Introduction to Benign Paroxysmal Positional Vertigo

Original Editor - Jess Bell based on the course by Bernard Tonks
Top Contributors - Jess Bell, Kim Jackson, Rucha Gadgil and Lucinda hampton

Introduction[edit | edit source]

Figure 1. Otoconia within the posterior canal endolymphatic duct.

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo arising from peripheral vestibular disorders. It accounts for 20 to 30 percent of all patients seen for vertigo in clinics that specialise in dizziness.[1] While the overall incidence of BPPV in the general population is around 2.5 percent,[1] it is more common in older adults. Some studies show that 50 percent of older adults have BPPV.[2]

Figure 2. Inner ear.

BPPV is a biomechanical problem that occurs when there is displacement of calcium-carbonate crystals or otoconia from the utricle into one of the three fluid-filled semicircular canals of the inner ear (see Figures 1 and 2).[3][4] This causes the semi-circular canal (or canals) to be inappropriately excited, resulting in vertigo, nystagmus and occasionally nausea.[3] For more information on the anatomy of the vestibular system, please click here.

Symptoms tend to be provoked by head movements, such as:[3]

  • Looking up
  • Lying down to a flat position quickly
  • Bending forwards
  • Rolling in bed

Aetiology[edit | edit source]

It is not yet known what causes BPPV. The majority of cases are idiopathic, but it is more likely to occur in older adults.[2]

The two primary theories about its aetiology are that it is:

  1. Related to ischaemia of the anterior vestibular artery and cardiovascular disease primarily involving the posterior circulation[5]
  2. Related to vitamin D deficiency and calcium metabolism (seasonal variations may be present)[6][7]

Predisposing factors include:

  • Head trauma in all age groups[7]
    • In a younger population, head trauma is a leading predisposing factor
    • The recurrence rate may be higher and treatment may not be as effective in this population[3]
  • Surgical trauma to the inner ear[8]
  • Vestibular labyrinthitis / neuritis[8]
  • Migraines[1]
  • Ischaemia of the anterior vestibular artery and cardiovascular disease[3][9]

It is estimated that 85 to 95 percent of BPPV occurs in the posterior canals. 5 to 15 percent occurs in the horizontal canals and 1 to 5 percent occurs in the anterior canals.[10]

Variants of BPPV[edit | edit source]

Two variants of BPPV can be present:

  1. Cupulolithiasis
  2. Canalithiasis

Cupulolithiasis (i.e. ‘stuck crystals’)[edit | edit source]

  • The debris adheres to the cupula of the affected canal, causing the cupula to be gravity sensitive
  • Changes in head position cause an inappropriate deflection of the cupula resulting in nystagmus, vertigo, and nausea
  • This is a relatively uncommon form of BPPV[2]

Canalithiasis (i.e. ‘free floating crystals’)[edit | edit source]

  • This theory better explains the typical characteristics of BPPV
  • Otoconia are floating freely within the endolymph of the semi-circular canals
  • When the head is moved into the plane of the affected canal, the debris moves into the most dependent portion causing movement of the endolymph which deflects the cupula producing vertigo, nystagmus and nausea[2]

The key characteristics of these two variants of BPPV are summarised in Table 1.

Table 1. Characteristics of BPPV variants.[3]
Canalithiasis Cupulolithiasis
Latency of onset >1 second before the onset of vertigo and nystagmus No latency
Duration Vertigo and nystagmus lasts < 60 seconds Vertigo and nystagmus persist > 1minute
Direction of nystagmus Characteristic nystagmus depending on which canal is involved Characteristic nystagmus depending on which canal is involved
Fatiguability Decreased intensity of vertigo and nystagmus with repeated movement of the patient in provoking positions Decreased intensity of vertigo and nystagmus with repeated movement of the patient in provoking positions

Assessment[edit | edit source]

Assessing the Vertical Canals[edit | edit source]

Dix-Hallpike Test[edit | edit source]

Figure 3. Dix-Hallpike test.

