Canal conversion between anterior and posterior semicircular canal in benign paroxysmal positional vertigo

Canal switch: a possible complication of physical therapeutic manoeuvers for posterior canal benign paroxysmal positional vertigo

Objective

To study the frequency of canal switch in posterior canal benign paroxysmal positional vertigo (BPPV) treated by canalith repositioning manoeuver (CRP), quick liberatory rotation manoeuver (QLR) or Semont manoeuver (SM).

Methods

Retrospective study on 1158 patients, 637 women and 521 men suffering from geotropic posterior canal BPPV treated by CRP, QLR, or SM, retested after 15 minutes and about seven days.

Results

1146 patients recovered from the acute phase; treatments failed in 12 patients treated with CRP. We observed 12 canal switches from posterior to lateral canal and 2 from posterior to anterior canal during or after CRP in 13/879 cases (1.5%) and after QLR in 1/158 (0.6%) with no significant difference between CRP vs SM and QLR. We did not consider slight positional downbeat nystagmus after the therapeutic manoeuvers as a sign of canal switch into the anterior canal, but as a sign of persistent small debris in the non-ampullar arm of the posterior canal.

Conclusions

Canal switch is rare for any manoeuver and it does not belong to the criteria to choose one manoeuver over another. Notably, due to the canal switching criteria, SM and QLR cannot be preferred over those with a more prolonged extension of the neck.

Adding Kinetic Energy Does Not Further Improve Treatment Outcomes With a Mechanical Reposition Chair: A Randomized Controlled Trial

OBJECTIVE

To test if the addition of abrupt deaccelerations (kinetic energy) during treatment with a mechanical repositional chair (MRC) provides improved treatment efficacy with treatment of posterior benign paroxysmal positional vertigo (BPPV).

STUDY DESIGN

Randomized two-armed parallel open-labeled clinical trial.

SETTING

Tertiary referral center.

PATIENTS

Seventy patients diagnosed with posterior canalolithiasis BPPV were included.

INTERVENTIONS

All patients underwent diagnostics and treatment with an MRC. Patients were randomized to either a traditional Epley maneuver or a potentiated version of the Epley maneuver where kinetic energy was applied in five positions with 45-degree turns between each step.

MAIN OUTCOME MEASURES

Primary endpoint was the number of treatments needed before complete resolution of both subjective symptoms and objective signs of BPPV within the semicircular canal of interest. Secondary endpoints included the following: 1) number of patients requiring more than 10 treatments, 2) length of treatment in days before treatment(s) were successful, and 3) changes in total Dizziness Handicap Inventory scores before and after treatment.

RESULTS

No significant difference in the number of required treatments between the two treatment arms was found. Approximately three of four subjects were cured after two repositional maneuvers regardless of type of treatment. An equal length of treatment was seen with both groups, and the Dizziness Handicap Inventory scores were significantly lowered after treatment with no significant differences between the two types of treatment.

CONCLUSIONS

Both the traditional and the potentiated Epley maneuver are efficient in treatment of canalolithiasis of the posterior semicircular canals with MRC. Addition of kinetic energy with this subgroup of BPPV patients does not seem to add further efficacy to the treatment.

Canal switch in benign paroxysmal positional vertigo: Clinical characteristics and possible mechanisms

BACKGROUND

Canal switch-benign paroxysmal positional vertigo (CS-BPPV) refers to the phenomenon in which otolith particles move from one canal to another (on the ipsilateral side) during or after canalith repositioning procedure (CRP). However, the clinical characteristics of CS-BPPV and the underlying pathological mechanisms remain unclear. In this study, we investigated the incidence of canal switch (CS) for the different semicircular canals in benign paroxysmal positional vertigo (BPPV), examined nystagmus characteristics, and explored the underlying mechanisms.

METHODS

Clinical data for 1,099 patients with single-canal BPPV were collected and retrospectively analyzed. The incidences of CS in the different types of BPPV were analyzed. Patients were divided into CS-BPPV and non-CS (NCS)-BPPV groups according to whether they exhibited CS after CRP. The baseline characteristics and nystagmus characteristics of patients were compared between the two groups.

