Factors affecting axillary lymph node retrieval and assessment in breast cancer patients.

BACKGROUND: Breast cancer is the most common female cancer in North America. Axillary lymph node dissection (ALND) is important for staging, prognosis, and adjuvant treatment decisions. The purpose of this study was to identify factors that affect the number of lymph nodes (LN) retrieved in ALND for breast cancer. METHODS: All patients who underwent ALND for breast cancer at Sunnybrook Health Sciences Centre and Women's College Hospital between July 1999 and June 2006 were included. The number of LN retrieved was identified from pathology reports. Univariate and multivariate analysis was undertaken to identify variables influencing this outcome. RESULTS: 1084 patients were identified with a mean number of LN of 14.5. In multivariate analyses, significant covariates included sentinel LN biopsy (P = 0.011), degree of extranodal extension (P = 0.005), tumor grade (P = 0.058), and age (P = 0.043). Thirteen percent of the variation in LN yield was accounted for by institutional, provider, patient, and tumor related factors, leaving 87% attributable to inherent biological or other differences between patients. CONCLUSION: The yield of ALND may be influenced by multiple factors, often not related to the surgery. In settings where >10 LNs are routinely retrieved at ALND, biological variation between patients should be recognized as major a contributor to the LN yield. Adjuvant treatment decisions based on this outcome should take this into consideration.

[Cystic tumor of the mediastinum of digestive origin. Apropos of a new case. Diagnostic and pathogenic hypotheses]. / Tumeur kystique du médiastin d'origine digestive. A propos d'un nouveau cas. Hypothèses diagnostiques et pathogéniques.

An incidental discovery of a posterior and inferior mediastinal cyst-like opacity allowed us to diagnose a pulmonary sequestration in a 45-year old woman. The operative findings showed an hour-glass tumor of the inferior mediastinum with an abdominal prolongation attached by a stalk onto the top of the stomach. These findings made us change our diagnosis in favour of an abdomino-thoracic gastric duplication. This new hypothesis was not confirmed by the results of the pathological report which revealed two kinds of tissue; intestinal in the abdomen and broncho-pulmonary in the chest. Two diagnoses where then proposed: complex hamartoma or mediastinal bronchogenic cyst. The pathogenic interpretation in such cases is still very controversial. English authors are prone to classify them as broncho-pulmonary foregut malformations. Macroscopic and microscopic data of the specimen led us to consider our case-report to be a foregut malformation.

Human temporary threshold shift (TTS) and damage risk.

Information regarding the relation of human temporary threshold shift (TTS) to properties of steady-state and intermittent noise published since the 1966 appearance of the CHABA damage risk contours is reviewed. The review focuses on results from four investigative areas relevant to potential revision of the CHABA contours including effects of long-duration exposure and asymptotic threshold shifts (ATS); equivalent quiet and/or safe noise levels; effects of intermittency; and use of noise-induced temporary threshold shift (NITTS) to predict susceptibility to noise-induced permanent threshold shift (NIPTS). These data indicate that two of three major postulates on which the original contours were based are not valid. First, recovery from TTS is not independent of the conditions that produced the TTS as was assumed. Second, the assumption that all exposures that produce equal TTS2 are equally hazardous is not substantiated. The third postulate was that NIPTS produced by 10 years of daily exposure is approximately equal to the TTS2 produced by the same noise after an 8-h exposure. Based upon several TTS experiments showing that TTS reaches an asymptote after about 8 h of exposure, the third CHABA postulate can be reworded to state the hypothesis that ATS produced by sound of fixed level and spectrum represents an upper bound on PTS produced by that sound regardless of the exposure duration or the number of times exposed. This hypothesis has a strong, logical foundation if ATS represents a true asymptote for TTS, not a temporary plateau, and if threshold shifts do not increase after the noise exposure ceases.

Hearing compensation evaluation.

Compensation claims for hearing loss are increasing. Physicians and audiologists supply necessary information regarding probable cause and amount of loss for evaluating these claims. Compensable hearing loss can arise from several sources. The principal activity has been claims based on industrial noise exposure. Compensation evaluation is considered as a consequence of noise-induced hearing loss, but the evaluation procedure is applicable regardless of the cause of hearing loss.

A clinically feasible method for determining frequency resolution.

Psychophysical tuning curves were generated by normally hearing and hearing-impaired subjects using two methods; a detailed laboratory method and a Bekesy method proposed as suitable for clinical use. The two methods were compared for stability, the amount of masking produced and the pattern of the masking functions. The two measures of frequency resolution were found to be equally reliable and showed the same range of repeatability as simple pure tone thresholds. The patterns of the masking functions were similar regardless of the method used. However, the absolute amounts of masking indicated with each method were significantly different, with more masking obtained when the clinical method was used.

