Hearing test

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Introduction

Newborn hearing test

The incidence of significant permanent hearing loss is approximately 1-3/1000 newborns. Neonatal hearing screening is carried out in the USA, UK and in Australia (2002 NSW Statewide Infant Screening Hearing Program, SWISH) There is a general guide giving a timetable for a number of simple responses that a neonate should make if hearing has developed normally (More? Neonatal Hearing Check List).


State Wide Infant Screening Hearing Program (SWISH) a newborn hearing testing program using an automated auditory response technology (AABR). Program was introduced in NSW Australia in 2002 across 17 area health service coordinators. It is thought that in NSW 86,000 births/year = 86-172 babies potentially born with significant permanent hearing loss.


Automated Auditory Brainstem Response (AABR) uses a stimulus which is delivered through earphones and detected by scalp electrodes. The test takes between 8 to 20 minutes and has a sensitivity 96-99%.


Hearing Links: Introduction | Science Lecture | Medicine Lecture | Inner Ear | Middle Ear | Outer Ear | Balance | Hearing - Neural Pathway | Stage 22 | Abnormalities | Neonatal Diagnosis - Hearing | Hearing test | Sensory Introduction | Placodes | Student project | Category:Hearing
Historic Embryology 
Historic Embryology: 1902 Development of Hearing | 1906 Membranous Labyrinth | 1913 Tectorial Membrane | 1918 Human Embryo Otic Capsule | 1918 Cochlea | 1918 Grays Anatomy | 1922 Human Auricle | 1922 Otic Primordia | 1931 Internal Ear Scalae | 1933 Endolymphatic Sac | 1934 Otic Vesicle | 1934 Membranous Labyrinth | 1963 Human Otocyst | Historic Disclaimer


Neonatal Diagnosis: APGAR test | Guthrie test | Hearing test | Electrocardiogram (ECG/EKG) | X-ray | Tandem mass spectrometry | Classification of Diseases

Some Recent Findings

  • Universal Neonatal Hearing Screening - Experience in a Tertiary Care Hospital in Southern India[1] "The neonates were subjected to a two stage sequential screening using the BERAphone. Neonates suspected of hearing loss underwent confirmatory testing using auditory steady state response audiometry and serological testing for TORCH infections and connexin 26 gene. ...Universal neonatal hearing screening using BERAphone is a feasible service, vital for early identification and rehabilitation of neonatal hearing loss. The estimated prevalence of confirmed hearing loss was comparable to that in literature. Overcoming the large numbers of loss to follow-up proves to be a challenge in the implementation of such a program." India Statistics
  • Cost-effectiveness analysis of a national neonatal hearing screening program in China[2] "In 2009, the Chinese Ministry of Health recommended scale-up of routine neonatal hearing screening - previously performed primarily only in select urban hospitals - throughout the entire country. A decision analytical model for a simulated population of all live births in china was developed to compare the costs and health effects of five mutually exclusive interventions: 1) universal screening using Otoacoustic Emission (OAE) and Automated Auditory Brainstem Response (AABR); 2) universal OAE; 3) targeted OAE and AABR; 4) targeted OAE; and 5) no screening. Disability-Adjusted Life Years (DALYs) were calculated for health effects. Based on the cost-effectiveness and potential health outcomes, the optimal path for scale-up would be to start with targeted OAE and then expand to universal OAE and universal OAE plus AABR." China Statistics
  • Incidence and Pattern of Hearing Impairment in Children with ≤ 800 Gram Birth Weight in British Columbia, Canada[3] "The incidence and severity of hearing impairment in a cohort of extremely low birth weight children increased significantly from 5% to 13% (p= 0.01) over a 24 year period. Comorbidities were common. Potentially modifiable causes are explored."
  • Overview of newborn hearing screening activities in Latin America[4] "In spite of several barriers, NHS programs have been implemented in at least some facilities and regions in Latin America. Additional efforts are needed to expand NHS activities in Latin America." Canada Statistics
More recent papers
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Search term: Neonatal Hearing Test

