The Journal of otolaryngology. Supplement最新文献

Lateral recumbency causes ipsilateral nasal congestion and contralateral decongestion. Nasal resistances were measured before, during and after the application of pressure either regionally or by lateral recumbency. In some experiments an attempt was made to block the response by local anesthetic injection, splinting the nasal vestibules, or topical decongestants. In others an electric blanket was employed as a stimulus instead of pressure. It was concluded that the nasal resistance changes during lateral recumbency are due to pressure receptors in the pelvic and pectoral girdles, and thorax. These adapt slowly. They are probably situated in the intercostal spaces, parietal pleura, or sterno-costal joints. Their centripetal fibers probably travel in the intercostal nerves, and their efferents in the cervical sympathetic outflow to the nasal erectile tissue. Lateral recumbency of 12 minutes' duration induces changes in nasal resistance which persist after the pressure asymmetry has been terminated. This may be due to temporal summation.

There seems to be a great difference of opinion among rhinoplastic surgeons concerning incisions to gain access to the nasal tip. Some state that the method of exposure is of secondary importance. This author firmly believes that many unsatisfactory results could be avoided if adequate surgical exposure were used for nasal tip surgery. Alar cartilage delivery and external approach rhinoplasty are recommended as the only methods for all cases. These methods are described in detail, and in accordance with the author's conviction that all pre- and postoperative photographs should be published to allow proper assessment, these are provided in selected cases.

Click BERA has several limitations, both physical and physiological, for early audiological assessment. It cannot quantify the audiometric contour, detect high or low frequency hearing loss, or reveal residual low frequency hearing. Several methods of cochlear place-specific BERA are reviewed briefly. BERA using tonepip stimuli in band-reject masking noise is described in more detail for both nil-risk and at-risk infants. Technical and normative problems are outlined. Most babies give clear ABRs to 40 dBnHL tonepips, but threshold distributions are broader at 500 Hz than for higher frequency tonepips or clicks. Thresholds improve over the first four months, especially at 500 Hz. Cases of click/tonepip threshold differences are presented. Place-specific testing may be a useful component of early assessment. Further research is needed to determine its limitations and relevance to early management.

The relationship between the results of an infant hearing screening program and neurological impairment may be considered in two ways: 1) Is there a correlation between incidence of neurological dysfunction and the incidence of sensorineural hearing loss in the target population? In our target population, the incidence of sensorineural hearing impairment was 3.13% for the group with a positive neurological history vs. 1.3% in those with a negative neurological history. 2) Do auditory evoked potentials used for hearing screening and follow-up provide any additional information on the neurological status of the target population, or, are certain neurological conditions associated with certain typical auditory evoked potential configurations? In our experience auditory evoked responses do provide additional information especially if for diagnostic purposes both the brainstem and the later components are considered. Often, specific neurological problems may be associated with typical auditory evoked response configurations.

The success of any test procedure that involves decision analysis must be based on sound principles, reasonably obtainable data, and a knowledge of response variability. The use of brainstem electric response audiometry (BERA) has gained a prominent role in the clinical assessment of auditory, otoneurologic, and neurologic deficits. However, the road to clinical utility has not been without obstacles. The brainstem response has been besieged with numerous variables which have curtailed universal acceptance and contributed to a lack of established standards. Before BERA is used with any degree of confidence, response variability must be defined and controlled. The purpose of this paper is to review those technical, physiologic, and pathologic conditions which affect response measurement.

Normative data are required when interpreting brainstem electric response audiometry results. An abnormal auditory brainstem response (ABR) cannot be identified without knowledge of the normal ABR and the variability associated with technical and physiological factors. Normative data obtained from babies in a neonatal intensive care unit in response to click stimulation are presented in this paper.

Sixteen hydrocephalic NICU babies and 16 age-matched, non-hydrocephalic NICU babies were tested with BERA. The latency and amplitude of waves I and V were compared between groups. Both waves were longer in latency and smaller in amplitude in the hydrocephalic group. The I-V latency interval was within normal limits, but the V/I amplitude ratio was significantly smaller. The reduced amplitude of wave V was the most noticeable ABR abnormality. A total of 11 hydrocephalic babies showed responses that were considered abnormal in amplitude, with all but one having an elevated ABR threshold in at least one ear. These threshold elevations may reflect a neurological condition rather than a peripheral hearing loss.

This paper reports on two studies, one in Halifax and the other in Ottawa, which compared behavioral methods and BERA in the screening of hearing loss in neonates. The Halifax study used BERA as the screening procedure for infants of a neonatal intensive care unit (NICU) and as a supplementary procedure to behavioral screening test for non-NICU but "at risk" infants. The results of this study indicate false positive rates with the behavioral test of 86.1 and 50.5% for NICU and at risk groups respectively. The Ottawa study evaluated the Crib-o-gram as a screening test for NICU infants using BERA as the standard. The results of this study indicated that approximately one third of babies with normal BERA thresholds failed Crib-o-gram screening and that Crib-o-gram could identify moderately/severe losses.

The incidence of hearing impairment in high risk infants is summarized for five programs which use brainstem electric response audiometry (BERA) to detect hearing loss in this population. Programs are compared with respect to the following variables which may affect reported incidence figures: population characteristics, stimulus and recording parameters, criteria for failure on the initial BERA test, and follow-up protocols. Between 10-30% of these infants fail an initial BERA test, with initial failure rate largely dependent on the failure criteria used. Approximately 10% will continue to show some degree of hearing impairment on follow-up tests at 2-5 months of age. Between 2-4% will have a moderate to profound bilateral sensorineural hearing loss requiring amplification and habilitation.

An in-depth investigation of the progression of noise induced hearing loss is reported for individuals working in three major Canadian industries. The particular approach taken was to select occupational groups within each industry, who had the same noise exposure for a continuous period, and on whom standard hearing tests were undertaken at regular intervals. Two methods of evaluating the audiometric data were used. The first was a cross-sectional design, in which one audiogram was analyzed for each employee. The second focused on the rate of hearing loss over time within individuals. The results confirmed previous reports that the effect of continuous noise exposure was maximal in the region of 2-6 kHz. Significant differences in hearing loss were noted across job types. Over a 10 year period the rate of loss within exposed individuals was on the average 1.5 dB per year for 4 kHz, as compared with 0.5 dB for control subjects who held office jobs. The absolute difference between hearing thresholds measured at the beginning and end of this period ranged widely from a slight improvement in hearing to losses often as great as 55 dB. In general the greatest loss occurred at 4 kHz. The number of frequencies at which there was a risk of exceeding a 25 dB fence increased with the number of years of exposure.