Blog Archives

Activity Patterns in Latissimus Dorsi and Sternocleidomastoid in Classical Singers

Conclusions
LD appears to play a significant role in maintaining chest expansion and the dynamic processes underlying vibrato and coloratura singing in classically trained singers.

from the Journal of Voice

Unstable distortion-product otoacoustic emission phase in Menière’s disease

The presence of endolymphatic hydrops as a marker of Menière’s disease (MD) suggests abnormal pressure in the intralabyrinthine compartments of patients and excessive stiffness of sound-sensitive structures. Otoacoustic emissions (OAEs) have been reported to respond to changes in the ear’s stiffness, including those produced by intracranial pressure steps, by a characteristic phase shift around 1 kHz, thereby suggesting a noninvasive means of monitoring MD. Here, body tilt was used for modulating intracranial pressure in forty-one patients with definite MD who were tentatively measured at two stages, with and without active symptoms. Their distortion-product OAEs (DPOAEs) were dynamically monitored around 1 kHz every few seconds in response to body tilt. In a control sample of thirty normal ears, the maximum phase rotation of DPOAEs produced by body tilt was between –18° and +37°. In MD ears with the complete set of symptoms, the posture-induced phase shifts in 32 out of 35 tests fell outside the normative interval, and in 10 tests, although DPOAEs were well above noise floor, their phase was always so abnormally erratic that body tilt produced hardly any additional effect. When MD ears were asymptomatic, nine out of 32 posture tests were abnormal. The excessive DPOAE phase shift is consistent with either a too stiff cochlear partition or a displacement of the operating point of outer hair cells by endolymphatic hydrops.

from Hearing Research

Relationships Between Vocal Structures, the Airway, and Craniocervical Posture Investigated Using Magnetic Resonance Imaging

Conclusion
Finding widespread correlations relating vocal structures to the craniofacial skeleton and cervical spine confirms the potential of this approach to uncover functional activity during voice production and demonstrates the importance of considering vocal structures and the airway within this wider context if important information is not to be missed.

from the Journal of Voice

Vocal and cervicoscapular evaluation in military wind instrumentalists

CONCLUSION: The military wind instrumentalists presented vocal and cervicoscapular alterations, and require actions to promote vocal and postural health.

from Revista de Sociedade Brasileira de Fonoaudiologia

Effects of unilateral dysfunction of the inferior vestibular nerve system on postural stability

Foam posturography is useful for making a preliminary assessment of unilateral vestibulopathy with abnormal cVEMPs. Selective damage of the unilateral IVN system could affect postural stability.

from Clinical Neurophysiology

Integration of nonlabyrinthine inputs by the vestibular system: Role in compensation following bilateral damage to the inner ear

Inputs from the skin and muscles of the limbs and trunk as well as the viscera are relayed to the medial, inferior, and lateral vestibular nuclei. Vestibular nucleus neurons very quickly regain spontaneous activity following a bilateral vestibular neurectomy, presumably due to the presence of such nonlabyrinthine inputs. The firing of a small fraction of vestibular nucleus neurons in animals lacking labyrinthine inputs can be modulated by whole-body tilts; these responses are eliminated by a spinal transection, showing that they are predominantly elicited by inputs from the trunk and limbs. The ability to adjust blood distribution in the body and maintain stable blood pressure during movement is diminished following a bilateral vestibular neurectomy, but compensation occurs within a week. However, bilateral lesions of the caudal portions of the vestibular nuclei produce severe and long-lasting cardiovascular disturbances during postural alterations, suggesting that the presence of nonlabyrinthine signals to the vestibular nuclei is essential for compensation of posturally-related autonomic responses to occur. Despite these observations, the functional significance of nonlabyrinthine inputs to the central vestibular system remains unclear, either in modulating the processing of vestibular inputs or compensating for their loss.

from the Journal of Vestibular Research

Increased vestibular contribution to posture control in individuals with chronic headache

Conclusions: People with chronic headache exhibit increased postural sway, which may reflect the re-weighting of sensory information with an increased vestibular and a reduced visual contribution to postural control.

Significance: These results support existing research on vestibular abnormalities in chronic headache sufferers that may provide a basis for future treatment therapies.

from Vestibular Research

A contemporary review of balance dysfunction following vestibular schwannoma surgery

Conclusions:
Further study is needed of the factors that influence vestibular compensation following vestibular schwannoma surgery. This will help to counsel patients prior to surgery and develop strategies for rehabilitation. Laryngoscope, 2009

from The Laryngoscope

Usefulness of some current balance tests for identifying individuals with disequilibrium due to vestibular impairments

