Ultrasound-Guided Physiological Saline Injection for Patients with Myofascial Pain.

BACKGROUND: Based on the histological confirmation of the presence of nerve structure in the fascia, hence, myofascial pain was treated by the mechanism referred to as interfascial block. To date, the studies of physiological saline for treating patients with myofascial pain has been limited. Ultrasound (US) guided with physiological saline injection (PSI) technique has been routinely practiced among patients with myofascial pain in outpatient service at the Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital. The main objective of this present study is to find the overview data including the percentage of patients responding, acceptable pain period, and adverse events.
MATERIALS AND METHODS: Electronic medical reports among 142 patients receiving US-guided PSI from August 1, 2016, to November 20, 2017, at the Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital, were retrospectively reviewed by the first author. Procedures were performed by the last author. The analysis was independently performed by the first author.
RESULTS: One hundred and forty-two patients with complete medical records were compatible with analysis. The average age of patients was 55 years. Most of the patients were female (68.3%). Most of the patients (76.8%) had chronic suffering from myofascial pain. Approximately half of the patients (56.4%) are currently received pain-relieving medications. Upper trapezius muscle (19.5%) was the most common muscle receiving the procedure, followed by multifidus (10.0%) and quadratus lumborum (9.5%). Most of the patients (86.8%) received the procedure one muscle. Approximately 30% of the patients were able to stop pain-relieving medications after the procedure. The median of acceptable pain period was 63 days. The percentage of patients having an acceptable pain period >3 months was 43.9%. No major adverse events were demonstrated.
CONCLUSION: US-guided PSI technique demonstrated pain reduction in 72.8% of the analyzed patients, with an acceptable pain period of 63 days. No major adverse events were demonstrated among all the patients. This technique should be considered as another invasive procedure for eradication myofascial trigger point. Copyright:

INTRODUCTION

Musculoskeletal ultrasound (MSK US) for pain management attracts physiatrists' attention to improve their patients' care and to develop new researches.[12] Based on the histological confirmation of the presence of nerve structure in the fascia, myofascial pain is treated by a mechanism called interfascial block.[3]

The US-guided interfascial block was published as the case report in a patient with myofascial pain recently. Piraccini reported that the solution of levobupivacaine 45 mg and triamcinolone 40 mg within 15 mL normal saline was injected on the deep fascia of the erector spinae muscle for pain relieving.[4] The same author reported one case with right postthoracotomy pain syndrome received the hydrodissection of fascial planes in the internal mammary region with triamcinolone and ropivacaine together with a nerve block.[5] Ueshima reported that using local anesthetic into the fascial plane between the multifidus and longissimus muscles among two patients who underwent spinal surgery can improve patients' recovery.[6] Ueshima also recently reported that normal saline 10 mL between the fascia of the internal and external intercostal muscles can successfully relieve pain; however, Ueshima proposed that interfascial adhesion is the cause of pain.[7] Hence, this technique has limited evidence for pain relief among patients with myofascial pain. A comparative study revealed that physiological saline could immediately relieve pain, similar to mepivacaine.[8] To date, studies regarding the use of physiological saline for treating patients with myofascial pain are limited.

Invasive procedures were frequently used among many patients suffering from myofascial pain failed for conservative treatment to eradicate the myofascial trigger point (MTrP). These procedures include dry needling, deep dry needling, local anesthetic injection, and local anesthetic plus steroid injection.[91011] The latest agents used for injection are ozone and botulinum toxin.[121314] However, serious adverse events such as pneumothorax have been found among patients receiving dry needling and deep dry needling and trigger point injection due to blinded technique.[91011] Cost-effectiveness is questioned for botulinum toxin using among these patients.[1314]

The US-guided with physiological saline injection (US-guided PSI) technique has been routinely practiced in our outpatient service at the MSK US clinic, Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital, since August 2016. Immediate pain relief and improving range of motion were demonstrated by clinical observation. Some patients remained symptom free during the follow-up visit. The main objective of this present study was to identify overview information before having the approval to perform the future randomized controlled trial. This information included the percentage of patients responding, acceptable pain period, and adverse events.