Michael A Wien, Matthew T Whitehead The association among prematurity, cochlear hyperintensity, and hearing loss. Neuroradiol J: 2017;1971400917709623 PubMed 28631523

Lucy Meyer, Bazak Sharon, Tina C Huang, Abby C Meyer, Kristin E Gravel, Lisa A Schimmenti, Elizabeth C Swanson, Hannah E Herd, Nelmary Hernandez-Alvarado, Kirsten R Coverstone, Mark McCann, Mark R Schleiss Analysis of archived newborn dried blood spots (DBS) identifies congenital cytomegalovirus as a major cause of unexplained pediatric sensorineural hearing loss. Am J Otolaryngol: 2017; PubMed 28629849

Mathilde Letouzey, Alexandra Chadie, Marie Brasseur-Daudruy, François Proust, Eric Verspyck, Pascal Boileau, Stéphane Marret Severe Apparently Isolated Fetal Ventriculomegaly And Neurodevelopmental Outcome. Prenat. Diagn.: 2017; PubMed 28622418

Jing-Ying Guo, Yu-Ying Liu, Teng-Fei Qu, Zhe Peng, Jing Xie, Guo-Peng Wang, Shu-Sheng Gong Cochleovestibular gene transfer in neonatal mice by canalostomy. Neuroreport: 2017; PubMed 28614181

Kavita Sachdeva, Tulsi Sao Outcomes of Newborn Hearing Screening Program: A Hospital Based Study. Indian J Otolaryngol Head Neck Surg: 2017, 69(2);194-198 PubMed 28607889

Automated Auditory Brainstem Response

(AABR) uses a stimulus which is delivered through earphones and detected by scalp electrodes. The test takes between 8 to 20 minutes and has a sensitivity 96-99%. The basis of a neonatal hearing test that uses a trigger stimulus delivered through earphones and subsequent brain electrical activity then detected by scalp electrodes. Then by computer analysis, averaging all the electrical activity following the trigger, peaks emerge reflecting signal passage activity through brain stem nuclei in the hearing central neural pathway. The infant test takes between 8 to 20 minutes, has a sensitivity 96-99%, and unlike other childhood auditory testing does not require a subject response. An increased absolute latency has been seen to occur in premature infants related to decreased myelinization affecting the electrical conduction delays up to the brainstem.

An alternative and simple test (pass/refer) used at a later stage is otoacoustic emission testing.

  • waves I and II - arise ipsilaterally to the stimulus and reflect the action potential of the auditory nerve.
  • waves III, IV and V - receive contralateral inputs.

Otoacoustic Emission Testing

(OAE) The basis of a simple infant hearing test of the inner ear. A small probe containing both a speaker producing "clicks" and a microphone to detect cochlea responses is placed inside the ear canal. Acoustic energy produced by vibration of the hair cells in response to the clicks is detected by the microphone within the probe. A more complex test that can be used at an earlier stage is the automated auditory brainstem response.

Neonatal Hearing Check List

The timing and types of responses listed below reflect only a rough guide for the general population. Abnormalities in neurological, visual or motor skill development can also affect responses.

  • Birth to 3 months - Reacts to loud sounds, Quiets to familiar voices or sounds, Makes cooing noises, Responds to speech by looking at speaker’s face
  • 3 to 6 months - Turns eyes or head toward sounds, Starts to make speech-like sounds, Laughs and makes noises to indicate pleasure and displeasure
  • 6 to 9 months - Babbles, ‘dada’‘ma-ma’‘baba’, Shouts/vocalises to get attention, Will often respond to ‘no’ and own name, Responds to singing and music
  • 9 to 12 months - Imitates speech sounds of others, Understands simple words, eg ‘ball’,‘dog’, ‘daddy’, Turns head to soft sounds, First words emerge
  • 12 to 18 months _ Appears to understand some new words each week, Follows simple spoken instructions, eg ‘get the ball’, Points to people, body parts or toys when asked, Continually learns new words to say although may be unclear
  • 18 to 24 months - Listens to simple stories or songs, Combines two or more words in short phrases eg ‘more juice’

Hearing check list text based upon NSW Health Pamphlet - Why does my baby need a hearing check?