Auditory brain stem response testing in anesthetized horses.

Auditory brain stem response testing, using insert earphones, was performed in 10 healthy horses given general anesthesia. The procedure involved clicks of alternating polarity delivered at a rate of 25 clicks/s. Wave forms, including five peaks, were commonly identified. Latencies were measured in milliseconds for waves I through V for all intensities. Latencies of all waves decreased as stimulus intensity increased. For waves I through V, a least-squares regression line was determined for each horse, using all responses between 87-dB sound pressure level (SPL) and 136-dB SPL, inclusive. Slopes were significantly (P less than 0.05) less than zero for waves I through IV, but not for wave V. Peak latencies of each wave averaged at 87-dB SPL for waves I through V were 1.73, 2.6, 3.82, 4.80, and 5.71 ms, respectively; latencies of these five waves at 136-dB SPL were 1.36, 2.2, 3.06, 3.92, and 4.71 ms, respectively. The decrease in latency among the five waves ranged from 0.13 to 0.004 ms/dB. When peak values were below 87-dB SPL, waves became essentially unrecognizable.

Medicinal therapy for hearing loss resulting from noise exposure.

A large-scale review of the literature concerning the effects of noise on hearing, published primarily during the 1970s, was initiated by the National Institute of Neurological and Communicative Disorders and Stroke in 1981. This review demonstrated a continuing search for medicinal treatment for the adverse effects of noise on hearing. The present article focuses on the results of investigations of human subjects. The literature in this area is primarily European and deals principally with treatment of acoustic trauma, although a few reports have described attempts to render the ear less susceptible to the hazards of chronic noise exposure. Much of the published information is of questionable value because of inadequate experimental design and control. To date, the search for effective medicinal treatment for hearing loss caused by noise has been unsuccessful. Results reported from studies of the effects of carbogen are encouraging and suggest that continued rigorous investigation of this agent is warranted.

Evaluation of industrial hearing conservation programs: a review and analysis.

In 1981, a large scale reviews of the literature concerning the effects of noise on hearing was initiated by the National Institute of Neurological and Communicative Diseases and Stroke. This review concentrated on the information published in the decade of the 1970's and underscored the importance of evaluating the effectiveness of industrial hearing conservation programs. Published information on this topic was scanty prior to 1970. Investigations of the application and utility of methods for this evaluation have only recently begun to appear in the literature. The status of evaluating hearing conservation programs is the subject of the present review. Three evaluation methods are considered in detail: use of various proposed criteria for significant threshold shift; methods used by Pell at DuPont; and more recent methods developed by Royster. The condition and availability of data do not permit selection of the optimum evaluation procedure. Systematic collection and analysis of data from industrial programs are necessary if acceptable standardized procedures for evaluation of hearing conservation programs are to be developed.

Auditory brain stem response and audiologic tests in idiopathic facial nerve paralysis.

Idiopathic facial nerve paralysis is believed by some to represent one aspect of a polyneuropathy. Conventional audiologic tests have not demonstrated involvement of the auditory portion of the eighth cranial nerve in this disorder. A case history is given of a patient with this disorder and an associated abnormal auditory brain stem response (ABR). Our study involved onetime evaluations of 17 patients with idiopathic facial nerve paralysis of varying durations. Each examination included clinical presentation and history, an audiogram, acoustic reflex, and ABR. Another patient had abnormal acoustic reflex test results ("unibox" pattern) suggestive of a brain stem lesion. On reexamination concurrent recovery of the paralysis and acoustic reflex was demonstrated. No auditory system disturbances secondary to the paralysis were detectable by ABR in this survey. The concurrent recovery of the "unibox" acoustic reflex and the facial paralysis suggests the association of a brain stem lesion with idiopathic facial nerve paralysis in this case.

Effects of prolonged noise exposure in chinchillas with severed middle ear muscles.