MATERIALS AND METHODS

Study design, setting, statistical analysis, and ethical considerations

Electronic medical reports among 142 patients receiving US-guided PSI at the Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital, were retrospectively reviewed by the first author from August 1, 2016, to November 20, 2017. Patient data regarding demographics, details of the procedure, current pain-relieving medications, and adverse events were independently analyzed by the first author.

These procedures were performed and recorded by the last author who has 5 years of experience in MSK US screening and interventions. All the patients have initially informed the procedure details, use of sterile saline at the physiological concentration for injection, and possible adverse events. Acetaminophen and cryotherapy were prescribed after intervention for 3 days.

Protocol for the present study was approved by the Institutional Review Board (IRB) of the Faculty of Medicine, Chulalongkorn University (IRB. No 1055/2017). Data were analyzed using SPSS Statistics version 22.0 (SPSS Inc., Chicago, IL, USA). Categorized data are reported as percentage or number. For continuous data, parametric data are reported as mean and standard deviation, whereas nonparametric data were reported as the median and interquartile range (IQR; Q3-Q1). Subgroup analysis was performed among patients who had the electronic medical record of the Numeric Rating Scale (NRS) at the date of intervention and during follow-up visits.

Inclusion criteria

Patients were diagnosed with myofascial pain syndrome that had MTrP causing pain and/or referred pain or autonomic symptoms during compression at MTrP. The symptoms were relieved after compression for 5–10 s[15]

Patients demonstrated a limited range of motion around the pain region[15]

Patients complained that pain was the moderate degree to the severe degree determined by NRS at least 4.

Exclusion criteria

Patients firstly receiving pain-relieving medications on the same day of the intervention.

Patients aged under 18 years old.

Operational definitions

These following operational definitions were used by the first author to retrieve appropriate data. These operational definitions are categorized into three dimensions:

Efficacy reported as the percentage of patients having pain reduction

Two criterions were used for retrieving medical records identified patient response to this technique including NRS criteria was analyzed as subgroup analysis.

NRS criteria were defined as the medical records demonstrating that patients have NRS reduction as 2 or greater point at the follow-up visit. Subgroup analysis was performed among these patients having a record of NRS at first and follow-up visit

Clinical record criteria were defined as the medical records demonstrating that patients have pain reduction >50% during the follow-up visits and/or improving range of motion after the intervention and during the follow-up visits.

For patients receiving the procedure more than one muscle in the same visit, the pain reduction is evaluated at the muscle having the highest pain.

Percentage of patient response to US-guided PSI was defined as the percentage of patients reported that they could discontinue pain-relieved medications until the follow-up visit

Percentage of patient request for the same technique to eradicate MTrPs occurring on the other muscles during the follow-up visits.

2. Efficacy reported as acceptable pain-tolerated duration

The acceptable pain-tolerated period was defined as intervention first follow-up interval period which patients did not seek for additional treatments for pain relieving. If patients have multiple sessions of the procedure on the same muscle, the shortest duration was retrieved as the data for these groups

Efficacy of acceptable pain-tolerated duration was defined as the percentage of patients having an acceptable pain-tolerated duration >3 months.

3. Adverse events after intervention were defined as major adverse events which lead to consultation for further management. The major adverse events included pneumothorax, skin & soft tissue infection.