Neural Exam

The following are examples of simple assessment of development in early hearing and understanding.

12 month Behaviour 18 month Behaviour 30 month Behaviour
Movie Source - Paul D. Larsen
Movies from the PediNeuroLogic Exam website are used by permission of Paul D. Larsen, M.D., University of Nebraska Medical Center and Suzanne S. Stensaas, Ph.D., University of Utah School of Medicine. Additional materials were drawn from resources provided by Alejandro Stern, Stern Foundation, Buenos Aires, Argentina; Kathleen Digre, M.D., University of Utah; and Daniel Jacobson, M.D., Marshfield Clinic, Wisconsin. The movies are licensed under a Creative Commons Attribution-NonCommerical-ShareAlike 2.5 License.

Neural Exam Movies | Movies

Hearing Loss Risk Factors

The following selected genetic and environmental conditions have been identified as risk factors for hearing loss.

  • syndrome known to be related to hearing loss
  • close family history of congenital hearing impairment (parent / sibling)
  • congenital abnormality of the head / neck (excluding minor pits/ ear tags)
  • maternal infections during pregnancy such as HIV, TORCH - (Toxoplasmosis, Other (syphilis, varicella), Rubella, CMV, Herpes)
  • meningitis / encephalitis
  • jaundice requiring exchange transfusion
  • ventilation greater than 5 days (excluding continuous positive airway pressure)
  • amino glycoside antibiotic therapy for greater than 3 days

Australia

  • New South Wales - State Wide Infant Screening Hearing Program (SWISH) was introduced in NSW Australia in 2002 across 17 area health service coordinators.
  • Victoria - Victorian Infant Hearing Screening Program (VIHSP) provides statewide newborn hearing screening to babies born at all Victorian maternity hospitals.

Latin America

The following data and modified text is from a recent review describing newborn hearing screening (NHS) activities in Latin America.[4]

  • Chile - since July 2005, Chilean law has required targeted hearing screening using otoacoustic emissions (OAE) and auditory brainstem response (ABR) technology for all premature newborns born before 32 weeks and weighing less than 1500 g who are discharged from the 28 facilities with a neonatal intensive care unit.
  • Costa Rica - since 2004, a few centers have been providing NHS services using OAE to screen some high-risk children.
  • Guatemala - does not have legislation requiring NHS. In 2004, high-risk targeted NHS was implemented in one hospital in the capital city, and a second site was established in 2008. These NHS programs were started with donated OAE equipment and there were plans to expand as additional (donated) equipment became available. In 2008, the OAE equipment in the first hospital broke, and as of June 2009 it had not been repaired, which left only one hospital performing hearing screenings.
  • Mexico - since February 2005, a national law was passed requiring hearing screening for all newborns and audiological evaluation. In July 2007, the program at HGM was expanded to include all newborns. Some NHS programs have been implemented in a few public and private hospitals around the country.
  • Panama - since 2000, Panama has offered targeted NHS in some public and private birthing hospitals. There is no NHS law in place, but a local group is advocating for implementation of universal NHS.
  • Puerto Rico - (Puerto Rico is a USA territory) and receives directives regarding health care initiatives from the U.S. government. An NHS program, Programa de Cernimiento Auditivo Neonatal Universal, operates in all birthing hospitals. The program was initiated in January 2000 and became required by law in December 2003.
  • Uruguay - in 2000, Uruguay started implementing targeted and universal NHS in a limited number of public and private hospitals. Several hospitals in the capital city of Montevideo and one hospital in the city of Paysandú offer NHS.

