Pulsed and Conventional Radiofrequency Treatment: Which Is Effective for Dental Procedure-Related Symptomatic Trigeminal Neuralgia?

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1 Pulsed and Conventional Radiofrequency Treatment: Which Is Effective for Dental Procedure-Related Symptomatic Trigeminal Neuralgia? Jae Hun Kim, MD, Hee Young Yu, DDS, Soo Young Park, MD, Sang Chul Lee, MD, PhD, FIPP, Yong Chul Kim, MD, PhD

2 bs_bs_banner Pain Medicine 2013; 14: Wiley Periodicals, Inc. Pulsed and Conventional Radiofrequency Treatment: Which Is Effective for Dental Procedure-Related Symptomatic Trigeminal Neuralgia? Jae Hun Kim, MD,* Hee Young Yu, DDS, Soo Young Park, MD, Sang Chul Lee, MD, PhD, FIPP, and Yong Chul Kim, MD, PhD *Anesthesiology and Pain Medicine, Konkuk University Medical Center, Seoul; Dentistry, National Rehabilitation Center, Seoul; Anesthesiology and Pain Medicine, Seoul National University Hospital, Seoul, Korea Reprint requests to: Yong Chul Kim, MD, PhD, Department of Anesthesiology and Pain Medicine, Seoul National University Hospital, 101 Daehang-ro, Jongro-gu, Seoul, , Korea. Tel: ; Fax: ; pain@snu.ac.kr. Disclosure/Conflict of interest information: No conflict of interest. Abstract Objectives. Many patients develop dental treatmentrelated symptomatic trigeminal neuralgia. However, the effectiveness of pulsed radiofrequency (PRF) treatment and conventional radiofrequency thermocoagulation (RFTC) for treatment of this disorder has not been determined. This retrospective study was conducted to compare the effectiveness and complications of PRF and RFTC in these patients. Methods. Fifty-four patients who experienced the onset of symptomatic trigeminal neuralgia after a dental treatment were managed by PRF or RFTC. Data were collected by reviewing their medical records and conducting a questionnaire. Patients characteristics, the dental procedures that caused the trigeminal neuralgia, the baseline and posttreatment pain intensities, duration of pain relief, complications, and satisfactions to the treatment were evaluated. Results. Pain intensities were lower at 1 week (3.0/10 vs 6.4/10), at 1 month (2.5/10 vs 5.9/10), 3 months (2.6/10 vs 5.5/10), 6 months (3.1/10 vs 7.1/10) and 1 year (4.8/10 vs 7.2/10) in the RFTC group (28 patients) than in the PRF group (26 patients) (P < 0.05). The duration of pain relief without medication in the RFTC group (10.8 months) was longer than that in the PRF group (0 months). The incidence of complications in the RFTC group (46.4%) was higher than that in the PRF group (3.8%) (P < 0.05). The RFTC group reported higher satisfaction ratings (3.86/5) than the PRF group (2.19/5) (P < 0.05). Conclusions. Although the RFTC group had more complications than the PRF group, most were minor and transient, and the patient satisfaction rate with RFTC was very high. Therefore, RFTC is an effective tool for the treatment of dental procedure-induced trigeminal neuralgia. Key Words. Dental Treatment; Pulsed Radiofrequency; Radiofrequency Thermocoagulation; Trigeminal Neuralgia Trigeminal neuralgia and other facial pains are generally diagnosed on the basis of the medical history and neurological examination [1 3]. We have treated many patients with chronic pain in the facial areas innervated by the trigeminal nerve that began immediately after a dental procedure. The International Headache Society has categorized these pains as symptomatic trigeminal neuralgias [4]. Zuniga [5] reported that wisdom tooth extraction can cause damage to the inferior alveolar and/or lingual nerves. Nerve damage may occur during tooth extraction because of unintentional incision of the nerve or because of the bone pressing against the mental canal, leading to paresthesia and persistent neuropathic pain [6]. The alveolar nerve, mental nerve, or lingual nerve can be damaged during root canal treatment, implantation, or apicoectomy [7 9]. Although drug therapy is the preferred treatment for classical trigeminal neuralgia, interventional treatments are the other options for patients whose conditions are unresponsive to drugs or for those who develop side effects. For treatment of symptomatic trigeminal neuralgia, minimally 430

