Hallpike test is a diagnostic test for BPPV & not for complete bilateral vestibular failure which can be assessed by caloric test.
There is no VOR. So, Hallpike Test will be always negative.
Hi. I Agree with Hazem & Roseli too. Dix-Hallpike, head thrust and head shaking tests are all for vestibulo ocular reflex testing, and if there is a complete bilateral vestibular failure there shoud be no answer for this tests, this is no nystagmus or vertigo should be elicited afterthose tests are performed.
Averyone agree with that? right?
I agree with all the above. Any eye movement during a Dix-Hallpike test in a person with bilateral vestibular loss would be unpredictable and should not follow a known pattern. At the bottom line, a person with bilateral vest.loss should not experience BPPV symptoms.
Dear colleagues
The HSN is a test documenting the VOR asymmetry between ears. If there is no response bilaterally, there is no asymmetry, so the test will always be negative.
On the other hand, the HIT is a specific test to document the absence of the VOR. Since there is no VOR on both sides, we hope that it will be positive for both sides. The patient can´t fix the eyes on the target if there is no vestibular command.
The Hallpike test may refer to BPPV (Dix-Hallpike), or to calorics, since the test protocol was established at Queen Square by Hallpike et al.
See extract from Gibson 1980):
"Thornval (1917) originally suggested the use of bithermal caloric testing, but it was Dr. C. S.. Hallpike and his colleagues (Cawthorne, Fitzgerald and Hallpike, ..."
Calorics only test part of the vestibular system, and even there iced water may be needed to demonstrate function in the part that is tested. It is not easy to show complete absence of vestibular function, and in fact I do not think there is a case of total congenital vestibular absence (see my RG question on this).
For me the Hallpike test is always negative if the the bilateral vestibular failure interest the 3 semi circular canals.
Hey, I just saw this. For what it is worth, I think that the Dix-Hallpike test for BPPV may well produce an abnormal response (although not a response characteristic of BPPV) in a patient with bilateral caloric areflexia, bilaterally positive head thrust test or even canal plane head thrust, absence of a response during rotary chair testing, absent cVEMP or oVEMP, etc. Whether or not such a patient has complete peripheral loss is unknown, I guess, although they probably don't have much vestibular input.
One reason for this is that neck afferent inputs underlying the cervico-ocular reflex are potentiated with a bilateral loss of vestibular function, and the classic Dix-Hallpike test will drive those afferent inputs. Centrally, the system is basically unstable. You can, in fact, occasionally see a significant nystagmus in response to the Dix-Hallpike maneuver in such patients. It is just not the classic rotary nystagmus that you would observe with a positive test for posterior canal BPPV.
WRT post head shake nystagmus, you can still get that in someone who has bilateral vestibular areflexia (as defined by the criteria above), for the same reason perhaps. Any head on trunk rotational testing or repositioning presents you with the same issue.
I think that the Dix-Hallpike test for BPPV may produce an absent response. That would be of course, in the case of a total bilateral vestibular loss (tested by vHIT, rotatory chair and DVA).
Concerning about the complete peripheral loss, what about Usher syndrome?
"Concerning about the complete peripheral loss, what about Usher syndrome?"
Usher syndrome is usually an acquired degeneration. If it has occurred in utero and completely destroyed the vestibular system, then I think the fetus would have died. I am still waiting for any example of a viable infant born without any vestibular system. One is enough to demolish this theory.
Usher syndrome is a genetic disorder characterised by a total abscense vestibular fucntion.
Later in the puberty they usually develop visual disorders.
I've seen many patients with Usher syndrome type I and II, and they do not have any vestibular function.
Caloric, rotatory test shows a lack of vestibular responses. Actually they have a significant motor retardation and slight oscilopsia which is usually increased in dark enviroments.
It is not as unusual to find from time to time a patient with bilateral vestibular loss.
The problem is that, we rather reach a correct diagnosis
Extracts from Wikipedia:
"People with Usher I are usually born deaf and often have difficulties in maintaining their balance owing to problems in the vestibular system. Babies with Usher I are usually slow to develop motor skills such as walking...These genes function in the development and maintenance of inner ear structures such as hair cells (stereocilia), which transmit sound and motion signals to the brain. Alterations in these genes can cause an inability to maintain balance (vestibular dysfunction) and hearing loss. The genes also play a role in the development and stability of the retina..
People with Usher II are generally hard-of-hearing rather than deaf, and their hearing does not degrade over time; moreover, they generally have a normal vestibular system. .
..people with Usher III experience a 'progressive' loss of hearing and roughly half have vestibular dysfunction."
