The Stenger Principle describes the observation that when two tones of the same frequency are presented simultaneously, a single tone is perceived only in the ear in which the tone is louder. This principle underlies the Stenger Test, which is used to identify the presence of unilateral nonorganic hearing loss (NOHL). Minimum contralateral interference levels (MCILs), which can be used to estimate true hearing thresholds in individuals with unilateral NOHL, are also based on this principle. In this study, the Stenger Principle is used to examine MCILs and the correspondence of the MCILs to true hearing thresholds in 16 adults with normal hearing. In Part I of the study, subjects were asked to feign a unilateral hearing loss. Average MCILs were 12.5, 15.1, and 13.5 dB HL for 1.0, 2.0, and 4.0 kHz, respectively. These were obtained with nearly equal interaural stimulus levels. The average difference between MCIL and true hearing threshold was 7.6, 9.7, and 8.9 dB, respectively. In Part II of this study, subjects were asked to make lateralization judgments for simultaneously presented tones with varying interaural intensity differences. Individual subject ratings were compared to MCILs obtained in Part I. Although most subjects showed the Stenger Effect with a midline percept of the two tones, variability between subjects existed. In some cases the Stenger Effect was not apparent until the tonal image was pulled nearly to the "poor" ear. Because of the potential differences in response bias (a client may show the Stenger Effect with a small shift in the tonal signal away from the "good" ear or may require the tonal signal to be fully lateralized to the "poor" ear), clinicians cannot predict exact hearing thresholds. Rather, it is useful to describe a range within which the true threshold will be. The 90% ranges (5th and 95th percentiles) calculated in this study were approximately 1 and 17 dB. That is, the MCILs for the majority of the subjects were within ~ 1 and 17 dB of true hearing thresholds.

No description available.

No description available.

Unilateral exercise can produce certain contralateral strength effects. Deleterious events can be cross-transferred as well, as illustrated by a strict symmetry in some chronic inflammatory diseases. To date, knowledge on the effects of marked overuse of skeletal muscles is limited, and there is largely no information if unilateral overuse affects the contralateral muscles. In view of this, the present study was undertaken to test the hypothesis that unilateral muscle overuse causes alterations in tissue structure and the tachykinin system, with a focus on substance P (SP), not only in the exercised muscles, but also in the contralateral muscles. SP is a well-known neuromodulator that is known to be proinflammatory. An experimental rabbit model with unilateral muscle overuse of the soleus and gastrocnemius muscles caused by exercise via electrical muscle stimulation (E/EMS) was used. In total, 40 rabbits were randomly divided into seven groups of which two groups served as controls. The rabbits were anaesthetized and then set on a “kicking machine” to perform exercise via EMS for 2h every second day. Experimental periods for groups 1-3 were 1, 3 and 6w, respectively, whereas groups 4-6 were exercised for 1w but also subjected to injections in the peritendinous tissue with SP, NaCL, Captopril (C), an ACE inhibitor, and DL-Thiorphan (Th) which inhibits the activity of neural endopeptidase. One group was not subjected to the experiment at all. The day after the last session of E/EMS, the soleus muscle and the gastrocnemius muscle from both legs were collected for analysis. Alterations in muscle structure and the tachykinin system were analyzed with enzyme and immunohistochemical techniques, in situ hybridization and EIA methods. After 1w of E/EMS, focal areas of the exercised muscles contained a mild infiltration of inflammatory cells (myositis) and small morphological changes. After 3 and 6w of E/EMS, distinct myositis and muscle changes were bilaterally present in focal areas of both muscles. The structural changes, which mainly were observed in myositis areas, consisted of increased fiber size variability, split fibers, internal myonuclei, necrotic fibers, fibrosis, fat infiltration, and small fibers containing developmental MyHCs. Bilateral morphological changes, such as loss of axons, were also observed in nerves. In addition, expressions of tachykinin and the SP-preferred receptor, the neurokinin-1 (NK-1R), were bilaterally upregulated in nerve structures and blood vessel walls.  Infiltrating white blood cells exhibited tachykinin–like and NK-1R immunoreactivity. NK-1R immunoreactions were also found in necrotic and regenerating muscle fibers. The concentration of tachykinin (SP) was significantly increased in both soleus and gastrocnemius muscles after E/EMS. There was a significant correlation between the two sides in concentration of tachykinin and in the intensity of tachykinin-like immunoreaction in blood vessel walls. The muscle fiber size and capillary supply of fibers were bilaterally decreased after 3w of EMS. The myositis areas contained an increased number of vessels with a larger size than capillaries, while areas with increased amount of connective tissue contained a very low number of capillaries. A bilateral fiber type shift against a lower proportion of slow MyHCI fibers and higher proportion of fast MyHCII fibers was observed in both muscles. The local injections of C+Th and SP+C+Th led to marked structural changes in the muscle tissue and marked increased NK-1R and tachykinin-like immunoreactivity in the myositis areas and increased tachykinin concentration in the tissue. In conclusion, the repetitive unilateral muscle overuse caused by E/EMS led overtime to muscle injury and myositis. The affected areas contained both degenerative and regenerative alterations in the muscle tissue and nerves, and an upregulation of the tachykinin system. Most interestingly, the changes not only occurred in the exercised side, but also in the homologous contralateral muscles. The tachykinin system appears to be an important factor in the processes of crossover effects.

