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Modification of auditory cortical functions in patients with temporary unilateral conductive hearing loss
Otolaryngology Head and Neck Surgery
Scientific Sessions- - Monday
Volume 115 Number 2
emissions. The purpose of this prospective study was to examine the effects of contralateral acoustic stimulation on transient evoked otoacoustic emissions after surgical ablation of the vestibular nerves. Data from four human subjects undergoing middle fossa surgical ablation of the vestibular nerves as indicated for Meniere's disease or acoustic neuroma are presented. One subject underwent middle fossa sectioning of the superior vestibular nerve, yet the integrity of the inferior vestibular nerve was preserved. Bilateral audiometry and transient evoked otoacoustic emissions (with and without contralateral acoustic stimulation) were obtained pre- and postoperatively on all patients. We conclude that sectioning of the efferent neural supply to the cochlea within the inferior vestibular nerve is responsible for the lack of suppression seen in posttreatment transient evoked otoacoustic emissions in the ear operated on. P o s t e r 60
Modification of Auditory Cortical Functions in Patients With Temporary Unilateral Conductive Hearing Loss JUHA-PEKKA VASAMA, MD (presenter), HANS RAMSAY, MD, and JYRKI MA,KEL)k, MD, Helsinki, Finland
The human auditory cortical areas lie embedded in the Sylvian fissures and are not easily studied. Therefore, information about human auditory cortical electrophysiology has remained sparse. New methods such as magnetoencephalography have made studies of auditory cortical functioning in awake healthy humans and in audiologic patients feasible. Magnetoencephalography allows simultaneous and noninvasive monitoring of neural activity over both hemispheres with good temporal and spatial resolution. We measured auditory-evoked magnetic responses with a wholescalp 122-channel SQUID neuromagnetometer from seven adult patients with unilateral conductive hearing loss (five with otosclerosis and two with disrupted ossicular chain) before and after the middle ear surgery and from normalhearing controls. The stimuli were 50-ms 1-kHz tone bursts, delivered to the healthy, not operated ear at interstimulus intervals (ISis) of l, 2, and 4 s. The preoperative pure tone average (PTA) in the affected ears was 57 dB HL (hearing level), and the postoperative PTA was 17 dB HL, respectively. Postoperative N100m, the 100-ms response originating in the auditory cortex, peaked 7.4 ms earlier than the preoperative one over the hemisphere contralateral to the stimulated ear (p < 0.005) and 2.1 ms earlier over the ipsilateral hemisphere (n.s.). The response strengths increased by 5% over the contralateral (n.s.) and 11% over the ipsilateral hemisphere (n,s.), respectively. The variation of the response latency and strength was within the values of controls. The ISI dependence was similar over both hemispheres both in patients and in controls. The postoperative source locations did not differ significantly from preoperative ones. These findings suggest that temporary unilateral conductive hearing loss also affects the auditory functions of the opposite healthy ear.
P97
Poster 61
Airway Anomalies in Pfeiffer Type 3 NANCY SCULERATI, MD, and TIMOTHY CHU, MD (presenter), New York, N.Y.
We illustrate the airway anomalies in an infant with Pfeiffer syndrome type 3, These anomalies offer one explanation for the early demise reported in these children. Features of classic Pfeiffer syndrome (Type 1) include midface retrusion and other craniofacial anomalies that cause upper airway obstruction. Pfeiffer type 3 is an unusual variant that is associated with a poor prognosis. The skull is not cloverleaf, as in type 2, but like type 2, there is exaggeration of the shallow orbits and short anterior cranial base resulting in extreme ocular proptosis, and marked central nervous system involvement with hydrocephalus. Additional features include elbow ankylosis as well as the usual broad first digits. There is early death in at least one third of patients. A neonate with Pfeiffer type 3 was transferred for airway management with a presumptive diagnosis of choanal atresia. Tracheotomy was performed after recognition of midface retrusion and craniosynostosis causing nasal obstruction. Bronchoscopy after cardiorespiratory arrest showed a type 1 laryngeal cleft and a tracheal sleeve anomaly with a moderate long segment stenosis caused by complete tracheal rings, with a circumferential shelf just above the carina. These anomalies are shown in endoscopic photographs and computed tomography of the airway. Review of the literature shows evidence that other specific cases of Pfeiffer type 3 may have had similar tracheal defects, although these are not well described. We suggest that tracheal and laryngeal anomalies should be evaluated with direct laryngoscopy and rigid bronchoscopy in cases of Pfeiffer syndrome subtypes with limb anomalies.
P o s t e r 62
Developmental Transition of Myosin Heavy Chain Isoforrns in Rat Laryngeal Muscles AKIHIRO SHIOTANI, MD (presenter). RICHARD M. JONES, MD, and PAUL W. FLINT, MD, Baltimore, Md.