The Dix-Hallpike (DH) test is used to assess BPPV (primarily the vertical canals). This test enables the therapist to identify the side of the lesion and frequently the specific canal involved (see Figure 3).[3]

  • Patient is seated with his / her head turned 45 degrees toward the test side
  • The therapist moves the patient as rapidly as is possible (considering safety) into a supine position with his / her head extended 30 degrees[3]
    • NB there are variations in the literature over the degree of extension required. Some texts recommend 20 degrees, but according to Tonks, 30 degrees appears to give better results clinically[3]
  • The therapist asks the patient to look at his / her nose and observes the patient's eyes for nystagmus, noting the direction of the movement, latency, and duration of nystagmus (see Table 2)
  • Wait until the nystagmus stops
  • Typically, the therapist will then proceed into treatment (see below) if indicated
  • Some therapists will, however, slowly sit the patient up in order to assess the other side, but nausea can be a problem

Kaplan and colleagues have found that shaking the head during the DH increases the diagnostic yield. Patients who have a negative DH, but a positive result when head shaking is introduced may have otoconia that are not moving well through the affected canal.[11]

If BPPV is likely present, but the DH is negative, this test can be repeated a couple of times to ensure that it is negative (in cases of “sticky canalithiasis”). [3]

It is important to try to assess the unaffected side first if possible. You can reason which side this might be based on the patient’s subjective report - i.e. the side she / he does not like to lie on. However, often the patient will not be able to tell you which side is worse.[3]

[12]

Side Lying Test[edit | edit source]

  • Patient is seated with head turned 45 degrees away from the side to be tested
  • Patient is moved quickly into side-lying on the side opposite to the side that the head is turned
  • Therapist observes patient's eyes for nystagmus
  • Repeat the test with the head turned to the other side

This test is a valid alternative that can be used when the DH is not considered a viable option (e.g. if there are range of motion limitations).[13]

[14]

Assessing the Horizontal Canals[edit | edit source]

Head Roll Test[edit | edit source]

The head roll test can be used to assess the horizontal canals as it places these canals in the plane of gravity. It is considered a positive test when:[3]

  • Horizontal nystagmus is provoked (see Table 2)
  • The patient reports vertigo when rolling to both the right and left sides

To perform the test:[3][10]

  • Patient lies supine with his / her head elevated 20 degrees on a pillow
  • Quickly roll the head 90 degrees to one side (NB it is possible to do whole body rolls)
  • Observe the patient’s eyes for nystagmus and note the direction, latency, and duration. Also watch for direction changing nystagmus
  • Bring the patient’s head back to the neutral position in supine and wait until his / her signs and symptoms settle. Then roll the head quickly to the other side and observe
  • Both side lying positions will be positive for vertigo and nystagmus (same pattern) in horizontal semi-circular canal BPPV

There are two types of nystagmus associated with the horizontal canals and they can be used to differentiate between cupulolithiasis and canalithiasis: [10]

  • Geotropic (quick phase towards the earth)
    • Associated with canalithiasis
      • Will have latency before onset and be shorter in duration
    • If geotropic nystagmus is provoked, assume that the most symptomatic side is the affected side and treat this side[3]
  • Ageotropic (quick phase towards the ceiling)
    • Associated with cupulolithiasis
      • Will have immediate onset and prolonged duration
    • If ageotropic nystagmus is provoked, assume the less symptomatic side is the affected side and treat this side[3]

[15]

Table 2. Identification of canal involvement - nystagmus
Involved Canal Dix-Hallpike (DH) and Head Roll Test
Right posterior

Right DH

Up beating, right torsion
Right anterior

Left DH

Down beating, right torsion
Left anterior

Right DH

Down beating, left torsion
Left posterior

Left DH

Up beating, left torsion
Right / left horizontal

canals

Head roll test

Horizontal nystagmus, no torsion

Distinguishing Between a Central Nervous System Lesion and BPPV[edit | edit source]

It is possible to distinguish central nervous system lesions with BPPV (see Table 3). Lesions of central origin often present with:[3][10] 

  • Atypical nystagmus (sustained down beating, no torsion)
  • No fatiguability of the response with repeated testing
  • No decrease in the nystagmus +/- vertigo with prolonged DH position
  • No reversal phenomenon (reversal of nystagmus)
Central Peripheral
Cupulolithiasis Canalithiasis
Latency No No Yes (>1 second)
Duration Persistent 1-2 minutes < 60 seconds
Direction Uniplanar Multiplanar Multiplanar
Fatiguability No Yes Yes

