Vol. 14, #3

Effect Of Local Injection Of Steroid
And Anesthetics On Electroacupuncture:
Prevention Of Immediate Analgesia
And Induction Of Hyperalgesia
Chong-hao Zhao, MD
Jimmie Kung, MD
Nancy Adachi, PT

ABSTRACT
Background     Both electroacupuncture (EA) and the local injection of combined anesthetic and steroid are widely used for acute and chronic pain management. It is unknown whether these modalities will interfere with each other when they are used at a close interval.
Objective     To determine the interaction of local injection of combined anesthetic and steroid and subsequent EA treatment.
Design, Setting, and Patients    Case reports of 2 patients at a Los Angeles pain clinic in 2001 who received local injection of combined anesthetic and steroid followed by EA 2 days later.
Main Outcome Measure     Patient reports of pain using a visual analog scale (VAS).
Results     EA administered to acupoints LR 9 and 10 in patient 1 and acupoints BL 10 and GB 21 in patient 2 did not relieve the pain. Instead, patients felt increased spontaneous pain the next day, recorded as VAS scores increasing from 5 and 4 up to 10, respectively. The pain then subsided within 2 days to the pre-EA level.
Conclusion     These cases demonstrated an adverse interaction between local injection of combined anesthetic and steroid and EA in pain management practice. The mechanism of anesthetic- and steroid-induced prevention of analgesia and development of hyperalgesia in EA is unclear. Further studies are needed to investigate the exact interactive mechanism and the optimal time intervals between these treatments.
KEY WORDS
Anesthetics, Electroacupuncture, Local Injection, Hyperalgesia, Pain Management, Trigger Points

INTRODUCTION
Local injection of the combination of anesthetics and steroids has long been used to treat musculoskeletal and neuropathic pain.1,2 Local anesthetics block the sodium channel on the neural membrane and prevent the firing of the anesthetized neuron.3 Steroids appear to stabilize the neural membrane as well as provide an anti-inflammatory effect.4

Acupuncture and electroacupuncture (EA) have been widely used to relieve a variety of pain problems.5-7 In comparison to traditional acupuncture performed manually, EA may provide convenience and a stronger stimulating effect.8 In clinical practice, 2-8 needles can be stimulated at the same time via parallel channels in the stimulator. EA, with a low frequency of 2-4 Hz/s, stimulates endorphin release, and a high frequency of 100-300 Hz/s stimulates serotonin release.8,9 EA is thought to suppress pain by reducing the production of inflammatory mediators such as prostaglandin E2 and interleukin-1;10,11 presynaptically inhibiting pain transmission in the dorsal horn by the gate control mechanism12-14 via the stimulation of Ab-fibers;15 activating the descending serotonergic and adrenergic pain inhibitory pathways in the brainstem;16,17 and stimulating the endogenous opioid system, especially the release of b-endorphin.18-21

Patients often seek alternative modalities, including EA, when they do not achieve enough pain relief from conventional treatments. We report a potential adverse interaction between local injection of combined anesthetic and steroid and EA, observed in our clinical practice.

METHODS
Both patients received local injection of combined anesthetic ans steroid 2 days prior to EA. Injection consisted of 1% lidocaine, 0.25% bupivacaine, and betamethasone sodium phosphate and betamethasone acetate, 6 mg/mL. Treatment was performed at UCLA-affiliated
Kaiser Permanente/Los Angeles Medical Center in 2001.

Sterile acupuncture needles (Gusu Acupuncture & Moxibustion Appliance Co, Suzhou City, China) and an electrical stimulator with 4-channel outlet (Model G 6805-1, Shanghai, China) were used for the EA treatment.

Acupuncture Treatment
Patients were placed in either the supine (patient 1) or prostrate position (patient 2). The skin was prepared using an alcohol pad. "Natural" 32-gauge, 40-mm sterile acupuncture needles were inserted into LR 9 and 10 to a depth of 30 mm in patient 1. In patient 2, 36-gauge, 25-mm needles were inserted into BL 10 to a depth of 15 mm and GB 21 to 25 mm. Accuracy of needle insertion was confirmed by the De Qi phenomenon.22 Both patients felt fullness at the needling sites. The needles were then connected to the electrical stimulator with a continuous frequency of 14 Hz and 12 Hz in patients 1 and 2, respectively. Stimulation intensity was increased gradually up to the maximal tolerability without discomfort. All the needles were removed after 30 minutes of EA treatment.

Case Reports
Information was obtained from a retrospective chart review. Informed consent was obtained before EA and acupuncture. Using a 10-point visual analog scale (VAS), pain scores were recorded before local injection of combined anesthetic and steroid, 2 days afterward and before EA, immediately after EA, the next day, and 3 days after EA. The sites for injection and EA are described in Figures 1 and 2.