Using the round window-recorded cochlear microphonic as the index of acoustic reflex activity, we noted a decay in the strength of middle ear muscle contraction in the chinchilla following an eight hour exposure to octave band noise (500 Hz. center frequency, 95 dB. sound pressure level). On the basis of this observation it was concluded that the prolonged exposure reduced the effectiveness of the acoustic reflex in protecting the cochlea. This reduction, however, may have been underestimated if the exposure was also sufficient to reduce cochlear output. The present investigation examined this possibility by comparing the effects of a similar exposure in chinchillas with intact (normal) and severed middle ear muscles. Following exposure, the cochlear microphonic magnitude increased slightly in the normal group. Decreases in the cochlear microphonic were observed in the animals with severed muscles even when the overall exposure level was reduced to simulate the effects of middle ear muscle contraction. These findings indicate that although the muscles did afford some degree of protection to the cochlea during the exposure, the protective effects of the acoustic reflex may have been reduced even beyond our original observations.

The effects of frequency modulation on middle ear reflex.

The effect of frequency modulation on acoustic middle ear muscle reflex persistence was studied. Changes in impedance at the tympanic membrane were used as an indirect indication of reflex activity. Signals were a 2-kHz pure tone, a narrow band of noise centered at 2-kHz, and FM signals centered at 2-kHz modulated 70, 140, and 280 times per second.

Acoustic reflex decay in chinchillas during a long-term exposure to noise.

Reflex decay to 0.5 kHz octave-band noise at 95 dB SPL was measured in chinchillas during four 2-hr exposure periods separated by 11-min quiet intervals. Round window electrodes were implanted in six animals. Measures of acoustic reflex decay were inferred from amplitude changes in the cochlear microphonic generated by the octave-band noise. Reflex decay followed essentially the same time course during each exposure period. Vigorous muscular contraction to the signal onset was followed by gradual decay that asymptoted between 30 and 50% of its initial value. The process of decay seemed to be complete sometime between 8 and 30 min. The results suggest that the middle ear muscles in chinchillas provide some protective function during exposures of fairly long duration.

Reflex threshold shift in chinchillas following a prolonged exposure to noise.

The acoustic reflex is considered to reduce transmission across the middle ear and thereby protect the inner ear from intense sounds. The dynamic properties of this reflex seem to be a function of the duration of the eliciting stimulus. Assessment of the protective action afforded by middle-ear muscle contractions for long-term noise exposures requires the knowledge of how these dynamic properties change under such conditions. Round window electrodes were implanted in eight chinchillas. Changes in the threshold of the acoustic reflex were measured during an eight-hour exposure at 95 dB SPL to an octave-band noise centered at 0.5 kHz. The criterion measure of the acoustic reflex was a change in the amplitude of the cochlear microphonic generated by a 0.5 kHz eliciting tone. Thresholds of the acoustic reflex increased systematically throughout the noise exposure up to approximately 14 dB after 8 hours. The time course of the changes in the threshold of the acoustic reflex was nearly identical to the time course of behaviorally measured changes in the auditory sensitivity as reported by Carder and Miller (1972).

Temporary threshold shift following 24-hour noise exposure.

Nine men were exposed to 24 hours of continuous noise in a sound field. The noise was an octave band centered at 4 kHz at levels 80 and 85 dB. Hearing thresholds were measured monaurally at 11 test frequencies ranging from 250 to 10000 Hz before, during, and after exposure. Temporary threshold shift (TTS) reached maximum levels at 8 to 12 hours of exposure. Maximum TTS occurred at 4 and 6 kHz. Mean asymptomtic threshold shifts (ATS) resulting from the 80 dB exposure level were 9.3 dB for 4 kHz and 7.2 dB for 6 kHz. For the 85 dB noise level, these threshold shifts were 17.8 dB and 14.6 dB respectively. The increase in ATS with increase of noise level for these two frequencies could be fitted with a straight line having a slope of 1.6.

Asymptotic threshold shift in people with sensorineural hearing loss.

Twelve men with mild to moderate sensorineural hearing loss in the frequency range of 3 to 6 kHz were exposed to 24 hours of continuous noise. The noise was an octave band centered at 4 kHz at a level of 85 dB. Hearing thresholds were measured monaurally at 11 test frequencies ranging from 250 to 10,000 Hz prior to exposure and at selected intervals during and after exposure. Temporary threshold shift (TTS) development followed a similar time course to that observed in normal hearing subjects, asymptotic levels being reached between 8 and 12 hours of noise exposure. Maximum TTS occurred at 4 and 6 kHz. The amount of TTS was less for the subjects with sensorineural hearing loss than for people with normal hearing. However, the sound pressure level required to detect pure tone (shifted thresholds) following noise exposure was greater in the group with hearing loss than was measured in the normal hearing subjects. Within the limits of this experiment, a sensorineural hearing loss does seem to exert a significant effect on change in hearing sensitivity resulting from noise exposure.