Atypical "reversed" paroxysmal positioning nystagmus in benign paroxysmal positional vertigo

Variants of posterior semicircular canal involvement in benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo is the most common cause of peripheral vertigo. It is characterized by short and recurrent episodes of vertigo, trigged by specific head movements that displace otoconia within the semicircular canals. The movement of dislodge otoconia from the utricle cause abnormal positional endolymphatic currents. Primary treatment involves reposition maneuvers aimed at moving the displaced otoconia out the affected canal, therefore correct identification of the affected canal is essential for the diagnosis. The posterior semicircular canal (PSC) is the most frequently affected due to its spatial orientation and the force of gravity. Recent technological advances have allowed for better assessment of positional nystagmus during diagnostic and therapeutic maneuvers, revealing various possible scenarios of PSC involvement. Regarding the PSC, otoconia may be found in different parts of the canal, and not just in the expected location, floating in the long arm of the canal. The understanding of these variants is crucial, as the prognosis and the disease progression differ in such cases. This review aims to describe the six possible variants of PSC involvement described so far.

Apogeotropic Posterior Semicircular Canal BPPV-A Case Series from South Rajasthan

Apogeotropic variant of posterior semicircular canal benign paroxysmal positional vertigo (apo-PSC-BPPV) is a rare peripheral vestibular disorder, characterized by paroxysms of positionally triggered dizzy spells associated with non-positional disequilibrium. It is diagnosed by observing characteristic diagnostic oculomotor responses (torsional downbeating positional nystagmus) during positional testing (Dix-Hallpike and enhanced straight head hanging tests), in conjunction with a response to physical therapy. Much rarer anterior semicircular canal benign paroxysmal positional vertigo (ASC-BPPV) elicits identical oculomotor responses during positional testing. Propter hoc, response to physical therapy at short-term follow-up is crucial in distinguishing the apo-PSC-BPPV from ASC-BPPV. We are presenting a case series of seven patients of apo-PSC-BPPV (of which three were bilaterally affected), who attended our otoneurology center, between February 1, 2023, and July 31, 2023. Demographic profile, clinical course, and physical therapy with responses at short-term follow-up at 1 hour and after 24 hours are discussed.

[Vertical downbeat nystagmus in benign paroxysmal positional vertigo]

Benign paroxysmal positional vertigo (BPPV) is the most common peripheral vestibulopathy. Ppatients with BPPV contact with otorhinolaryngologists in 25% of cases. Due to the polymorphism of this pathology, an urgent task is to asess differential diagnosis of BPPV with various variants of the central positional syndrome: vestibular migraine, myofascial cervical syndrome, organic changes in the structures of the cerebellum.

OBJECTIVE

To distinguish atypical forms of BPPV with downbeating vertical nystagmus and the central positional syndrome.

Less common forms of posterior canal benign paroxysmal positional vertigo

The most common form of posterior canal benign paroxysmal positional vertigo (BPPV) is characterised by positional, paroxysmal, upbeat nystagmus, with a torsional component beating towards the downward ear. Rarer variants have been reported, putatively due to either the position of otoconia in the canal or anatomic variations of the semicircular canals. The most frequent less common form is apogeotropic posterior canal BPPV, in which the positional nystagmus is downbeat and torsional apogeotropic. In this form, the main problems are differential diagnosis with central mimics of BPPV and identification of the affected canal and its side. The authors propose a new subtype of apogeotropic posterior canal BPPV hypothesising the localization of otoconia in the ampullary tract of the affected canal, which might explain the modality of the conversion in typical posterior canal BPPV which they observed in some of these cases. If nystagmus of the less common forms of posterior canal BPPV is explicable through purely peripheral mechanisms, these forms should no longer be defined as “atypical” but, in a less demanding way, as “less common” variants, which must be recognised by any expert otoneurologist.

