Anesth Pain Med 2012; 7: 117～120 ￭Case Report￭
The effect of pulsed radiofrequency (PRF) for the treatment of supraorbital neuropathic pain -A report of three cases-
Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
Hyun-Min Bae, Young Hoon Kim, Sang-Wook Kim, and Dong Eon Moon
Historically, peripheral neuropathic pain has occasionally been is often difficult to treat [1]. Both a systematic review of difficult to treat. Both a systematic review of the evidence as well evidence and a clinical experience show that medical treatment as clinical experience have demonstrated that treatment options provides effective pain relief in only about 50% of patient including polypharmacy provide effective pain relief in only half of the patients with neuropathic pain. After peripheral nerve injury, with neuropathic pain [2]. Recently new interventional method, the incidence of degenerative alterations in the spinal cord and pulsed radiofrequency (PRF) has been introduced for the central pathologic sensitization are possible. Due to this obser- treatment of peripheral neuropathic pain. PRF is a neuromo- vation, It may be difficult to treat this group of patients with peripheral neuropathic pain by therapeutic intervention of the peripheral nerve. dulatory technique that is felt to be safer than conventional Pulsed radiofrequency (PRF) has several benefits for treatment of continuous radiofrequency (CRF). Although the exact mecha- this condition including, accuracy and safety, and the elimination nism of action for PRF is unknown, current literature supports of thermal lesions due to the reduction in the target tissue involvement of electromagnetic fields resulting in neuromodu- temperature (below 42 degrees). We treated three cases of supra- orbital neuropathic pain using PRF, and discovered that two of the lation. Numerous case reports and case series of PRF of patients had significant pain relief at the six month time point. numerous peripheral nerves and ganglions for treatment of (Anesth Pain Med 2012; 7: 117∼120) chronic neuropathic pain can be found in the literature. The majority of the uncontrolled and observational studies are not Key Words: Central sensitization, Peripheral neuropathy, Pulsed radiofrequency, Supraorbital neuropathic pain yet to prove therapeutic effect of PRF in neuropathic pain. We performed PRF in three cases of supraorbital neuralgia, two cases had a good pain relief for six months, but one case had Supraorbital neuropathic pain involves severe sharp pain little. along the route of the supraorbital nerve, and may have symptoms such as allodynia, hyperalgesia, hypoesthesia and CASE REPORTS dysesthesia. Current therapies include medical treatment, supraorbital nerve block, neuromodulation with implanted pulse Case 1 generators. Unlike pain resulting from nociceptive processes, neuropathic pain is associated with primary lesion or disease A 74-year-old male presented with complaint of left fore- of the nervous system itself. Chronic peripheral neuropathic head and temporal pain for 8 months after occurrence of pain sometimes reflects sensitization and altered processing of herpes zoster. He noted a sharp, burning pain, paresthesia, and pain signals by the peripheral and central nervous systems and mild hypoesthesia. Just before his visit, the patient underwent a left supraorbital nerve block and received pregabalin 75 mg Received: January 4, 2012. twice a day, tramadol (75 mg)/acetaminophen (650 mg) combi- Revised: January 27, 2012. nation three times a day in other hospital. He rated his pain Accepted: February 14, 2012. Corresponding author: Dong Eon Moon, M.D., Department of as 70/100 using VAS (consisting of a 100 mm line with 0 on Anesthesiology and Pain Medicine, College of Medicine, The Catholic one end, representing no pain, and 100 on the other, represen- University of Korea, 505, Banpo-dong, Seocho-gu, Seoul 137-040, Korea. ting the worst pain ever experienced) score in first visit. He Tel: 82-2-2258-2236, Fax: 82-2-537-1951, E-mail: [email protected]
