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Adaptation of otolith responses assessed by off-vertical axis rotation
Otolaryngology– Head and Neck Surgery Volume 131 Number 2
Adaptation of Otolith Responses Assessed by OffVertical Axis Rotation Glenn W Knox, MD (presenter); Daniel Woodard, MD Jacksonville FL; Cape Cannaveral FL
Objectives: During rotation in darkness at constant velocity about an axis tilted relative to gravity (OVAR) the otolith organs are stimulated by the change in head orientation relative to gravity. The frequency of the linear acceleration stimulus during OVAR is determined by the speed of rotation. The magnitude of the linear acceleration stimulus during OVAR is demonstrated by how far the axis of rotation is tilted (20 degrees ⫽ 0.34 g). Methods: Tilt angles used were 10 degrees and 20 degrees. Rotational frequencies were 0.125 Hz and 0.5 Hz. Directions were clockwise and counterclockwise. The subjects were normative controls (n ⫽ 14), unilateral vestibular deficient patients (n ⫽ 3) and astronauts pre- and postflight (n ⫽ 14). Results: In normal subjects during OVAR, there is a clear correspondence between eye movements and motion perception data. In patients with unilateral vestibular loss, OVAR responses were not substantially different than healthy control subjects (compensation from the intact side and/or proprioceptive inputs). Astronauts returning from spaceflight experienced a larger sense of both tilt and translation during OVAR at low and high frequency, respectively. Torsion at 0.125 Hz and modulation of horizontal SPV at 0.5 Hz appear similar to preflight values. Conclusion: The overestimation of tilt and translation during OVAR in returning astronauts is in agreement with previous results. It is due to a decrease in the weight of the inertial body vertical after adaptation to microgravity. We have isolated the otolith inputs from the semicircular canals, proprioceptive, and visual inputs. Eye movements from otolith stimulation were not altered after spaceflight. P071 Hyperacusis and Tinnitus in Children: Prevalence and Risk Factors Claudia Coelho, MD (presenter); Tanit Ganz Sanchez, MD PhD Taquari RS Brazil; Sao Paulo Brazil
Objectives: Hyperacusis and tinnitus are otological symptoms that may present together or separated/isolated. In childhood, they often decrease severely the quality of life, disturbing their normal development, changing behavior and restricting the social life. The objective of this study is to estimate the prevalence of hyperacusis and tinnitus in children population. Methods: This prospective transversal study randomly evaluated 506 scholars from 5 to 12 years old. Among them, 47.4% were females and 52.6% were males, with mean age of 9.18 years. Medical and audiological evaluation was always performed by the same professionals and included a questionnaire
P263
to children and parents, ENT exam, pure-tone audiometry, acoustic impedance, and loudness discomfort level (LDL). Tinnitus presence was based on the questionnaire, while hyperacusis depended on the suggestive symptoms associated to an altered LDL (less than 100 dBHL) in at least one frequency. Results: Tinnitus was present in 40.5% of the children and caused annoyance in 19.8% of them. Suggestive symptoms of hyperacusis were present in 46% of the questionnaires. The loudness discomfort levels were altered (⬍100 dB) in at least one frequency in both ears in 14.9% and in all frequencies in both ears in 1.8% of the children. The risk factors studied were history of middle otitis, ear surgery, and noise exposition. Conclusion: Both tinnitus and hyperacusis are surprisingly frequent in childhood and should be actively investigated by otolaryngologists and pediatricians when assisting this population, especially in the presence of risk factors. P072 Surgical Approaches to the Hypoglossal Canal Gabriel Calzada, MD (presenter); Daniel Yoshor, Oghalai, MD Houston TX; Houston TX; Houston TX
MD;
John S
Objectives: The surgical management of tumors involving the hypoglossal canal presents unique challenges. Traditional skull base approaches provide only limited access to this region. Additionally, because the hypoglossal canal lies medial and anterior to the jugular foramen, preservation of surrounding neurovascular structures, such as the sigmoid sinus and jugular foramen nerves, is potentially possible. We sought to illustrate our decision-making strategy when faced with a tumor involving the hypoglossal canal. Methods: Our case series of 3 patients describe the different forms of hypoglossal canal involvement (extra-dural, intra-dural, and trans-dural). Tumor pathologies included a hypoglossal nerve schwannoma, a meningioma, and a paraganglioma. Results: We use 3 main surgical approaches to the hypoglossal canal. Extra-dural tumors are accessed via a unique, modified infratemporal fossa procedure. The jugular vein, carotid artery, and cranial nerves IX, X, and XI are followed up to the skull base. The facial nerve is skeletonized but not re-routed; the jugular bulb is identified but not resected. Cranial nerve XII is microdissected free from the jugular foramen and traced to the hypoglossal canal. Intra-dural tumors are managed using a far-lateral craniotomy. Removal of the jugular tubercule provides circumferential visualization of the hypoglossal canal. Combining the 2 approaches permits resection of dumbbell-shaped trans-dural tumors. Larger trans-dural tumors require a transjugular craniotomy. Conclusion: The intra- and extra-dural involvement of the hypoglossal canal defines our decision-making strategy when choosing a surgical approach to this region. Preservation of surrounding neurovascular structures should be considered for smaller tumors.
