tissue in epilepsy. Noninvasive localization of cortical areas associated with interictal epileptiform spikes may provide important information to facilitate presurgical planning for intractable epilepsy patients. Methods: A cortical potential imaging (CPI) technique was used to deconvolve the smeared scalp potentials into the cortical potentials. A 3-spheres inhomogeneous head model was used to approximately represent the head volume conductor. Five pediatric epilepsy patients were studied. The estimated cortical potential distributions of interictal spikes were compared with the subsequent surgical resections of these same patients. Results: The areas of negativity in the reconstructed cortical potentials of interictal spikes in 5 patients were consistent with the areas of surgical resections for these patients. Conclusions: The CPI technique may become a useful alternative for noninvasive mapping of cortical regions displaying epileptiform activity from scalp electroencephalogram recordings. q 2003 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

We assessed physicians working in the field of child neurology with the aim of improving the physicians' mental health. Our questionnaire included a burnout inventory and a general health questionnaire. We analyzed 29 responses from physicians in a variety of countries obtained through the Internet. According to their responses, 8 (27.5%) of the respondents had attained a burnout status, and 27 respondents (93.1%) had neurotic conditions. We found a greater percentage of physicians in poor mental health than we had found previously in assessments made in Japan. However, the respondents in the present survey had more positive styles for coping with stress. The length of time working as a physician affected respondents in Japan and internationally, whereas nationality or working environment (workplace, night shifts, and so on) did not. Consultants or mentors on work and assertive stress coping would be effective. Copyright 2003, Elsevier Science (USA). All rights reserved.

Neuropsychological and behavioral status were examined in 57 children aged 7 to 16 years with complex partial seizures (CPS) and compared with 27 sibling control children of the same age. Epilepsy had a significant effect on both cognitive and behavioral adjustment measures. Children with CPS had significant impairment across all seven cognitive domains assessed, reflective of a profile of relatively diffuse and generalized cognitive dysfunction. Age at onset of recurrent seizures was the strongest and most consistent predictor of adequacy of cognitive functioning; earlier age at onset was associated with poorer cognitive status. Children with CPS also had more problems compared with sibling control children on measures of social and school competence and internalizing behavior problems, but not externalizing behaviors. Further, frequency of seizure activity in the past year, rather than age at seizure onset, emerged as the strongest predictor of these behavioral difficulties. These findings are discussed in the context of understanding the impact of CPS on cognition and behavioral adjustment, and identifying the contribution of various aspects of the neurodevelopmental course of CPS to these issues.

We report 3 children without any brainstem auditory evoked potential (BAEP) neural component who all retained isolated cochlear microphonic potentials as well as click-evoked otoacoustic emissions. Two of them demonstrated only moderately impaired audiometric thresholds. These features correspond to a peculiar pattern of auditory dysfunction recently coined 'auditory neuropathy'. In contrast with the published previous cases of auditory neuropathy presenting with an acquired hearing deficit as children or young adults, all 3 children had a history of major neonatal illness and the auditory neuropathy was already demonstrated in the first months of their lives. (C) 1997 Elsevier Science Ireland Ltd.

When special pseudo-random stimuli sequences (maximum length sequences: MLS) are combined with a deconvolution analysis technique, it is possible to derive new evoked potential components that are called kernels. The kernels give a measure of the temporal interactions that take place between the responses to successive stimuli. This may provide an objective neurophysiological test for the exploration of a dimension of hearing which has hitherto been limited to psychophysical methods. Until now, auditory short-latency kernels obtained by the MLS method have been related to the late portion of the brainstem auditory evoked potential (BAEP), suggesting that temporal interactions occur rather late in the auditory pathways. We report 4 children without any BAEP neural components, who all retained isolated cochlear microphonic potentials. Three of them produced click-evoked otoacoustic emissions and two of them demonstrated only moderately impaired audiometric thresholds. This combination of absent BAEP neural components with preserved otoacoustic emissions and cochlear microphonic potential corresponds to a peculiar pattern of auditory dysfunction recently coined 'auditory neuropathy'. All 4 children exhibited well-defined kernels at latencies consistent with the microphonic potential. These data indicate that the cochlea itself can generate kernels at a presynaptic level. They open up the question of the identification of the physiological site(s) responsible for the generation of MLS-evoked kernels. (C) 1997 Elsevier Science Inland Ltd.