RESULTS

Patients with BPPV who developed or did not develop CS accounted for 4.6% (51/1,099) and 95.4% (1,048/1,099), respectively, of the patients included in the study. There were no statistically significant differences between the two groups in terms of sex, age, side of the canals involved, hypertension, or diabetes. CS was observed in 3.7% (25/677) of patients with PC-BPPV, including conversion between posterior canal (PC) and horizontal canal (HC) (1.6%, 11/677), and between PC and anterior canal (AC) (2.1%, 14/677). CS was observed in 5.2% (17/327) of patients with HC-BPPV, including from HC to PC (4.3%, 14/327), and from HC to AC (0.9%, 3/327). CS was found in 9.5% (9/95) of patients with AC-BPPV, including from AC to PC (8.4%, 8/95), and from AC to HC (1.1%, 1/95). The intensity of nystagmus was significantly greater in the CS-BPPV group compared with that in the NCS-BPPV group [24.00 (11-39) vs. 12.00 (7-24), P < 0.001]. Furthermore, the incidence of direction-reversing nystagmus was significantly higher in the CS-BPPV group than in the NCS-BPPV group [31.4% (16/51) vs. 4.3% (45/1,048), P < 0.001].

CONCLUSIONS

CS in BPPV is uncommon. Patients with AC-BPPV are more likely to develop CS, followed by patients with HC-BPPV and PC-BPPV. The occurrence of CS-BPPV may be related to the anatomical structure of the semicircular canals. When the canals contain large/heavy accumulations of otolith particles, CS may be more common during re-examination after CRP.

Simulation Study of Canal Switching in BPPV

The objective of this research was to investigate the mechanism of canal switching in benign paroxysmal positional vertigo through a virtual simulation model. Using Unity 3D software and a built-in NVIDIA Physx physics engine, the virtual simulation software is developed using a browser-server architecture, and different models are imported. Based on the benign paroxysmal positional vertigo virtual simulation model, we constructed five different virtual reality scenes of diagnosis and treatment, set otoliths in different positions of the semicircular canals, and analyzed the effects of diagnostic and therapeutic procedures on otolith location. Through the analysis of otolith movement in five virtual scenes, we found that canal switching may be caused by otoliths in the utricle entering the semicircular canal in the supine position. Then, we used different methods to reposition the otolith, improved the repositioning maneuver, and explored in depth the mechanism of the canal switching. The results showed that the main reason for the canal switch is that in the supine position, the otolith in the utricle enters the semicircular canal. The repositioning maneuvers, including the Epley maneuver and Barbecue maneuver, will not directly lead to the canal switch in the ipsilateral inner ear. The supine roll maneuver leads to the otolith in the utricle entering the posterior or lateral semicircular canal, which is the most likely mechanism for canal switching.

Diagnosis strategy and Yacovino maneuver for anterior canal-benign paroxysmal positional vertigo

OBJECTIVE

To investigate the diagnosis strategy of anterior canal-benign paroxysmal positional vertigo (AC-BPPV) and the therapeutic effects of the Yacovino maneuver.

METHODS

The clinical data of 40 AC-BPPV patients were collected. The nystagmus characteristics induced by the Dix-Hallpike (D-H) and straight head-hanging (SHH) tests, the diagnostic methods used, and the effectiveness of the Yacovino maneuver for the treatment of AC-BPPV were all retrospectively analyzed.

RESULTS

Among the 40 cases analyzed, 19 patients had simple AC-BPPV, 11 patients had AC-posterior canal BPPV, and 10 patients had AC-horizontal canal BPPV. D-H and SHH tests showed down-beating nystagmus in 26 and 33 patients, respectively, and showed down-beating and torsional nystagmus in 14 and 7 patients, respectively. AC-BPPV was diagnosed in 15 patients based on the presence of typical BPPV in other canals, in 9 patients based on typical disease history and the results of position tests, in 6 patients based on effectiveness of the treatment with the Yacovino maneuver, in 4 patients based on the treatment effectiveness and the presence of typical BPPV in other canals, in 3 patients based on the treatment effectiveness and the follow-up outcome, in 2 patients based on the typical BPPV in other canals and occurrence of canal conversion, and in 1 patient based on the treatment effectiveness and occurrence of canal conversion. Thirteen patients with canalolithiasis and four patients with cupulolithiasis were cured after the initial Yacovino maneuver treatment. Twenty-one patients with canalolithiasis and seven patients with cupulolithiasis were cured following 1 week of treatment.

