As someone who did impedance tests for many years, I never had any problem with this.  The probe went in one ear, the sound stimulus in the other, and the contralateral stapedial reflex was measured.  I never saw any real need for an ipsilateral reflex, ie sound stimulus into the same ear as the recording probe.  Admittedly, I did also record tactile stapedial reflexes, testing ossicular integrity homolaterally, which I regard as essential.   I reported results on a form containing a diagram of the head, so there was no doubt as to which ear(s) had been tested.

Nowadays, with frequent clinical use of tests of the ipsilateral stapedial reflex arc, the situation is so confusing that I often have to give up reading recent papers as I can rarely work out which ear(s) and which arc has been tested.  So my every sympathy for any student nowadays having to work this out.   People are entitled to do whatever tests they like, but in reporting them, they should make crystal clear which are the stimulus and probe ears, and a diagram of the arc should be mandatory. Actually,  I am yet to be persuaded that homolateral acoustic reflex testing is worth the bother.

There two schools on measuring Acoustic Reflex in Contra-lateral ear.  One is contra with reference to Probe ear (Right Contra : Probe in Left ear and Stimulus in Right Ear). Some Other consider contra with reference to stimulus ear (i.e Right Contra: Stimulus Presented in Left ear). Usually what specified in books is contra with reference to Probe Ear. 

Vijay

As Vijayakumar says, the situation is hoplessly confused.   The convention used needs to be explicitly stated in each published paper.

Thanks Vijayakumar. Yes, I really do agree with Anthony as it is extremely confusing which ear to be the probe or stimulus ear. Several research papers describes in different ways and in most of the instruments the contralateral reflexes are measured with reference to the probe ear. It is high time that the term is clearly defined.

Also, while doing the Right Reflex decay test which contralateral (Probe in Right Ear, Stimulus in Left)  threshold need to be considered?

I do completely agree Anthony G Gordon that it needs one standard term to be followed at least across Audiologist.  As far I know In the older books used convention of Probe ear. I definitely don't remember when did it change. now both conventions been followed. This is causing a lot of confusion across readers and also for students.

"And while testing reflex decay in the right ear, which contralateral reflex threshold is to be taken?"

Let us suppose you suspect a neuroma in the right ear, and you wish to test for decreased loudness (reflex tone decay).   In my day, the loud stimulus went into the right ear, and the reflex was recorded by the probe in the left ear.   I never had any problem or difficulty with this, and cannot see any advantage in measuring an ipsilateral acoustic reflex (ie, probe in right ear, sound simulus in right ear).   In fact, there is a potential advantage in recording the reflex from the normal side, where the non-acoustic sections of the reflex arc are more likely to be normal.

Thought I'd add my two cents of confusion to the discussion. It has been about two decades since I was involved with acoustic reflex research, but I recall that between 8-12% of nerve fibers in the reflext were ipsilaterall and the rest contralateral, so I've always assumed that any acoustic reflex test performed on human ears could be safely considered a contralateral side test. The fact that screeners for impedance assume a ipsilateral response in impedance does not apply in my thinking to reflex testing. An interesting example about 15 years ago one of my staff handed over what appeared to be a confusing test result--female in late 30s who had been on the shooting range a few of weeks before complaing of a unilateral tinnitus and a dead sensation at the TM. Upon closer inspection via video otoscopy I noted coming straight out of the umbo region of the TM a long fairly straight piece of keratin rolled out like a DNA strand. I would estimate, at the growth rate of about 1mm/day, that this was about a three week length of keratin. In the earlier audiometric test results acoustic threholds were about 30 dB PTA on the opposite ear and tinnitus buzz subjectively emanated from the opposite ear, as well. I showed the patient the keratin strand and asked if she minded if I removed it with lighted tweezers. She consented, and a small pull and momentary surprise from her it came out easily with my tweezers. Within seconds she reported the contralateral tinnitus stopped completely and upon threshold verification acoustic thresholds returned to the same 0-10dB PTA level of the opposing ear. Now, the moral to the story as it may apply as we have a number reflex arcs surround the auditory function, and all of them are dominated with contralateral reflexes (in this case tensor tympani) and only weakly ipsilateral. Only the acoustic signal as heard through the sequela of outer/middle/inner ear are direct perceptions--and they, too, lateralize to the opposite cortical apparatus--until the signal is heard bilaterally, then, ipsilateral additions come into play for an additive effect.  