Conclusions:
1. Usher syndrome is a complex and varied mixture of sub-syndromes.
2. Vestibular function may be normal.
3. Progressive loss of sense organs may occur.
4. Whilst there may be total loss of vestibular function, the timing of this remains to be established, especially in an individual case.
I accept that Ushers is heterogeneous, but kids with Usher type I virtually always present with complete vestibular areflexia and profound bilateral hearing loss on testing. I take your point that you can't rule out some residual vestibular function that is missed by testing, but vestibular assessment is used reliably to screen for Ushers Type I. Yes, there may be very rare examples of an Usher's type I variant that may have some sort of progressive loss of auditory/vestibular function, but this is not really clear. WRT the other types of Ushers, sure, vestibular loss is either progressive, mixed or non-existant. But in Type 1, that presentation is rare as a hens tooth even for a rare disorder.
WRT your hypothesis that absence of vestibular function before birth results invariably in death, which I think is cool to think about: What evidence would you accept in a living human infant? Would you accept bilateral absence of a defined vestibular labyrinth on imaging? How about bilateral absence of an 8th nerve? At what point would these images need to be obtained? Is histology required? When would the histology have to be obtained? I am simply wondering how this hypothesis could actually be tested. Short of histological confirmation, you could always assert correctly that the imaging of the temporal bone and posterior fossa in general is crummy (you can't even see a dehiscence half the time unless you use specialized protocols, and even then you are occasionally wrong), or that the anatomical defect progressed after birth, or whatever. Just curious.
there are no answers at the Hallpike test if all the functions of the inner ear including the otolith system are destroyed.
"What evidence would you accept in a living human infant? Would you accept bilateral absence of a defined vestibular labyrinth on imaging?"
No.
How about bilateral absence of an 8th nerve?"
No
" Is histology required?"
In the first instance, we need histological studies showing complete absence of vestibular sense organs in BOTH ears of an infant. When I checked some years ago, I could not find such a reported case. Just one such case of an infant surviving birth would seriously undermine my thesis.
" Short of histological confirmation, you could always assert correctly that the imaging of the temporal bone and posterior fossa in general is crummy"
I vividly remember witnessing this conversaion many years ago:
Mother: My son definitely heard before a recent infection.
Pediatric Otologist: Impossible! The scan shows complete absence of an inner ear on that side.
The mother may have lost the battle, but I think she has won the war.
Studies of miscarriages may be more to the point. For example, congenital syphilis affects the ear, so is that the reason for increased miscarriages? A minor consideration perhaps, but this probably completely altered the course of English history (cf Henry VIII's syphilis and the disastrous obstetric history of his wives).
Hi:
I take your points. However:
I guess my point is that this is basically an entertaining but untestable hypothesis. It is so unlikely that this rare situation would come to autopsy and the temporal bone would be disected, or that such an infant would be recruited into a temporal bone bank, that it is just sort of a plausibility argument. The absence of available "adequate" evidence that such infants can survive is basically meaningless. It surely doesn't indicate that they do not survive, or that such a situation is impossible.
Indeed, the best available evidence is that such patients do in fact exist. That they are rare, is perhaps an argument on your side. But, such patients have no evidence of vestibular function on testing, and the MRI, CT, or both suggest that they have no semicricular canals and they have complete bilateral atresia of the IAC. You can argue that there must be some vestige of vestibular function, but the weight of evidence is against your argument (Heny the VIII not withstanding).
This is a very interesting and perhaps philosophical question. We are a long way from being able to measure the function of the vestibular system. It is worth considering that the amount of neuroepithelium within each utricle is roughly the same as in the cochlea. We can measure (presumably) utricular function using oVEMP, but the results are essentially either 'present' or 'absent'. If a patient is sent for an audiogram and the result comes back as 'present' or 'absent' we would consider this wholly inadequate - we would ask about thresholds, frequencies, discrimination and all of the wealth of information we get get from a hearing test. 'Present' would just not cut it. Getting a 'present/absent' result from an oVEMP is all we have right now, but we need to be mindful that the detail we need from otolith testing is a long way from being available.
With this in mind and also taking into account that caloric tests can be extremely misleading (near areflexia on vHIT or scleral coil testing with normal caloric tests is not an uncommon finding) it is nearly impossible to be certain of vestibular 'areflexia'. What this says about the expected Hallpike results in 'areflexia', in my view, is that we cannot know for certain anything about a system we cannot test.
The obvious 'Catch-22' is that anyone with relatively certain areflexia (such as some of the examples mentioned above) or even a theoretical case of total areflexia, would not be able to be shown to have cupulo/canalithiasis in any meaningful way so as to test the theory of what occurs when the Hallpike test is performed.