CONCLUSIONS

The effectiveness of the Yacovino maneuver, the follow-up outcome, the presence of typical BPPV in other canals, and the occurrence of canal conversions contribute to AC-BPPV diagnosis. The Yacovino maneuver was found to be more effective in AC-BPPV patients with canalolithiasis than in those with cupulolithiasis.

Diagnosis and treatment of anterior canal benign paroxysmal positional vertigo

OBJECTIVE

To investigate the diagnosis and treatment of anterior canal benign paroxysmal positional vertigo (AC-BPPV).

DESIGN

Retrospective analysis of clinical data regarding the diagnosis and treatment of patients with AC-BPPV.

STUDY SAMPLE

Six patients with AC-BPPV.

RESULTS

All patients underwent the Dix-Hallpike test and/or the straight head-hanging test to induce vertigo and down-beating nystagmus with or without torsional components. Down-beating nystagmus in patients 1, 3 and 6 lasted <1 min and was successfully treated with the Yacovino manoeuvre. Down-beating nystagmus in patients 2, 4 and 5 lasted >1 min. The Yacovino manoeuvre was not effective in patient 4, whereas it was effective in patient 2 but with frequently recurring symptoms. Patients 3, 4 and 6 also had other types of typical BPPV. Canal conversion appeared in patients 4 and 5 during the follow-up period.

CONCLUSION

Typical BPPV, canal conversion, a therapeutic diagnosis after applying the Yacovino manoeuvre, and the follow-up outcome contribute to AC-BPPV diagnosis in patients with dizziness and vertigo presenting with down-beating positional nystagmus. Yacovino manoeuvre was more effective in AC-BPPV patients with down-beating positional nystagmus lasted <1 min than in those in whom it lasted >1 min.

Persistent Down-Beating Torsional Positional Nystagmus: Posterior Semicircular Canal Light Cupula?

A 16-year-old boy with rotatory positional vertigo and nausea, particularly when lying down, visited our clinic. Initially, we observed vertical/torsional (downward/leftward) nystagmus in the supine position, and it did not diminish. In the sitting position, nystagmus was not provoked. Neurological examinations were normal. We speculated that persistent torsional down-beating nystagmus was caused by the light cupula of the posterior semicircular canal. This case provides novel insights into the light cupula pathophysiology.

Comparative Study on the Roles of the Number of Accelerations and Rotation Angle in the Treatment Maneuvers for Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo

AIMS

This study aims to investigate the roles of the number of accelerations and rotation angle in the treatment of posterior semicircular canal benign paroxysmal positional vertigo (PC-BPPV).

METHODS

We enrolled 344 patients with unilateral PC-BPPV. Of these, 167 patients in the simple-step maneuver (SSM) group were accelerated twice and rotated 120° per step, whereas 177 patients in the multi-step maneuver (MSM) group were accelerated 4 times and rotated 60° per step. Dix-Hallpike (DH) tests were performed to categorize the treatment outcome as follows: 'symptom free' if the result was negative, 'symptom persistent' if the result remained positive after performing the maneuver 3 times or 'canal conversion' if horizontal nystagmus was evoked.

RESULTS

Of the patients in the SSM and MSM groups, 78.4 and 91.5% became symptom free, respectively, while canal conversion occurred in 13.8 and 5.1%, respectively (p = 0.003, χ(2) test). The success rate after performing the maneuver once was 57.1% in the MSM and 32.3% in the SSM symptom-free patients (p = 0.001, χ(2) test). One month after the treatment, 22.0 and 9.6% of the SSM and MSM patients had symptom relapse, respectively (p = 0.007, χ(2) test).

CONCLUSIONS

More accelerations and a smaller rotation angle improved the effectiveness and efficiency of the repositioning maneuvers and reduced canal conversion.

