Virtual Reality for Decreasing Procedural Pain during Botulinum Toxin Injection Related to Spasticity Treatment in Adults: A Pilot Study

1. Introduction

Neurological impairments such as stroke, multiple sclerosis and cerebral palsy, represent a major public health issue worldwide (WHO report 2007). Motor impairments associated with these pathologies, and more specifically spasticity, are associated with loss of mobility and social participation [2]. Spasticity is defined as a motor disorder characterized by a velocity-dependent increase in the tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflexes as one component of the upper motor neuron (UMN) syndrome (Lance, 1980). Intramuscular botulinum toxin injection is a first-line treatment guidelines for the management of spasticity in adult patients [3]. Toxin injections help to reduce disturbing muscle hypertonia, and consequently improve functional capacities, relieve pain related to spasticity, enhance hygiene gesture capabilities, and in fine, improve quality of life [3,4]. While the literature provides strong evidence on the clinical benefits of botulinum toxin, the injection procedure is associated with procedural pain and anxiety [5,6,7].

Several factors influence procedural pain, such as the use of an anesthetic or not at the injection site [8], or method of injection site location (ultrasound or electrostimulation) [6,9]. Regardless of the type of procedures, pain is still reported by patients [9], and repetitions of injection exacerbate pain symptoms [10]. Ultimately, pain could lead to discontinuation of the injection process, representing a loss of chance for the patient [11]. In this context, pain should be managed in view of improving treatment adherence and optimizing therapy.

In first intention, pharmacological approaches, such as local anesthetic cream of Lidocaine/Prilocaine (EMLA®) or systemic therapeutics like MEOPA and midazolam, showed clinical efficacy in relieving pain and discomfort during toxin botulinum injection [3,11,12,13,14,15,16]. However, these drugs have been associated with adverse effects including sleepiness, nausea and dizziness [14,17].

As a non-pharmacological complementary, innovative technology such as Virtual Reality (VR) has recently been introduced in different departments to manage pain (in acute, chronic and experimental settings) [1,18,19,20,21]. VR is defined by a computerized system that creates a virtual environment where a person undergoes an immersive sensory experience with an enriched environment involving augmented multiple sensory feedbacks (auditory, visual, tactile VR enriched environment) [22]. VR has the advantage of being easy to use, quick to set up, accessible with very short training, not requiring any supplementary staff and having few non-serious undesirable effects (0 to 8% of nausea and dizziness)[23]. The immersive environment is reinforced by combining audio guidance with display of an appeasing visual scene. VR has proven its effectiveness in management of procedural pain[24], particularly pain associated with venipuncture [23,25]. In a retrospective chart review, Chau et al. [26] showed the feasibility of using VR during botulinum toxin injections in 14 pediatric patients, and reported benefits in management of procedural pain [26]. In adults, VR also seems to offer advantages in some hospital settings, even in other types of injections, regarding pain, anxiety and anger management, related to the distraction provided by this technology[27,28,29]. However, the effects and feasibility of VR during intramuscular injection of botulinum toxin in adults presenting with spasticity have yet to be determined.

The main objective of our study was to assess VR efficacy in management of procedural pain during intramuscular injections of botulinum toxin in adult patients presenting with spasticity. Based on the literature, we hypothesized that in comparison with non-VR, VR would induce a decrease in procedural pain. The secondary objectives were to determine the potential efficacy of VR to alleviate anxiety and to assess level of patient satisfaction.

2. Materials and Methods

2.1. Study Design

This is a retrospective study conducted in the Physical Medicine and Rehabilitation Department of the University Hospital of Poitiers between February and August 2022. Data collection was conducted according to the guidelines of the Declaration of Helsinki and the French Data Protection Authority (CNIL, MR-004). All data collection was declared to Health Data Hub (number F20220719114034). All participants received a non-opposition form and thus agreed that their data was used for research purposes.

2.2. Inclusion and Exclusion Criteria

To be included, patients had to be over 18 years old, to have undergone botulinum toxin injection in their care pathway, to present with focal spastic hypertonia in at least 1 muscle of the upper or lower limbs justifying the use of botulinum toxin, and to be able to provide answers with no cognitive disease for evaluating pain intensity and level of anxiety. All contraindications to toxin botulinum injection (myasthenia, pregnancy, breast-feeding, hypersensitivity to one of the substances in the product, infection at the injection site) and any pathological condition not allowing optimal use of the virtual reality helmet (blindness, major visual acuity disorders, deafness) were not included. Patients who were unable to retain the virtual reality headset during the procedure (appearance of adverse effects, patient wishing to stop during the procedure) were excluded from the study.