3 RF, Dental Procedure-Related Symptomatic Trigeminal Neuralgia invasive procedures such as percutaneous radiofrequency treatment have been widely performed [10,11]. Limited reports are available on dental treatment-related symptomatic trigeminal neuralgia, more so its treatment is unclear. In our hospital, we have two experienced pain physicians who treat symptomatic trigeminal neuralgia by using different radiofrequency methods: one uses pulsed radiofrequency (PRF) treatment on the maxillary or mandibular nerve, whereas the other uses conventional radiofrequency thermocoagulation (RFTC) on the trigeminal rootlets. Almost all patients were treated by a single physician of their own choosing. Therefore, we investigated the etiology of dental treatment-related symptomatic trigeminal neuralgia and conducted this study to compare the effectiveness and complications of PRF on the trigeminal nerve and RFTC on the trigeminal rootlets for the treatment of this disease. Materials and Methods We performed this retrospective study after gaining approval from our Institutional Review Board. This study was included patients who visited our university pain clinic for management after dental procedure-related trigeminal nerve area pain and were subsequently treated with PRF on maxillary or mandibular nerve or RFTC on trigeminal rootlets between 2005 to December All patients were diagnosed with symptomatic trigeminal neuralgia, and the onset of symptoms was immediately after dental treatment. In all patients, brain magnetic resonance imaging prior to the procedure revealed no remarkable pathology. We retrospectively reviewed medical records and survey results to determine age, sex, height, weight, laterality (unilateral/ bilateral), site of radiofrequency treatment, location of pain, pain intensities at baseline and 1 week, 1 month, 3 months, 6 months and 1 year after, duration of pain relief after the treatment, medication or any other treatment after radiofrequency treatment, and satisfaction of the treatment. The mean pain during the course of a day was rated using a 10-cm visual analog scale (VAS; 0 = no pain and 10 = the worst pain imaginable). A successful treatment was defined as over a 50% reduction in VAS score pre- to postprocedure with the ability to endure pain without medication. Recurrence was defined if the patient who received radiofrequency treatment could not bear pain without medication. The satisfaction was evaluated using a 5-point Likert scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, and 5 = very satisfactory. Written informed consent was obtained from all patients. Patients were informed about details of the method and possible complications. PRF on Maxillary or Mandibular Nerve With a patient in a supine position on the operating table, a pillow beneath the shoulders, and the head hyperextended, electrocardiography, pulse oxygen saturation monitoring, and non-invasive blood pressure monitoring were initiated. After ascertaining the foramen ovale (for mandibular nerve) or the pterygopalatine fossa (for maxillary nerve) on the lesion side using a C-arm fluoroscope, the area was anesthetized with 1% lidocaine, and a 22-G SMK-C10 curved needle (NeuroTherm, Radionics, Burlington, MA, USA) with a 2-mm active tip was inserted to the target nerve (just below the foramen ovale for the mandibular nerve and within the pterygopalatine fossa for the maxillary nerve). Using the C-arm fluoroscope to ascertain the needle position, the needle was advanced to the target nerve until the pain site was stimulated at a frequency of 50 Hz at V. After obtaining paresthesia during the stimulation, PRF was performed for 360 seconds at 42 C. After the procedure, patients were observed for 1 or 2 hours for side effects and complications. RFTC on Trigeminal Rootlets With the patient in a supine position on the operating table, a pillow