OBJECTIVES: To study the case characteristics of forensic medical identification of traumatic tympanic membrane perforations, and to discuss the key points of forensic medical identification and evaluations methods for tympanic membrane perforations. METHODS: Twenty-four cases of traumatic tympanic membrane perforations accepted by the Academy of Forensic Science during 2017 were retrospectively analysed. The data of perforation size, form, predilection site, healing time and healing mode were evaluated. RESULTS: For the traumatic tympanic membrane perforations, the study showed that the small size of perforation （<1/2 quadrant） with irregular shape was common. The location of perforations was almost on the anterior and inferior quadrant, and centripetal migration healing was common. The healing rate within 6 weeks was up to 90%. CONCLUSIONS In the identification cases of traumatic tympanic membrane perforations, the key is to determine whether it is traumatic and whether it will heal spontaneously within 6 weeks. It is suggested to check the tympanic membrane weekly by an otic endoscope combined with acoustic impedance measurement at the sixth week, which can improve the accuracy, objectivity and scientificity of the identification.
Humans ; Retrospective Studies ; Tympanic Membrane/injuries* ; Tympanic Membrane Perforation/physiopathology* ; Wound Healing/physiology*

OBJECTIVETo explore the protective effects of earplug and barrel on auditory organs of guinea pigs exposed to experimental blast underpressure (BUP).

METHODSThe hearing thresholds of the guinea pigs were assessed with auditory brainstem responses (ABR). The traumatic levels of tympanic membrane and ossicular chain were observed under stereo-microscope. The rate of outer hair cells (OHCs) loss was analyzed using a light microscope. The changes of guinea pigs protected with barrel and earplug were compared with those of the control group without any protection.

RESULTSAn important ABR threshold shift of the guinea pigs without any protection was detected from 8h to 14d after being exposed to BUP with a peak ranging from -64.5 kPa to -69.3 kPa ( P<0.01). The rate of perforation of tympanic membrane reached 87.5% and that of total OHCs loss was 19.46% +/- 5.38% at 14d after exposure. The guinea pigs protected with barrel and earplug had lower ABR threshold and total OHCs loss rate compared with the animals without any protection (P<0.01). All of the tympanic membrane and ossicular chain of the protected animals maintained their integrities. Meanwhile, the guinea pigs protected with the barrel had lower ABR threshold and total OHCs loss rate than those with earplug (P<0.01).

CONCLUSIONSThe earplug and barrel have protective effects against BUP-induced trauma on auditory organs of the guinea pigs and the protective effects of barrel are better than those of earplug.

Animals ; Auditory Threshold ; Blast Injuries ; prevention & control ; Ear Protective Devices ; Guinea Pigs ; Hair Cells, Auditory, Outer ; metabolism ; Pressure ; Tympanic Membrane ; injuries ; Tympanic Membrane Perforation ; etiology ; physiopathology ; prevention & control

In order to study the influence of tympanic membrane lesion and ossicular erosion caused by otitis media on the hearing compensation performance of round-window stimulation, a human ear finite element model including cochlear asymmetric structure was established by computed tomography (CT) technique and reverse engineering technique. The reliability of the model was verified by comparing with the published experimental data. Based on this model, the tympanic membrane lesion and ossicular erosion caused by otitis media were simulated by changing the corresponding tissue structure. Besides, these simulated diseases' effects on the round-window stimulation were studied by comparing the corresponding basilar-membrane's displacement at the frequency-dependent characteristic position. The results show that the thickening and the hardening of the tympanic membrane mainly deteriorated the hearing compensation performance of round-window stimulation in the low frequency; tympanic membrane perforation and the minor erosion of ossicle with ossicular chain connected slightly effected the hearing compensation performance of round-window stimulation. Whereas, different from the influence of the aforementioned lesions, the ossicular erosion involving the ossicular chain detachment increased its influence on performance of round-window stimulation at the low frequency. Therefore, the effect of otitis media on the hearing compensation performance of round-window stimulation should be considered comprehensively when designing its actuator, especially the low-frequency deterioration caused by the thickening and the hardening of the tympanic membrane; the actuator's low-frequency output should be enhanced accordingly to ensure its postoperative hearing compensation performance.
Acoustic Stimulation ; Ear Ossicles ; pathology ; Finite Element Analysis ; Hearing ; Humans ; Otitis Media ; physiopathology ; Reproducibility of Results ; Round Window, Ear ; physiology ; Tomography, X-Ray Computed ; Tympanic Membrane Perforation

OBJECTIVE: To investigate the effects of tympanic membrane perforation on real-ear to coupler difference (RECD) in adults. METHOD: RECD was measured in 34 ears with dry tympanic membrane perforation, 34 normal subjects served as controls. RESULT: There was significant difference (P<0.05) below 1 kHz (including 1 kHz) and in 4 kHz between experimental group and control group. For perforated ears, RECD was 3.5-15 dB less from 250 Hz to 1 kHz while the values of RECD was negative from 250 Hz to 750 Hz. A larger standard deviation was found in experimental group. The mean intra-subject standard deviation was 4.4 dB in experimental group as contrasted with 1.4 dB in control group. The equivalent ear canal volume appeared to be negatively correlated with the RECD reduction below 0.75 kHz and no correlation above 1 kHz. The more the equivalent ear canal volume, the smaller the RECD. It was found that the size of tympanic membrane perforation had no effect on RECD. CONCLUSION It is recommended to perform real-ear measurement individually instead of using the age-appropriate average values, and to increase low frequency gain appropriately when fitting hearing aids for patients with dry tympanic membrane perforation.
Adolescent ; Adult ; Aged ; Case-Control Studies ; Female ; Hearing Aids ; Hearing Tests ; Humans ; Male ; Middle Aged ; Tympanic Membrane Perforation ; physiopathology ; Young Adult