Wave V on BERA is generated at:
A. Cochlear nerveB. Superior olivary nucleus
C. ventral nucleus of lateral lemniscus
D. Inferior colliculus
E. nuclei of lateral laminiscus
The
Answer is. E. nuclei of lateral laminiscus[Refer Figure # 13]
BERA:
Synonyms: Brain stem evoked response
audiometry, auditory brain stem response, ABR audiometry, BAER (Brainstem
auditory evoked response audiometry).
Bera is an objective way of eliciting
brain stem potentials in response to audiological click stimuli. These waves
are recorded by electrodes placed over the scalp.
MCQ: - first described by Jewett and
Williston in 1971.
Process: The stimulus either in the form
of click or tone ‘pip’ is transmitted to the ear via a transducer placed in the
insert ear phone or head phone. The wave froms of impulses generated at the
level of brain stem are recorded by the placement of electrodes over the scalp.
In auditory brain stem evoked response
audiometry, the impulses are generated by the brain stem. These impulses when
recorded contains a series of peaks and troughs. The positive peaks (vortex
positive) are referred to by the Roman numerals I - VII.
These peaks are considered to originate
from the following anatomical sites:[vFAQ]
1. Cochlear nerves - waves I and II
2. Cochlear nucleus - wave III
3. Superior olivary complex - wave IV
4. Nulclei of lateral lemniscus - wave V
5. Inferior colliculus - waves VI and VII
These peaks occur in most readable form in
response to click stimuli over a period of 1 - 10 milliseconds after the
stimulus in normal hearing adults.
BERA is resistant to the effects of sleep,
sedation, sleep and anesthesia. Its threshold has been found to be within 10dB
as elicited by conventional audiometry.