beneath the shoulders, and the head hyperextended, electrocardiography, pulse oxygen saturation monitoring, and noninvasive blood pressure monitoring were initiated, and oxygen was supplied at 5 L/min through a facial mask with a reservoir bag. After ascertaining the foramen ovale on the lesion side using a C-arm fluoroscope, the area was anesthetized with 1% lidocaine, and a 22-G SMK-C10 curved needle (NeuroTherm, Radionics, Burlington, MA, USA) with a 2-mm active tip was inserted to a point about 2.5 cm away from the mouth angle using a perioral approach. Using the C-arm fluoroscope to ascertain the needle position on oblique and lateral images, the needle was advanced to the front of the foramen ovale. After injecting propofol ( mg/kg) and fentanyl (1 mg/kg) for sedation, the needle was introduced into the foramen ovale and passed the trigeminal ganglion. The fluoroscope was to ascertain that the needle was at the petroclival junction, and/or cerebrospinal fluid flow from the needle was confirmed. When the patient regained consciousness, we located the needle tip at the source of pain by slowly rotating a curved radiofrequency needle stimulated at a frequency of 50 Hz at V. The patient was then re-anesthetized with propofol 1.0 mg/ kg, and RFTC was performed three times for seconds at C. Propofol was injected for the first RFTC application; no further propofol injections were made thereafter. After the procedure, patients were observed for 1 day for side effects and complications. Statistical Methods The mean differences were analyzed using Student s t-test or analysis of variance. The proportional differences were evaluated using a chi-square test. Pain relief duration postprocedure was analyzed using Kaplan Meier analysis. The satisfaction rate was analyzed by Student s t-test. Statistical significance was defined as P values of <

4 Kim et al. Results Demographics Eighteen men (33.3%) and 36 women (66.7%) were enrolled. Disease duration was at least 3 months, and the pain scores were >5 of 10 with multiple medications (including carbamazepine, pregabalin, and gabapentin). The dental procedures that led to symptoms were 28 molar extractions (51.8%), 7 root canal treatment (13.0%), 3 apicoectomy (5.6%), 6 implantation (11.1%), and 10 other or unknown dental treatments (18.5%). Seventeen patients (31.5%) exhibited symptoms in the second trigeminal branch and 37 in the third trigeminal branch (68.5%). Twenty-three patients (42.6%) exhibited symptoms on the right side, 28 patients (51.8%) on the left side, and 3 patients (5.6%) on the bilateral sides. Forty-three patients (79.6%) experienced intermittent pain, and 35 (81.4%) of these experienced pain when speaking, chewing, washing, or brushing teeth. The remaining 11 (20.4%) patients experienced persistent pain. PRF Group vs RFTC Group Twenty-six patients (PRF group) were treated by PRF treatment, 28 patients (RFTC group) were treated by RFTC. The demographic data (sex, age, height, weight, the lesion of trigeminal branch, dental procedure which might be the cause of the disease) of each group except pain side (right, left, and both) were not significantly different (Table 1). In both groups, there were no differences in the average VAS scores of baseline (PRF group: , RFTC group: ), but the VAS scores at 1 week (PRF group: , RFTC group: ), 1 month (PRF group: , RFTC group: ), 3 months (PRF group: , RFTC group: ), 6 months (PRF group: , RFTC group: ), and 1 year (PRF group: , RFTC group: ) of the RFTC group were smaller than those of the PRF group (P < 0.05) (Figure 1). One month after the treatment, 21 patients (75.0%) reported that pain had been reduced by 50% without medication, and 25 patients (89.3%) reported that pain had been reduced by 30% without medication in the RFTC group, whereas no patient (0%) had pain reduction over 50% without medication in the PRF group (Table 2, Figure 2). Although 8 patients (30.8%) pain was decreased by over 50%, and 12 patients (46.2%) pain was decreased by >30% after 1 month of treatment, there was