1

Introduction

Benign positional paroxysmal vertigo (BPPV) is a peripheral vestibular disorder characterized by brief episodes of vertigo when the head is moved to certain positions . It was proposed that the vertigo was due to the dislodgement of degenerative debris from the utricle into the semicircular canals resulting in inappropriate deflection of the cupula by either deposition of debris onto the cupula namely cupulolithiasis or free-flowing debris in the endolymph namely canalithiasis .

According to the epidemiological study by von Brevern et al , the lifetime prevalence of BPPV was 2.4% and the 1-year incidence was 0.6% in general populations. Two more studies investigated the incidence of BPPV in general population who had seek medical help not related to BPPV and found a low incidence of 0.01% and 0.06% , respectively. These results might not adequately represent the general population, as people who did not seek medical help were not included. On the other hand, there are very few studies investigating the epidemiology of BPPV in specific disease groups. Study by Motin et al demonstrated the prevalence of BPPV in the studied traumatic brain injury (TBI) population as 13% and BPPV actually accounted for about half of all positional vertigo in this patient group. Similarly, Gordon et al found 15% of the head trauma patients suffered from BPPV. It was also reported that almost 34% of the included Whiplash patients had BPPV . In summary, BPPV incidence is considered low in general population, but it warrants more attention from clinicians or researchers who are working with the more affected patient groups with traumatic injuries.

There is currently no study to investigate the epidemiology of BPPV and evaluate its treatment efficacy in traumatic SCI populations. However, in clinical settings, BPPV does exist in people with traumatic SCI and it is often left unreported, undiagnosed and thus untreated. As a result, the vertigo that is not accounted for, affects clients’ activities of daily living (ADL) and participation in rehabilitation activities. The symptoms might persist even after discharge and thus adversely affects clients’ long-term safety and quality of life (QOL). Based on the available literature, we propose traumatic SCI is one of the potential causes for BPPV, especially high-level cervical SCI, in view of the close proximity of the upper cervical spine to the inner ear and possible force transmission to the utricle causing the dislodgement of debris during spinal trauma. Similar concepts have been used to explain the occurrence of BPPV after dental or ear surgery that indirect trauma or vibration to the labyrinth by various operation tools may induce the mechanism as mentioned previously, causing BPPV . Therefore, BPPV research in traumatic SCI population is essential for problem identification and solution development. Initially, it is important to look into the incidence of BPPV in traumatic SCI population to understand the extent of problem. From there, clinicians might need to revamp the current standard care, such as introduction of BPPV screening for people with vertigo, provision of adequate training for BPPV assessments and treatment techniques to physicians and therapists. Subsequently, the treatment efficacy for BPPV needs to be evaluated so as to confirm the existing treatment strategies are also useful and applicable in traumatic SCI population.

Although the Dix Hallpike and supine roll tests for BPPV are fairly well established in the general population and certain disease groups , these tests are not routinely done for traumatic SCI clients and staff are often not adequately trained to perform these tests. Despite of this, Dix-Hallpike and roll tests could still be applied to people with traumatic SCI safely, provided the stability of their spines are ensured throughout the tests. The treatments for BPPV including the canalith repositioning procedure (CRP) and liberatory maneuver for respective anterior/ posterior canal canalithiasis and cupulolithiasis have high treatment efficacy of about 67–95% , whereas the barbecue roll and barbecue roll with quick movements for respective horizontal canal canalithiasis and cupulolithiasis also have high treatment efficacy of about 50–100% . Although these treatments are well accepted and widely used by clinicians, they are yet to be tested for their efficacy in people with traumatic SCI.

Therefore, the primary aim of this study is to identify the incidence of BPPV and its treatment efficacy as well as the safety of conventional and modified BPPV assessments and treatments techniques in traumatic SCI population. Secondary aim is to investigate the factors that might be associated with the incidence of BPPV. With the results, the authors will arrive at implications for clinical practices and future research directions.

2

Methods

2.2

Procedures

To ensure safety, the followings were done before implementation of the assessments and treatments: (1) obtain clearance from the medical team regarding spinal stability; (2) ensure clients are cognitively capable to provide verbal consent and follow instructions; (3) provide clients with adequate information regarding the procedures; (4) ensure pain free neck and back range of motion required for the procedures; (5) ensure the procedures do not trigger any pain or neurological symptoms by prior screening assessments; (6) provide adequate support for the neck and trunk throughout the procedures; (7) prepare environment for fall prevention and other unforeseen circumstances; and (8) plan for necessary procedural modifications for clients with cervical collars or thoraco-lumbar orthosis or other limitations. Each participant underwent two tests: (1) Dix-Hallpike test and (2) Roll test on an adjustable plinth, which take about 5 minutes to complete . For people with cervical SCI, modified Dix-Hallpike and roll tests were employed as shown in Figs. 1 and 2 . While for people with thoracic and lumbar SCI, conventional Dix-Hallpike and roll tests were used. Repeated tests might be done in case of uncertainty or in the case of multiple canals involvement. Participants were asked to report vertigo and their eyes were observed for nystagmus during the tests to confirm the vestibular diagnosis.