Ultrasound-guided physiological saline injection technique

Sterile normal saline at physiological concentration of 5–10 mL was used per injection site. The volume depended on muscle size. The 5 mL was used for muscles lying on the chest wall, paracervical spine, and limbs. The 10 mL was used for muscles lying on the lower back and hip region

US-guided injection in-plane needle approaching was performed with aseptic technique [Figure 1]

Figure 1

Ultrasound-guided physiological saline injection technique on the upper trapezius muscle

The interfascial injection was performed over the affected fascia [Figure 2]. For the US-guided PSI technique, the affected fascia was defined as the muscle fascia that causes either local pain or referred pain similarly to compression during physical examination together with or without local twitch response

Figure 2

Sonographic imaging during intervention with in-plane technique. (a) Demonstrating needle tip touch the affected muscle fascia. (b) Demonstrating the bolus of normal saline 5 mL spread over the muscle fascia causing local pressure at this fascia

Pain improvement was immediately assessed after the intervention

Range of motion was assessed by physical examination compared before and immediately after the intervention

Postinjection soreness was prevented by acetaminophen and cryotherapy after the intervention.

RESULTS

There were 142 patients who had complete electronic medical records for treating myofascial pain with this technique. The average age of patients was 55 ± 15.1 years. Most of the patients were female (68.3%). Most of the patients (76.8%) had chronic suffering from myofascial pain with onset >6 months [Table 1]. Approximately half of the patients (56.4%) had currently received pain-relieving medications such as gabapentin and pregabalin (39.3%), nonsteroidal anti-inflammatory drugs (7.4%), tricyclic antidepressant (3.7%), muscle relaxant (3.7%), acetaminophen plus opioid (2.5%), and selective serotonin–norepinephrine reuptake inhibitor (0.6%). Upper trapezius muscle (19.5%) was the most common muscle receiving the procedure, followed by multifidus (10.0%) and quadratus lumborum (9.5%). Rhomboid muscle (6.8%) was another muscle lying on the chest wall receiving the procedure. Deltoid (8.4%) and pyriformis (8.4%) were the most common muscles receiving the procedure on the upper and lower limbs. Most of the patients (86.8%) received a procedure on one muscle. None of the analyzed patients has taken acetaminophen after the intervention. Cryotherapy was only used among these patients.

Table 1

Demographic data among the total reviewed outpatient record

Demographic data	n=142
Female (%)	68.3
Average age (mean±SD)	55±15.1
Duration of symptom, months (%)
<3	12.7
3-5	23.2
≥6	76.8
Receiving pain-reliving medication (%)	56.4
Common muscles receiving procedure (%)	62.6
Muscles over the chest wall
Upper trapezius	19.5
Rhomboid	6.8
Core muscle stabilizers
Multifidus	10.0
Quadratus lumborum	9.5
Limbs
Deltoid	8.4
Pyriformis	8.4

SD: Standard deviation

Most of the patients (114 of 142 patients; 80.28%) were identified as a response group [Table 2]. Patients discontinuing or reducing pain-relieving medications after the procedure were 29.8%. Patients who could immediately stop using medication were 21.1%. Among the response patients, approximately half (54.4%) requested for the repeated procedure on the other muscles. The median of acceptable tolerated pain period was 63 days, from 7 days to 365 days with IQR (Q3-Q1 as 84–118 days). The percentage of patients having an acceptable pain period >3 months was 43.9%. NRS was completely recorded among 31 patients. Data from subgroup analysis were demonstrated among these patients [Table 3]. No major adverse events were demonstrated among all of the 142 patients.

Table 2

Efficacy of ultrasound-guided physiological saline injection among response patients

Efficacy	(n=114)
Percentage of response patient
Based on the NRS criteria	27.2
Based on clinical record criteria	72.8
Acceptable tolerated pain period, weeks (%)
<4	15.8
4-8	25.4
9-11	14.9
≥12	43.9
Discontinuing pain-relived medications after the procedure (%)	30.0

NRS: Numeric Rating Scale

Table 3

Subgroup analysis among patients having completely recorded Numeric Rating Scale

Demographic data	(n=31)
Female (n)	22.0
Average age (mean±SD)	54±14.1
Duration of symptom, months (n)
<3
3-5	25.0
≥6	6.0
Pretreatment NRS, median (IQR)	6 (5-8)
Posttreatment NRS, median (IQR)	0 (0-2)
NRS difference, median (IQR)	5 (3-7)
Acceptable tolerated pain period (days), median (IQR)	56 (58-125)
Acceptable tolerated pain period , weeks (n)
<4	7
4-8	8
9-11	4
≥12	12
Receiving pain-relived medications (n)	12
Discontinuing/reducing pain relieving medications after the procedure (n)	6