no patient who could stop the medication in the PRF group. The number of patients whose pain decreased by >50% without medication in the RFTC group was greater than the corresponding number in the PRF group (Figure 1). The period of pain relief in the RFTC group (10.8 months) was longer than that of the PRF group (0 month). Even the effective mean period in the PRF group with medication (0.7 month) was less than that in the RFTC group without medication (10.8 months). At 6 months after the treatment, 19 patients (67.9%) in the RFTC group and no patient (0%) in the PRF group had successful pain relief without medication (Figure 2). Eleven patients (39.3%) at 1 year and five patients (17.9%) at 2 Table 1 Demographic data and pain characteristics in PRF and RFTC group Parameters years after treatment in the RFTC group had successful pain control without medication. Complications The complication rate in the RFTC group (13, 46.4%) was higher than that in the PRF group (1, 3.8%) (P = 0.000, Table 1). In the RFTC group, postoperative hypesthesia occurred in 13 patients (46.4%), of whom four (14.3%) experienced sensory loss in the treated trigeminal area, but almost symptom was minor and transient and no one needed medications, admission, or other treatments. Of these four patients, one had hypotonia, one had mild difficulty chewing, one had minor discomfort during speaking, and one had reported a sensation that his face was edematous without actually having edema. In the PRF group, one (3.6%) had transient difficulty opening of the mouth and chewing. Satisfaction PRF Group (N = 26) RFTC Group (N = 28) Sex (M/F) 8 (30.1%)/ 18 (69.9%) 10 (35.7%)/ 18 (64.3%) Age (year) Height (cm) Weight (kg) Pain side* Right 6 (23.1%) 17 (60.7%) Left 17 (65.4%) 11 (39.3%) Both 3 (11.5%) 0 (0%) Associated nerve (V2/V3) 6 (23.1%)/ 20 (76.9%) 11 (39.3%)/ 17 (60.7%) Persistent pain 7 (26.9%) 4 (14.3%) Intermittent pain 19 (73.1%) 24 (85.7%) Trigger factor (yes/no) 14 (73.7%)/ 5 (26.3%) 19 (79.2%)/ 5 (20.8%) Satisfaction* Complication* 1 (3.8%) 13 (46.4%) * P < Satisfaction scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, and 5 = very satisfactory. PRF = pulsed radiofrequency; RFTC = radiofrequency thermocoagulation; V2 = mandibular nerve; V3 = maxillary nerve. Data are presented as numbers (%) of patients or mean SD. Mean satisfaction scale was 3.86 in the RFTC group and 2.19 in the PRF group (P = 0.000, Table 1). In the RFTC group, the satisfaction scale scores of the patients who had hypesthesia (3.85) and the other patients (3.87) was not statistically different (Table 3). The mean satisfaction scale score of the patients who had sensory loss was 2.75, and the others was 4.04 (P = 0.083). 432

5 RF, Dental Procedure-Related Symptomatic Trigeminal Neuralgia Figure 1 Changes in visual analog scale (VAS) scores after radiofrequency treatment. *P < PRF = pulsed radiofrequency; RFTC = radiofrequency thermocoagulation. Discussion The RFTC treatment showed longer pain relief than the PRF treatment. In particular, no patient was able to stop the medication after PRF in this study, but the mean pain relief duration without medication in the RFTC group is 10.8 months. This finding suggests that RFTC could be more effective treatment than PRF in dental treatmentrelated symptomatic trigeminal neuralgia. In general, pharmacotherapy is the first treatment option for posttraumatic facial neuropathic pain [11,12]. However, pharmacotherapy is less effective at treating this type of facial pain than the classical trigeminal neuralgia [1]. Furthermore, unlike classical trigeminal neuralgia, neurotomy and ablative procedures are known to sometimes worsen or trigger pain [1]. However, in this study, dental treatment-related symptomatic trigeminal neuralgia could be effectively treated with RFTC. The mean effective Table 2 Pain improved over 50% in PRF and RFTC group period of RFTC was 10.8 months without medication and other treatments. With coadministration of medication, the period of pain relief might be increased. The