Auditory functioning was assessed in two groups of adult rhesus monkeys (11 years of age). One (n = 11) received modest exposure to lead early in life and the other (n = 8) served as controls and did not receive any lead supplementation. Two lead-exposed monkeys had abnormal distortion product otoacoustic emissions (DPEs) and smaller amplitude or absent evoked potentials. These monkeys had abnormal distortion product otoacoustic emission (DPEs) and smaller amplitude or absent evoked potentials. These monkeys had the highest blood levels recorded in their respective groups. For the remaining lead-exposed monkeys there was little difference between their DPEs and the DPEs of the control monkeys with one exception. DPE amplitudes of the control monkeys increased more rapidly as a function of stimulus level than those of the lead-exposed monkeys at most frequencies. There was also a significant but modest effect of lead exposure on the auditory brain stem evoked responses (ABRs) of these lead-exposed monkeys. There was no apparent effect on the middle latency evoked responses (MLRs), although that result could be due to the relatively greater variability of the MLR.

Early (ABRs) and middle (MLRs) surface-recorded auditory evoked potentials were compared in eight adult monkeys (Macaca mulatta) and eight adult humans. Responses whose probable generators were the cochlear nucleus and lateral lemniscus were of shorter latency and larger amplitude in monkeys. Relative to humans, ABR response latencies in monkeys were less affected by stimulus intensity, stimulus rate, and masker level. In contrast, monkey amplitudes were relatively more affected by those same stimulus parameters. The most prominent MLR wave was longer in latency and greater in amplitude in humans than the homologous wave in monkeys. The reduction in amplitude of that wave with increasing rate was greater for humans than monkeys. Temporal interactions (the effect of prior stimuli on the response to current stimulation) were investigated from a non-linear systems identification framework using maximum length sequences (MLSs). Both monkey and human auditory systems were second and probably third-order systems at the levels assessed. As the separations between the stimulus pulses decreased, evidence for temporal interactions became more prominent, reached a maximum, and then decreased with further decreases in stimulus pulse separation. At the highest stimulus rates presented, variations in temporal spacing among stimuli had less of an effect on monkey than human evoked responses.

A functional representation is proposed for complex valued (amplitude and phase) head-related transfer functions (HRTFs), including both frequency and spatial dependence. The frequency variation is spanned by a set of eigentransfer functions (EFs) that are generated using the Karhunen-Loève expansion. Any HRTF is represented as a weighted combination of the EFs where the weights are functions of the HRTFs spatial location and are termed spatial characteristic functions (SCFs). Samples of the SCFs are obtained by projecting the measured HRTFs onto the EFs. A regularization framework is employed to obtain a functional representation for the SCFs by fitting each set of SCF samples with a two-dimensional spline. Acoustic validation of the model's fidelity and predictive capability is provided using 2188 measured HRTFs from a KEMAR manikin and 1816 measured HRTFs from an anesthetized live cat. Errors between measured and modeled HRTFs are generally less than one percent. Larger errors occur in the contralateral regions for KEMAR and lower back regions for the cat as a consequence of the relatively small HRTF amplitudes resulting from head shadowing. Methods for reducing these errors are discussed.

A consecutive, retrospective analysis of seizure control and quality of life was performed among 83 pediatric patients undergoing epilepsy surgery at Children's Hospital of Wisconsin. Seizure outcomes were generally favorable, with 68.7% class I outcomes; class II, 12%; and class III, 19.3%. Seizure freedom was highest among temporal lobectomies (84.2%) and hemispherectomies (76.2%). Outcomes among hemispherectomies were substantially superior to those of multilobar resections. Cortical dysplasia was associated with lower seizure freedom, at 57.5%. Among age groups, seizure-free outcomes in infants were lowest, at 50%. The lower infant seizure-free rate was likely attributable to frequency of multilobar resections and type of pathology (cortical dysplasia). Quality-of-life measures generally paralleled seizure outcomes. These results indicate that epilepsy surgery in children with intractable epilepsy can result in significant improvements in seizure control, quality of life, and development. Anticipated type of surgery, presumed location of epileptogenic site, absence of a defined lesion on magnetic resonance imaging scan of the brain, and patient's age should not prevent surgical evaluations of children with intractable epilepsy.

Botulism in infants, unless recognized early, is associated with high mortality and morbidity. The diagnosis is suspected when infants present with sudden onset of weakness, respiratory failure, and constipation and is confirmed by demonstration of botulinum toxin in stool several weeks later. Electrodiagnosis allows quick and reliable confirmation of botulism. Low-amplitude compound muscle action potentials, tetanic or post-tetanic facilitation, and the absence of post-tetanic exhaustion support the diagnosis. Two infants with confirmed botulism did not exhibit the characteristic electrodiagnostic features, demonstrating the pitfalls in electrodiagnosis of infantile botulism. (J Child Neurol 1999;14:156-158).

