Although the repositioning maneuvers have a substantial success rate, they are not expected to solve the at yet unknown origin of clod or debris formation, which may explain the substantial number of re/occurrences of BPPV. Patients with persistent symptoms of vertigo, dizziness, or unsteadiness at the time of reassessment of the initial treatment response are classified as treatment failures. Treatment failures require reevaluation for the following reasons: 1) Persistent BPPV may be present and responsive to additional maneuvers; 2) coexisting vestibular conditions may be present that can be identified and treated; and 3) serious CNS disorders may simulate BPPV and need to be identified (Furman, et al., 1995) (Furman, et al., 1999) (Rupa, et al., 2004).

Persistent BPPV

Patients with BPPV who initially are treated with observation may fail to resolve spontaneously and have persistent BPPV at the time reassessment. Also, on the basis of failure rates of vestibular rehabilitation or a single-session PRM ranging from 15 to 50 percent, a significant number of patients initially managed with vestibular rehabilitation or PRM will have persistent BPPV at reassessment, which also indicates a treatment failure Furman, et al., 1999) (Hilton, et al., 2004) (Cohen, et al., 2005) (Teixeira, et al., 2006) (von Brevern, et al., 2006). Reevaluation of a treatment failure should include obtaining a history of vertigo, determining if the vertigo is provoked by positional change relative to gravity (ie, lying down in bed, rolling over, bending down, or tilting the head back), which then suggests persistent BPPV. As with the original diagnostic criteria, the Dix-Hallpike test should be repeated to confirm the diagnosis of BPPV. If the Dix-Hallpike maneuver is still positive, repeat PRMs can then be performed as a preferred treatment. The rate of successful treatment of BPPV reaches 90 to 98 percent when additional repositioning maneuvers are subsequently performed (Brocchetti, et al., 2003) (Beynon, et al., 2000). Therefore, the PRMs are the treatment of choice for initial BPPV treatment failures deemed to be due to persistent BPPV.

A similar approach may be adopted for the reevaluation of persistent symptoms of vertigo after an initial diagnosis of lateral canal BPPV. The supine roll test should be repeated and, if characteristic nystagmus is elicited, a PRM appropriate for lateral canal BPPV may be repeated as well. There are limited data regarding the management of treatment failures after PRM for lateral canal BPPV, because this condition seems to respond more consistently to PRM and it also has a higher spontaneous resolution rate (Tirelli, et al., 2004) (Sekine, et al., 2006) (Fife, et al., 1998) (Asprella Libonati, et al., 2005). Some studies indicate cure rates of 86 to 100 percent with up to four PRM treatments in lateral canal BPPV (Casani, et al., 2002) (Chiou, et al., 2005). Further subanalysis suggests that the apogeoptropic variant of lateral canal BPPV may be more refractory to therapy (White, et al., 2005) (Casani, et al., 2002).

A small percentage of patients initially diagnosed and treated for lateral canal BPPV or horizontal canal BPPV may experience a canal switch. In these cases, initial horizontal canal BPPV may transform into posterior canalBPPV in up to 6 percent of cases (Nuti, et al., 1998) (Tirelli, et al., 2004). Similarly, a small fraction of patients (also approximating 6%) initially presenting with posterior canal BPPV may transition after treatment to lateral canal BPPV (Yimtae, et al., 2003) (Herdman, et al., 1996). A small subset of patients who do not respond to treatment for posterior canal and/or lateral canal BPPV may suffer from anterior canal BPPV, and may need to be evaluated accordingly (Jackson, et al., 2007). Finally, although rare, two semicircular canals may be simultaneously involved. The second canal’s involvement may become evident at the time of reassessment if one of the involved canals was appropriately treated (Rupa, et al., 2004). Thus, reassessment of persistent positional vertigo in BPPV should include examination for involvement of other semicircular canals than originally diagnosed. Coexisting Vestibular System Dysfunction A BPPV treatment failure subsequently may be found to be a case manifesting vertiginous symptoms that are provoked by head and body movements in general (ie, not primarily provoked by positional changes relative to gravity); unprovoked (ie, spontaneous) episodes of vertigo occurring while not moving; or in fact, a constant unsteadiness. These specific findings should be identified by clinicians at the time of reevaluation; such findings suggest the presence of vestibular system dysfunction associated with or in addition to the initially treated BPPV. There may be several possible factors at play when vestibular system dysfunction accompanies BPPV.

In a study by Monobe et al, (Monobe, et al., 2001) treatment failure of the PRM was most commonly seen in patients with BPPV secondary to head trauma or vestibular neuritis. Because vestibular neuritis and head trauma are both frequently associated with vestibular dysfunction, the cause of persistent symptoms following treatment of BPPV is likely related to widespread dysfunction within the vestibular system in this setting (Bergenius, et al., 1999). Because BPPV is more common in patients with Ménière’s disease and migraine, vestibular system dysfunction associated with these disorders can lead to prolonged symptoms of BPPV, greater chance for recurrence of BPPV, and increased risk for falls, particularly in older persons (Gordon, et al., 2004) (Roberts, et al., 2005) (Hughes, et al., 1997) (Dornhoffer, et al., 2000) (Uneri, et al., 2004) (Kayan, et al., 1984).

In addition, BPPV not associated with any other ontological or neurological disease can still be associated with an underlying impaired vestibular function, and these individuals are more likely to have incomplete resolution of symptoms even if their Dix-Hallpike testing normalizes with PRM (Pollak, et al., 2002). Finally, transient vestibular dysfunction can also occur following repositioning maneuvers. Evidence suggests that balance function continues to be affected between 1 to 3 months after repositioning maneuvers, and that some of these patients may need additional balance therapy (ie, counseling, vestibular rehabilitation) to prevent falls and decrease their fear of falling after the vertigo from BPPV has resolved (Blatt, et al., 2000) (Chang, et al., 2006) (Giacomini, et al., 2002) (Black, et al., 1984). Thus, reevaluation of BPPV treatment failures should include a search for these associated conditions.

When coexisting vestibular system dysfunction is suspected, additional testing should be considered. This testing may include audiometric testing to screen for Ménière’s disease and nerve VIII pathology such as acoustic neuroma, vestibular function testing to detect central and peripheral vestibular dysfunction, and CNS imaging to detect CNS pathology. Such subsequent testing will need to be tailored to the clinical presentation, and clinicians should exercise their clinical judgment. Vestibular rehabilitation has been shown to be an effective treatment for vestibular symptoms due to the potentially persistent vestibular dysfunction associated with BPPV; this treatment may reduce the risk for falls (Angeli, et al., 2003).

CNS Disorders Masquerading as BPPV Although vertigo of central origin is frequently associated with neurological symptoms such as gait, speech, and autonomic dysfunction, it is important to recognize that, rarely, CNS disorders can masquerade as BPPV (Bertholon, et al., 2002). Many of these have been previously discussed in the section on differential diagnosis, but the relative likelihood of their diagnosis increases in the face of initial treatment failure. In one study, a CNS disorder that explained BPPV treatment failure was found in 3 percent of patients (Dal, et al., 2000).

Whenever the signs and symptoms of BPPV are atypical or refractory to treatment, additional history and physical examination should be obtained to address the possibility of undiagnosed CNS disease (Smouha, et al., 1995). Patients with symptoms consistent with those of BPPV who do not show improvement or resolution after undergoing the PRM, especially after two or three attempted maneuvers, or those who describe associated auditory or neurological symptoms should be evaluated with a thorough neurological examination, additional CNS testing, and/or MRI of the brain and posterior fossa to identify possible intracranial pathological conditions (Dunniway, et al., 1998) (Buttner, et al., 1999).