Diagnosis of IgE-mediated allergy in the upper respiratory tract.

A statistical analysis was made of data concerning diagnosis of IgE-mediated allergy in the upper respiratory tract in 292 patients. A study was made of: skin test, total and specific IgE (RAST), X-sinus, red blood investigation, and cytology of nasal smear. It appears that screening for the presence of an IgE-mediated allergy in the upper respiratory tract can be performed efficiently with a limited number of skin tests (rye grass, timothy, birch, house dust mite and cat). In this study a greater number of skin tests (15 instead of 5) yielded little additional information (in 2% of the patients). A rather poor correlation between skin test and RAST was found.

[The diagnosis of IgE-mediated allergy of the upper airways]. / Diagnostiek van IgE-gemedieerde allergie van de bovenste luchtwegen.

A statistical analysis was made of data concerning diagnosis of IgE-mediated allergy in the upper respiratory tract in 292 patients. It appears that screening for an IgE-mediated allergy can be performed with a limited number of skin tests (rye grass, timothy, birch, house dust mite and cat). In this study a larger number of skin tests (15 instead of 5) and investigation of specific IgE (RAST) yielded little additional information (in 2% and 3% of the patients, respectively). When indicated, an extended series of skin tests, immuno-assay (total IgE and specific IgE) and eosinophil counts in the serum and nasal smear should be performed.

Verification of the air-bone gap using cancellation and evoked responses.

Using the cancellation method as well as evoked responses, we investigated their application in the estimation of the air-bone gap in patients undergoing operation on middle ear structures. The cancellation method had a closer relationship with pure-tone audiometry than evoked responses in predicting the air-bone gap. This was caused by recruitment, by which the cancellation method was not affected. The results of brainstem-evoked responses to bone and air conduction signals showed therefore an underestimation in the prediction of the air-bone gap. Combining the cancellation method with evoked responses elicited to air conduction signals permitted the estimation of the cochlear reserve without the need of threshold measurement by bone conduction.

Phase relationship between bone and air conducted impulse signals in the human head.

Using the cancellation method we investigated the phase relationship as well as the amplitude ratio between impulse signals transmitted simultaneously via both bone and air conduction channels. The psychophysical findings indicated a phase difference corresponding to a time delay of about 0.9 ms by which the air input led the bone input in the case of frontal bone stimulation. Changing the polarity of the bone conduction signal a maximum in the loudness sensation was found just in the same phase difference. The psychophysical findings, predicted mathematically, were verified with brainstem evoked potentials elicited to similar signals. Preliminary results showed that the time lag observed relied on the location of the bone vibrator on the head and furthermore on the frequency used. This suggests different transmissions of vibratory energy reaching the inner ear along the skull.

Comparison of the latencies between bone and air conduction in the auditory brain stem evoked potential.

Brain stem auditory evoked potentials obtained by air and bone conduction were investigated in 22 subjects. The necessity for a carefully selected stimulus being presented to the headphone and the bone vibrator is discussed. Latency values of both responses are presented for wave V. Bone conduction showed latencies which were longer than those obtained by air conduction (about 0.9 msec). Possible mechanisms for this delay are discussed.

Effect of contralateral and ipsilateral masking of acoustic stimulation on the latencies of auditory evoked potentials from cochlea and brain stem.

Masking techniques were applied to a group of 10 subjects with normal hearing, to investigate the influence of masking on the latencies of brain stem auditory evoked potentials. The levels of sufficient masking and overmasking were determined. Central masking, as established in a psychophysiological manner, cannot be clearly demonstrated by auditory brain stem evoked potentials. When masking the untested ear, the alterations in the response are small and this can be ignored in clinical practice if masking of the untested ear is necessary.

The cancellation method for an accurate determination of an air-bone gap.

For a reliable detection of the bone conduction threshold blocking of the contralateral ear can be necessary but then the noise will affect the threshold in the test ear. To resolve this problem the cancellation method is used. The equalization of air and bone conduction sound level in the inner ear is very accurate, the relation between the intensities has been proved to be linear and independent of noise at the contralateral ear. An application for calibration of the bone conduction vibrator to the head phone is discussed. The benefit of the method for measuring an air-bone gap in an accurate way in patients suffering bilaterally from a severe conductive hearing loss is shown.