(A–C): BPPV assessments – Modified Dix Hallpike test for anterior or posterior canal BPPV. (A) Patient sits with legs straightened on a tilt table tilted 30 degrees downward. This aims to accommodate the requirement of 30 degrees neck extension at the end of traditional Dix-Hallpike test. Main therapist supports patient’s neck in neutral position by placing hands around, whereas patient holds onto therapist’s arms for support before the start of the maneuver. Another helper should stand at the other side of the tilt table to ensure smooth movement and safety throughout the test. (B) Patient’s trunk then needs to be turned 45 degrees towards to the side to be tested keeping the neck in neutral. This is in contrast to the traditional Dix-Hallpike test, which requires 45° of neck rotation. (C) The helper prepares a pillow to be put on the tilt table prior. The patient is then brought down and lies on the pillow such that 45 degrees of trunk rotation could be maintained at the end of the maneuver. Both therapist and helper work together to ensure a safe and controlled descend with patient’s neck kept in neutral position throughout the movement. The therapist observes patient’s eyes for nystagmus and makes vestibular diagnosis.

(A) and (B): BPPV Assessments – Modified roll test for horizontal canal BPPV. (A) Therapist prepares patient to lie supine on a wedge with neck in neutral position. This aims to accommodate the requirement of 30 degrees neck flexion in traditional roll test. The helper assists patient to bend up the knee opposite to the side to be tested. (B) The patient is then turned 90 degrees towards the side to be tested with the neck fully supported in neutral position by the therapist. The helper assists trunk rotation by placing hands at trunk and opposite knee. The therapist observes patient’s eyes for nystagmus and makes vestibular diagnosis.

2.3

Diagnosis and treatment

Table 1 and 2 show how different types of nystagmus correspond to different vestibular diagnosis. The researchers also ruled out any central vestibular disorder before making diagnosis. Anterior or posterior canal canalithiasis was treated with the CRP, while respective cupulolithiasis was treated with the liberatory maneuvers . For the horizontal canals, its canalithiasis and cupulolithiasis were treated with the barbecue roll and barbecue roll with quick movements, respectively . For people with cervical SCI, modified treatment techniques were used as shown in Figs. 3 and 4 . While for people with thoracic and lumbar SCI, conventional treatment techniques were used. Treatments were repeated until complete resolution of nystagmus and vertigo and each treatment would roughly take 5 minutes. A re-assessment involving the Dix-Hallpike and roll tests were done to confirm whether the BPPV was successfully treated. If the number of treatments exceeded five, the treatments were considered as failed and the interventions were discontinued.

Table 1

Criteria for diagnosing different subtypes of BPPV for Dix-Hallpike test

Nystagmus	Canals involved	Vestibular diagnosis
(L) rotational up-beating	(L) posterior canal	Canalithiasis: Nystagmus has latency and last < 30s Cupulolithiasis: Nystagmus has no latency and last > 30s
(L) rotational downbeating	(L) anterior canal
(R) rotational upbeating	(R) posterior canal
(R) rotational downbeating	(R) anterior canal

Table 2

Criteria for diagnosing different subtypes of BPPV for roll test

Nystagmus	Vestibular diagnosis	Canal involved
Geotropic	Canalithiasis	(L) horizontal canal when intensity of vertigo and / or nystagmus is higher during (L) roll test or vice versa
Ageotropic	Cupulolithiasis

(A) to (D): BPPV treatments – Canalith Repositioning Techniques (CRT) for anterior or posterior canal canalithiasis. (A) Patient lies on a plinth with the upper part of the plinth tilted 30 degrees downward and a pillow was placed under the opposite shoulder/trunk such that patient’s trunk could be rotated 45 degrees towards the affected side. This aims to accommodate the requirement of 30 degrees of cervical extension and 45 degree of cervical rotation in the traditional procedure. Main therapist provides support to patient’s neck and ensures it is in neutral position. Patient is maintained at this position for about 1 minute before moving to the next position. (B) The patient is then turned away from the affected side and faces up by the main therapist. The helper removes the pillow under the opposite shoulder/ trunk before the movement. Patient is maintained at this position for about 1 minute before moving to the next position. (C) Therapist turns the patient 90 degrees further away from the affected side with the neck supported in neutral position. The helper turns the lower part of the body with the knee at the affected side bended. Patient is maintained at this position for about 1 minute before moving to the next position. (D) Therapist turns the patient 45 degrees further away from the affected side with the neck supported in neutral position such that the patient could see the floor. Similarly, the helper facilitates turning of the hip and legs. Patient is maintained at this position for about 1 minute. Upon completion, the helper helps patient to put the legs down and both therapist and helper assist patient to sit up at the edge of the plinth making sure that the neck is kept in neutral during the movement.

(A) to (C): BPPV treatments – Barbecue Roll for horizontal canal canalithiasis. (A) Patient side-lies on the affected side on a plinth with the upper part of the plinth propped up 30 degrees. Therapist supports patient’s neck in neutral position, while the helper supports patient’s hip and legs. (B) Therapist then turns the patient 90 degrees away from the affected side such that patient lies supine on the plinth with the neck kept in neutral position. Patient is maintained at this position for about 1 minute. (C) Subsequently, both the therapist and the helper continue to turn the patient 90 degrees away from the affected side for another two times until the patient achieves a prone position. Patient’s neck is fully supported in neutral position throughout and patient is maintained at each position for about 1 minute. After completion, both the therapist and the helper assist the patient back to sitting.