What are contralateral reflexes?
The crossed extensor reflex is contralateral, meaning the reflex occurs on the opposite side of the body from the stimulus. To produce this reflex, branches of the afferent nerve fibers cross from the stimulated side of the body to the contralateral side of the spinal cord.
What is the acoustic reflex pathway?
The acoustic reflex involves sound-elicited middle ear muscle contraction via a neural chain comprising the eighth nerve, cochlear nucleus, superior olivary complex, and ipsi- and contralateral medial facial nerve motoneurons. Acoustic reflexes are recorded using a tympanometer.
What do acoustic reflexes tell us?
Acoustic reflexes measure the stapedius and the tensor tympani reflex generated eardrum movement in response to intense sound. They can be helpful in checking for particular types of hearing loss in situations where patient reliability is questionable. They also occasionally point to central nervous system pathology.
How does the acoustic reflex work?
The acoustic reflex mostly protects against low frequency sounds. When triggered by sounds 20 dB above the reflex threshold, the stapedius reflex decreases the intensity of the sound transmitted to the cochlea by around 15 dB. The acoustic reflex is also invoked when a person vocalizes.
What does elevated acoustic reflexes mean?
An elevated or ab- sent acoustic reflex threshold is consistent with a middle ear disorder, hearing loss in the stimulated ear, and/or interruption of neural innervation of the stapedius muscle.
Which is better ipsilateral or contralateral acoustic reflex?
The mean difference between ipsilateral (86.79 dB peSPL) and contralateral (98.21 dB peSPL) acoustic reflex thresholds was 11.42 dB. These results revealed that acoustic reflex thresholds are significantly better (lower) in the ipsilateral mode.
When is an acoustic reflex pattern considered normal?
An acoustic reflex pattern is considered normal when all four reflexes, right ipsilateral, right contralateral, left ipsilateral and left contralateral are present at normal threshold levels. This demonstrates the functional integrity of all components of both the ipsilateral and contralateral reflex pathways bilaterally.
Where does the contralateral reflex go in the brain?
contralateral acoustic reflex pathways pass through the SOC of the lower brainstem before proceeding to the facial nerve. Con-sequently, brainstem lesions can interrupt transduction of neural impulses resulting in an absence or reduction of acoustic reflex-es elicited with ipsi- and/or contralateral stimulation.
Where does the ipsilateral reflex occur in the ear?
The reflex that occurs in the ear where the stimulus is presented is called the ipsilateral reflex. The reflex that occurs in the ear opposite to where the stimulus is presented is called the contralateral reflex. The Acoustic Reflex Pathway Different neural pathways are involved in eliciting the ipsilateral and contralateral acoustic reflexes.