Summary: Purpose: To develop and evaluate a new cortical activation mapping (CAM) method to obtain the neuronal activation sequences from the cortical potential distributions. Methods: Interictal electrocorticogram (ECoG) recordings were analyzed for eight pediatric epilepsy patients to find the cortical activation maps, which were compared with the patients' seizure-onset zones identified from ictal ECoG recordings. Various relations between the local activation time and cortical potential were assumed. The most effective relation was determined by accessing their capability to predict the seizure-onset zone. Computer simulations using a moving dipole source model were also conducted to test the present approach in imaging the propagated cortical activity. Results: In both clinical data analysis and computer simulations, the maximal amplitude proved to be the most effective criterion with which to determine the local cortical activation time. The present method successfully predicted the seizure-onset zone in seven of eight patients by the CAM analysis of ECoG-recorded interictal spikes (IISs). For patients with multiple seizure foci, each focus can be revealed by analyzing IISs with different spatial patterns. Conclusions: The time difference between spike peaks of the interictal events in the leading channel and other channels can be effectively defined as the local cortical activation time. The cortical activation mapping method based on this time latency can be used to predict the seizure-onset zones, suggesting that the present CAM method is useful to assist the presurgical evaluation for the epilepsy patients.

Invasive EEG monitoring is one of the best tools available for localization of epileptogenic foci in the brain. However, published data in mixed series of adult and pediatric patients show high incidence of epidural bacterial contamination, cerebrospinal fluid leakage, and skin infection after subdural electrode implantation. We sought to determine whether the complication rate from prolonged subdural electrode implantation would be lower in a purely pediatric series. Thirty-three subdural electrode implantation procedures were performed in 29 pediatric patients (age range 4–19) for an average of 7.2 days (range 3–14 days). Electrode number varied from 32 to >128 with a range of 4–11 electrode wires piercing the skin >1 cm from the primary incision. Of the 33 implantations and resections (66 craniotomies), 5 were for reimplantation. There were no permanent complications related to grid implantation. Transient complications included 1 case of prolonged prothrombin time and 1 patient with unexplained fever, both of which resolved upon removal of the grids. There were two culture-positive infections, one epidural and one superficial, both in patients undergoing reimplantation. There was no percutaneous cerebrospinal fluid leakage noted and no operation was aborted due to bleeding caused by grid placement. Our data suggest that subdural grid implantation in children is remarkably safe even for prolonged implantation, though infectious risk is significantly higher in reoperation (p = 0.019). This observation may contribute to lowering the threshold for two-stage invasive monitoring approaches in children with epilepsy.

Distortion product otoacoustic emissions (DPOAEs) were compared in eight rhesus monkeys (Macaca mulatta) and eight normal hearing humans. DPOAEs were recorded in three conditions. In the first condition, DPOAEgrams were generated for monkeys and humans from approximately f2 = 0.5-20 kHz. Monkeys had larger amplitude DPOAEs at all frequencies except around f2 = 1 kHz. In the second condition, DPOAE amplitudes increased and then decreased as the separation between the primaries increased. These functions were similar in the two species except at the lowest frequencies assessed. In the third condition, the levels of the primaries were varied independently. Monkeys had steeper input/output (I/O) functions than humans. The slopes of DPOAE I/O functions increased with frequency in both species. When the levels of both primaries were increased simultaneously, DPOAE I/O functions were well described by power functions throughout the intensity range assessed (from threshold to 65 dB SPL). Monkey I/O functions tended to be expansive power functions at all but the lowest frequencies, while human I/O functions tended to be compressive power functions except at the highest frequencies assessed. Other differences in I/O functions f2 = 8 kHz may indicate species specific differences at high (for human) frequencies.

Two simultaneously presented maximum length sequences (MLSs) were used to investigate temporal nonlinearities. Not only did the recorded auditory evoked brain stem responses to these stimuli predictably increase in latency and decrease in amplitude as a function of the temporal interactions between MLSs, but thresholds were elevated by more than 20 dB. Simultaneous MLS paradigms make it possible to investigate a number of nonlinearities in the auditory system efficiently. This study also demonstrated that binaural MLS techniques can be used to assess auditory function even in individuals with asymmetric hearing losses without fear of crossover effects.

This study compared monaural and binaural maximum length sequence auditory‐evoked brain‐stem responses (MLS ABRs) in normal hearing adults. The first experiment demonstrated that reliable binaural MLS ABRs could be recorded which were essentially the same as those recorded monaurally. The second experiment generalized this finding by assessing a range of intensities including threshold stimuli. ABR thresholds, wave V latency × intensity and amplitude × intensity functions, wave V latency and amplitude reproducibility, and waveform reproducibility were comparable for the monaural and binaural MLS ABRs with some minor qualifications. In the third experiment, comparability of monaural and binaural MLS ABRs was generalized to a range of rates from those used conventionally to rates far faster than possible with signal averaging. Again, there was little difference between the binaural and monaural MLS ABRs over the range of rates assessed.

