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ABSTRACT: To analyze the difference of subjective hearing threshold and objective hearing threshold, and to discuss the importance of standard for hearing evaluation in forensic medicine.
Three hundred and fifty-five cases (387 ears) of forensic medical identification with hearing impairment were retrospectively analyzed including the items entrusted and hearing test results. All cases were collected from 2004 to 2012 in the forensic science center.
In the 387 ears, 218 ears (56.3%) were evaluated the degree of disability and 106 ears (27.4%) were identified the degree of damage. In the disability degree evaluation, the subjective hearing threshold and the objective hearing threshold were significant different in 120 ears (55.0%), while in damage degree evaluation, the subjective hearing threshold and the objective hearing threshold were significant different in 69 ears (65.1%).
Because of camouflaging or exaggerating the hearing impairment by the wounded, the subjective hearing threshold can't accurately assess the existence and the degree of hearing impairment. In the forensic identification, auditory brainstem response, 40 Hz auditory event related potential and auditory steady-state response should be combined in the application to evaluate the hearing impairment for the wounded in order to ensure the reliability of the evaluation of hearing impairment.
Fa yi xue za zhi 12/2012; 28(6):441-4.
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ABSTRACT: To provide supports for the application of auditory evoked potential (AEP) in the evaluation of behavioral threshold, by studying the difference and relevance between the pure tone audiometry (PTA) and three frequency-specific auditory evoked potentials, including 40 Hz auditory event related potentials (40 Hz AERP), tone burst auditory brainstem response (Tb-ABR) and auditory steady-state response (ASSR).
Three frequency-specific AEP and PTA thresholds were recorded at speech frequency (0.5, 1, 2, 4 kHz) from thirty-four adults with normal hearing (68 ears). Then, the relationship between the AEP thresholds and PTA thresholds were analyzed respectively.
There were good correlations between three frequency-specific AEP thresholds and PTA thresholds at speech frequency. However, the difference of thresholds between each frequency-specific AEP and PTA was not same. The difference of thresholds were the smallest and the relevance were the best between 40 Hz AERP and PTA at 0.5 kHz, and between ASSR and PTA at 2, 4 kHz. At 1 kHz, there were not statistical difference between ASSR, 40 Hz AERP and PTA, while the relevance of 40 Hz AERP was better than ASSR.
Different methods should be chosen to assess the objective behavioral thresholds at different frequency.
Fa yi xue za zhi 04/2012; 28(2):100-3.
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ABSTRACT: To develop an objective criteria with computerized dynamic posturography (CDP) for identification of non-organic or malingering symptoms of balance disorders.
One hundred and four normal subjects were instructed to feign balance disturbance after naturally performing on CDP. Paired t-test was used to determine if there was significant difference of CDP equilibrium scores between normal and malingering performance. The CDP records including raw curve of 50 subjects were critically evaluated by previously published seven criteria in indicating malingering performance. If the sensitivity of a criterion was greater than 90%, it would be accepted as our laboratory's identifying criterion. The CDP records of remaining 54 subjects were used to test the sensitivity and specificity of the accepted criteria.
There were statistically significant differences of CDP equilibrium scores between normal and malingering performance (P < 0.01). The mean equilibrium scores of malingering performance were lower than that of normal performance. The sensitivity and specificity of our criteria for identifying malingerers were 92.5% and 98.2%, respectively.
It is necessary to identify malingering performance before analyzing the CDP equilibrium scores. Our identifying criteria of malingerers seems to be quite useful and accurate.
Fa yi xue za zhi 12/2011; 27(6):413-6, 420.
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ABSTRACT: Auditory evoked potential (AEP) is the electric activities originating from auditory systems evoked by sound stimulus. AEP include cortical electric response audiometry (CERA), auditory brainstem evoked response (ABR), 40 Hz auditory event related potentials (40 Hz AERP), auditory steady-state response (ASSR), etc. For the subjects who cannot provide reliable or accurate behavioral hearing threshold, those techniques have been explored to evaluate the behavioral hearing threshold objectively. These techniques are reviewed in this article and are found that they could reflect the behavioral hearing threshold very well. CERA is difficult to operate because it is affected by the subject's wakefulness. ABR is the most widely used method currently and is not affected by the subject's consciousness, but it only reflects high frequencies. 40 Hz AERP has good sensitivity, while its results highly depend on the subject's consciousness. ASSR can be operated by using multiple frequency stimuli simultaneously to both ears and the test time is short. It is still a very difficult task to combine different techniques according to their characteristics in forensic audiology.
Fa yi xue za zhi 06/2011; 27(3):211-5.
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ABSTRACT: To study the value of slow vertex response (SVR) in the evaluation of hearing loss by comparing the hearing thresholds acquired with SVR and pure tone audiometry (PTA).
Twenty-five subjects (40 ears) with sensorineural hearing loss were tested by PTA and SVR. According to the thresholds of PTA, these ears were subdivided into mild, moderate and severe hearing loss groups, and rank sum test was performed on the thresholds of SVR and PTA for all the hearing loss groups. Then, the correlation between PTA thresholds and SVR thresholds was analyzed and the mathematical models were established for predicting behavioral thresholds by the thresholds of SVR.
At four test frequencies (0.5, 1, 2 and 4kHz), the thresholds of SVR had high correlations with thresholds of PTA. Four liner regression equations were established, and the correlation coefficient(r) were 0.971, 0.976, 0.957 and 0.928, respectively (P < 0.05). Back substitution test showed that the liner regression equations would be an easy method for estimating the behavior thresholds.
The behavioral threshold can be well judged and evaluated by the liner regression equations established with SVR thresholds.
Fa yi xue za zhi 06/2011; 27(3):182-5.
