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Shy-Drager Syndrome and Multiple System Atrophy
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
Although the EEG is not particularly valuable in evaluating patients with MSA, brainstem auditory evoked potentials may help to differentiate the disorder from PAF and Parkinson’s disease. There is abnormal latency and amplitude (ratio of wave V/I) in most patients with MSA; this was not present in any PAF patients and occurred in only one patient with Parkinson’s disease (Prasher and Bannister, 1986). The auditory pathway disruption was felt likely to occur in the superior olivary complex. In another study (Uematsu, Hamada and Gotoh, 1987), prolonged interpeak (I—III) latency correlated with the degree of pontine atrophy determined by computerized tomography (CT).
Anatomy
Published in Stanley A. Gelfand, Hearing, 2017
The superior olivary complex constitutes the next way station in the auditory pathway, and is distinguished as the first (lowest) level that receives information originating from both sides of the head (bilateral representation). The SOC is made up of the medial superior olive (MSO), the lateral superior olive (LSO), and the medial nucleus of the trapezoid body (MNTB), as well as rather diffuse accumulations of cell bodies known as the periolivary nuclei (Moore, 1987, 2000; Schwartz, 1992; Helfert and Aschoff, 1997; Kulesza, 2007). Each MSO receives bilateral inputs from the right and left AVCNs, and then projects to the ipsilateral inferior colliculus via the lateral lemniscus on its own side. The LSO also receives inputs directly from the AVCN on the same side as well as from the opposite AVCN via the ipsilateral MNTB. In turn, the LSO projects bilaterally to the inferior colliculi via the lateral lemnisci on both sides. As just implied, the MNTB receives its input from the opposite AVCN and then projects to the LSO on its own side. Although generally similar to the SOCs of lower mammals in many ways, the human SOC has a relatively smaller LSO, which has a nub that gives it an almost Y-like configuration instead of the other (often S) shapes found in many lower animals (Kulesza, 2007). The human SOC also has more prominent periolivary cell groups and the trapezoid body does not appear to be quite as well organized into an identifiable nucleus (Moore, 2000).
Discussions (D)
Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
Most authors of recent texts in basic neuroanatomy who describe several nuclei within the superior olivary complex include either lateral and medial superior olivary nuclei (e.g., C&S, p. 368; K&S, p. 406–407) or else principal (or main, or chief) and accessory superior olivary nuclei (e.g., A&B, p. 147–148; MarMar, p. 183; M&F, p. 58). Usually, the principal nucleus is described as lateral to the accessory nucleus (e.g., A&B, p. 147 [Fig. 6–7]), and occasionally the medial nucleus is also listed as being the accessory nucleus (e.g., W&W, p. 909; N&D, p. 352). Thus, the principal nucleus and the lateral nucleus seem to be identical, as do the accessory nucleus and the medial nucleus. Crosby, Humphrey, and Lauer, however, clearly disagree: “It [the “superior olivary nucleus’] is often represented by two cell groups, a more medial chief and a more lateral accessory olive. …… In the cat, where the superior olivary complex is divided into medial and lateral portions (instead of chief and accessory olivary nuclei),. …” (1962, p. 161)
Diffusion tensor imaging and auditory tractography to evaluate cochlear implant candidacy: a pilot study
Published in Acta Oto-Laryngologica, 2023
Badr E. Mostafa, Yasser Abdel Azim, Lobna Elfiky
R.A. 9 years old girl with fluctuating hearing loss. Radiology revealed bilateral IP 2 inner ear anomaly. Tractography was performed to select the most suitable side to implant. Cochlear nerves [CN], cochlear nuclei, SOC (superior olivary complex), LL (lateral lemniscus), IC (inferior colliculus), MGB (medial geniculate body), and thalamic nuclei were all normal bilaterally. Heschel gyrus on the right side showed focal cortical dysplasia with pachygyria and polymicrogyria. Because of her residual hearing, functional MRI was performed and revealed robust activation of Heschel gyrus and area 41 on the left side and significantly reduced activation on the right side. The right CN showed reduced FA and elevated ADC. The left side was implanted with a very satisfactory result (Figure 1).
Assessment of auditory processing in children with non-syndromic cleft lip and/or palate
Published in Hearing, Balance and Communication, 2022
Melika Zarei, Zahra Hosseini Dastgerdi, Alireza Momeni, Nayyereh Sadat Nouri
The significantly higher dichotic digit score of the right ear in NSCLP children compared to control group was a noteworthy finding is this study. The right ear seems to be stronger in the NSCLP children than control group. Mechanism of transmitting auditory information in auditory dichotic system helps to understand REA. Auditory message is transmitted from each ear to the hemispheres via ipsilateral and contralateral pathways. The ipsilateral pathway of one ear and the contralateral of the opposite ear simultaneously overlap in the ascending pathways of the central auditory system. Ipsilateral signals are suppressed by contralateral one given the stronger contralateral pathway in transmission of auditory message. This central competition between ears triggers from the lower levels of auditory apparatus including the superior olivary complex [20]. Higher right ear scores in the NSCLP group might be caused by dysfunction of left ear neural pathways. Therefore, ipsilateral transmission from the right ear is less suppressed by contralateral of the left ear and might have larger contribution to auditory information transmission. So, it is possible that right ear is more involved in auditory information transmission, which lead to higher score in DD test. Higher right ear scores might also be due to plasticity of its neural pathways to compensate for poor function of the left ear central pathway.
Masking level difference among brazilian military personnel: a comparison between pilots and non-pilots
Published in International Journal of Audiology, 2021
Graziela Maria Martins-Moreira, Alessandra Spada Durante
In Brazil, the hearing of military pilots is monitored by means of regular periodic audiometry (Brasil, 2003, 2013), but there is no recommendation to also evaluate how they perform in the SIN recognition task which closely reflects the pilots’ typical operational environment and requires binaural interaction. Among central auditory abilities potentially affected by noise exposure, binaural interaction, assessed by the masking level difference test (MLD), is critical to pilot performance as it can improve speech intelligibility by an amount equivalent to a 4 dB shift in signal-to-noise ratio (S/N) in the cockpit of an aircraft during flight (Tobias 1972). To achieve this improvement, the auditory system uses subtle interaural time differences caused by phase inversion of the acoustic stimulus to better detect sounds presented in noise under a binaural condition. Such subtle stimulus differences aid in sound lateralisation and speech recognition in the presence of competitive auditory information. The seat of this ability is the lower brainstem, more specifically the superior olivary complex and the inferior colliculus (Bartz et al. 2015; Clinard, Hodgson, and Scherer 2017), but also receives contributions from the cortex (Fowler 2017). In order to confirm the neural correlations for MLD, which involve the thalamus, the insula, and a neural process that crosses the corpus callosum, researchers used functional magnetic resonance imaging (Wack et al. 2012) and diffusion tensor imaging (Wack et al. 2014).