2.3. Procedure

The patient was informed about the procedure of VR utilization and consented to wear the device. The patient was comfortably seated on the examination table. The VR device (HYPNOVR, https://hypnovr.io/fr/produits/hypnovr/) combined with headset (TaoTronic, model TT-BH085, reference 6972103466158) was set on the patient as comfortably as possible, and a movie showing calm visual environments (walking on the beach, diving among colored fishes, or traveling in space) combined with relaxing music was displayed. The VR program consisted of a 2-minutef induction phase (before injection), 10-20 minutes of the main VR pathway (during injection), and a 2-minute exit phase. Data were collected before and after the procedures.

Figure 1. Virtual images in the headset (pictures from https://hypnovr.io/fr/, all rights reserved).

Figure 1. Virtual images in the headset (pictures from https://hypnovr.io/fr/, all rights reserved).

2.4. Outcomes

Pain intensity, considered as the primary endpoint, was determined using a numerical rating scale (NRS) ranging from 0 (no pain) to 10 (maximum imaginable pain)[30,31]. The patient reported the pain experienced during previous injections without VR before injection and the pain experienced in the current procedure with VR after the end of the procedure. In addition, perceived improvement was determined by the patient as a percentage of added value of VR on pain intensity compared to procedure without VR.

Level of anxiety, related to previous injection without VR and current injection with VR, was determined with a numerical anxiety rating scale from 0 (no anxiety) to 10 (maximum imaginable anxiety)[32]. In addition, perceived improvement was determined by the patient as a percentage of added value of VR on level of anxiety compared to procedure without VR.

Level of satisfaction was determined using an 11-point scale ranging from 0 (not satisfied at all) to 10 (very satisfied) and asking if they agreed to reuse VR for the subsequent toxin botulinum injection, and if they would recommend VR to other patients.

The muscles targeted for injection, the method of localizing injection sites (ultrasound or electrostimulation), analgesic medication intake, use of additive analgesic for toxin injection, time of the day, and occurrence of adverse events were collected.

Figure 2. Patient with virtual reality headset.

Figure 2. Patient with virtual reality headset.

2.5. Statistical Analysis

The study population was described by age, sex, disease, and baseline pain intensity. Quantitative variables were described by either mean and standard deviation or median and interquartile range depending on data normality. Categorical variables were described by numbers and percentages. Normality was verified using the Shapiro-Wilk test.

Pain intensity NRS and level of anxiety during the procedure with and without VR were compared using a Wilcoxon signed-rank test (paired test) since the variable was not normally distributed.

Mean and standard deviation of perceived improvement using VR and satisfaction with VR were also reported. R software version 4.2.0 was used for the analyses. All statistical tests were two-sided and the significance threshold was fixed at 0.05.

3. Results

3.1. Participants

Twenty-one patients were identified over the 7-month inclusion period. Four patients were excluded, three due to incomplete data collection and one due to cybersickness occurrence with VR[33]. All in all, 17 patients were included and analyzed.

Patient characteristics are presented in Table 1. The mean participant age was 49.9 ± 10.6 years, with 9 females (53%). Spasticity was subsequent to stroke for 9 (52.9%) patients, cerebral palsy for 3 (17.6%), multiple sclerosis for 2 (11.8%), cervico-arthrosic myelopathy for 1 (5.9%), hereditary spastic paraplegia for 1 (5.9%), and meningitis for 1 (5.9%). One patient received MEOPA and 1 patient EMLA®. One patient was treated with long-term TRAMADOL.

On average, 5.4 muscles were targeted per person, and the median of injected muscles was 5. The different injection sites are presented in Table 2 and Table 3.

3.2. Primary and secondary outcomes

Pain intensity was significantly lower during injection procedure with VR (2.3 ± 1.5) than without VR (4.3 ± 2.7, p=0.014) (Figure 4 and Table 4). The proportion of responding patients was 76%

Level of anxiety NRS was not significantly different between injection with (1.3 ± 2.1) and without VR (2.1 ± 3.0, p=0.054) (Figure 4 and Table 4). The proportion of responding patients was 29%.

