The majority of cases of positional vertigo are attributed to the condition of benign paroxysmal positional vertigo (BPPV). BPPV occurs when otoconia migrate into the semicircular canals of the inner ear, resulting in nystagmus and a sense of vertigo that occurs with head movement or position change. Most cases of BPPV impact the posterior semicircular and are readily treated with canalith repositioning procedures. Unfortunately, we frequently see patients that have been misdiagnosed with BPPV that never received appropriate evaluation.
The diagnosis of BPPV should be made by attempting to elicit symptoms through dynamic positioning testing such as the Dix Hallpike/Roll test, while monitoring for nystagmus consistent with BPPV. It is worth noting that BPPV can have a high false negative exam rate and a negative exam doesn’t rule out BPPV. In cases where we suspect BPPV, but were unable to elicit nystagmus or symptoms on examination, we typically recommend a trial of canalith repositioning. We complete a vestibular evaluation and ensure that the individual is capable prior to recommending home canalith repositioning procedures. We also make it clear to our patients that additional in office follow up is indicated if the symptoms do not improve with home repositioning.
For those unfamiliar with BPPV, a more thorough review can be found here.
What is positional vertigo when it’s not posterior semicircular canal BPPV?
There are a multitude of potential other causes for positional vertigo and I will attempt to summarize many of the potential pathologies. Some of these conditions may or may not have nystagmus associated. In cases where nystagmus is present, it is key to take note as to whether the nystagmus is spontaneous or if it is only provoked by position change. There are also a variety of potential patterns of nystagmus that may present, well beyond the scope of this blog. Instead of detailing the many potential nystagmus patterns for each condition, I will instead include links or references for the majority of these conditions where more information can be found. In general, central (brain) nystagmus will present differently than peripheral (ear) nystagmus and there are general rules that are utilized to differentiate between them.
It is worth noting that some patients may exhibit clinically insignificant positional nystagmus. Reports show that 10 to 20% of the time there may be evidence of mild, clinically insignificant positional nystagmus, typically less than a 5 degree/second slow phase velocity. (Roberts, Bittel and Gans 2016) Clinically insignificant positional nystagmus will not be discussed.
Peripheral or Labyrinth Related
- Atypical BPPV: geotropic and ageotropic horizontal semicircular canal, cupulolithiasis, as well as anterior semicircular canal BPPV (more on these here). This could also include other theoretical variants such as a canalith jam or even type II BPPV.
- Labyrinthine instability: semi-acute vestibular neuritis, cases of labyrinthine trauma or pneumolabyrinth, and Ménière’s disease. Even cases of vestibular schwannoma may cause nystagmus that is most evident with change in position
- Light cupula
- Third mobile window syndromes (TMWS)
Central or Brain Related
- Orthostatic hypotension– Based on clinical experience, some individuals do report the dizziness associated with orthostatic hypotension as being a sensation of vertigo rather than the more typical sensation of lightheadedness. Nystagmus would not be expected with orthostasis.
- Idiopathic intracranial hypertension
- Vestibular paroxysmia
- Medications/drugs- There are a multitude of prescription medications and illicit drugs that can result in a variety of positional nystagmus patterns. One of the most comprehensive lists that I am aware of can be found in the Neurology of Eye Movements text, fifth edition, on page 990
- A brain tumor has the potential to cause positional nystagmus.
- Chiari malformation– often results in a persistent down-beating positional nystagmus
- Cervical vertigo– could account for a number of disorders including: vertebrobasilar insufficiency, rotational vertebral artery compression such as bow hunter syndrome, and cervical chord compression to name a few.
- Multiple sclerosis
- Spinocerebellar ataxia type VI
- Persistent postural perceptual dizziness (PPPD)
Below I have included some of the key features of central and peripheral nystagmus patterns. A more in depth review of central versus peripheral nystagmus can be found here.
- Purely vertical, torsional, or oblique
- Could be nystagmus patterns other than jerk nystagmus (pendular, etc.)
- Direction changing nystagmus
- Nystagmus may increase in intensity or change nystagmus pattern with horizontal gaze
- Doesn’t suppress with visual fixation
- Jerk nystagmus
- Typically horizontal (BPPV is the main exception and is most often a transient up-beating and torsional)
- Direction fixed as long as the same position is maintained
- Should increase in intensity with gaze toward the fast phase (Alexanders law)
- Suppresses with visual fixation
In summary, there are a plethora of potential causes of positional vertigo other than BPPV. It is essential to be able to interpret nystagmus patterns, as well as integrate additional medical history and examination findings, in order to determine the source of the positional vertigo.
If the symptom time course and findings are not clearly BPPV, then it is key to realize the multitude of other pathologies on the differential.