Rhythmic arm cycling is known to suppress the Hoffmann (H-) reflex in the soleus muscles of stationary legs; however, it is still unclear if this suppression is modulated by the phase of movement in the cycle path. In the present study we investigated phase-dependent modulation of the Sol H-reflex induced by rhythmic arm cycling. Modulation of the Soleus H-reflex was examined at 12 phases of the cycle path in 4 conditions; static arm positioning, as well as 3 arm cycling conditions, bilateral, ipsilateral and contralateral. H-reflexes were evoked and recorded at constant motor wave amplitudes across the conditions. Suppression of Sol H-reflex amplitude was dependent (main effect p<0.0001) upon the phase of movement during arm cycling, but not during static positioning. Results suggest that locomotor central pattern generators may contribute to the phasic reflex modulation observed in this study.

Introdução: A otite média crônica é definida pela presença de alterações inflamatórias teciduais irreversíveis na fenda auditiva. A teoria do continuum a respeito da sua patogênese sugere que as fases mais precoces da otite média, aguda, serosa ou secretora podem progredir para cronificação. Desta forma, pode-se supor que a grande prevalência de bilateralidade da otite média secretora também pode ser observada na otite crônica. Objetivo: determinar a prevalência de alterações na orelha contralateral em ossos temporais humanos de portadores de otite média crônica. Metodologia: Os ossos temporais humanos foram analisados sob microscopia óptica. Definiu-se como orelha contralateral a orelha normal ou menos comprometida. As alterações histopatológicas foram classificadas por ordem crescente de gravidade. Para comparação entre as variáveis qualitativas, utilizou-se o teste de Chi-quadrado, nas correlações o coeficiente de Spearman, sendo estatisticamente significativos P≤0,05. Resultados: Foram estudados 85 pares de ossos temporais, 22,4% com colesteatoma no lado mais comprometido. A prevalência de orelhas contra laterais com alterações foi de 91,8%, sendo as principais tecido de granulação (81%), efusão (58%) e retração da membrana timpânica (35%). Não houve diferença na prevalência de alterações significativas na orelha contralateral entre os gêneros, crianças e adultos, imunossuprimidos ou não e com ou sem colesteatoma na pior orelha. Houve correlação da extensão do tecido de granulação (rS=0,345, P=0,004) e do colesteatoma (rS=0,617, P<0,0001) entre as orelhas. Conclusão: Podemos observar alta prevalência de alterações orelha contralateral. A correlação entre a extensão tanto do tecido de granulação quanto do colesteatoma entre os dois lados, sugere, corroborando a hipótese do continnuum, que as alterações constitucionais do indivíduo podem estar implicadas na cascada de eventos que leva à cronificação e que isto pode ocorrer bilateralmente. / Objective: To determine the prevalence of contra lateral middle ear cleft pathologic findings in human temporal bones with chronic otitis media. Study design: Transversal Material and Methods: The humam temporal bones was analised under optical microscopy. Chronic otites media was definied by the presence of irreversible inflammatory alterations in the middle ear cleft. The contralateral ear was defined as the normal or the less alterated one. The histopathologic alterations were described and classified in a crescent severity order. To compare the quantitative variables it was used the Chi square test and for correlations it was used Sperman coefficient (P≤0.05) Results: It has been studied 85 pairs of temporal bones. 22.4% had cholesteatoma in the most damaged ear. The prevalence of contra lateral ears with alterations was 91.8%. The main alterations were granulation tissue (81%), effusion (58%) and tympanic membrane retractions (35%). There was not difference between the genders, adults and children, imunossupressed or not, with or without cholesteatoma. There was a direct correlation between the both ears in relation to granulation tissue (rS=0.345, P=0.004) or cholesteatoma extension (rs=0.617, P<0.001). Conclusion: We can observe a high prevalence of contralateral ears alterations and the granulation tissue was the most frequent. The correlation between the ears about the granulation tissue and cholesteatoma extension suggest, in agreement with the continuum, that the individual constitutional alterations are involved in the sequential events that go to cronification.

