Timothy C. Hain, MD
Page last modified:
July 4, 2011
Although BPPV accounts for the overwhelming majority of cases of positional vertigo, there are also other possibilities.
This entity is also called "bow hunter's syndrome". It consists of central symptoms caused by interruption of one of the vertebral arteries when the head is turned to the opposite side. It is usually of significance only in persons who have a substantial asymmetry in their vertebral circulation -- one being much smaller, or one being absent or terminating in PICA.
It is presently considered a problem when there is mechanical compression during head rotation due to muscular and tendinous insertions, osteophytes, and arthritis around the C1-C2 level. Dynamic cerebral angiography is the preferred method of documenting this diagnosis.
This is not a common syndrome -- the author has seen only 2 patients in his 20 year career that fit this pattern. According to Choi et al (2005), who reported 4 cases, vertigo, tinnitus and nystagmus are due to labyrinthine ischemia. In general there is a mixed downbeat/torsional/horizontal nystagmus beating towards the compressed vertebral artery (i.e. away from the direction of head turning). In three patients the nystagmus spontaneously reversed direction. The nystagmus appears after a latency of about 5 seconds (the author has seen a patient in which it took 20 seconds). On repeat of head rotation, the nystagmus may be lessened.
Surgical intervention, when the patient is a good candidate, is recommended in persons with bow hunter's sydrome. As it would seem that all of these cases must be congenital, and also many persons function quite well with only one vertebral artery, in our opinion, this should be considered with great care.
Cervical vertigo is a more general term for dizziness that is provoked by turning of the head on trunk, largely independently of gravity. Vertebral artery compression is a rare variant of cervical vertigo. See the link above for more.
CPV is a rare cause of positional vertigo, due to structural lesions in the cerebellum, especially the cerebellar nodulus and uvula. There are a number of potential causes -- CPV is nearly universal in persons with medulloblastoma, which is a tumor that arises in the cerebellar nodulus. CPV is also somewhat common in the Arnold-Chiari malformation and the related disorder of basilar invagination, and after strokes, tumors or multiple-sclerosis lesions involving the brainstem or cerebellum area. There are numerous rare cerebellar degenerations that can also result in central positional vertigo.
Ordinarily this diagnosis is made by noting a positional vertigo, finding that it does not respond to exercises for BPPV, and then further investigation.
Concerning BPPV, posterior canal BPPV is rarely confused with CPV. On the other hand, the physical findings of anterior canal and lateral canal BPPV (non-PC BPPV) are less specific. Non-PC BPPV can be misidentified as CPV, and CPV can be misidentified as non-PC bppv. We have had several cases in which lateral canal BPPV was initially diagnosed, and later on a brain tumor was discovered. In our opinion, imaging of every patient with vertigo is not needed, but if patients do not respond to the usual treatments effective for their diagnosis, then further imaging is reasonable.
Treatment of central positional vertigo, other than attempting to correct the cause, is not well worked out. Generally one attempts treatment with vestibular suppressants and centrally acting drugs.
Microvascular compression syndrome
In this syndrome, mechanical compression of a normal or irritable 8th nerve is postulated to create vertigo. The general idea is reasonable enough but current diagnostic technology is not good enough yet to diagnose this syndrome.
Orthostatic hypotension (dizzy on standing)
This is not a vestibular syndrome, but rather a simple situation where blood pressure drops on standing. It is discussed in detail in the link above.
Meniere's syndrome and otolithic disturbances
As the otiliths are gravity sensors, it follows that otolithic disorders should cause abnormal reactions to gravity.
Yagi has suggested that lateral canal BPPV is sometimes actually due to utricular damage (2001). This conclusion was based on the observation that geotrophic direction changing nystagmus is not directed in canal coordinates. While we accept Yagi's observations, the conclusion that the utricle is the generator seems somewhat tenuous. Follow this link for more information about the utricle.
In hydrops, which is universal in Meniere's disease as well as common in the general population (about 10% on autopsy), the otolithic organs are distended. Follow the links above for more.
With respect to disorders in which there is a mismatch of endolymph and cupula density, the most commonly encountered is positional alcohol nystagmus (PAN). Commonly, when people imbibe a fair amount of an alcoholic beverage, they discover that upon lying down a strong vertigo ensues. This is caused by a difference in the rate that alcohol (which is lighter than water) enters the cupula of the inner ear compared to the endolymph.
We have seen a case in which we suspected that pneuomolabyrinth caused a positional nystagmus. This was a case of a man with a temporal bone fracture.
Similar syndromes occur in situations where the cupula is weighted down (e.g. cupulolithiasis), and perhaps also in situations where there is an alteration of the density of the endolymph by disease (i.e. Waldenstrom's macroglobulinemia, and perhaps autoimmune disorders). This possibility has not been considered in detail in the otologic literature.
Hearing has positional modulation to a lesser extent than does vertigo. Low-CSF pressure syndrome may cause hearing to be reduced on standing.
It may be possible for people with gastroesophageal reflux to have reduced hearing on lying flat, as well as serous otitis media from reflux (Heavner et al, 2001; Tasker et al, 2002).
Occasionally persons with sleep-apnea develop positional hearing syndromes, presumably related to pressurization of the middle ear during sleep, making it a variant of barotrauma.
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