The goal of this study was to determine which of several clinical balance tests best identifies patients with vestibular disorders. We compared the scores of normals and patients on the Berg Balance Scale (Berg), Dynamic Gait Index (DGI), Timed Up and Go (TUG), Computerized Dynamic Posturography Sensory Organization Test (SOT), and a new obstacle avoidance test: the Functional Mobility Test (FMT). The study was performed in an out-patient balance laboratory at a tertiary care center. Subjects were 40 normal adults, and 40 adults with vestibular impairments. The main outcome measures were the sensitivity of tests to patients and specificity to normals. When adjusted for age the Berg, TUG, DGI and FMT had moderate sensitivity and specificity. SOT had moderately high sensitivity and specificity. SOT and FMT, combined, had high sensitivity and moderate specificity. Therefore, the kinds of tests of standing and walking balance that clinicians may use to screen patients for falling are not as good for screening for vestibular disorders as SOT. SOT combined with FMT is better. When screening patients for vestibular disorders, when objective diagnostic tests of the vestibular system, itself, are unavailable, tests of both standing and walking balance, together, give the most information about community-dwelling patients. These tests may also indicate the presence of sub-clinical balance problems in community-dwelling, asymptomatic adults.

from the Journal of Vestibular Research

Non-invasive measurements of intralabyrinthine pressure changes by electrocochleography and otoacoustic emissions

Abstract
By varying the mechanical load on the stapes footplate, intralabyrinthine pressure (ILP) influences the stiffness of the middle ear and modifies its transfer function. This results in a characteristic phase shift of the otoacoustic emissions (OAEs) around 1 kHz [Buki, B., Avan, P., Lemaire, J.J., Dordain, M., Chazal, J., Ribari, O., 1996. Otoacoustic emissions: a new tool for monitoring intracranial pressure changes through stapes displacements. Hear. Res. 94, 125–139]. This finding provides non-invasive means of monitoring changes of ILP and indirectly of intracranial pressure. Yet the vulnerability of OAEs to sensorineural hearing loss excludes many patients from being monitored in this manner. Being dependent on the middle-ear transfer function, the phase of the cochlear microphonic potential (CM) around 1 kHz should also respond to ILP changes while being less affected by impaired hearing than OAEs. Here, normal volunteers were subjected to body tilt resulting in stepwise changes in their intracranial pressure and ILP. Their CM around 1 kHz was recorded by extratympanic electrocochleography and its dependence on body position was compared to that of distortion-product OAEs. The posture-induced CM changes were also monitored in ears with sensorineural deafness and impaired OAEs to assess the usefulness of CM in the presence of hearing impairment. Last, OAEs and CM were simultaneously monitored in gerbils during intracranial pressure changes brought about via an intracranial catheter. The phase and level shifts induced by body tilt in man and intracranial pressure changes in gerbils showed up both in distortion-product OAEs and CM with similar time courses. In normally-hearing subjects, the mean phase shifts reached 16.3° for CM and 41.6° for OAEs, and CM remained large enough in hearing-impaired subjects for ILP to be monitored. The ratio of about two of OAEs to CM phase shifts matched the prediction of middle-ear models allowing for the fact that CM does not travel back through the middle ear while OAEs do. It follows that CM phase around 1 kHz provides non-invasive access to ILP changes even if OAEs cannot be measured due to sensorineural hearing loss.

from Hearing Research

Non-invasive Measurements of Intralabyrinthine Pressure Changes by Electrocochleography and Otoacoustic Emissions

By varying the mechanical load on the stapes footplate, intralabyrinthine pressure (ILP) influences the stiffness of the middle ear and modifies its transfer function. This results in a characteristic phase-shift of the otoacoustic emissions (OAEs) around 1 kHz (Büki et al. 1996). This finding provides non-invasive means of monitoring changes of ILP and indirectly of intracranial pressure. Yet the vulnerability of OAEs to sensorineural hearing loss excludes many patients from being monitored in this manner. Being dependent on the middle-ear transfer function, the phase of the cochlear microphonic potential (CM) around 1 kHz should also respond to ILP changes while being less affected by impaired hearing than OAEs. Here, normal volunteers were subjected to body tilt resulting in stepwise changes in their intracranial pressure and ILP. Their CM around 1 kHz was recorded by extratympanic electrocochleography and its dependence on body position was compared to that of distortion-product OAEs. The posture-induced CM changes were also monitored in ears with sensorineural deafness and impaired OAEs to assess the usefulness of CM in the presence of hearing impairment. Last, OAEs and CM were simultaneously monitored in gerbils during intracranial pressure changes brought about via an intracranial catheter. The phase and level shifts induced by body tilt in man and intracranial pressure changes in gerbils showed up both in distortion-product OAEs and CM with similar time courses. In normally hearing subjects, the mean phase shifts reached 16.3° for CM and 41.6° for OAEs, and CM remained large enough in hearing impaired subjects for ILP to be monitored. The ratio of about 2 of OAEs to CM phase shifts matched the prediction of middle-ear models allowing for the fact that CM does not travel back through the middle ear while OAEs do. It follows that CM phase around 1 kHz provides non-invasive access to ILP changes even if OAEs cannot be measured due to sensorineural hearing loss.

from Hearing Research