Table 3. Distinguishing central nervous system lesion and BPPV

Treatment[edit | edit source]

Vertical Canal Canalithiasis[edit | edit source]

Epley Manoeuvre[edit | edit source]

The Epley manoeuvre (also known as canalith repositioning treatment) is used to treat posterior and anterior canal canalithiasis.[3]

The manoeuvre is performed as follows:[3]

  • The patient is moved into DH on his / her affected side
  • The therapist rotates the patient’s head through 90 degrees to the opposite side; maintaining 30 degrees of extension
  • The patient is rolled onto the unaffected side with his / her head looking down
  • Maintaining head rotation, the patient gently sits up at side of bed
  • Each position is held until the vertigo and nystagmus has stopped and then for an additional 2 to 3 minutes

[16]

Gans Manoeuvre[edit | edit source]

The Gans manoeuvre is a modified Epley manoeuvre. It is performed as follows (assuming the right side is affected:[3]

  • Patient is positioned in side lying test position - i.e. sitting.
  • Patient turns head 45 degrees to the left
  • Patient lies down quickly onto his / her right side (no pillow), and holds this position for 2-3 minutes until the vertigo / nystagmus resolves
  • The patient then rolls over onto his / her left side, while maintaining the same head position
  • Wait 2-3 minutes as above
  • The patient sits up to complete the manoeuvre

Efficacy of Treatment for Vertical Canal BPPV[edit | edit source]

Epley Manoeuvre[edit | edit source]

The Epley manoeuvre is a safe and effective treatment for posterior canal BPPV (the most common variant) It can be effective for anterior canal canalithiasis as well, but it is not effective for horizontal canal canalithiasis or anterior, posterior or horizontal cupulolithiasis.[3] It has no serious side effects, but there is no evidence that it provides long-term resolution of symptoms and recurrence rates are high.[17] The Gans manoeuvre has been shown to have similar outcomes as the Epley.[17]

  • 93.5 percent of patients treated with an Epley manoeuvre had positive responses compared to 50 percent of the control group[18]
  • Macias and colleagues looked at 259 BPPV patients who received the Epley manoeuvre:[19]
    • 74.8 percent required  only one treatment
    • 19 percent required two treatments
    • 98.4 percent of patients were successfully treated after three sessions

Epley manoeuvre head positions in patients with posterior canal BPPV:[20]

  • During an Epley manoeuvre, if the patient was returned to a sitting position without rolling over onto his / her side with the head down at 45 degrees, the remission rate was found to be 50 percent
  • This suggests that the last component of the Epley manoeuvre facilitates the movement of the debris into the common crus[3]
Gans Manoeuvre[edit | edit source]

The Gans manoeuvre was developed because certain aspects of other BPPV manoeuvres, such as hyperextension of the neck during the Epley, are contraindicated for patients with vertebrobasilar insufficiency, cervical spondylosis, back problems etc.[21] Roberts and colleagues assessed the efficacy of the Gans manoeuvre and found that:[21]

  • On average, 1.25 treatments were needed to resolve the posterior semi-circular canal BPPV
  • Most patients (80.2%) were cleared with one treatment
  • 95.6 percent were cleared after two treatments
  • The Gans is, therefore, a good option for patients who cannot have the Epley or liberatory manoeuvres (see below)

Horizontal Canal Canalithiasis Treatment[edit | edit source]

There are two key treatments for horizontal canal canalithiasis:

  1. Forced prolonged positioning (i.e. 8 to 12 hours) lying on the unaffected side
  2. Barbeque roll (also known as the Lempert roll)

Barbeque Roll[edit | edit source]

To perform this canalith repositioning treatment:[3]

  1. The patient is positioned in supine with his / her head elevated 20 degrees and turned toward the affected side
  2. The therapist slowly rolls the patient’s head away from the affected side in 90 degree increments until the head has moved through 360 degrees
  3. Each position is maintained until the vertigo has stopped plus an additional 15 seconds
  4. The patient should have no vertigo or nystagmus once they are prone

NB usually whole body rolls are performed instead of just neck rotations

[22]