Cubic distortion-product otoacoustic emissions (DPEs) may have clinical and research applications. We reliably recorded DPEs at some frequencies in all of the normal-hearing human adults and newborns tested. Adult and newborn DPEs were of comparable amplitude, with the exception that a prominent dip between 1 and 3 kHz in the adult data was less evident in the newborn data. DPE amplitude was a linear function of the intensity of the eliciting primary stimuli. The slopes of the linear input-output functions increased with increasing frequency. Except at the highest frequencies assessed, adult input-output functions were steeper than newborn input-output functions.

Experiments were conducted to assess the contribution of place mechanisms to the effect of rise--fall time on wave V of the human brainstem auditory evoked response (BAER). Noise bursts of 4- and 10-ms duration were presented at various rise-fall times (0, 1, 2, and 5 ms). Subtractive high-pass masking techniques were used to determine the effect of rise time as a function of derived-band frequency. In general, increasing rise time prolonged wave V latency but did not affect amplitude. Rise-time effects did not depend on derived-band frequency and similar effects were seen in the unmasked conditions. In addition, narrowing the derived band did not alter the observed effects on latency and amplitude. Signal envelope showed no effects on traveling wave velocity. These results suggest that place mechanisms contribute little to changes in the BAER associated with rise--fall time.

Brain stem evoked potentials were recorded by conventional scalp electrodes in infants (3 weeks to 3 years of age) and adults. The latency of one of the major response components (wave V) is shown to be a function both of click intensity and the age of the subject; this latency at a given signal strength shortens postnatally to reach the adult value (about 6 msec) by 12 to 18 months of age. The demonstrated reliability and limited variability of these brain stem electrophysiological responses provide the basis for an optimistic estimate of their usefulness as an objective method for assessing hearing in infants and adults.

A series of experiments evaluated the effects of broadband noise (ipsilateral) on wave V of the brainstem auditory evoked response (BAER) elicited by tone bursts or clicks in the presence of high‐pass masking noise. Experiment 1 used 1000‐ and 4000‐Hz, 60‐dB nHL tone bursts in the presence of broadband noise. With increasing noise level, wave V latency shift was greater for the 1000‐Hz tone bursts, while amplitude decrements were similar for both tone‐burst frequencies. Experiment 2 varied high‐pass masker cutoff frequency and the level of subtotal masking in the presence of 50‐dB nHL clicks. The effects of subtotal masking on wave V (increase in latency and decrease in amplitude) increased with increasing derived‐band frequency. Experiment 3 covaried high‐pass masker cutoff frequency and subtotal masking level for 1000‐ and 4000‐Hz tone‐burst stimuli. The effect of subtotal masking on wave V latency was reduced for both tone‐burst frequencies when the response‐generating region of the cochlear partition was limited by high‐pass maskers. The results of these three experiments suggest that most of the wave V latency shift associated with increasing levels of broadband noise is mediated by a place mechanism when the stimulus is a moderate intensity (60 dB nHL), low‐frequency (1000 Hz) tone burst. However, the interpretation of the latency shifts produced by broadband noise for 4000‐Hz tone‐burst stimuli is made more complex by multiple technical factors discussed herein.

Bilirubin encephalopathy causes potentially preventable brain damage and hearing loss. The site of auditory dysfunction is controversial, despite pathologic studies showing damage to brain stem auditory nuclei in humans and experimental animals. We studied the effects of bilirubin toxicity on the auditory system of homozygous jaundiced Gunn rats by use of brain stem auditory evoked potentials. Small but statistically significant abnormalities were found for wave latencies, interwave intervals, and amplitudes.

A series of experiments investigated the effects of continuous broadband noise (ipsilateral) on wave V of the click‐evoked brainstem auditory evoked response (BAER). In general, a broadband noise masker increases the latency and decreases the amplitude of wave V. Varying both click and noise intensity, it was found that noise levels above about 40 dB SPL increase the latency and decrease the amplitude of wave V, regardless of click intensity. The effects of noise on wave V amplitude appear constant across click intensity, whereas the effects of a constant noise level on wave V latency decrease at higher click intensities. Both masking and adaptation increase wave V latency, but their combined effects are occlusive: rate‐induced wave V latency shift decreases in the presence of continuous broadband noise. The clinical and theoretical implications of these findings are discussed.