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Fig. 1. Fluoroscopic image shows AP view (A) and lateral view (B) of 22-gauge RF needle, 5 cm with 4 mm active tip inserted supraorbital notch. told us his pain relief for 1 week to undergo a left supraor- After 1 week of her first visit, change of her pain is a little. bital nerve block in other hospital. After 1 week, PRF was She underwent PRF in a left supraorbital nerve in the same performed in a left supraorbital nerve. A radiofrequency method as a case 1, her pain reduced to 30/100 using VAS thermocouple machine (model neuro N50, stockett GmbH, score. Following 2 weeks, her VAS score was 30/100 and we Germany) was used for the procedure. The patient's left reduced her medication to pregabalin 75 mg, tramadol (18.75 forehead was prepped with betadine and draped in a sterile mg)/acetaminophen (162.5 mg) combination twice a day. Her manner. We advanced the 22 gauge, 50 mm radiofrequency VAS score (30/100) was maintained for 6 months. needle with 4 mm active blunt tip via supraorbital notch Case 3 without any anesthetic infiltration under C-arm fluoroscopic guidance (Fig. 1). And stimulating at 50 Hz and 0.5 mA until A 77-year-old female reported of left forehead pain more paresthesia of the patient's left supraorbital nerve concordant than 3 years after occurrence of herpes zoster. She described a with his area of pain was obtained. Paresthesia was detected at sharp pain with dysesthesia, severe hypoesthesia, and dynamic 0.4 volt. After 1% lidocaine 1 ml was injected, PRF was per- allodynia. She rated her pain as 90/100 using VAS score. She formed for 120 second at 42 degrees Celsius. One additional received pregabalin 150 mg, tramadol (37.5 mg)/acetaminophen PRF was given after half turn of the needle. After he (325 mg) combination three times a day. After a left supraor- underwent PRF, his VAS score decreased 10/100. Following 2 bital nerve block was offered, she informed of some pain weeks, he rated his pain as 20/100 using VAS score, and relief for a few hours. After one week, she underwent PRF in reported decreased severity and frequency of pain. We a left supraorbital nerve in the same method as a case 1, there decreased his medication to pregabalin 75 mg twice a day, was little effect in 80/100 using VAS score. Following 2 tramadol (37.5 mg)/acetaminophen (325 mg) combination three weeks, she still complained severe pain. Thereafter her VAS times a day. At 6 months follow up, his VAS score (20/100) score was maintained 70/100 to 90/100. is maintained.
Case 2 DISCUSSION
We evaluated a 27-year-old female who had a left forehead Neuropathic pain is conceptualized as the result of an area pain for 12 months. 13 months ago, she was placed on aberrant learning process, associated with maladaptive plasticity the implant in left forehead for aesthetic purpose. It was of the nervous system [3]. In the absence of nerve damage, removed 10 months ago because of left forehead area pain. responses to noxious stimuli are reversible. In contrast, the Nevertheless her VAS score of 70/100 was lasted. She com- development of neuropathic pain requires persistent injury or plained sharp pain and hyperalgesia. She underwent a supraor- abnormal function of the peripheral or central nervous system. bital nerve block, her VAS score decreased to 3/10 for 3 Neuropathic pain syndromes may be divided into two groups, days. Medication included pregabalin 75 mg, tramadol (18.75 central and peripheral, based on the location of the nervous mg)/acetaminophen (162.5 mg) combination three times a day. system lesion. In fact, alterations of central nervous system Hyun-Min Bae, et al：Pulsed radiofrequency for supraorbital neuropathic pain 119 physiology may play an important role in many of the panied severe symptoms with dysesthesia, sensory loss, dyna- neuropathic pain conditions connected with peripheral patho- mic allodynia for more than 3 years. We thought that the logy, being difficult to differentiate certainly between peripheral patient had great central component of pain generation to be and central pain [4]. When conservative treatment including considered his severe symptoms. If central sensitization is medical therapy was not effective in neuropathic pain, PRF induced in the patient, PRF in peripheral nerve alone may also may be used in the additional treatment. have little effect. We assumed that one case had no effect of CRF and PRF are 2 types of RF that are used clinically. In PRF because of central sensitization. We guessed that the general, the advantage of RF includes the ability to stimulate patients of successful cases had generally a little or little neural elements before lesioning, thereby offering precise central component of pain generation. Because the patients targeting with avoidance of ablating the wrong nerves and have generally mild to moderate symptoms as follows: static providing long-lasting analgesia [5]. PRF is a newer alternative allodynia, sharp pain, paresthesia, burning pain, and relatively to CRF with the proposed advantage of avoiding the compli- short duration [8-10]. cation of deafferentation pain and unintended nerve damage Central sensitization has been altered the particular functional that infrequently can be seen after neural ablation. It uses states of circuits in the CNS and no longer directly reflects radiofrequency current in short (20 ms), high-voltage bursts the specific qualities of peripheral noxious stimuli [12]. At the and the silent phase (480 ms) to allow time for heat elimina- time of peripheral injury, an abnormal injury discharge may be tion. Generally, keeping the target tissue below 42 degrees sufficient to produce long term changes in the excitability of Celsius, so PRF does not cause thermal lesions [6]. It induces the spinal cord and/or an excitotoxic death of dorsal horn changes in the nerve cells and has a neuromodulatory effect neurons. These changes lead to sensory disorders both as a on pain-processing mechanism [7]. But the exact mechanism of result of an induction of central sensitization and of a struc- action has not been established. tural reorganization of the synaptic connections of the dorsal Many cases had been reported that treatment of peripheral horn [13]. The thermal and static mechanical hyperalgesia are neuropathic pain was successful after using PRF. Jun et al. [8] present exclusively in area where the C-nociceptors are directly reported that two patients with PHN of forehead area felt activated by peripheral nerve injury, this phenomenon is also relief for more than 4 months after using PRF of a supraor- called primary hyperalgesia. The concept that abnormally bital and a supratrochlear nerve. Todorov reported the patient activated C-fibers contribute to neuropathic pain is also with chronic ankle pain had been pain free for 4 months after supported by clinical reports of patients with spontaneous pain using PRF of a sural nerve [9]. Philip et al. [10] reported the and thermal and static mechanical hyperalgesia. This sponta- case which is successful treatment of meralgia paresthetica neous pain generated in damaged primary afferents is highly with PRF of the lateral femoral cutaneous nerve for 6 months. susceptible to drugs like antiarrhythmics and anticonvulsants Also, Shabat et al. [11] reported that nineteen patients (68%) that block voltage dependent sodium channels. A different reported long-term pain relief (more than 1 year) which was form of hyperalgesia develops in the surrounding skin where defined as a reduction of VAS by at least 30%, when the C-nociceptors have not been activated. This form of twenty-eight patients of spinal neuropathic pain with a minimal hyperalgesia (secondary hyperalgesia) depends on mechanisms follow-up of 1 year were examined after having undergone within the central nervous system. When central sensitization is PRF procedures. The early clinical studies of PRF reported its present, Ab-fibers become capable of activating central nervous clinical efficacy, however they consisted of case reports, system pain-signaling neurons leading to touch evoked pain. retrospective studies and small uncontrolled prospective trials. Consequently, dynamic mechanical allodynia is due to central The beneficial effects of PRF in these observational are sensitization of pain transmission neurons that is initiated and difficult to ignore, however it is also possible that therapeutic maintained by activity in pathologically sensitized C-fibers failure with PRF were not reported. To prove therapeutic effect [14]. Since central sensitization involves the NMDA receptor, of PRF in neuropathic pain, the well designed uncontrolled the NMDA receptor antagonists relieve pain. and observational studies on large scale are still required. Criteria to establish the presence of central sensitization in We performed PRF in 3 cases of supraorbital neuropathic patients will be a great help to determine therapy methods in pain, 2 cases had a significant pain relief, but one case didn’t chronic neuropathic pain. But it is difficult to decide to be improve pain. Third patient who failed treatment was accom- accompanied central sensitization. Because there is no single 120 Anesth Pain Med Vol. 7, No. 2, 2012 defining molecular mechanism of central sensitization but rather 5. Lord SM, Bogduk N. Radiofrequency procedures in chronic pain. that is a general phenomenon. The patient who has dynamic Best Pract Res Clin Anaesthesiol 2002; 16: 597-617. 6. Bogduk N. Pulsed radiofrequency. Pain Med 2006; 7: 396-407. allodynia, long term spontaneous pain, no effect of single 7. 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