Efficacy of Treatment for Horizontal Canal Canalithiasis[edit | edit source]

Nuti and colleagues compared these two techniques for horizontal canal canalithiasis with an untreated control group.[23]

  • Barbeque roll – patients were rotated around the longitudinal axis in 90 degree stages
  • Prolonged positioning – patients lay on their uninvolved side for prolonged periods

Both treatments had similar remission rates:[23]

  • 71 percent in the rolling group
  • 73 percent in the forced prolonged positioning treatment
  • 33 percent in the control group

A more recent study by Wang and colleagues also supports the use of the barbeque roll.[24]

Vertical Canal Cupulolithiasis[edit | edit source]

Liberatory (Semont) Manoeuvre[edit | edit source]

To treat posterior canal BPPV using the liberatory (semont) manoeuvre:[3][10]

  • The patient sits with his / her legs over the side of the bed
  • The patient's head is turned 45 degrees toward the unaffected side
  • The therapist quickly moves the patient into side-lying on the affected side
  • This position is held for 5 minutes
  • The patient is then quickly moved all the way back up and then down to the opposite side-lying position, maintaining his / her head position
  • This position is held for 5 minutes
  • In this second position, nystagmus and vertigo typically appear.  If they do not, the head is abruptly shaken once or twice to free the debris[3]
  • The patient is slowly sat back up

[25]

To treat anterior canal BPPV with the liberatory (semont) manoeuvre, the manoeuvre is similar, but the patient’s head is turned to the affected side to begin:[3]

  • Patient sits with legs over the side of the bed
  • Patient's head is turned 45 degrees towards the affected side
  • The therapist quickly moves the patient into side-lying on the affected side - essentially, the patient is lying on his / her affected canal
  • This position is held for 5 minutes
  • The patient is then quickly moved all the way back up and then down to the opposite side-lying position, maintaining his / her head position
  • This position is held for 5 minutes
  • In this second position, nystagmus and vertigo typically appear.  If they do not, the patient’s head is abruptly shaken once or twice to free the debris
  • The patient is slowly sat back up

Efficacy of the Liberatory Manoeuvre[edit | edit source]

Semont and colleagues found that in 711 patients with BPPV there was complete remission in 84 percent of patients after one treatment and 93 percent after a second procedure one week later.[26]

Salvinilli and colleagues also found that the liberatory manoeuvre had good results. They found there was a remission rate of 92.5 percent with one manoeuvre while the untreated control group had a remission rate of 37.5 percent.[27]

Horizontal Canal Cupulolithiasis[edit | edit source]

The modified semont manoeuvre can be used to treat horizontal canal cupulolithiasis.[28] It is performed as follows:[3]

  • The patient starts in sitting on a bed. Lie him / her quickly down into side-lying on the affected side (i.e. the less symptomatic side to the patient)
  • Immediately at this point, conduct a 45 degree rotation downward
  • This position is held for 2 to 3 minutes
  • The patient is then quickly returned to the sitting position

This modified semont manoeuvre was found to result in resolution of symptoms for 77.8 percent of patients with horizontal canal cupulolithiasis after three sessions.[3][28]

The efficacy of these treatments for BPPV are summarised in Table 4.

Table 4. Efficacy of Treatment for BPPV
BPPV variant Efficacy

- one treatment applied

- outcome complete resolution

Anterior / posterior canal canalithiasis Epley manoeuvre: 93.5 percent [18]

Gans manoeuvre: 80.2 percent[21]

Horizontal canal canalithiasis Barbeque roll: 71 percent[23]
Anterior / posterior canal cupulolithiasis Liberatory manoeuvre: 92.5 percent[27]
Horizontal canal cupulolithiasis Modified semont manoeuvre: 77.8 percent[28]

(3 applications)

Brandt-Daroff Treatment: Home exercise program for BPPV[edit | edit source]

To perform these exercise programme, patients are instructed to:[3]

  • Turn their head 45 degrees away from the affected side and lie quickly onto the affected side
  • Hold this position until vertigo stops (+ 30 seconds)
  • Then return to sitting position and hold for 30 seconds or until the vertigo stops
  • Repeat these steps on the opposite side
  • Repeat this sequence 10-20 times, three times per day

NB patients are advised they can stop the exercise when they have two consecutive days with no symptoms or if there has been no improvement within 2 weeks.