Introdução: A otite média crônica é definida pela presença de alterações inflamatórias teciduais irreversíveis na fenda auditiva. A teoria do continuum a respeito da sua patogênese sugere que as fases mais precoces da otite média, aguda, serosa ou secretora podem progredir para cronificação. Desta forma, pode-se supor que a grande prevalência de bilateralidade da otite média secretora também pode ser observada na otite crônica. Objetivo: determinar a prevalência de alterações na orelha contralateral em ossos temporais humanos de portadores de otite média crônica. Metodologia: Os ossos temporais humanos foram analisados sob microscopia óptica. Definiu-se como orelha contralateral a orelha normal ou menos comprometida. As alterações histopatológicas foram classificadas por ordem crescente de gravidade. Para comparação entre as variáveis qualitativas, utilizou-se o teste de Chi-quadrado, nas correlações o coeficiente de Spearman, sendo estatisticamente significativos P≤0,05. Resultados: Foram estudados 85 pares de ossos temporais, 22,4% com colesteatoma no lado mais comprometido. A prevalência de orelhas contra laterais com alterações foi de 91,8%, sendo as principais tecido de granulação (81%), efusão (58%) e retração da membrana timpânica (35%). Não houve diferença na prevalência de alterações significativas na orelha contralateral entre os gêneros, crianças e adultos, imunossuprimidos ou não e com ou sem colesteatoma na pior orelha. Houve correlação da extensão do tecido de granulação (rS=0,345, P=0,004) e do colesteatoma (rS=0,617, P<0,0001) entre as orelhas. Conclusão: Podemos observar alta prevalência de alterações orelha contralateral. A correlação entre a extensão tanto do tecido de granulação quanto do colesteatoma entre os dois lados, sugere, corroborando a hipótese do continnuum, que as alterações constitucionais do indivíduo podem estar implicadas na cascada de eventos que leva à cronificação e que isto pode ocorrer bilateralmente. / Objective: To determine the prevalence of contra lateral middle ear cleft pathologic findings in human temporal bones with chronic otitis media. Study design: Transversal Material and Methods: The humam temporal bones was analised under optical microscopy. Chronic otites media was definied by the presence of irreversible inflammatory alterations in the middle ear cleft. The contralateral ear was defined as the normal or the less alterated one. The histopathologic alterations were described and classified in a crescent severity order. To compare the quantitative variables it was used the Chi square test and for correlations it was used Sperman coefficient (P≤0.05) Results: It has been studied 85 pairs of temporal bones. 22.4% had cholesteatoma in the most damaged ear. The prevalence of contra lateral ears with alterations was 91.8%. The main alterations were granulation tissue (81%), effusion (58%) and tympanic membrane retractions (35%). There was not difference between the genders, adults and children, imunossupressed or not, with or without cholesteatoma. There was a direct correlation between the both ears in relation to granulation tissue (rS=0.345, P=0.004) or cholesteatoma extension (rs=0.617, P<0.001). Conclusion: We can observe a high prevalence of contralateral ears alterations and the granulation tissue was the most frequent. The correlation between the ears about the granulation tissue and cholesteatoma extension suggest, in agreement with the continuum, that the individual constitutional alterations are involved in the sequential events that go to cronification.