References

  1. Ann Mary Augustine, Atanu Kumar Jana, Kurien Anil Kuruvilla, Sumita Danda, Anjali Lepcha, Jareen Ebenezer, Roshna Rose Paul, Amit Tyagi, Achamma Balraj Neonatal hearing screening--experience from a tertiary care hospital in southern India. Indian Pediatr: 2014, 51(3);179-83 PubMed 24277966
  2. Ruoyan Gai Tobe, Rintaro Mori, Lihui Huang, Lingzhong Xu, Demin Han, Kenji Shibuya Cost-effectiveness analysis of a national neonatal hearing screening program in China: conditions for the scale-up. PLoS ONE: 2013, 8(1);e51990 PubMed 23341887 | PLoS One.
  3. Anne R Synnes, Shelagh Anson, Julia Baum, Laurie Usher Incidence and pattern of hearing impairment in children with ≤ 800 g birthweight in British Columbia, Canada. Acta Paediatr.: 2012, 101(2);e48-54 PubMed 21824192
  4. 4.0 4.1 Barbara Gerner de Garcia, Claudia Gaffney, Susan Chacon, Marcus Gaffney Overview of newborn hearing screening activities in Latin America. Rev. Panam. Salud Publica: 2011, 29(3);145-52 PubMed 21484013



Search PubMed: neonatal hearing diagnosis | neonatal diagnosis | neonatal screening | Automated Auditory Brainstem Response | Otoacoustic Emission Testing