Effectiveness of the Brandt-Daroff Exercises[edit | edit source]

Brandt and Daroff studied the effectiveness of these exercises on a series of 67 patients with BPPV. They found that after 3 to 14 days of exercises, 98% of the subjects had no symptoms of BPPV.[29] More recent studies have also found these exercises to be effective.[30]

Clinically, however, this exercise programme often requires a prolonged period of time for patients to experience an improvement in their symptoms.[3]

Relevance of Postural Restrictions for BPPV[edit | edit source]

Postural restrictions post-Epley manoeuvre did not improve the efficacy of treatment or diminish the recurrence rate. At present, it is not, therefore, advised to place postural restrictions on patients after an Epley manoeuvre.[31][32]

Daily Epley Manoeuvres and BPPV[edit | edit source]

A daily routine of self-canalith repositioning exercises does not affect the time to recurrence or the rate of recurrence of posterior canal BPPV.[33] Patients should not, therefore, do the Epley manoeuvre as a home exercise to prevent recurrence of BPPV. [3]

Sleep Position and Laterality of BPPV[edit | edit source]

It has been found that there is an association between the ear affected by BPPV and the preferred head-lying side during sleep onset. Moreover, there are higher recurrence rates of BPPV in patients who sleep on their affected side.[34][35][36] Patients may, therefore, want to change or vary the side they sleep on sleep on if BPPV is recurring.[3]

Canal Conversion[edit | edit source]

During treatment of posterior semi-circular canal BPPV, debris may move from the posterior canal to the horizontal canal (usually) or to the anterior canal (rarely – 2.9%).[37]

This will be obvious when a DH retest results in dramatically different nystagmus patterns after an Epley manoeuvre has been performed. If this occurs, it is necessary to re-evaluate and treat the newly involved canal.[3] The Epley manoeuvre may have a higher rate of conversion than the liberatory manoeuvre.[38]

What Happens to the Otoconia?[edit | edit source]

A number of theories have been proposed to explain where the otoconia go after repositioning techniques, including:[3]

  • They simply dissolve[39]
  • The ‘dark cells’ of the labyrinth, which are adjacent to the utricle and crista, reabsorb the displaced otoconia[40]
  • They stick back to the utricle[41]

Management Issues in BPPV[edit | edit source]

  • BPPV is frequently considered a self-limiting disorder as the spontaneous remission rate can be as high as 50 percent
  • However, for many individuals it persists for years if not decades
  • Recurrence rate varies from 18 to 37 percent
  • Antivertiginous drugs are not helpful
  • Some patients may experience increased dizziness, nausea and imbalance for a day or two after treatment – possibly due to an autonomic dysfunction[42]
  • It is important to bring a patient back for re-evaluation, usually in 3 to 5 days if possible
  • Evaluate the patient's postural control, vestibular function and motion sensitivity
  • If the patient has a vestibular hypofunction and BPPV, treat the BPPV first
  • Be alert to central signs and symptoms[3]

References[edit | edit source]