Feasibility of Using the Video-Head Impulse Test to Detect the Involved Canal in Benign Paroxysmal Positional Vertigo Presenting With Positional Downbeat Nystagmus

Positional downbeat nystagmus (pDBN) represents a relatively frequent finding. Its possible peripheral origin has been widely ascertained. Nevertheless, distinguishing features of peripheral positional nystagmus, including latency, paroxysm and torsional components, may be missing, resulting in challenging differential diagnosis with central pDBN. Moreover, in case of benign paroxysmal positional vertigo (BPPV), detection of the affected canal may be challenging as involvement of the non-ampullary arm of posterior semicircular canal (PSC) results in the same oculomotor responses generated by contralateral anterior canal (ASC)-canalolithiasis. Recent acquisitions suggest that patients with persistent pDBN due to vertical canal-BPPV may exhibit impaired vestibulo-ocular reflex (VOR) for the involved canal on video-head impulse test (vHIT). Since canal hypofunction normalizes following proper canalith repositioning procedures (CRP), an incomplete canalith jam acting as a "low-pass filter" for the affected ampullary receptor has been hypothesized. This study aims to determine the sensitivity of vHIT in detecting canal involvement in patients presenting with pDBN due to vertical canal-BPPV. We retrospectively reviewed the clinical records of 59 consecutive subjects presenting with peripheral pDBN. All patients were tested with video-Frenzel examination and vHIT at presentation and after resolution of symptoms or transformation in typical BPPV-variant. BPPV involving non-ampullary tract of PSC was diagnosed in 78%, ASC-BPPV in 11.9% whereas in 6 cases the involved canal remained unidentified. Presenting VOR-gain values for the affected canal were greatly impaired in cases with persistent pDBN compared to subjects with paroxysmal/transitory nystagmus (p < 0.001). Each patient received CRP for BPPV involving the hypoactive canal or, in case of normal VOR-gain, the assumed affected canal. Each subject exhibiting VOR-gain reduction for the involved canal developed normalization of vHIT data after proper repositioning (p < 0.001), proving a close relationship with otoliths altering high-frequency cupular responses. According to our results, overall vHIT sensitivity in detecting the affected SC was 72.9%, increasing up to 88.6% when considering only cases with persistent pDBN where an incomplete canal plug is more likely to occur. vHIT should be routinely used in patients with pDBN as it may enable to localize otoconia within the labyrinth, providing further insights to the pathophysiology of peripheral pDBN.

A new variant of posterior canal-benign paroxysmal positional vertigo-canalolithiasis

OBJECTIVE

The characteristics of typical posterior canal-benign paroxysmal positional vertigo-canalolithiasis (P-BPPV-Can) are well known. We found 10 patients with a new variant of P-BPPV-Can: Reverse (Rev)-P-BPPV-Can. The characteristics and pathophysiology of Rev-P-BPPV-Can are discussed.

METHODS

For 4 years and 9 months, 10 patients with Rev-P-BPPV-Can (9 women and 1 man; mean age: 73 years) visited our clinic. Within the same period, 268 patients with unilateral typical P-BPPV-Can were treated. During the Dix-Hallpike and Epley maneuvers, nystagmus was recorded using an infrared charge-coupled device camera mounted on a pair of spectacles.

RESULTS

The patients exhibited entirely opposite direction of nystagmus from typical P-BPPV-Can in both the Dix-Hallpike head position and upright sitting position. The patients had typical characteristics of nystagmus due to canalolithiasis, such as latency, duration of <1 min, linear-torsional nystagmus, and fatigability. Rev-P-BPPV-Can appeared after the Epley maneuver for typical P-BPPV-Can; in other patients, Rev-P-BPPV-Can changed to typical P-BPPV-Can. The affected sides of Rev-P-BPPV-Can were decided by those of typical P-BPPV-Can.

CONCLUSION

Canalolithiasis in the non-ampullary distal portion of the posterior semicircular canal may be a potential pathophysiology of Rev-P-BPPV-Can. The Epley maneuver has little effect for treating Rev-P-BPPV-Can, but spontaneous transition to typical P-BPPV-Can or spontaneous recovery is expected.