External Links

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Terms

Hearing Terms  
Hearing and Balance Development
  • altricial animal - Term used to describe an animal born in a helpless state, with incomplete development of sensory systems at birth. For example rats and mice are born with incomplete development of visual and auditory systems. (More? Animal Development)
  • ampulla - Term used to describe an anatomical dilation of a tube or canal lumen. Anatomical description of the opening end of the uterine tube lying above the ovary and the enlarged initial segmeny of the semicircular canals of the inner ear vestibular system. (More? Inner Ear)
  • aneurism - (Greek, aneurysma = a widening, aneurysm) A term used to describe an abnormal widening of a vessel or anatomical tubal structure.
  • aquaeductus vestibuli - see vestibular aqueduct (More? Inner Ear)
  • auditory neuropathy - (AN) abnormality of transmission of sound information to the brain.
  • auditory tube - (eustachian tube) between the middle ear and oral cavity, has a bony (tympanic 1/3) and cartilaginous (pharyngeal 2/3) portion. The main role is equalization of pressure and fluid drainage in the middle ear. (More? Middle Ear)
  • auricular hillock - see hillock (More? Middle Ear)
  • atresia - narrowing, usually of an anatomical tube or cavity.
  • autophagocytosis - (Greek, auto = self, phagy = eating, also called autophagy) a cell death mechanism that uses the cell's own lysosomes to self digest.
  • border cells - columnar cells within the organ of Corti on the medial portion of the basilar membrane. (More? Inner Ear)
  • canalis reuniens - (ductus reuniens, canaliculus reuniens, canalis reuniens, Hensen's canal, Hensen's duct, uniting canal, canalis reuniens of Hensen) short narrow canal connecting the cochlea duct to the saccule. (Victor Hensen, 1835-1924) (More? Inner Ear)
  • cerumen - (ear wax) produced by glands in the skin of the outer portion of the ear canal. (More? Outer Ear)
  • chondrified - the developmental differentiation of cartilage from mesenchye, an embryonic connective tissue.
  • cristae ampullaris - located in the ampulla of the membranous semicircular canals a region with both supporting and hair cells. The hair cell cilia are embedded in the gelatinous cupula. (More? Inner Ear)
  • claudius cells - (cells of Claudius) columnar cells with microvilli overlying the basilar membrane and extend from Hensen's cells to the spiral prominence. Barrier cells that lie external to the organ of corti in endolymph. (More? Inner Ear)
  • cochlear sac - embryonic structure, which will form the coiled cochlear duct and contribute to the saccule. (More? Inner Ear)
  • cochlear aqueduct - a bony channel containing the fibrous periotic duct. It connects the basal turn of the cochlea perilymphatic space with the subarachnoid space of the posterior cranial cavity. (More? Inner Ear)
  • cochlin - major constituent of the inner ear extracellular matrix. (More? Inner Ear)
  • collagen type II - major constituent of the inner ear extracellular matrix. (More? Inner Ear)
  • conductive loss - term used to describe one of the two major classes of hearing loss involving external and middle ear abnormalities (other form is Sensorineural loss).
  • connexins - channel proteins of the gap junctions that allow rapid communication between adjacent cells. The two connexins Cx26 and Cx30 are the major proteins of cochlear gap junctions.
  • connexin 26 - A strikingly high proportion (50%) of congenital bilateral nonsyndromic sensorineural deafness cases have been linked to mutations in the GJB2 coding for the connexin26
  • cupular deposits - basophilic material on the cupulae of the semicircular ducts, an postnatal ageing phenomenon seen in some vestibular labyrinth. (More? Inner Ear)
  • clinical weeks - taken from last menstrual period (LMP) and therefore approximately two weeks before fertilization occurs.
  • Deiters' cells - (outer phalangeal cells)
  • discoidin domain receptor 1 - (DDR1) a tyrosine kinase receptor activated by native collagen, expressed in the basement membrane and with fibrillar collagens. Found in basal cells of the stria vascularis, type III fibrocytes, and cells lining the basilar membrane of the organ of Corti. {Meyer zum Gottesberge, 2008 #1877}
  • ductus utriculosaccularis - (More? Inner Ear)
  • endochondral ossification - the process of bone formation from a pre-existing cartilage template. (More? Middle Ear)
  • endoderm - One of the initial 3 germ cell layers (ectoderm, mesoderm and endoderm) formed by the process of gastrulation. The endoderm forms as a cuboidal epithelium and contributes not only to the trilaminar embryo, but also lines the yolk sac. It will form the entire epithelial lining of the gastrointestinal tract (GIT), contribute to the accessory organs of GIT and also forms the epithelial lining of the respiratory tract.
  • endolymphatic fluid - (endolymph, Scarpa's fluid) fluid that fills all the membranous labyrinth of the inner ear, except for the cochlea scala tympani and scala vestibuli which are filled with perilymph.
  • endolymphatic sac - inner ear structure that has anatomically both an intraosseous and extraosseous component. Th e sac has functions regulating endolymph that are both secretory and absorptive. Also the site of endolymphatic sac tumors either sporadical occurring or associated with the autosomal-dominant von Hippel-Lindau (VHL) disease, due to a germ line mutation. (More? Inner Ear)
  • embryological weeks - taken from the time of fertilization which typically occurs around the middle (day 14), or just after, of the typical 28 day menstrual cycle. (More? Embryonic Development)
  • Emx2 - homeobox gene affecting middle ear and inner ear development.
  • eustachian tube - (auditory tube) A cavity linking the pharynx to the middle ear, which develops from the first pharyngeal pouch. Named after Bartolomeo Eustachi (1500 - 1574) an Italian anatomist. (More? Middle Ear)
  • external auditory meatus - (ear canal) develops from the first pharyngeal cleft. (More? Outer Ear)
  • ear wax - see cerumen. (More? Outer Ear)
  • espins - calcium-resistant actin-bundling proteins enriched in hair cell stereocilia and sensory cell microvilli and spiral ganglion neurons (SGNs)
  • eustachian tube - (auditory tube) between the middle ear and oral cavity, equalization of pressure in the middle ear. (More? Middle Ear)
  • external auditory meatus - (EAM, ear canal) cavity connecting the external ear to the tympanic membrane. The adult human ear canal is about 2.5 cm long and 0.7 cm in diameter. (More? Outer Ear)
  • fenestra ovalis - (oval window) separates the tympanic cavity from the vestibule of the osseous labyrinth. (More? Inner Ear)
  • fenestra rotunda - (round window) separates the tympanic cavity from the scala tympani of the cochlea. (More? Inner Ear)
  • fetus - (foetus) term used to describe human development after the 8th week (10th clinical week, LPM) and covers the developmental periods of second and third trimester.
  • fibroblast growth factor 1 - (Fgf-1) a growth factor released from cochlea sensory epithelium which stimulates spiral ganglion neurite branching.
  • fibroblast growth factor 8 - (Fgf-8) a growth factor released by inner hair cells which regulates pillar cell number, position and rate of development.
  • fibroblast growth factor receptor 3 - (Fgfr-3) a tyrosine kinase receptor with a role in the commitment, differentiation and position of pillar cells in the organ of corti
  • fundamental frequency - (natural frequency) the lowest frequency in a harmonic series, for the female voice this is about 225 Hz.
  • helicotrema - term used to describe the cochlear apex. (More? Inner Ear)
  • Hes - (hairy and enhancer of split) family of factors, which has been shown to be a general negative regulator of neurogenesis (Zheng, 2000).
  • hillock - a small hill, used to describe the six surface elevations on pharyngeal arch one and two. (More? Outer Ear)
  • Incus - (anvil) auditory ossicle (More? Middle Ear)
  • inner phalangeal cells - in the cochlea a single row of cells, that along with and three rows of outer phalangeal cells (Deiter's cells), are the hair cell supporting cells. (More? Inner Ear)
  • inner pillar cells - organ of Corti cells arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. These cells have surface-associated microtubule bundles. (More? Inner Ear)
  • inner sulcus - area of the cochlear duct. (More? Inner Ear)
  • internal auditory meatus - (internal acoustic meatus, IAM) Anatomical canal in which CN VII and CN VIII ganglia reside and pass through to the brainstem. This bony canal lies between the posterior surface of the petrous pyramid and the bony labyrinth within the dense petrous bone. Also associated clinically with the site where acoustic neuromas may occur. (More? Inner Ear)
  • kinocilium - inner ear hair cell specialised type of cilium on the cell apex.
  • Kolliker's organ - (Kollicker's organ, greater epithelial ridge) Developing cochlear structure consisting of columnar-shaped supporting cells filling the inner sulcus and lying directly under the tectorial membrane. This transient organ regresses and generates the space of the inner sulcus. Rudolph Albert von Kolliker (1817-1905)?? (More? Inner Ear)
  • lateral semicircular duct
  • limbus -
  • LMP - acronym for last menstrual period, used to clinically measure gestation.
  • malleus - (hammer) auditory ossicle (More? Middle Ear)
  • mastoid process - of temporal bone (More? Middle Ear)
  • Math1 - homolog of the Drosophila proneural gene atonal, necessary and sufficient for the production of hair cells in the mouse inner ear. Negatively regulated by Hes1 and Hes5
  • meatal plug - temporary blockage of the external auditory meatus which forms at the end of the embryonic period and remains present until the seventh month.
  • meatus - anatomical opening, cavity or space (external acoustic meatus, internal auditory meatus)
  • mechano-electrical transduction - (MET) occurs within the cochlear hair cells hair bundle. A mechanical stimulus of the hair bundle causes the tip-links to be tensioned, opening ion channels, resulting in the generation of the cell receptor potential. (More? Inner Ear)
  • Meckel's cartilage - first pharyngeal ach cartilage, located within the mandibular prominence. This cartilage first appears at stage 16, stage 20 the beginning of membranous ossification. Named after Johann Friedrich Meckel, (1781 - 1833) a German anatomist. (http://www.whonamedit.com/doctor.cfm/1840.html) (More? Middle Ear)
  • membranous labyrinth - (More? Inner Ear)
  • mucopolysaccharidosis - (MPS IIIB, Sanfilippo Syndrome type B) abnormality caused by a deficiency in the lysosomal enzyme N-acetyl-glucosaminidase (Naglu). Children with MPS IIIB develop abnormal hearing, and mental functioning culminating in early death.
  • netrin-1 - secreted growth factor, expressed in the organ of Corti and spiral ganglion cells, role in process outgrowth. (More? Inner Ear)
  • otoacoustic emissions testing - (OET) hearing test measures sounds generated by the outer hair cells of the cochlea in response to clicks or tone bursts emitted and recorded by a tiny microphone placed in the infant’s external ear canal. (More? Hearing test)
  • olivocochlear - brainstem cholinergic and GABAergic efferent system that innervates sensory cells and sensory neurons of the inner ear.
  • organ of Corti - (More? Inner Ear)
  • organ of Corti protein II - (OCP-II) cytosolic protein or transcription factor? (More? Inner Ear)
  • otolithic membrane - extracellular matrix that cover the sensory epithelia of the inner ear. (More? Inner Ear)
  • ossicle - (small bone) the individual bone of the three middle ear bones (auditory ossicles), which reduce vibrational amplitude but increase force to drive fluid-filled inner ear. (More? Middle Ear)
  • ossify - (More? Middle Ear)
  • otic capsule -
  • otic cup -
  • otic placode - Embryonic ectodermal epithelium giving rise to inner ear structures. (More? Inner Ear | Placodes)
  • otic vesicle - (More? Inner Ear)
  • otoconin - inner ear biominerals required for vestibular apparatus function. (More? Inner Ear)
  • otogelin - (Otog) an inner ear specific glycoprotein expressed in cochlea cells at different developmental times. (More? Inner Ear)
  • otolithic membrane - a membrane within the utricle and saccule containing embedded hair cell cilia and small crystalline bodies of calcium carbonate (otoliths). Functions to detect head motion.
  • otoliths - small crystalline bodies of calcium carbonate found within the otolitic membrane of the utricle and saccule. (More? Inner Ear)
  • ototoxic - compound or drug causing temporary or permanent hearing loss.
  • outer hair cells - (OHCs) three rows of hair cells that function to increase basilar membrane motion through a local mechanical feedback process within the cochlea, the " cochlear amplifier".
  • outer pillar cells - arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. (More? Inner Ear)
  • paratubal musculature - muscles lying beside the auditory (Eustachian) tube. The tensor veli, palatini (TVP) and tensor tympani muscles. (More? Middle Ear)
  • perilymph - perilymphatic space - Periotic Capsule - petrous portion - of temporal bone
  • pejvakin gene - in humans, two missense mutations in this gene cause nonsyndromic recessive deafness (DFNB59) by affecting the function of auditory neurons.
  • pharyngeal arch - (More? Outer Ear) pharyngeal pouch pharyngeal membrane Pharynx
  • pillar cells - (PC) form an inner and outer row of support cells that form a boundary between inner and outer hair cells. (More? Inner Ear)
  • preyer reflex - ear flick in mouse in response to sound.
  • presbyacusis
  • prestin - a motor protein structurally similar to the anion transporter family expressed in cochlear outer hair cells. (More? Inner Ear)
  • preauricular tag - skin tags located in front of the external ear opening, are common in neonates and in most cases are normal, though in some cases are indicative of other associated abnormalities.
  • protocadherin 15 - (Pcdh15) required for initial formation of stereocilia bundles and changes in the actin meshwork within hair cells. The Ames waltzer (av) mouse mutant has both auditory and vestibular abnormalities from a mutation in this gene.
  • Reichert's cartilage - pharyngeal ach 2 cartilage, named after Karl Bogislaus Reichert (1811 - 1883) a German anatomist.
  • Reissner's membrane - (vestibular membrane, vestibular wall) is a membrane located inside the cochlea separating the scala media from scala vestibuli. Named after Ernst Reissner (1824-1878) a German anatomist. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth.
  • rhombomere -
  • saccular macula -
  • Saccule - (Latin, sacculus = a small pouch)
  • sacculocollic reflex -
  • scala tympani - one of the three Cochlea cavities, it is filled with perilymph.
  • Scarpa's ganglion - (vestibular ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus. (More? Inner Ear)
  • semicircular canals - series of fluid-filled loops of the inner ear required for balance and sensing acceleration. (More? Inner Ear)
  • sensorineural - term used to describe one of the two major classes of hearing loss involving the central pathway from the cochlear (other form is conductive loss).
  • space of Nuel - within the cochlea, an organ of Corti space between the outer pillar cells and the phalangeal and hair cells. Named after Jean-Pierre Nuel (1847-1920) a Belgian ophthalmologist. (More? Inner Ear)
  • spiral ganglion neurons - (SGN) innervate the inner (Type I) and outer (Type II) hair cells of the cochlea. (More? Inner Ear)
  • stapedius muscle - (innervated by CN VII tympanic branch) one of the two muscles in the middle ear, contraction of this muscle pulls the stapes and dampens auditory ossicle movement. (More? Middle Ear)
  • stapes - (stirrup) a middle ear auditory ossicle (bone) (More? Middle Ear)
  • stapes footplate - (More? Middle Ear)
  • startle response -
  • stereocilia -finger-like projections from the apical surface of sensory hair cells forming the hair bundle in the cochlea. Formed by tightly cross-linked parallel actin filaments in a paracrystalline array with cell surface specializations (tip links, horizontal top connectors, and tectorial membrane attachment crowns).
  • stratified squamous epithelia - classification of epithelium which transiently forms a plug in external ear canal to the outer eardrum.
  • stria vascularis - forms the outer wall of the cochlear duct of the mammalian cochlea is composed primarily of three types of cells. Marginal cells line the lumen of the cochlear duct and are of epithelial origin. Basal cells also form a continuous layer and they may be mesodermal or derived from the neural crest. Intermediate cells are melanocyte-like cells, presumably derived from the neural crest, and are scattered between the marginal and basal cell layers. The stria forms endolymph and also contains a rich supply of blood vessels. (More? Inner Ear)
  • sulcus -
  • synostotically - anatomically normally separate skeletal bones fused together. (More? Middle Ear)
  • tectorial membrane - within the cochlea an extracellular matrix produced by interdental cells, that covers the sensory epithelial hair cells of the organ of corti. (More? Inner Ear)
  • alpha-tectorin and beta- (TECTA, TECTB) major non-collagenous protein component of the tectorial membrane forming a striated-sheet matrix. Synthesized as glycosylphosphatidylinositol-linked, membrane bound precursors.
  • temporal bone - (More? Middle Ear)
  • tensor tympani - (innervated by CN V mandibular nerve) one of the two muscles in the middle ear, contraction of this muscle pulls the malleus and tenses the tympanic membrane, dampening auditory ossicle movement. The muscle arises from auditory tube (cartilaginous portion) and is inserted into the malleus (manubrium near the root).
  • teratogens -
  • tonotopy - term describing the mapping along the tectorial membrane within the cochlea of the different sound frequencies. (More? Inner Ear)
  • tympanic membrane - (ear drum)
  • utricle -
  • vacuolization -
  • vesicle -
  • vestibular apparatus -
  • vestibular evoked myogenic potential (VEMP) test
  • vestibular ganglion - (Scarpa's ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus. (More? Inner Ear)
  • vestibular membrane - (Reissner's) extends from the spiral lamina to the outer wall and divides the cochlea into an upper scala vestibuli, a lower scala tympani. (More? Inner Ear)
  • Vestibulocochlear Nerve - Cranial Nerve VIII
  • Whirlin - A PDZ scaffold protein expressed in hair cells at the stereocilia tips, essential for the stereocilia elongation process. The DFNB31 gene mutations cause hearing loss in human and mouse. This protein can interact with membrane-associated guanylate kinase (MAGUK) protein, erythrocyte protein p55 (p55). (More? Inner Ear)
  • Wnt7a - signaling through the Wnt pathway regulates the development of hair cell unidirectional stereociliary bundle orientation. (More? Inner Ear)
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Cite this page: Hill, M.A. 2017 Embryology Hearing test. Retrieved June 29, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Hearing_test

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© Dr Mark Hill 2017, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G