Introdução: A otite média crônica é definida pela presença de alterações inflamatórias teciduais irreversíveis na fenda auditiva. A teoria do continuum a respeito da sua patogênese sugere que as fases mais precoces da otite média, aguda, serosa ou secretora podem progredir para cronificação. Desta forma, pode-se supor que a grande prevalência de bilateralidade da otite média secretora também pode ser observada na otite crônica. Objetivo: determinar a prevalência de alterações na orelha contralateral em ossos temporais humanos de portadores de otite média crônica. Metodologia: Os ossos temporais humanos foram analisados sob microscopia óptica. Definiu-se como orelha contralateral a orelha normal ou menos comprometida. As alterações histopatológicas foram classificadas por ordem crescente de gravidade. Para comparação entre as variáveis qualitativas, utilizou-se o teste de Chi-quadrado, nas correlações o coeficiente de Spearman, sendo estatisticamente significativos P≤0,05. Resultados: Foram estudados 85 pares de ossos temporais, 22,4% com colesteatoma no lado mais comprometido. A prevalência de orelhas contra laterais com alterações foi de 91,8%, sendo as principais tecido de granulação (81%), efusão (58%) e retração da membrana timpânica (35%). Não houve diferença na prevalência de alterações significativas na orelha contralateral entre os gêneros, crianças e adultos, imunossuprimidos ou não e com ou sem colesteatoma na pior orelha. Houve correlação da extensão do tecido de granulação (rS=0,345, P=0,004) e do colesteatoma (rS=0,617, P<0,0001) entre as orelhas. Conclusão: Podemos observar alta prevalência de alterações orelha contralateral. A correlação entre a extensão tanto do tecido de granulação quanto do colesteatoma entre os dois lados, sugere, corroborando a hipótese do continnuum, que as alterações constitucionais do indivíduo podem estar implicadas na cascada de eventos que leva à cronificação e que isto pode ocorrer bilateralmente. / Objective: To determine the prevalence of contra lateral middle ear cleft pathologic findings in human temporal bones with chronic otitis media. Study design: Transversal Material and Methods: The humam temporal bones was analised under optical microscopy. Chronic otites media was definied by the presence of irreversible inflammatory alterations in the middle ear cleft. The contralateral ear was defined as the normal or the less alterated one. The histopathologic alterations were described and classified in a crescent severity order. To compare the quantitative variables it was used the Chi square test and for correlations it was used Sperman coefficient (P≤0.05) Results: It has been studied 85 pairs of temporal bones. 22.4% had cholesteatoma in the most damaged ear. The prevalence of contra lateral ears with alterations was 91.8%. The main alterations were granulation tissue (81%), effusion (58%) and tympanic membrane retractions (35%). There was not difference between the genders, adults and children, imunossupressed or not, with or without cholesteatoma. There was a direct correlation between the both ears in relation to granulation tissue (rS=0.345, P=0.004) or cholesteatoma extension (rs=0.617, P<0.001). Conclusion: We can observe a high prevalence of contralateral ears alterations and the granulation tissue was the most frequent. The correlation between the ears about the granulation tissue and cholesteatoma extension suggest, in agreement with the continuum, that the individual constitutional alterations are involved in the sequential events that go to cronification.

Although the suppressive effect of the medial olivocochlear system (MOCS) on peripheral auditory active mechanisms is well documented in humans, the effect of efferent inhibition over prolonged periods of acoustic stimulation is less well documented, especially as observed in suppression of transient evoked otoacoustic emissions (TEOAE’s). The present study therefore evaluated the relationship between the duration of contralateral acoustic stimulation and the suppression of TEOAE’s in ten adults with normal hearing. TEOAE recordings with linear clicks (60 dB sound pressure level) were measured at four intervals during 15 minutes of continuous contralateral white noise (45 dB sound pressure level), followed by two post-noise recordings. An identical within-subject control condition was recorded without contralateral noise. Experimental and control measurements were repeated three times, on separate days. Results revealed significant and sustained TEOAE amplitude reduction for the entire duration of contralateral stimulation. Suppression increased across the duration of contralateral noise, but not sufficiently to be statistically significant. After noise termination, TEOAE amplitudes increased to values significantly above control recordings. The sustained suppression of TEOAE’s indicates continuous efferent inhibition over time in normal adults, with a significant increase in TEOAE amplitude after noise cessation possibly indicating increased outer hair cell responsiveness after prolonged contralateral noise. / Dissertation (MCommunication Pathology)--University of Pretoria, 2009. / Speech-Language Pathology and Audiology / Unrestricted

Title: The Appearance of the reflex locomotion elements in the hurdle clearance stride Thesis Objective: The main objective of this thesis is to state the frequency of the presence of reciprocal inhibition (RI) and cross extensor reflex (CI - contralateral inhibition) during hurdle overrun. Methods: The subjects were tested during running over three hurdles with modified distances similar to the 110m hurdles. The height of the hurdles was set to 0,99 m. The muscle activity was monitored by surface electromyography and video was recorded simultaneously. The hurdle clearance was divided into particular phases which altogether formed one cycle. Collected data was analyzed by the software Megawin (rectification, smoothing, and synchronization with camera) and subsequently converted into software MATLAB. Nine cycles of each subject were averaged. Such modified cycle was evaluated consequently. Results: Reflex locomotion (RI and CI) was presented more often in the group with less experience with the hurdles. Co-activation of antagonist muscles was typical for the group consisting of more experienced individuals, rather than RI and CI. Key Words: hurdles, biomechanics, sEMG, reciprocal inhibition, contralateral inhibition