  1. 1.0 1.1 1.2 von Brevern M, Radtke A, Lezius F, Feldmann M, Ziese T, Lempert T et al. Epidemiology of benign paroxysmal positional vertigo: a population based study. J Neurol Neurosurg Psychiatry. 2007;78(7):710-5.
  2. 2.0 2.1 2.2 2.3 Balatsouras DG, Koukoutsis G, Fassolis A, Moukos A, Apris A. Benign paroxysmal positional vertigo in the elderly: current insights. Clin Interv Aging. 2018;13:2251-66.
  3. 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 3.22 3.23 3.24 3.25 3.26 3.27 3.28 3.29 3.30 3.31 3.32 3.33 Tonks B. Benign Paroxysmal Positional Vertigo Course. Physioplus, 2021.
  4. Palmeri R, Kumar A. Benign Paroxysmal Positional Vertigo. [Updated 2020 Jun 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470308/
  5. Zhang D, Zhang S, Zhang H, Xu Y, Fu S, Yu M, Ji P. Evaluation of vertebrobasilar artery changes in patients with benign paroxysmal positional vertigo. Neuroreport. 2013;24(13):741-5.
  6. Jeong SH, Kim JS, Shin JW, Kim S, Lee H, Lee AY et al. Decreased serum vitamin D in idiopathic benign paroxysmal positional vertigo. J Neurol. 2013;260(3):832-8.
  7. 7.0 7.1 Chen J, Zhao W, Yue X, Zhang P. Risk factors for the occurrence of benign paroxysmal positional vertigo: A systematic review and meta-analysis. Front Neurol. 2020;11:506.
  8. 8.0 8.1 Kansu L, Aydin E, Gulsahi K. Benign paroxysmal positional vertigo after nonotologic surgery: case series. J Maxillofac Oral Surg. 2015;14(Suppl 1):113-5.
  9. Li S, Wang Z, Liu Y, Cao J, Zheng H, Jing Y et al. Risk factors for the recurrence of benign paroxysmal positional vertigo: a systematic review and meta-analysis. Ear Nose Throat J. 2020:145561320943362.
  10. 10.0 10.1 10.2 10.3 10.4 Bhattacharyya N, Gubbels SP, Schwartz SR, Edlow JA, El-Kashlan H, Fife T et al. Clinical practice guideline: benign paroxysmal positional vertigo (update). Otolaryngol Head Neck Surg. 2017;156(3_suppl):S1-S47.
  11. Kaplan DM, Slovik Y, Joshua BZ, Puterman M, Kraus M. Head shaking during Dix-Hallpike exam increases the diagnostic yield of posterior semicircular canal BPPV. Otol Neurotol. 2013;34(8):1444-7.
  12. BMJ Learning. Vertigo - Dix-Hallpike Manoeuvre from BMJ Learning. Available from: https://www.youtube.com/watch?v=8RYB2QlO1N4&t=1s [last accessed 13/6/2021[
  13. Cohen HS. Side-lying as an alternative to the Dix-Hallpike test of the posterior canal. Otol Neurotol. 2004;25(2):130-4.
  14. Physical Therapy Nation. Sidelying Test for Posterior Canal BPPV. Available from: https://www.youtube.com/watch?v=fe63hTHR2cw [last accessed 13/6/2021]
  15. EducatedPT. Supine Roll Test for Horizontal Canal BPPV. Available from: https://www.youtube.com/watch?v=ns8XZ4rKiJc [last accessed 13/6/2021]
  16. BMJ Learning. Vertigo - Epley manoeuvre from BMJ Learning. Available from: https://www.youtube.com/watch?v=jBzID5nVQjk [last accessed 13/6/2021]
  17. 17.0 17.1 Hilton MP, Pinder DK. The Epley (canalith repositioning) manoeuvre for benign paroxysmal positional vertigo. Cochrane Database Syst Rev. 2014 Dec 8;(12):CD003162.
  18. 18.0 18.1 Wolf M, Hertanu T, Novikov I, Kronenberg J. Epley's manoeuvre for benign paroxysmal positional vertigo: a prospective study. Clin Otolaryngol Allied Sci. 1999;24(1):43-6.
  19. Macias JD, Lambert KM, Massingale S, Ellensohn A, Fritz JA. Variables affecting treatment in benign paroxysmal positional vertigo. Laryngoscope. 2000;110(11):1921-4.
  20. Herdman SJ, Tusa RJ, Zee DS, Proctor LR, Mattox DE. Single treatment approaches to benign paroxysmal positional vertigo. Archives of Otolaryngology ‐ Head & Neck Surgery 1993;119(4):450‐4.
  21. 21.0 21.1 21.2 Roberts RA, Gans RE, Montaudo RL. Efficacy of a new treatment maneuver for posterior canal benign paroxysmal positional vertigo. J Am Acad Audiol. 2006;17(8):598-604.