Diagnosis and Treatment of Anterior-Canal Benign Paroxysmal Positional Vertigo: A Systematic Review

Background and Purpose

In contrast to the posterior- and horizontal-canal variants, data on the frequency and therapeutic management of anterior-canal benign paroxysmal positional vertigo (AC-BPPV) are sparse. To synthesize the existing body of evidence into a systematic review regarding the incidence and treatment of AC-BPPV.

Methods

Systematic search of medical databases employing predefined criteria, using the term "anterior canal benign paroxysmal positional vertigo."

Results

The electronic search retrieved 178 unique citations, 31 of which were considered eligible for further analysis. Analysis of the collected data revealed an estimated occurrence of AC-BPPV among benign paroxysmal positional vertigo patients of 3% (range 1-17.1%). No controlled therapeutic trials could be identified, and so the analysis was focused on uncontrolled case series. Treatment was categorized into three groups: Epley maneuver, Yacovino maneuver, and specific, nonstandard maneuvers described in individual articles. All three categories demonstrated success rates of over 75%, and the overall sample-size-weighted mean was 85.6%.

Conclusions

The present analysis demonstrated that AC-BPPV comprises about 3% of all BPPV cases. It can be treated safely using the Epley, Yacovino, and other maneuvers with rates of symptom resolution lying in the range of that reported for the other, more frequent canal variants. Multicenter controlled trials are needed in order to develop evidence-based guidelines for the treatment of AC-BPPV.

Efficacy of computer-controlled repositioning procedure for benign paroxysmal positional vertigo

OBJECTIVES/HYPOTHESIS

To evaluate the short-term efficacy of the computer-controlled canalith repositioning procedure (CRP) for treatment of posterior canal benign paroxysmal positional vertigo (BPPV) compared with the current standard CRP.

STUDY DESIGN

Prospective case series.

METHODS

One hundred thirty-two patients diagnosed as having idiopathic posterior canal BPPV, with an age range of 28 to 86 years (mean 56 years), 47 men and 85 women, were treated with computer-controlled CRP mimicking the Epley maneuver. Resolution of vertigo and nystagmus on the Dix-Hallpike test at 1-week follow-up after treatment was the main outcome measure to assess the efficacy of treatment.

RESULTS

At 1-week follow-up after treatment with computer-controlled CRP, 108 (81.8%) of 132 patients had complete resolution of vertigo and nystagmus, nine (6.8%) had resolution of vertigo but presence of nystagmus, and 15 (11.4%) had provoked vertigo and nystagmus on the Dix-Hallpike test. The 81.8% success rate was comparable to those who received current standard CRP treatment in randomized controlled trials at about 80%. No significant adverse effects or complications occurred in the patients treated with computer-controlled CRP, aside from two patients (1.5%) with conversion into lateral canal BPPV.

CONCLUSIONS

Computer-controlled CRP is effective for the treatment of posterior canal BPPV, with a success rate similar to those treated with the Epley maneuver, and is safe and easy to perform on patients.

Vestibulo-ocular reflex in patients with superior semicircular canal benign paroxysmal positional vertigo (BPPV)

CONCLUSION

The function of all the semicircular canals in patients with idiopathic benign paroxysmal positional vertigo (BPPV) in whom otoconial debris is located in the superior semicircular canal (SSC) is normal.

OBJECTIVE

BPPV of SSC is an infrequent entity in which otoconial debris evokes vertigo and nystagmus in the head-hanging position and during anterior flexion of the patient.

METHODS

We studied the vestibulo-ocular reflex (VOR) in 12 patients with this particular type of BPPV. The reflex was evoked by rapid head impulses in the plane of the three semicircular canals in the affected and the normal ear. The reflex was evaluated with a video system that analyzes the head and eye velocity: the gain (the relation between both magnitudes) was the objective measure.

RESULTS

The mean gain of VOR was within normal limits for the six semicircular canals and there were no significant differences between the same canals on each side of patients with BPPV in whom canalolithiasis was located in the SSC. However, gain asymmetry was different for each pair of canals.