complication rate in the RFTC group was higher than in the PRF group. Hypesthesia, although not a serious one, was the most common complication in the RFTC group [11,13,14]. In this study, the patients who had only hypesthesia did not complain, and their satisfaction was not lower than the other patients (Table 3). Four (14.3%) patients suffered from sensory loss and other complications (hypotonia, mild difficulty chewing, minor discomfort during speaking, or edematous feeling), and their mean satisfaction scale was 2.75 (Table 3). But, medications, admission, or other managements were not required to treat their symptoms. Other major complications did not exist. To reduce complications, doctors have to be careful not to apply too much coagulation [15]. The needle should be positioned carefully at only the trigger rootlets related to 1 Month 3 Months 6 Months 12 Months PRF group without medication (N = 26) PRF group with medication (N = 26) 8 (30.8%) 1 (3.8%) 0 0 RFTC group without medication (N = 28)* 21 (75.0%) 21 (75.0%) 19 (67.9%) 11 (39.3%) * P < 0.05 than PRF group with and without medication. PRF = pulsed radiofrequency; RFTC = radiofrequency thermocoagulation. Data are presented as numbers (%) of patients. 433

6 Kim et al. Figure 2 Durations of effective pain control after radiofrequency treatment as determined by Kaplan Meier analysis. PRF = pulsed radiofrequency; RFTC = radiofrequency thermocoagulation. the symptoms. Some physicians use relatively low temperature and the small size of the active tip to reduce the lesion size, but the effects must be evaluated. In terms of patient number, women were two times more than men, which is the same as in classical trigeminal neuralgia [16]. However, in the dental procedure-related symptomatic trigeminal neuralgia, third trigeminal branch Table 3 Complications Satisfaction related to complications in RFTC group was the most common lesion (Table 1). This is different from the classical trigeminal neuralgia, in which the second trigeminal branch is the most common lesion [12,16]. The cause is that the lower teeth lie close to the mandibular nerve and the branch [9,17]. Surgical extraction of impacted inferior third molars is one of the most frequent surgical procedures in dental surgery [18,19]. The apex of the inferior third molar is close to the inferior alveolar nerve, which sometimes makes contact with or crosses the roots [18]. The third trigeminal branch can be more easily susceptible to trauma. Thus, molar extraction can be the most common dental procedure that caused the symptomatic trigeminal neuralgia in this study. Nerve injury-related trigeminal neuralgia accompanies pain that has a continuous nature [1,20]. But interestingly, the majority (43 patients, 79.6%) of the patients in this study reported intermittent pain, and 35 patients (64.8%) pain was triggered by trivial stimuli. This showed that the trigeminal nerve damage caused by a dental procedure may manifest as intermittent and stimuli-triggered pain [21], leading to symptoms resembling those of classical trigeminal neuralgia. In RFTC group, the needle position at the rootlets might be deeper than that in other methods, but we believe that our method can allow more selective lesioning at the rootlets than that at the Gasserian ganglion. Nevertheless, some limitations of the present study require consideration. In particular, the cohort size was not a large number (54 subjects). In addition, despite the chronological link between pain onset and the dental procedure, no definitive link based on analysis or examination was established due to the limitations of available techniques. This study was not a randomized controlled trial; rather, it was a retrospective study. Although there were no demographic differences between the two groups, the user-dependent procedures in this study could have biases other than the procedures. Further, randomized controlled trials will be required. However, research on dental procedure-related trigeminal pain is rather limited, The Number of Patients (N = 28) Satisfaction* P Value Hypesthesia Present 13 (46.4%) Absent 15 (53.6%) Sensory loss with other complications Present 4 (14.3%) Absent 24 (85.7%) * Satisfaction scale: 1 = very unsatisfactory, 2 = unsatisfactory, 3 = neutral, 4 = satisfactory, and 5 = very satisfactory. Other complications: one had hypotonia, one had difficulty chewing, one had difficulty speaking, and one felt that his face was edematous after the radiofrequency thermocoagulation (RFTC). 434

