This ailment is recent as far as its incidence is concerned. The majority of cases are labelled BPPV although neither the cause nor the treatment are those of BPPV. We will therefore describe these in detail.
The following concerns a subject who states the following:
"I woke up and while turning over, I was struck by a strong sense of dizziness. I tried to stand up but had to sit back down on my bed and I didn’t know which way was up or down, and I could no longer balance. I lay down with my head upright and after an hour or two, the spinning sensation stopped but I felt very bad. I tried to stand up again but the result wasn’t much better."
"I woke up very early and needed to urinate. I stood up but fell back down again with a very strong dizzy sensation. I had to make my way to the bathroom on all fours and then I went back to bed to lie down. Everything was still spinning. So I lay down with my head tightly wedged in place so as not to move and after about an hour, the spinning sensation faded away. …." These are the ends of the very same story.
In order to differentiate this initial event to those of BPPV, the following can be noted:
- The vertigo is produced by an association of movements: one moves from one position to another followed by a standing up movement.
- The vertigo is stronger when standing up than when lying down and is associated with a non-lateralised debilitating sense of imbalance.
- Rotatory vertigo is the most spectacular of its type, lasting longer than BPPV followed by a sense of unease that the subject tries to avoid by lying down and staying perfectly still.
- This initial event always occurs during the second half of the night, in the early morning as opposed to at night when going to bed.
- As more and more questions are asked, one discovers that the subject also complains of a deep pain in the nape of the neck, in the middle or to one side.
- The vertigo is associated with a constrictive cephalalgia - sensation of their head being “in a clamp”.
- For some time now, the subject has been very tired or has returned from a long and uncomfortable journey.
- Since then, the subject has complained of difficulty in maintaining their concentration (some times) and an irrepressible urge to sleep.
Effectively, all of the above would appear to indicate a vascular disorder of the vertebrobasilar region.
Looking for clues
The apparent similarity of these complaints with BPPV obliges us to verify and look for significant nystagmic signs that evoke BPPV.
The subject, the same as for BPPV, is sitting on the examination table ready to lie down to be able to observe the provoked nystagmus using videoscopy.
When the patient is made to lie down, they say "it’s spinning" but the saccadic eye movements are weak and unrelated to the subject’s complaint. The continuation of provocation manoeuvres does not bring about any significant changes to the minor saccadic eye movement but the repeated action of moving from a seated to a lying position increases the symptoms.
We then put the eye patch on the open eye and continue with the examination. We then see, very distinctly, a torsional nystagmus beating in one direction. This is true whatever the position the head is in. It dissipates gradually, if it dissipates at all. It has a lower amplitude than that of BPPV and the frequency is much lower. Paroxysm is not reached.
When the subject is brought back to the sitting position, the nystagmus beats in the same direction, both amplitude and frequency increase. This observation confirms an increase in the symptoms upon a return to the sitting position. And generally speaking, this is associated with hypotonia, where the subject gives the impression of being a "rag doll".
Experience compels us to note that this vertigo brought on by a change in position is more readily observed in two quite stereotypic population types as far as their morphology is concerned.
A young population type (20-25 years), hypotonic, without actively exercising, sedentary with dismal computer workspace ergonomics. Upon observing their profile when seated, we note a subsidence of the torso with an increase in spinal curvature, compensated by a “jutting chin” head position. We also observe that the head position has moved forward. The cervical-occipital hinge is therefore found with posterior abutment.
The second, older population type (50-60 years old) is one that you would expect to find if the aforementioned young population had put on several years and were at a point where osteoarthritis had set in on their cervical thoracic architecture. We observe a major upper-thoracic kyphosis, compensated by a cervical hyperextension so that the head remains in the vertical position. From the side, we get the same impression that the head is jutting forward. The resulting shearing at the height of the cervical-occipital hinge can be seen as any chains or small necklaces worn by the subject around their neck disappear into the skin fold at the nape of the neck. This population is very familiar with light-headedness when “their head and arms are raised” as they try to reach an object from a height. They might also get the same sensations following an extended period of reading wearing multifocal lenses.
The association of symptoms such as: vertigo, imbalance, headaches, difficulties in staying alert, dysarthria, blurred vision, difficulty with posture etc. from the lying down position to the upright position have been described as being the result of transient haemodynamic ischemic attacks of the vertebrobasilar region (G. RANCUREL).
Some very respected anatomical studies have shown that positional compression of the vertebral arteries between the atlas and axis primarily occur on the edge of the foramen of the axis vertebra (95.4%), that positional compressions between the atlas and the occipital vertebrae occur at the level of the annular ligament of the atlas and/or between the artery and the outer surface of the occipital bone during extension. (F.KOSKAS et al.).
Studies carried out on the influence of the position of the head on the four cervico-cephalic axes have shown that with a rotation of the head of more than 45°, the contralateral vertebral artery could become occluded, as could the ipsilateral carotid artery. When an extension is associated with a rotation, both vertebrae could be occluded. (J. TOOLE).
By associating the morphology of the subjects with the contents of the anatomical studies, we can make the following physiopathalogical hypotheses:
- The onset of an initial event, one that we have called "positional- change vertigo " is the result of a random accident.
- It is the unfortunate association of a number of factors which, when taken in isolation, would be of no importance.