Treatment of Benign Paroxysmal Positional Vertigo: No Need for Postmaneuver Restrictions

The liberatory maneuver of Semont is an effective physical treatment for benign paroxysmal positional vertigo. It works because it causes otoconia to move out the posterior canal. The effectiveness of the maneuver is thought to be indicated by the appearance of a liberatory nystagmus. After the maneuver, patients are usually instructed to keep their heads erect for several days and not to lie on the pathologic side for about a week. Here we investigated the prognostic value of liberatory nystagmus and whether restrictions are necessary after treatment. Fifty-six patients with posterior canal benign paroxysmal positional vertigo underwent the Semont maneuver and were checked after 20 minutes, 24 hours, and 1 week. The patients were told that they could sleep or move as they pleased, without any particular precautions. We found that liberatory nystagmus had a high prognostic value and that it was not necessary for patients to avoid certain positions or movements after treatment.

A New Variant of Posterior Canal Benign Paroxysmal Positional Vertigo: A Nonampullary or Common Crus Canalolithiasis

Clockwise or counterclockwise, rotational, upbeating nystagmus is seen in patients with posterior canal benign paroxysmal positional vertigo during left or right head-hanging test, respectively. Rotating of nystagmus in opposite direction to the ear tested or even reversal of initial positioning rotational nystagmus is not usual and has never been reported before. We propose a new variant of posterior canal benign paroxysmal positional vertigo due to unusual behavior and location of the otoliths inside the membranous labyrinth. Unexpected rotational direction may lead to confusion about the site. The examiner should be aware of this abnormal or atypical variant of posterior canal benign paroxysmal positional vertigo.

Natural course of positional down-beating nystagmus of peripheral origin

The aim of this study was to assess the natural course of positional down-beating nystagmus (pDBN) and vertigo in patients with no evidence of central nervous system involvement and of presumed peripheral origin. Fifty-three patients with pDBN had a complete otoneurological examination. All subjects, apart from three (excluded from the study), showed no additional neurological signs and normal brain imaging. Patients were randomly assigned to two groups: with or without treatment with exercise. Patients were seen again after 24 h, and then weekly for up to 6 months. Forty-seven patients (94%) showed pDBN in the straight head-hanging position and in a Dix-Hallpike position. A torsional component was detected in 17 patients (34%). The mean latency and duration of pDBN was 4.7 ± 5 s and 40.1 ± 22 s, respectively. After 2 weeks, only 12 patients (24%) still had pDBN and all but one patient had recovered by 1 month. Twenty patients (40%) were diagnosed with a typical posterior canal benign paroxysmal positional vertigo (PC BPPV) before or after pDBN. This study assessed for the first time the natural course of presumed peripheral pDBN, which was characterized by a spontaneous remission in 24 patients in the first week and in 49 patients within 4 weeks. pDBN is much more common than previously suggested, with about the same frequency as lateral canal BPPV. Furthermore, the clinical characteristics of pDBN have been highlighted, as well as its possible relationship to PC BPPV.

Posterior semicircular canal benign paroxysmal positional vertigo presenting with torsional downbeating nystagmus: an apogeotropic variant

The aim of this study is to verify the hypothesis that free-floating particles could sometimes localize into the distal portion of the non ampullary arm of the posterior semicircular canal (PSC) so that assuming the Dix-Hallpike's positions, the clot could move towards the ampulla eliciting a inhibitory torsional-down beating paroxysmal positional nystagmus (PPNy), instead of typical excitatory torsional-up beating PPNy. Among 45 patients with vestibular signs suggesting anterior semicircular canal paroxysmal positional vertigo (PPV), collected from February 2003 to August 2006, we detected a group of 6 subjects whose clinical findings showed a singular behaviour during follow-up. At the first check-up, all patients were submitted to different types of physical manoeuvres for ASC canalolithiasis. Patients were controlled during the same session and after one week. When we found that nystagmus was qualitatively changed we adopted the appropriate physical therapies for that sign. At a next check-up, after having performed some physical therapies, all patients had a typical PSC PPNy of the opposite side, with respect to that of the ASC initially diagnosed. Basing on these observations we conclude that PSC PPV, similarly to lateral semicircular canal PPV, could manifests in a apogeotropic variant.