 "and all of them are dominated with contralateral reflexes (in this case tensor tympani)"

In my experience (longer ago than Max!) the tensor tympani is only activated as part of the startle reflex.  As one of the few non-Scandinavians who routinely tested the homolateral tactile stapedial reflex (gently touching the outer ear around the probe), my impression was that this is stronger and larger than the acoustic stapedial reflex.  This tactile reflex protects the ear against loud sound, as the pressure wave is detected by the skin near the ear so can cause stapedial contraction before the sound reaches the cochlea.

Excellent description, Anthony and my findings exactly. I first lectured on the startle reflex/tensor tympani reflex back in 1978 at age 30 (smile), whch was a novel construct at the time. We also found that acoustic levels above about 90-92dB SPL could incite the tactile reflex. I might be off on the number, but I recall we were amazed it was so consistent from person to person. When I see the FDA warnings at 130 dbSPL on hearing aids I wonder where they came up with that figure--the tensor tympani, the acoustic reflex, and spiral ganglia are all in shockwaves by that point. Years later I was discussing this with my late dear friend Margo Skinner at Washington U, as were working on contraindications for the then new multichannel cochlear implant...some of the long time users of power body worn aids had been bombarded for so long that getting a promuntory stimulus response at even 90 dB+ on I think 100 Hz was impossible, technically invalidating candidacy. We then went on a campaign to warn clinicians everywhere to be careful at such high sound levels as they risk keeping their patients from ever benefitting from cochlear implants.     

 "I first lectured on the startle reflex/tensor tympani reflex back in 1978 at age 30 (smile), whch was a novel construct at the time."

I was using the startle/TT reflex from the early 1970s, but all my information on it came from Scandinavian authors.

"We also found that acoustic levels above about 90-92dB SPL could incite the tactile reflex"

I don't follow this.  Is this the sound level loud enough to elicit the tensor tympani reflex? I would routinely elicit the TT reflex by a strong unanounced air puff into the ipsilateral eye.   By tactile reflex, I mean the stapedial reflex elicited by minimal circa-aural touch.

As Dr. Vijaya Kumar Narne explained - Contralateral reflex is identified based on Probe ear method (Right contra - tone in left ear) or stimulus ear method (Right contra - tone in right ear). 

There is a need for usage of a common method among audiologists as the interpretation varies depending on the method used. Thus, for a common understanding among audiologists, it is important to use a common method for representing contralateral reflexes. 

Most of the books and also immittance instruments (Grason-Stadler 1738 and Tympstar; Madsen Zodiac 901; Maico RaceCar, MI-24, MI-26, and MI-34; Micro Audiometrics EarScan) etc use "Probe Ear orientation".  However, ANSI recommends usage of "Stimulus Ear orientation". 

There was a survey done by Emanuel (2004) on use of stimulus or probe ear for contralateral reflex among practicing audiologists. Result showed 69% were using "Stimulus ear" orientation. I have attached the article for reference. 

This is a very relevant question and needs to be addressed universally among audiologists to use a common interpretation method which assists in better communication of test results.

Regards,

Prashanth 

Regarding Reflex decay test - According to the actual test procedure described by Anderson, Barr, Wedenberg (1970) - reflex decay test is done in the stimulus ear. Probe ear testing is avoided because of artifacts. With the advanced immittance instruments, there are less chances of artifacts but still preferred method is assessing stimulus ear. 

Thus, when reporting the results for Reflex decay test - We need to just report saying reflex decay is positive or negative in the ear in which the stimulus was presented. 

Regards,

Prashanth 

"Ipsilateral stimulation is necessary for measuring wide-band reflectance."

Could you expand on this, please William?  How does this help with clinical diagnosis?  What useful information is gathered that is not obtained with the probe in one ear, loud sound stimuli in the other, and homolateral tensor tympani and tactile stapedial reflexes?

As some of you might remember (if you are old like me) there was a time when the acoustic reflex was always "contralateral".  Stimulation was to one ear, and the resultant impedance change was measured from the other (probe) ear.  The practice of measuring the ipsilateral acoustic reflex added the potential for confusion, particularly when talking about the reflex.  This confusion can be avoided by using language such as "the acoustic reflex was present in the right ear, following ipsilateral and/or contralateral stimulation".  When measuring reflex decay, the ear of concern should be receive the acoustic stimulation.  I would suggest contralateral stimulation (probe in one ear and stimulation of the other ear).  If there is concern for retrocochlear involvement in right ear measuring reflex decay with ipsilateral stimulation (probe and sound stimulation in same ear) maybe useful if the left ear has an abnormal tympanogram.