This study reviews the critical stages in the prenatal development of the rat larynx with emphasis on the neuroanatomy. Immunehistochemical techniques are used to clearly demonstrate the innervation patterns of developing of the larynx. Serially sectioned rat embryos from collections in our laboratory are reexamined and stored as digitized images, Computer-generated three-dimensional images, from stored sections, are used to aid in understanding the events that lead to the innervation patterns of the mature larynx. Specimens that demonstrated critical changes in the pattern of innervation or morphology of the larynx, Carnegie stages 13-20 are represented. Three-dimensional images better demonstrate the medley of interactions between the dual nerve supply of the larynx. Temporal and spatial relationships to the developing
Scientific Sessions- - Monday
Volume 115 Number 2
emissions. The purpose of this prospective study was to examine the effects of contralateral acoustic stimulation on transient evoked otoacoustic emissions after surgical ablation of the vestibular nerves. Data from four human subjects undergoing middle fossa surgical ablation of the vestibular nerves as indicated for Meniere's disease or acoustic neuroma are presented. One subject underwent middle fossa sectioning of the superior vestibular nerve, yet the integrity of the inferior vestibular nerve was preserved. Bilateral audiometry and transient evoked otoacoustic emissions (with and without contralateral acoustic stimulation) were obtained pre- and postoperatively on all patients. We conclude that sectioning of the efferent neural supply to the cochlea within the inferior vestibular nerve is responsible for the lack of suppression seen in posttreatment transient evoked otoacoustic emissions in the ear operated on. P o s t e r 60
Modification of Auditory Cortical Functions in Patients With Temporary Unilateral Conductive Hearing Loss JUHA-PEKKA VASAMA, MD (presenter), HANS RAMSAY, MD, and JYRKI MA,KEL)k, MD, Helsinki, Finland
The human auditory cortical areas lie embedded in the Sylvian fissures and are not easily studied. Therefore, information about human auditory cortical electrophysiology has remained sparse. New methods such as magnetoencephalography have made studies of auditory cortical functioning in awake healthy humans and in audiologic patients feasible. Magnetoencephalography allows simultaneous and noninvasive monitoring of neural activity over both hemispheres with good temporal and spatial resolution. We measured auditory-evoked magnetic responses with a wholescalp 122-channel SQUID neuromagnetometer from seven adult patients with unilateral conductive hearing loss (five with otosclerosis and two with disrupted ossicular chain) before and after the middle ear surgery and from normalhearing controls. The stimuli were 50-ms 1-kHz tone bursts, delivered to the healthy, not operated ear at interstimulus intervals (ISis) of l, 2, and 4 s. The preoperative pure tone average (PTA) in the affected ears was 57 dB HL (hearing level), and the postoperative PTA was 17 dB HL, respectively. Postoperative N100m, the 100-ms response originating in the auditory cortex, peaked 7.4 ms earlier than the preoperative one over the hemisphere contralateral to the stimulated ear (p < 0.005) and 2.1 ms earlier over the ipsilateral hemisphere (n.s.). The response strengths increased by 5% over the contralateral (n.s.) and 11% over the ipsilateral hemisphere (n,s.), respectively. The variation of the response latency and strength was within the values of controls. The ISI dependence was similar over both hemispheres both in patients and in controls. The postoperative source locations did not differ significantly from preoperative ones. These findings suggest that temporary unilateral conductive hearing loss also affects the auditory functions of the opposite healthy ear.
P97
Poster 61
Airway Anomalies in Pfeiffer Type 3 NANCY SCULERATI, MD, and TIMOTHY CHU, MD (presenter), New York, N.Y.
We illustrate the airway anomalies in an infant with Pfeiffer syndrome type 3, These anomalies offer one explanation for the early demise reported in these children. Features of classic Pfeiffer syndrome (Type 1) include midface retrusion and other craniofacial anomalies that cause upper airway obstruction. Pfeiffer type 3 is an unusual variant that is associated with a poor prognosis. The skull is not cloverleaf, as in type 2, but like type 2, there is exaggeration of the shallow orbits and short anterior cranial base resulting in extreme ocular proptosis, and marked central nervous system involvement with hydrocephalus. Additional features include elbow ankylosis as well as the usual broad first digits. There is early death in at least one third of patients. A neonate with Pfeiffer type 3 was transferred for airway management with a presumptive diagnosis of choanal atresia. Tracheotomy was performed after recognition of midface retrusion and craniosynostosis causing nasal obstruction. Bronchoscopy after cardiorespiratory arrest showed a type 1 laryngeal cleft and a tracheal sleeve anomaly with a moderate long segment stenosis caused by complete tracheal rings, with a circumferential shelf just above the carina. These anomalies are shown in endoscopic photographs and computed tomography of the airway. Review of the literature shows evidence that other specific cases of Pfeiffer type 3 may have had similar tracheal defects, although these are not well described. We suggest that tracheal and laryngeal anomalies should be evaluated with direct laryngoscopy and rigid bronchoscopy in cases of Pfeiffer syndrome subtypes with limb anomalies.
P o s t e r 62
Developmental Transition of Myosin Heavy Chain Isoforrns in Rat Laryngeal Muscles AKIHIRO SHIOTANI, MD (presenter). RICHARD M. JONES, MD, and PAUL W. FLINT, MD, Baltimore, Md.
This study reviews the critical stages in the prenatal development of the rat larynx with emphasis on the neuroanatomy. Immunehistochemical techniques are used to clearly demonstrate the innervation patterns of developing of the larynx. Serially sectioned rat embryos from collections in our laboratory are reexamined and stored as digitized images, Computer-generated three-dimensional images, from stored sections, are used to aid in understanding the events that lead to the innervation patterns of the mature larynx. Specimens that demonstrated critical changes in the pattern of innervation or morphology of the larynx, Carnegie stages 13-20 are represented. Three-dimensional images better demonstrate the medley of interactions between the dual nerve supply of the larynx. Temporal and spatial relationships to the developing