7 RF, Dental Procedure-Related Symptomatic Trigeminal Neuralgia and this is the first study to investigate RFTC and PRF for the treatment of trigeminal neuralgia developing after a dental procedure. Furthermore, this study provides a clinical basis for the use of RFTC and PRF on trigeminal nerve in patients with dental procedure-related trigeminal nerve damage. Conclusions Although more complications occurred in RFTC more than in PRF, they were minor and transient. The reported hypesthesia did not lead to a lower satisfaction rate. By contrast, in the PRF group, the effect and effective period were insufficient. In conclusion, RFTC for the treatment of dental treatment-related symptomatic trigeminal neuralgia can be effective, resulting in high satisfaction and relatively long-term relief of pain without medication and the need for other treatments. References 1 Kapur N, Kamel IR, Herlich A. Oral and craniofacial pain: Diagnosis, pathophysiology, and treatment. Int Anesthesiol Clin 2003;41: Burchiel KJ. A new classification for facial pain. Neurosurgery 2003;53:1164 6; discussion Nurmikko TJ, Eldridge PR. Trigeminal neuralgia Pathophysiology, diagnosis and current treatment. Br J Anaesth 2001;87: Olesen J. The international classification of headache disorders. 2nd edition. (ICHD-II). Rev Neurol 2005; 161: Zuniga JR. Management of third molar-related nerve injuries: Observe or treat? Alpha Omegan 2009;102: Loescher AR, Smith KG, Robinson PP. Nerve damage and third molar removal. Dent Update 2003;30: Pogrel MA. Damage to the inferior alveolar nerve as the result of root canal therapy. J Am Dent Assoc 2007;138: Abarca M, van Steenberghe D, Malevez C, De Ridder J, Jacobs R. Neurosensory disturbances after immediate loading of implants in the anterior mandible: An initial questionnaire approach followed by a psychophysical assessment. Clin Oral Investig 2006; 10: Kraut RA, Chahal O. Management of patients with trigeminal nerve injuries after mandibular implant placement. J Am Dent Assoc 2002;133: Bagheri SC, Farhidvash F, Perciaccante VJ. Diagnosis and treatment of patients with trigeminal neuralgia. J Am Dent Assoc 2004;135: Teixeira MJ, Siqueira SR, Almeida GM. Percutaneous radiofrequency rhizotomy and neurovascular decompression of the trigeminal nerve for the treatment of facial pain. Arq Neuropsiquiatr 2006;64: Gonella MC, Fischbein NJ, So YT. Disorders of the trigeminal system. Semin Neurol 2009;29: Huibin Q, Jianxing L, Guangyu H, Dianen F. The treatment of first division idiopathic trigeminal neuralgia with radiofrequency thermocoagulation of the peripheral branches compared to conventional radiofrequency. J Clin Neurosci 2009;16: Choi YS, Kim YC, Park SH, et al. Percutaneous radiofrequency thermocoagulation for trigeminal neuralgia. Korean J Anesthesiol 2008;54: Koopman JS, de Vries LM, Dieleman JP, et al. A nationwide study of three invasive treatments for trigeminal neuralgia. Pain 2011;152: Bennetto L, Patel NK, Fuller G. Trigeminal neuralgia and its management. BMJ 2007;334: Friedman JW. The prophylactic extraction of third molars: A public health hazard. Am J Public Health 2007;97: Gallesio C, Berrone M, Ruga E, Boffano P. Surgical extraction of impacted inferior third molars at risk for inferior alveolar nerve injury. J Craniofac Surg 2010; 21: Ramadas Y, Sealey CM. Third molar removal and nerve injury. N Z Dent J 2001;97: Graff-Radford SB. Facial pain. Neurologist 2009;15: Renton T, Yilmaz Z. Profiling of patients presenting with posttraumatic neuropathy of the trigeminal nerve. J Orofac Pain 2011;25: