Loudness recruitment phenomenon is associated with
Correct Answer: Cochlear deafness
Description: Ans. d (Cochlear deafness) (Ref. Dhingra 3rd ed., 4, 49; 29, 148)The rapid growth of loudness in ears with sensorineural hearing loss is known as loudness recruitment. Its presence helps signify that the hearing loss is caused by pathology within the cochlea. Recruitment is a symptom of cochlear pathology associated with hair cell damage, particularly to outer hair cells.ASSESSMENT OF HEARING LOSS1. Clinical testsa. Finger friction testb. Watch testc. Speech testd. Tuning fork tests2. Audiometric testsa. Pure tone audiometry (measures threshold of hearing by air and bone conduction and thus the degree and type of hearing loss)b. Speech audiometry (measures ability of patient to hear and understand speech)c. Bekesy audiometry (differentiates cochlear from retrocochlear and organic from functional hearing loss)d. Impedance audiometry, i.e., tympanometry and acoustic reflex measurements (particularly useful in children).3. Special testsa. Recruitment (seen typically in lesions of cochlea, e.g., Meniere's disease, presbycusis)b. Short increment sensitivity index (SISI test)c. Threshold tone decay (Carhart's) test (a decay more than 25dB is diagnostic of a retrocochlear lesion)d. Evoked response audiometry (e.g., BERA)e. Otoacoustic emissionsf. Central auditory testsAcoustic Reflex# Loud sound > 70 dB; causes bilateral contraction of stapedial muscles which can be detected by tympanometry.# Reflex mediated by VII and VIII nerves.# It is protective reflex against loud sound.# Normally, stapedial reflex is elicited at 70-100 dB SL. If patient claims total deafness but the reflex can be elicited, it indicates NOHL (non-organic hearing loss). Hyperacusis in Bell's palsy is due to the paralysis of the stapedius muscle.# Uses:1. Objective method to detect hearing in infants and children.2. To find malingering3. To detect cochlear pathology. Presence of Stapedial reflex at lower frequencies, instead of 70 dB indicates Recruitment and cochlear pathology.4. To detect VIII and VII nerve lesions.
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