[Oculographic findings in 145 patients with benign paroxysmal positional vertigo]

OBJECTIVE

Benign paroxysmal positional vertigo (BPPV) can be produced by specific manoeuvres and be studied by electrooculography (EOG). It allows an exhaustive study of features in the positional nystagmus. Although most of the patients with BPPV express typical nystagmus, there exists a group of them that exhibit a non typical form. In this work, a comparative study was carried out between two groups of patients.

MATERIAL AND METHODS

We have studied retrospectively 145 patients with BPPV and Dix-Hallpicke (D-H) positive manoeuvre registered by EOG techniques. All patients were explored in a complete EOG tests. Two groups were identified: typical response/atypical response according to the features of nystagmus response. Possible alterations in other EOG tests in each group were investigated and differences between both types of response were analyzed.

RESULTS

83.5% of cases showed typical nystagmus and atypical in the rest. Other EOG alterations observed in these patients, were (group typical response/atypical response): caloric hypofunction (17.3%/23%), positional nystagmus (12.4%/62.5%), alterations in visual-oculomotor function tests (10%/50%).

CONCLUSIONS

Frequent alterations were observed in the classic manoeuvres and also in the rest of EOG tests. Probably atypical response in the first is due to or can explain the existence of the second.

Repositioning maneuver for the treatment of the apogeotropic variant of horizontal canal benign paroxysmal positional vertigo

OBJECTIVE

The purpose of this study was to determine the effectiveness of a new physical maneuver in the treatment of the apogeotropic variant of horizontal canal benign paroxysmal positional vertigo.

STUDY DESIGN

Case review.

SETTING

Outpatient clinic.

PATIENTS

The diagnosis of apogeotropic horizontal canal benign paroxysmal positional vertigo was based on the history of recurrent sudden crisis of vertigo associated with bursts of horizontal apogeotropic paroxysmal nystagmus provoked by turning the head from the supine to either lateral position. The patients were three men and five women ranging in age from 31 to 73 years (average, 49.2 yr).

INTERVENTIONS

All patients were treated with a repositioning maneuver based on the hypothesis that the syndrome is caused by the presence of free-floating dense particles inside the endolymph of the anterior arm of the horizontal canal. The maneuver favors their shifting into the posterior arm of the canal. Patients were reexamined immediately after the treatment and underwent Gufoni's liberatory maneuver for the geotropic variant of horizontal canal benign paroxysmal positional vertigo.

MAIN OUTCOME MEASURE

The treatment outcome was considered as responsive when, after one repositioning maneuver, nystagmus shifted from apogeotropic to geotropic.

RESULTS

The repositioning maneuver resulted in a transformation from the apogeotropic variant into a geotropic variant of horizontal canal benign paroxysmal positional vertigo in all patients.

CONCLUSION

This maneuver represents a simple and effective approach to the treatment of the apogeotropic variant of horizontal canal benign paroxysmal positional vertigo. It favors the shifting of the canaliths from the anterior into the posterior arm of the horizontal canal from where they can migrate into the utricle with Gufoni's maneuver.

Treatment of benign paroxysmal positional vertigo: no need for postmaneuver restrictions

The liberatory maneuver of Semont is an effective physical treatment for benign paroxysmal positional vertigo. It works because it causes otoconia to move out the posterior canal. The effectiveness of the maneuver is thought to be indicated by the appearance of a liberatory nystagmus. After the maneuver, patients are usually instructed to keep their heads erect for several days and not to lie on the pathologic side for about a week. Here we investigated the prognostic value of liberatory nystagmus and whether restrictions are necessary after treatment. Fifty-six patients with posterior canal benign paroxysmal positional vertigo underwent the Semont maneuver and were checked after 20 minutes, 24 hours, and 1 week. The patients were told that they could sleep or move as they pleased, without any particular precautions. We found that liberatory nystagmus had a high prognostic value and that it was not necessary for patients to avoid certain positions or movements after treatment.