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ABSTRACT: To explore characteristics and causes of equilibrium function deficits after traumatic brain injury(TBI).
Ninety-five patients after TBI in traffic accidents were tested using computerized dynamic posturography (CDP). The CDP findings of patients were compared with normal value. The patients were grouped based on TBI and audition disorders degrees. The results were compared within the patients groups.
The equilibrium scores of the TBI group were significantly lower than the normal value. The utilization rate decreased for vision and vestibular sensation information in the TBI group, especially for vestibular sensation. The primary TBI degree and audition decrease had no significant affect on posture stability.
The poor posture stability was observed in TBI patients without limbs disturbance. The response and adaptation abilities decrease in these patients. This could be explained by the damage to peripheral vestibular and central balance structures.
Fa yi xue za zhi 12/2010; 26(6):428-31.
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ABSTRACT: Slow vertex response (SVR) is one of long latency auditory evoked potentials. It is a biological and electric response originating from brain cortical neuron evoked by sound stimulus with the latency from 50 to 500 milliseconds. Of all the neuroelectric physiological audiometries, it is the earliest method applied in assessing the function of the auditory neural conduction pathway. The concept, neural generators of SVR have been introduced in this article. Influencing factors on SVR were discussed such as stimulus parameters, consciousness state, age, maturation of the subject. Applications of SVR in clinical and forensic medicine identification were also discussed.
Fa yi xue za zhi 04/2010; 26(2):128-31.
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ABSTRACT: To investigate the value of slow vertex response (SVR) for forensic appraisement of hearing dysfunction by comparing the thresholds acquired with SVR and pure tone audiometry (PTA).
Forty-six subjects with normal hearing were tested with PTA (0.125-8 kHz) and SVR (0.5-4 kHz). Paired t-test analysis was performed on the thresholds of SVR and PTA at each frequency (0.5, 1, 2 and 4 kHz), and analysis of variance was performed on the difference between the pure tone audiometry threshold and the evoked potential threshold among different frequency.
At each frequency(0.5, 1, 2 kHz and 4 kHz), difference between the thresholds acquired with SVR and PTA was statistically significant(P < 0.05). The mean difference of the two thresholds were (5.98 +/- 6.72) dB HL at 0.5 kHz, (3.86 +/- 6.12) dB HL at 1 kHz, (7.12 +/- 6.56) dB HL at 2 kHz, (8.53 +/- 7.90) dB HL at 4kHz, and the mean difference at 1 kHz was the smallest. This variation between frequencies was also statistically significant.
The thresholds acquired with SVR were higher than those acquired with PTA. The adjusted thresholds should be established at each frequency, when the SVR thresholds are used to evaluate the behavioural hearing thresholds.
Fa yi xue za zhi 02/2010; 26(1):18-21.
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ABSTRACT: To explore the correlativity between the thresholds acquired with auditory steady-state responses (ASSR) and pure tone audiometry (PTA).
Eighty-six subjects with normal and abnormal hearing (172 ears) were tested with ASSR and PTA at 500, 1000, 2000, 4000 Hz to get the thresholds of ASSR (single frequency) and PTA. Correlation analysis were done between the thresholds acquired with ASSR and PTA at different frequency (500, 1000, 2000, 4000 Hz) for each different hearing loss degree (< or = 20, 21-39, 40-59, 60-79, > or = 80 dB).
At each frequency, there was a close correlativity between the thresholds acquired with ASSR and PTA. The rectified threshold of ASSR and PTA at different frequency and hearing loss degree had been obtained.
The rectified ASSR threshold could be applied as an objective method for evaluating hearing loss to distinguish malingering deafness in the practice of forensic medicine.
Fa yi xue za zhi 10/2008; 24(5):321-4.
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ABSTRACT: To provide new objective technology in evaluating hearing loss for forensic expert by comparing the thresholds acquired with auditory steady-state responses (ASSR) and pure tone audiometry (PTA) in our laboratory.
Twenty-seven subjects with normal hearing (54 ears, 18-28 years) were tested with PTA and ASSR at 500, 1000, 2000 and 4000 Hz. Paired t-test analysis was performed on threshold of ASSR and PTA at difference frequency (500, 1000, 2000 and 4000 Hz).
At each frequency (500, 1000, 2000 and 4000 Hz), the thresholds acquired with ASSR were higher than those acquired with PTA (P<0.05). The mean difference of each frequency were (22.04+/-5.79) dB (500 Hz), (11.02+/-5.44) dB (1000 Hz), (12.59+/-5.89) dB (2000 Hz) and (17.78+/-7.25) dB (4000 Hz). The mean difference between the system automatically adjusted threshold of ASSR and PTA were (-3.96+/-5.79) dB at 500 Hz, (0.02+/-5.44) dB at 1000 Hz, (-0.41+/-5.89) dB at 2000 Hz, and(-1.25+/-7.25) dB at 4000 Hz.
At each frequency (500, 1000, 2000 and 4000 Hz), the thresholds acquired with ASSR were higher than those acquired with PTA. The mean difference is 16.9 dB. As an objective and mature method, ASSR could be used in evaluation of hearing-loss degree for forensic expert. But adjusted threshold value should be established when ASSR is used to estimate hearing threshold in each laboratory.
Fa yi xue za zhi 09/2008; 24(4):248-51.
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ABSTRACT: Accurate determination of the wound depth has long been a difficult task in forensic medicine due to lack of technology. Nowadays, the depth of the wound can be accurately determined by using high frequency 2-D ultrasound and Color Doppler Flow Imaging (CDFI). Two typical cases with ultrasonic images were reported to show the importance of ultrasound technology in forensic medicine. The new technology provides scientific evidence of the injury assessment.
Fa yi xue za zhi 07/2008; 24(3):197-9.
