The diagnosis of BPPV can be made based upon the history and examination. Patients usually report episodes of spinning evoked by certain movements, such as lying back or getting out of bed, turning in bed, looking up or straightening after bending over. The episodes of vertigo last 10 to 30 seconds and are not accompanied by any additional symptoms aside from nausea in some patients. Some patients that are susceptible to motion sickness may feel queasy and lightheaded for hours after the attack of vertigo, but most patients feel well between episodes of vertigo. If the patient reports spontaneous episodes of vertigo, or vertigo lasting more than 1 or 2 minutes, or if episodes never occur in bed or with head position changes, then one should question the diagnosis of BPPV.
Posterior Canal Type
The diagnosis of BPPV of the posterior canal is confirmed by observing paroxysmal positional nystagmus with the Dix-Hallpike maneuver. The Dix-Hallpike maneuver is performed by rapidly moving the head from an upright to head hanging position with one ear 45 degrees to the side. In Fig. 3, movement from sitting to head hanging comprises the Dix-Hallpike maneuver to each side. The Dix-Hallpike maneuver results in torsional upbeating nystagmus corresponding in duration to the patient's subjective vertigo, and occurring only after Dix-Hallpike positioning on the affected side (Table 1). A presumptive diagnosis can be made by history alone, but paroxysmal positional nystagmus confirms the diagnosis.
(A) Dix-Hallpike positioning maneuver to the right. (B) Dix-Hallpike maneuver to the left. Observe for a latency of 2 to 6 seconds after positioning before the onset of nystagmus. Observe for nystagmus that is upbeating and torsional with duration of 10 to 30 seconds. The side with the downward ear is the affected side in benign paroxysmal positional vertigo of the posterior canal.
Lateral Canal Type
Horizontal canal BPPV may sometimes be evoked by the Dix-Hallpike maneuver. However, the most reliable way to diagnose horizontal BPPV is by a supine head turn maneuver (Pagnini-McClure maneuver) (Fig. 4). The examiner looks for horizontal nystagmus upon turning the patient's head to one side, then turns the head back to the supine face-up position. Then the head is turned to the other side. The side with the most prominent horizontal nystagmus is generally assumed to be the affected side.[14,15]
Supine head turn maneuver to determine the presence and affected side of horizontal canal benign paroxysmal positional vertigo.
The nystagmus of horizontal canal BPPV, unlike that of posterior canal BPPV, is distinctly horizontal and changes direction with changes in head position. The paroxysmal direction changing nystagmus may be either geotropic or apogeotropic (Table 1). Geotropic direction-changing positional nystagmus is right beating upon turning the head to the right and then left beating when turning the head back to the left side. Conversely, the apogeotropic form indicates the nystagmus is right beating with turning to the left and left beating with turning to the right. The latency is often brief, and the duration may be 15 to 60 seconds. This nystagmus appears less apt to fatigue with repeat positioning than in cases of posterior canal BPPV; consequently, patients are more likely to become ill with attempts to fatigue this form of BPPV.
Anterior Canal and Polycanalicular Types
The anterior canal form of BPPV is associated with paroxysmal downbeating nystagmus, sometimes with a minor torsional component following Dix-Hallpike positioning.[17–19] This form may be encountered briefly in the course of treating other forms of BPPV, but occasionally presents de novo. Chronic or persistent anterior canal BPPV is rare. Of all the types of BPPV, anterior canal BPPV seems to resolve spontaneously most often. Its diagnosis should be considered with caution because downbeating positional nystagmus related to brainstem or cerebellar lesions can produce a similar pattern. In a review of 50 patients with downbeat positional nystagmus, Bertholon et al found that three-fourths had central nervous system (CNS) disease, while at least some of the remaining one-fourth of cases were thought to have a form of anterior canal BPPV.
Polycanalicular BPPV is uncommon, but indicates that two or more canals are simultaneously affected at the same time.[19,21] The most common circumstance is posterior canal BPPV combined with horizontal canal BPPV. The nystagmus will nevertheless continue to follow the patterns of single canal BPPV, although treatment may have to be undertaken in stages in some cases.
Occasionally, freely mobile otoconia moving within the lumen of one semicircular canal can be moved during the course of treatment; not back to the vestibule as intended, but to one of the adjacent canals, as the canals all directly communicate with one another. This "canal switch" changes the appearance of nystagmus from that of the original affected canal to that of the newly affected canal.[10,22,23] The most common canal switch is from the posterior to the horizontal and posterior to anterior canals.
Distinguishing from Central Causes
Typical BPPV is usually easily recognized as such and responds to treatment. The forms of positional vertigo that most commonly lead to confusion are those with downbeating nystagmus (see discussion on anterior canal BPPV above), or those in which the nystagmus is not truly evoked by the positional maneuver, but are nevertheless evident while the patient is in the head hanging position. Table 2 outlines some of the features that may help separate central from peripheral positional vertigo. As a general rule, if the nystagmus is anything other than the typical, or if it fails to respond readily to positioning treatments, a central cause should be considered.
Dizziness without Nystagmus during Dix-Hallpike Positioning
Sometimes patients with a history compatible with BPPV report dizziness upon Dix-Hallpike positioning, but no nystagmus is seen. If this occurs on one side but not the other, it is suggestive of BPPV. Repeat positioning is worth trying as sometimes the nystagmus emerges on a second or third attempt, possibly based on the concept of "canal jam." An alternative possibility, especially when the dizziness without nystagmus occurs with Dix-Hallpike positioning on both sides, is another type of vestibular disturbance that is aggravated by the process of quick motion. In the absence of any other neurologic symptoms, some home positioning exercises followed by reevaluation or a limited course of vestibular physiotherapy can be considered.
Semin Neurol. 2009;29(5):500-508. © 2009 Thieme Medical Publishers
Cite this: Benign Paroxysmal Positional Vertigo - Medscape - Nov 01, 2009.