- Nocturnal muscular hypotonia, bad head position with respect to the torso, and low blood pressure.
- This association will occasionally cause a decrease in the vertebral flow contributing to the irrigation of the vertebrobasilar region.
- This pseudo-ischemia will be compensated by the carotid flow (as long as the posterior communicating arteries are functional).
- When there is a change of position, the flow of the vertebral arteries is restored in a region that was compensated. It is the easing of the ischemia that is going to generate the pain in the brain stem brought on by the torsional nystagmus.
- When moving to an upright position, the vascular baroreceptors react by provoking a vasoconstriction which should be compensated by a rise in the heart rate upon moving to the upright position. For some unknown reason, the reaction is unlikely to happen.
- The appearance of symptoms of AIT of the vertebrobasilar region become obvious.
During provocation or research manoeuvres to better understand and provide a diagnosis for this disorder, a position must be found in which the nystagmus disappears.
We have seen that there is, when the subject is lying down on the examination table facing down, a torsional nystagmus beating towards the same side, regardless of head position. In fact, there is, apart from returning to the upright position, a head position where the nystagmus is more intense. This position is generally a rotation to one side (of more than 45°) with the head in extension.
Once the position is reached, the subject must be placed in a diametrically opposed position. In other words, a rotation of the opposite side and flexion.
Example: the subject is lying down and we find that the nystagmus is more intense with the head turned to the left and in extension. The patient is then put into the right lateral decubitus (lying on their right side) with the head turned towards the table and the chin on the chest. In this position, the nystagmus disappears.
We ask the patient to only sleep in one position, no other. They are also asked to avoid any extension movements of the head associated (or not) with raising the arms. They are also asked not to sleep in the "nose on elbow" position or with the hands behind their neck. They are also asked, as part of their activities, not to let themselves slip into their favourite position "with the chin forward ".
Four days later, there is a 75% reduction in the symptoms. This is always the case if the subject follows the recommendations. And regardless of the length of time of the original event.
Why is this not a BPPV of the anterior canal?
BPPV is produced by the movement of an amalgam floating freely in the endolymph. If the head is moved into different and opposing positions, the amalgam should be able to move in any direction. Regardless of which canal the amalgam is in. That is why we believe that the inversion of the nystagmus is essential as it proves that amalgam is moving freely. In VCP, the nystagmus changes in intensity but not in direction.
Could it not be a simple orthostatic hypotension?
Whether it is a vasovagal response, a hypoglycaemia, an orthostatic hypotension, or fainting, there is no rotational vertigo. Conversely, there are always falls with variable-length loss of consciousness.
We thought about carotid sinus syndrome but in the initial description, there was a stimulus such as a tight collar, an electric razor. Furthermore, the stimulus is on the neck, not on the nape of the neck. It is surprising to discover among our sample populations some of the oldest subjects so that the event can almost be produced at will since being fitted with a so-called “anatomic” hearing aid.
We also thought of an autonomic disorder of the nervous system. We read that it is produced in a population of subjects older than our one. Furthermore, there are often signs of cerebellar degeneration.
We thought of a vagoglossopharyngeal neuralgia. ENT specialists are well aware and know that there is always an association of pain at the base of the tongue, pharynx, larynx etc.
How do you test for it?
It is indeed a very likely hypothesis but which, with all humility, has not been verified.
Angiography does not contribute a great deal, and nor does echo-doppler.
This is quite perplexing but can be explained. These two exploration techniques are not used with the head positions that might indicate compression. Conversely, they are able to bring to light certain anatomical differentiations such as an asymmetry of calibre of the vertebral arteries, one dominant and one small, the one with termination into PICA etc. These discoveries (quite rare in our experience) would just be another argument for the precision of the position resulting in compression but nothing more.
Conversely, what are the positive and replicable arguments to support the robustness of this hypothesis?
- the particular morphology of the subjects,
- acknowledgement by the subjects that they are rather hypotensive and subject to orthostatic hypotension (iatrogenic in cases of antihypertensivity),
- the existence in the proceedings days of a fatiguing activity, or raising their arms in the air, or a hyper extension position at the dentist or the after effects of a general anaesthetic (hyper extension through intubation),
- the replicability of significant relief in 3-4 days,
- the association, in addition to the nystagmus of at least three symptoms indicating vascular damage to the brain stem,
- the demonstration, on the cadaver, of the position factors of compression of the vertebral arteries.
There is an obvious need to find arguments and proof to support this hypothesis. But when one sees the deterioration caused by a succession of positional changes from lying down to sitting to confirm the diagnosis, it is certain that the probability of the observed torsional nystagmus being the result of distress of the brain stem is very strong. It appears that the most important thing is not to succumb to the eagerness to carry out a liberating manoeuvre because it is not a BPPV.
In addition to the unrivalled work of Alain Sémont, scientific and medical details about differential diagnosis and the pathophysiologies of VCP are taken from the following publications:
Principles of Neurology by Raymond D. Adams and Maurice Victor
McGRAW-HILL Book Company A Blackston Publication
Vertebrobasilar Arterial Disease by Ramon Berguer and Louis R. Kaplan
Quality Medical Publishing, Inc St Louis
>> Please also consult the bibliography section of this site.