Case 1
A 55-year-old man presented with a 3-month history of pain in the right medial inguinal groove radiating to the medial thigh, and a sensation of burning, tingling, and numbness on the anterior and lateral thigh. He had fallen backward off a ladder 2 weeks prior to the onset of pain. The patient had initially been diagnosed with lumbar radiculitis in the L 3 nerve root distribution and treated with oral steroids and ibuprofen without benefit. Oral morphine sulfate had minimal effect on the pain. He was referred to a physical medicine and pain management clinic for further evaluation. He reported a VAS score of 8 despite taking hydrocodone/acetaminophen. Physical examination revealed a tender spot next to the femoral nerve on the inguinal groove at the adductor muscle. Pressure at this spot caused pain radiation to the anterior and medial thigh. Sensory examination yielded responses intact to light touch and pinprick. Magnetic resonance imaging of the lumbar spine showed degenerative disks at L3-L4 and L4-L5 causing mild canal stenosis with degenerative facet disease at L3-L4, L4-L5, and L5-S1. A clinical diagnosis of adductor tendinitis (causing groin strain) and meralgia paresthetica (entrapment of lateral femoral cutaneous nerve) was made.

Figure 1. Trigger point (TP) at the Adductor Muscle

Acupoint LR 10 (Zuwuli) is 8 in (20.3 cm) below the umbilicus and 2 in (5 cm) away from the midline, lateral to the adductor muscle. LR 9 is not labeled. Figure courtesy of the Cleveland Clinic.

The patient was given a local injection to the trigger point with a solution of 3 mL of 1% lidocaine, 3 mL of 0.25% bupivacaine, and 2 mL of betamethasone. He reported an immediate decrease in pain (VAS score decreased from 8 to 5) which remained the same for the next 2 days. The patient then requested acupuncture for additional pain control and EA treatment was completed as described above. The patient felt relaxed during the treatment but reported no immediate pain relief after the needling. The next day (approximately 14 hours) after EA, the patient felt escalating pain up to a VAS score of 10 spontaneously and when touching the right medial groin. He had to take oral morphine to relieve the pain. The pain gradually subsided to the pre-EA level 2 days later (VAS score of 5).

Case 2
A 65-year-old woman complained of left-sided head and neck pain for more than 1 year. The pain was accompanied by difficulty in concentration and fatigue. Magnetic resonance imaging of the cervical spine produced unremarkable findings. She was diagnosed as having fibromyalgia. The patient enrolled in an 8-week chronic pain program with a multidisciplinary team. She received physical therapy including neck traction, manual manipulation, ultrasonography, and transcutaneous electrical nerve stimulation. She also received naproxen,
acetaminophen, and amitriptyline for chronic pain and hydrocodone/acetaminophen for breakthrough pain. At week 6 of the 8-week program, the patient requested further pain management due to unsatisfactory relief.

In the physical examination, pressure to trigger points at the left splenius capitis muscle (trigger point 1) and the left upper trapezius muscle (trigger point 2) induced referred pain to the head and neck, respectively. The patient was given local injections to each of these points with a mixture of 2 mL of 1% lidocaine, 2 mL of 0.25% bupivacaine, and 1 mL of betamethasone. The VAS score was reduced from 8 to 4 after the injection. Two days later, she requested acupuncture therapy for additional relief; EA was given using the technique mentioned above. She had no immediate pain relief after EA. The patient contacted the physician the next day (about 12 hours after EA) about gradually increased neck pain (VAS score of 10) and received hydrocodone/acetaminophen for pain control. The severe pain subsided to the pre-EA level in 2 days (VAS score of 4). She requested a 2nd local injection to the neck with only anesthetics 2 months after the 1st one, which resulted in further pain relief (VAS score reduced from 5 to 2).

DISCUSSION

Figure 2. Trigger Points at the Splenius Capitis Muscle (TP1) and Trapezius Muscle (TP2)

Acupoints BL 10 and GB 21 are indicated at these muscles. BL 10 (Tianzhu) is right on the natural hairline at the back of the head, on the lateral margin of the upper trapezius muscle. GB 21 (Jianjing) is midway of the line between C7 spine and the acromion, at the hump of the shoulder. Figure courtesy of the Cleveland Clinic.