POSTERS
P070
Scientific Posters
Adaptation of Otolith Responses Assessed by OffVertical Axis Rotation Glenn W Knox, MD (presenter); Daniel Woodard, MD Jacksonville FL; Cape Cannaveral FL
Objectives: During rotation in darkness at constant velocity about an axis tilted relative to gravity (OVAR) the otolith organs are stimulated by the change in head orientation relative to gravity. The frequency of the linear acceleration stimulus during OVAR is determined by the speed of rotation. The magnitude of the linear acceleration stimulus during OVAR is demonstrated by how far the axis of rotation is tilted (20 degrees ⫽ 0.34 g). Methods: Tilt angles used were 10 degrees and 20 degrees. Rotational frequencies were 0.125 Hz and 0.5 Hz. Directions were clockwise and counterclockwise. The subjects were normative controls (n ⫽ 14), unilateral vestibular deficient patients (n ⫽ 3) and astronauts pre- and postflight (n ⫽ 14). Results: In normal subjects during OVAR, there is a clear correspondence between eye movements and motion perception data. In patients with unilateral vestibular loss, OVAR responses were not substantially different than healthy control subjects (compensation from the intact side and/or proprioceptive inputs). Astronauts returning from spaceflight experienced a larger sense of both tilt and translation during OVAR at low and high frequency, respectively. Torsion at 0.125 Hz and modulation of horizontal SPV at 0.5 Hz appear similar to preflight values. Conclusion: The overestimation of tilt and translation during OVAR in returning astronauts is in agreement with previous results. It is due to a decrease in the weight of the inertial body vertical after adaptation to microgravity. We have isolated the otolith inputs from the semicircular canals, proprioceptive, and visual inputs. Eye movements from otolith stimulation were not altered after spaceflight. P071 Hyperacusis and Tinnitus in Children: Prevalence and Risk Factors Claudia Coelho, MD (presenter); Tanit Ganz Sanchez, MD PhD Taquari RS Brazil; Sao Paulo Brazil
Objectives: Hyperacusis and tinnitus are otological symptoms that may present together or separated/isolated. In childhood, they often decrease severely the quality of life, disturbing their normal development, changing behavior and restricting the social life. The objective of this study is to estimate the prevalence of hyperacusis and tinnitus in children population. Methods: This prospective transversal study randomly evaluated 506 scholars from 5 to 12 years old. Among them, 47.4% were females and 52.6% were males, with mean age of 9.18 years. Medical and audiological evaluation was always performed by the same professionals and included a questionnaire
P263
to children and parents, ENT exam, pure-tone audiometry, acoustic impedance, and loudness discomfort level (LDL). Tinnitus presence was based on the questionnaire, while hyperacusis depended on the suggestive symptoms associated to an altered LDL (less than 100 dBHL) in at least one frequency. Results: Tinnitus was present in 40.5% of the children and caused annoyance in 19.8% of them. Suggestive symptoms of hyperacusis were present in 46% of the questionnaires. The loudness discomfort levels were altered (⬍100 dB) in at least one frequency in both ears in 14.9% and in all frequencies in both ears in 1.8% of the children. The risk factors studied were history of middle otitis, ear surgery, and noise exposition. Conclusion: Both tinnitus and hyperacusis are surprisingly frequent in childhood and should be actively investigated by otolaryngologists and pediatricians when assisting this population, especially in the presence of risk factors. P072 Surgical Approaches to the Hypoglossal Canal Gabriel Calzada, MD (presenter); Daniel Yoshor, Oghalai, MD Houston TX; Houston TX; Houston TX
MD;
John S
Objectives: The surgical management of tumors involving the hypoglossal canal presents unique challenges. Traditional skull base approaches provide only limited access to this region. Additionally, because the hypoglossal canal lies medial and anterior to the jugular foramen, preservation of surrounding neurovascular structures, such as the sigmoid sinus and jugular foramen nerves, is potentially possible. We sought to illustrate our decision-making strategy when faced with a tumor involving the hypoglossal canal. Methods: Our case series of 3 patients describe the different forms of hypoglossal canal involvement (extra-dural, intra-dural, and trans-dural). Tumor pathologies included a hypoglossal nerve schwannoma, a meningioma, and a paraganglioma. Results: We use 3 main surgical approaches to the hypoglossal canal. Extra-dural tumors are accessed via a unique, modified infratemporal fossa procedure. The jugular vein, carotid artery, and cranial nerves IX, X, and XI are followed up to the skull base. The facial nerve is skeletonized but not re-routed; the jugular bulb is identified but not resected. Cranial nerve XII is microdissected free from the jugular foramen and traced to the hypoglossal canal. Intra-dural tumors are managed using a far-lateral craniotomy. Removal of the jugular tubercule provides circumferential visualization of the hypoglossal canal. Combining the 2 approaches permits resection of dumbbell-shaped trans-dural tumors. Larger trans-dural tumors require a transjugular craniotomy. Conclusion: The intra- and extra-dural involvement of the hypoglossal canal defines our decision-making strategy when choosing a surgical approach to this region. Preservation of surrounding neurovascular structures should be considered for smaller tumors.
POSTERS
P070
Scientific Posters