Reference data for DPOAE in healthy newborns.

Distortion Product Otoacoustic Emissions (DPOAE) can be used as an alternative to Transient Evoked Otoacoustic Emissions (TEOAE). This study aims to establish normal values for DPOAE in healthy newborns. DPOAE were determined with the Madsen Celesta 503 at 0.5, 1, 2, 4 and 8 kHz with an unequal stimulus level of the primaries (L1 = 65 dB SPL, L2 = 50 dB SPL). DPOAE were present in 92.4% of the ears of the 185 babies tested at 4 days after birth. The 5% quantile and the median of the DPOAE of the right and left ears were calculated for the five frequencies tested. At 4 kHz there was a significant sex effect (mean amplitude of DPOAE was higher in female than in male babies) and at 2 kHz a significant interaction effect was found between sex and side. The calculated reference limits are open to comparison with data obtained using other commercial equipment.

Distortion product oto-acoustic emissions as objective audiometry in a group of children with ventilation tubes.

The aim of this study was to evaluate distortion product oto-acoustic emissions (DPOAEs) as a means of objective audiometry in a population of children with ventilation tubes. We measured DPOAEs at two different stimulus levels--recorded transient evoked oto-acoustic emissions (TEOAEs) and obtained pure-tone audiometry (PTA). DPOAEs were compared with the normal range proposed by the Madsen company: the CELESTA 503 provides a 'normalized' distortion-product-gram which we compared with the pure-tone threshold of the test group. DPOAEs at 60 dBSPL were more easily obtained in the test group than TEOAEs and PTA. Correlation between 'normalized' DPOAEs and pure-tone thresholds was the strongest at 2 and 4 kHz. Surprisingly, DPOAEs at 60 dBSPL showed significant differences also at 2 and 4 kHz compared with the Madsen data. DPOAEs at 60 dBSPL might be an easy, objective test for evaluating auditory function and for determining hearing threshold at 2 and 4 kHz.

Interictal and ictal video-EEG monitoring.

PURPOSE: The purpose of this paper is to demonstrate the diagnostic efficacy and therapeutic relevance of video-EEG monitoring in an large patient population with long-term follow-up. PATIENTS AND METHODS: Between October 1990 and May 1997, 400 patients were monitored at the Epilepsy Monitoring Unit (EMU) of the University Hospital in Gent. In all patients, the following parameters were retrospectively examined: reason for referral, tentative diagnosis, prescribed antiepileptic drugs (AEDs), seizure frequency, number of admission days, number of recorded seizures, ictal and interictal EEG, clinical and electroencephalographic diagnosis following the monitoring session. During follow-up visits at the Epilepsy Clinic, we prospectively collected data on different types of treatment and post-monitoring seizure control. RESULTS: 255/400 (64%) patients were referred for refractory epilepsy. 145/400 (36%) patients were evaluated for attacks of uncertain origin. Mean follow-up, available in 225 patients, was 28 months (range: 6-80 months). Mean duration of a single monitoring session was 4 days (range: 2-7 days). Prolonged interictal EEG was recorded in all patients and ictal EEG in 258 (65%) patients. Following the monitoring session, the diagnosis of epilepsy was confirmed in 217 patients. Pseudoseizures were diagnosed in 31 patients (8%). AEDs were started in 19 patients, stopped in 6 and left unchanged in 110. The type and/or number of AEDs was changed in 111 patients. Sixty patients underwent epilepsy surgery. In 48 surgery patients, follow-up data were available, 29 of whom became seizure-free, and 16 of whom experienced a greater than 90% seizure reduction. Vagus nerve stimulation was performed in 11 patients, 2 became seizure-free, and 7 improved markedly. Of the non-invasively treated patients in whom follow-up was available (n = 135), 70 became seizure-free or experienced a greater than 50% reduction in seizure frequency; 51 patients experienced no change in seizure frequency. Outcome was unrelated to the availability of ictal video-EEG recording. In patients with complex partial seizures, seizure control was significantly improved when a well-defined ictal onset zone could be defined during video-EEG monitoring. CONCLUSION: Prolonged interictal EEG monitoring is mandatory in the successful management of patients with refractory epilepsy. Ictal video-EEG monitoring is very helpful but not indispensable, except in patients enrolled for presurgical evaluation or suspected of having pseudoseizures.

Re-evaluation of the ABR in the diagnosis of CPA tumors in the MRI-era.

Auditory Brainstem Response (ABR) findings in a series of 20 patients with cerebellopontine-angle (CPA) tumors are reported. Every patient was examined by computed tomography (CT) or magnetic resonance imaging (MRI) The aim of this study is to evaluate the usefulness of ABR since the introduction of MRI. Should the strategy for early diagnosis be changed? This paper tries to answer the question both by analyzing our data and by reviewing the literature. MRI is mandatory for diagnosis of small acoustic tumors because ABR lacks adequate sensitivity in this group.