Two patients received local injection of combined anesthetic and steroid followed by EA 2 days later. The injections reduced the VAS pain scores in both patients.  EA given 2 days later did not relieve the remaining pain. Instead, patients felt increased spontaneous pain the day after EA. The pain then subsided within 2 days to the pre-EA level In the presented cases, local injection of combined anesthetic and steroid was found to not only prevent the immediate analgesic effect of EA, but to interact with EA to increase spontaneous pain. We searched MEDLINE and could not find any literature demonstrating this phenomenon. Hyperalgesia is characterized by increased spontaneous pain and decreased pain threshold.23 The mechanism for prevention of EA analgesia and induction of hyperalgesia by local injection of combined anesthetic and steroid is unclear. This may be due to the decreased release of b-endorphin secondary to the suppression of hypothalamus/pituitary function and the reduced pain threshold induced by the systemically-absorbed betamethasone. Both components of the injected form of betamethasone, betamethasone sodium phosphate and acetate, can be absorbed.24 There is evidence that local administration of betamethasone can suppress corticotropin and b-endorphin release from the hypothalamus/pituitary.25,26  Because the tissue half-life of betamethasone is 36-54 hours,24 it is likely that there still existed local absorption and thus, systemic effects of betamethasone during treatment with EA. Because EA analgesia is mediated by b-endorphin, the suppression of b-endorphin release by betamethasone could likely prevent EA analgesia as has been demonstrated in dexamethasone studies.27,28 Furthermore, Liu et al29 found that the mean tail-flick response latency (a parameter to assess pain threshold) in rats pretreated with dexamethasone was reduced after EA administration. This implicates the development of dexamethasone-induced hyperalgesia in response to the subsequent EA. We speculate that pretreatment with betamethasone, like dexamethasone, may also induce hyperalgesia in patients receiving EA.

Local anesthetics may not play an important role in the blockade of EA analgesia and induction of hyperalgesia. Lidocaine has a rapid onset of action and short duration of 90-120 minutes. Bupivacaine has a slower onset of action and longer duration of 480-780 minutes.30 Because the duration of long-acting bupivacaine is less than 780 minutes (13 hours), it may be less likely for local anesthetics to mediate the effect of EA given 2 days later.

CONCLUSION
It is not uncommon for patients with acute or chronic pain to seek different types of analgesic intervention simultaneously or in close proximity. Blockade of EA analgesia and induction of transient hyperalgesia in response to EA by the previous local injection of betamethasone and anesthetics was observed in our clinical practice. The mechanism of the interaction is unclear. Further studies are needed to investigate the optimal time interval and the exact interactive mechanism between local injection of combined anesthetic and steroid and EA.

ACKNOWLEDGEMENTS
We thank Drs Mark Stillman, Todd Rozen, Hilary Fausett, and Sheldon Wolf for reviewing this article. We thank the Office of Academic Affairs at Kaiser Permanente Southern California/Los Angeles Medical  Center and the Media Service at the Cleveland Clinic Foundation for technical support during the preparation of this article.

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AUTHORS' INFORMATION
Dr Chong-hao Zhao is Senior Instructor, Department of Orofacial Pain, University of California Los Angeles (UCLA) Dental School in Los Angeles, California, and is on the staff at Section of Headache and Pain, Department of Neurology, Cleveland Clinic Foundation in Cleveland, Ohio. Dr Zhao was recently appointed as the author for the section of  "The Use of Acupuncture in Headache Treatment" in Medlink Neurology online (Neurobase), an information resource solely for clinical neurologists.

Chong-hao Zhao, MD, PhD, DABMA*
The Cleveland Clinic Foundation
Neurology/T33
9500 Euclid Ave
Cleveland, OH 44195
Phone: 216-444-4771 • Fax: 216-445-1696
E-mail: Chonghaozhao@hotmail.com

Dr Jimmie Kung is Director of the Chronic Pain Program, Department of Physical Medicine and Rehabilitation, Kaiser Permanente Southern California/Los Angeles Medical Center in Los Angeles, Calif.

Jimmie Kung, MD, PhD
Dept of Physical Medicine and Rehabilitation
Kaiser Permanente Southern California/Los Angeles Medical Center
1526 No Edgemont St, 3rd Floor
Los Angeles, CA 90027
Phone: 323-783-4248 • E-mail: Jimmie.s.kung@kp.org

Nancy Adachi is a Senior Physical Therapist of Headache and TMJ disorder. She is involved in headache and pain rehabilitation at UCLA and Kaiser Permanente Southern California in Los Angeles, Calif.

Nancy Adachi, PT, BS
Dept of Physical Therapy
Kaiser Permanente Southern California
Los Angeles Medical Center
1526 No Edgemont St, 4th Floor
Los Angeles, CA 90027
Phone: 323-783-1341 • E-mail: nancy.y.adachi@kp.org

*Correspondence and reprint requests

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