IQR: Q3-Q1. IQR: Interquartile range, NRS: Numeric Rating Scale, SD: Standard deviation

DISCUSSION

The presence of neural structure on the fascia confirms that MTrP was related to the fascia and possibly related to the peripheral and central sensitization. Previous article mentioning US-guided interfascial hydrodissection in myofascial pain is only the case report. The similar technique using anesthetic and steroid solution was successfully reduced pain on one case with myofascial pain.[4] However, the interfascial block can occur without an anesthetic agent. MTrP is eradicated by injection of normal saline with the volume targeting at the fascia. The MTrP eradication occurs from reactive hyperemia mechanism.

Reactive hyperemia was the accepted concept for explaining the mechanical effect of massage and ischemic compression.[1617] Reactive hyperemia as known as the increased microvascular exchange was found among the previous studies leading to an increase in blood flow.[181920] Then, full oxidize glucose and lactate were re-established. The zone around MTrP was mentioned by Simon that it is in an ischemic condition.[21] Then, the shortage of glucose and oxygen for metabolism occurred after a muscle is in the overload state.

This is the first study that retrospectively reveals the overview of this technique among 142 patients with myofascial pain. Instead of using the anesthetic agent, the authors chose normal saline with precise injection on the affected fascia. The improvement of pain and the range of motions were clinically observed. The response group was the patients having pain reduction greater than 50% or NRS reduction greater than half. More than half of the patients can completely solve MTrPs at injected muscle; then, they request the same technique on the other muscles. Hence, placebo effect may be unlikely explained the significant effect for few months. The first author did not involve in the MSK US clinic and independently analyze the data to avoid bias.

This present study demonstrates longer pain relief duration than dry needling (8 weeks vs. 6 weeks), the most common invasive procedure performed among patients with myofascial pain.[222324] Dry needling is a blinded procedure; thus, pneumothorax may incidentally occur.[1011] However, US-guided PSI requires skilled interventionist and costs higher than dry needling. This technique provided a close duration to local injection of anesthetic agent plus a steroid for 8.5 weeks.[25] This technique has two components as US-guided during the procedure and using the physiological normal saline injection; hence, these components did not lead to adverse events, whereas the adverse events can occur from anesthetic agent injection (hypokalemic paralysis), muscle atrophy (steroid), and botulinum toxin (muscle weakness and antibody).[26] Moreover, saline is more susceptible to steroid phobia patients.

US-guided PSI demonstrated efficacy in most of the patients. More than half of the patients who requested for the same technique to eradicate MTrPs implied that this group impressed this technique. No adverse events were demonstrated among all the patients. To avoid pneumothorax, this procedure requires skilled interventionists, especially when performing in muscles lying on the chest wall. This technique could immediately reduce pain and increase muscle flexibility; thus, it could help patients to start exercise immediately after the intervention. Stretching and strengthening exercises are considered as mandatory treatments for myofascial pain.[27]

Furthermore, this procedure can be performed among special populations including pregnant and lactating women, children, the elderly, patients with either hepatic or renal impairment, and athletes without concern for the detrimental effect on vital organs, overdosage, drug interaction, and doping. The present study provided an overview of patients who require this procedure, especially safety issue. These data are important for having the approval to perform the further randomized controlled trial study for having objective measurements (improvement of pain and range of motion) and controlling confounding factors.

CONCLUSION

US-guided PSI technique demonstrated pain reduction in 72.8% of the analyzed patients, with an acceptable pain period of 63 days. No major adverse events were demonstrated among all the patients. This technique should be considered as another invasive procedure for eradication MTrP.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.