Patients reported a mean subjective impression of improvement of 39.7 ± 30.9% for pain and 21.5 ± 25.0% for anxiety during the procedure with VR. Patients’ mean overall satisfaction was 7.9 ± 1.6 out of 10 (Table 2).

Regarding adverse events, only 1 patient (5.9%) experienced cyberkinetosis.

Fifteen patients (88.2%) agreed to reuse VR for the subsequent toxin botulinum injection, and all patients (100%) would recommend VR to other patients (Table 2).

4. Discussion

The objective of this study was to assess VR efficacy in reducing procedural pain and anxiety during toxin botulinum injection in adults presenting with spasticity. We showed that VR was able to significantly decrease procedural pain. Patients were very satisfied with use of VR during the injection and agreed to reuse the VR helmet and recommend this approach for other patients.

In a systematic review including 18 studies, Smith et al. [23] reported that 12 studies demonstrated that VR led to significant pain reduction during painful procedure for burns, wounds, or injection . Similarly, in a systematic review with meta-analysis, Mallari et al. [34] showed that VR could reduce acute procedural pain in adults. More specifically for botulinum injection procedure, using the Face, Legs, Activity, Cry, Consolability (FLACC) test for pain assessment, Chau et al. [26] reported a median score of 2.5 in 14 children treated for spasticity. In an adult population, we reported a pain intensity score of 2.3 with VR. Although previous research did not focus on procedural pain for Botulinum toxin in adults, our study suggests that a non-invasive VR device can easily improve procedural injection, lasting every 3 months and may ultimately enhance therapeutic adherence.

The main principle of VR is to provide strong and sufficient distraction to redirect attention initially focused on pain to a calm environment[35]. Thereby, VR can effectively modify sensory perceptions such as pain by monopolizing a high amount of attentional resources [39]. By having attention compete between VR environment and pain, Rutter et al. [40] reported that VR led to maintenance of an increased pain threshold and pain tolerance over 8 weeks (8 testing sessions) in 28 healthy participants during the cold-pressor task. In the current study, VR was applied with an immersive device providing high degree of immersion in a specific peaceful environment during one session of Botulinum toxin injection [41,42,43]. While VR successfully managed chronic pain [44], the long-term and sustainable effect of VR in Botulinum toxin injection in adults remains to be determined. In addition, combining hypnosis with VR could potentiate the effect of VR in managing procedural pain [45,46,47,48,49], and should be investigated in the future.

Although a positive effect of VR on anxiety has been reported in the literature [35,50], our results showed only a trend toward decrease. That said, while we failed to observe a strong effect on anxiety, it safe to assume that the level of anxiety at baseline (2.1) was too low for it to be significantly reduced in a population having already undergone several botulinum toxin injection procedures. Investigation of a population of patients receiving their very first injection would probably yield significantly decreased procedural anxiety in Botulinum toxin injection in adult populations.

Patients in the current study were very satisfied with VR (7.9 out of 10) and would agree to reuse VR for their next injection (88%) and to recommend VR for other patients (100%). Smith et al. [23] highlighted rare adverse events (8-10%) which are consistent with the single case of cybersickness observed in our study. The side effects observed during VR are considered as transient and reversible, making VR a safe approach to manage procedural pain in neurologic populations[33]. In addition, VR might be considered as a valuable alternative to medical therapies insofar as, in comparison with pharmacological management, it does not necessitate additional practitioners and cost other than the VR device itself. A medico-economic study should be conducted to validate this hypothesis.

This pilot study is associated with limitations. While the retrospective design in clinical routine provides real world, data it entails potential bias connected with declarative assessment; what is more, the results were not compared with those of a parallel control group. The long-term added value of VR in Botulinum toxin injection remains to be determined in a randomized controlled trial.

5. Conclusions

Our study showed that VR was useful for management of pain related to botulinum toxin injection in adults, as patients were very satisfied with the device. In addition, they agreed to reuse VR for their next injection and to recommend this approach to other patients presenting with spasticity. While VR should be considered as an alternative treatment option to pharmacological approaches in Botulinum toxin injection a prospective randomized controlled trial with long-term follow-up and cost-effectiveness analysis is still required.