Suprascapular Nerve Block Versus Intraarticular Steroid Injection in Hemiplegic Shoulder Pain

1. INTRODUCTION

1.1 Research Area

Hemiplegic shoulder pain (HSP) is a common clinical consequence of stroke with reported frequency as high as 72% (1). Onset of HSP is more common at 2-3 months post stroke(2). HSP can reduce participation in rehabilitation activities and reduce quality of life(3). The etiology of HSP includes neurological and mechanical factors, although mechanical factors are more common. Mechanical factors include structural injury from glenohumeral subluxation, or rotator cuff pathology (3). In hemiplegic patients, the nociceptive pain ratio was higher at 86.7% compared to neuropathic pain ratio; 13.3% (4). Management of HSP focused on reducing pain and improving shoulder ROM. Minimally invasive treatment of HSP with intra-articular steroid (IAS) injection and supra-scapular nerve block (SSNB) have lately gained interest. However, 2 studies done so far showed that while both SSNB and IAS showed significant differences in reducing shoulder pain and improving ROM with time, there was no significant difference of these injection method in comparison to conventional treatment. None of the studies done to date documents functional outcome of patients post injection with IAS or SSNB. The main purpose of this study is to assess the analgesic effect of SSNB vs IAS in HSP among Malaysian stroke population as well as to look at the improvement of shoulder ROM and functional outcome measure.

1.2 Research Questions

Does supra-scapular nerve block (SSNB) provide better pain relief, passive range of motion (PROM) and functional outcome compared to intraarticular steroid (IAS) injection in hemiplegic shoulder pain?

1.3 Significance of this study

SSNB is an effective and safe method for pain relief and increases ROM in many group of patients who had shoulder pain such as non specific shoulder pain (5),chronic shoulder pain(6) and rotator cuff tendinitis(7). SSNB can be performed using ultrasound guidance where injection of Bupivacaine is made at posterior shoulder towards suprascapular notch. Side effects include; worsening pain, soreness, bruising, nerve damage, allergic reaction.

IAS on the other hand is performed by injecting 40 mg of Triamcinolone Acetonide along with 2 ml of Lidocaine 1% into glenohumeral articular space (8). Systematic reviews of treatments for sub acromial pain favor IAS over the following options: ergonomic changes, NSAID, acupuncture, ROM and strengthening exercises, ultrasound, ice, heat, and physical therapy (9,10). Side effects include; post injection flare, disturbance of menstrual pattern, facial flushing, subcutaneous tissue atrophy, skin depigmentation, infection, and tendon rupture (13).

2 studies done so far that compare IAS vs SSNB head to head; Yasar et al,2011 and Jeon et al, 2014 only followed up the patients up to 1/12 only. Besides, there was no functional outcome measure done (11,12). Other study done with longer follow up times such as Adey-Wakeling et al, 2013 SSNB vs s/c saline (Placebo) consistently demonstrated superior, statistically significant pain reduction compared with s/c saline (placebo) even at 12/52 post injection (13).

Another randomized controlled trial (RCT) by Rah et al,2012 in comparing IAS vs subacromial lignocaine (placebo) showed significant improvement of visual analogue scale (VAS)-day/night, ROM as well as SDQ, in the treatment group even at 8/52(14). Besides, stroke is extremely common in Malaysia and is the 3rd leading cause of death in our country. Stroke patients in Malaysia is generally younger with mean age of stroke onset between 54.5 and 62.6 (15).

HSP will affect stroke recovery as the pain interfere with rehabilitation and has a potential to worsen the disability in hemiplegic patients and negatively impaired quality of life (QOL) (16).

2.0 Methodology

2.1 Study Design

This study design is prospective, double blinded interventional study. In this study, patient will be blinded from the interventions they are receiving; intraarticular steroid injection or supra-scapular nerve block. Investigator that will be assessor will also be blinded from knowing the interventions that patients received.

2.1.1 Enrollment Patients referred to SMART Clinic for hemiplegic shoulder pain will be examined and recruited. Patients who did not fulfill the inclusion and exclusion criteria will be excluded.

Numerical rating score (NRS) pain score at maximum passive ROM of shoulder flexion, abduction, internal and external rotation, Maximum passive ROM of shoulder flexion, abduction, internal and external rotation, Shoulder Pain and Disability Index (SPADI) and Shoulder Disability Questionnaire (SDQ) will be measured prior to intervention.

2.1.2 Allocation The patients recruited will then be randomly allocated using a randomization computer program into 2 separate groups; Suprascapular nerve block(SSNB) group and Intraarticular steroid(IAS) group. The assessor and patients are blinded to the type of intervention the patient is receiving. The injector who is a skilled interventionist will not be blinded.

2.1.3 Intervention Suprascapular nerve block (SSNB) and Intraaticular steoid(IAS) injection will be performed by skilled interventionist.

2.1.4 Evaluations Numerical rating score (NRS) pain score at maximum passive ROM of shoulder flexion, abduction, internal and external rotation and maximum passive ROM of shoulder flexion, abduction, internal and external rotation will be assessed and recorded at 1 hour, 1 month and 3 months after intervention. Shoulder Pain and Disability Index (SPADI) and Shoulder Disability Questionnaire (SDQ) will be measured at 1 month and 3 months post intervention.

2.2 Setting

• Rehabilitation Clinic, University of Malaya Medical Center (UMMC)

2.3 Sample Size

A power analysis program G* Power was used to calculate the sample size. The effect size of study by Jeon et al is 0.3. With the power of study set at 0.8 and alpha set at 0.05, the sample size for this study based on G* Power sample size calculator is set at 64; 32 each arm. However, to allow for 25% attrition rate, the sample size is set at 86; 43 each arm.

3.0 Data Collection Methods

Primary Outcome :

- Numerical rating score (NRS) pain score at maximum passive ROM of shoulder flexion, abduction, internal and external rotation

- To be collected at baseline, 1 hour, 1 month and 3 months post injection

Secondary outcome :

- Maximum passive ROM of shoulder flexion, abduction, internal and external rotation

- Measured at baseline, 1 hour, 1 month and 3 months post injection.

- Shoulder Pain and Disability Index (SPADI) and Shoulder Disability Questionnaire (SDQ)

- Measured at baseline, 1 month and 3 months post intervention.

- Using face to face interview

3.1 Data Analysis

Data from this study will be analysed using Statistical Package for Social Science (SPSS) software.

Demographics of 2 groups will be analyzed using Mann-Whitney U tests and Chi-Square test of association.

Primary objective:

Pain reduction:

Pre-post intervention intra-group; post-intervention inter-group: paired t-test

Secondary objectives:

ROM improvement: pre-post intragroup; post-intervention inter-group: paired t-test and analysis of variance (ANOVA)

Functional improvement of SDQ and SPADI: pre-post intra-group; post-intervention inter-group: paired t-test

4.0 Strength and Limitation

Strength

- Secondary outcomes include functional outcomes such as SPADI Score and SDQ

- Longer follow up period at 3 months compared to study by Jeon et al and Yasar et al at 1 month

- Bigger sample size Limitation

- Single center study

- Risk of patient loss to follow-up

- Recruitment will be a challenge