  22. Ascension Via Christi. Barbeque Roll Lempert maneuver. Available from: https://www.youtube.com/watch?v=ufD_tcSx5dQ [last accessed 13/6/2021]
  23. 23.0 23.1 23.2 Nuti D, Agus G, Barbieri MT, Passali D. The management of horizontal-canal paroxysmal positional vertigo. Acta Otolaryngol. 1998;118(4):455-60.
  24. Wang YH, Chan CY, Liu QH. Benign paroxsymal positional vertigo - recommendations for treatment in primary care. Ther Clin Risk Manag. 2019;15:719-725.
  25. EducatedPT. Liberatory (Semont) Maneuver for BPPV. Available from: https://www.youtube.com/watch?v=pK9qaprUU64 [last accessed 13/6/2021]
  26. Parnes LS, Agrawal SK, Atlas J. Diagnosis and management of benign paroxysmal positional vertigo (BPPV). CMAJ. 2003;169(7):681-93.
  27. 27.0 27.1 Salvinelli F, Casale M, Trivelli M, D'Ascanio L, Firrisi L, Lamanna F et al. Benign paroxysmal positional vertigo: a comparative prospective study on the efficacy of Semont's maneuver and no treatment strategy. Clin Ter. 2003;154(1):7-11.
  28. 28.0 28.1 28.2 Casani AP, Vannucci G, Fattori B, Berrettini S. The treatment of horizontal canal positional vertigo: our experience in 66 cases. Laryngoscope. 2002;112(1):172-8.
  29. Brandt T, Daroff RB. Physical therapy for benign paroxysmal positional vertigo. Arch Otolaryngol. 1980;106(8):484-5.
  30. Cetin YS, Ozmen OA, Demir UL, Kasapoglu F, Basut O, Coskun H. Comparison of the effectiveness of Brandt-Daroff Vestibular training and Epley Canalith repositioning maneuver in benign Paroxysmal positional vertigo long term result: A randomized prospective clinical trial. Pak J Med Sci. 2018;34(3):558-63.
  31. Casqueiro JC, Ayala A, Monedero G. No more postural restrictions in posterior canal benign paroxysmal positional vertigo. Otol Neurotol. 2008;29(5):706-9.
  32. Balikci HH, Ozbay I. Effects of postural restriction after modified Epley maneuver on recurrence of benign paroxysmal positional vertigo. Auris Nasus Larynx. 2014;41(5):428-31.
  33. Helminski JO, Janssen I, Hain TC. Daily exercise does not prevent recurrence of benign paroxysmal positional vertigo. Otol Neurotol. 2008;29(7):976-81.
  34. Korres SG, Papadakis CE, Riga MG, Balatsouras DG, Dikeos DG, Soldatos CR. Sleep position and laterality of benign paroxysmal positional vertigo. J Laryngol Otol. 2008;122(12):1295-8.
  35. Shigeno K, Ogita H, Funabiki K. Benign paroxysmal positional vertigo and head position during sleep. J Vestib Res. 2012;22(4):197-203.
  36. Li S, Tian L, Han Z, Wang J. Impact of postmaneuver sleep position on recurrence of benign paroxysmal positional vertigo. PLoS One. 2013;8(12):e83566.
  37. Park S, Kim BG, Kim SH, Chu H, Song MY, Kim M. Canal conversion between anterior and posterior semicircular canal in benign paroxysmal positional vertigo. Otol Neurotol. 2013;34(9):1725-8.
  38. Anagnostou E, Stamboulis E, Kararizou E. Canal conversion after repositioning procedures: comparison of Semont and Epley maneuver. J Neurol. 2014;261(5):866-9.
  39. Parker DE, Covell WP, von Gierke HE. Exploration of vestibular damage in guinea pigs following mechanical stimulation. Acta Otolaryngol. 1968:Suppl 239:7+.
  40. Lim DJ The development and structure of otoconia. In: I Friedman, J Ballantyne (eds). Ultrastructural Atlas of the Inner Ear. London: Butterworth, 1984. p. 245-69.
  41. Otsuka K, Suzuki M, Shimizu S, Konomi U, Inagaki T, Iimura Y et al. Model experiments of otoconia stability after canalith repositioning procedure of BPPV. Acta Otolaryngol. 2010 Jul;130(7):804-9.
  42. Kim HA, Lee H. Autonomic dysfunction as a possible cause of residual dizziness after successful treatment in benign paroxysmal positional vertigo. Clin Neurophysiol. 2014;125(3):608-14.