|Year : 2021 | Volume
| Issue : 1 | Page : 14-19
Radiofrequency treatment of idiopathic trigeminal neuralgia (Conventional vs. Pulsed): A prospective randomized control study
Anurag Agarwal1, Shivani Rastogi1, Manjari Bansal1, Suraj Kumar1, Deepak Malviya1, Anup K Thacker2
1 Department of Anesthesiology, CCM and Pain Medicine, Dr. RMLIMS, Lucknow, Uttar Pradesh, India
2 Department of Neurology, Dr. RMLIMS, Lucknow, Uttar Pradesh, India
|Date of Submission||12-Apr-2021|
|Date of Acceptance||01-Jun-2021|
|Date of Web Publication||30-Aug-2021|
Dr. Suraj Kumar
Department of Anesthesiology, CCM and Pain Medicine, Dr. RMLIMS, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Idiopathic trigeminal neuralgia (TGN) is a chronic pain disorder causing unilateral, severe brief stabbing recurrent pain in the distribution of one or more branches of the trigeminal nerve. Conventional radiofrequency (CRF) and pulsed radiofrequency (PRF) are two types of minimally invasive treatment. CRF selectively ablates the part of ganglion to provide the relief, but it has been found to be associated with some side effects such as dysesthesia or sensory loss in 6%–28% and loss of corneal reflex in 3%–8% of patients. PRF is a comparatively newer modality which is a nondestructive and neuromodulatory method of delivering radiofrequency energy to the gasserian ganglion to produce a therapeutic effect. Aims: We aimed to compare the efficacy of CRF with long-duration, fixed voltage PRF in the treatment of idiopathic TGN. Setting: This study was conducted in a tertiary care center research institute. Study Design: This was a prospective randomized trial. Materials and Methods: Twenty-seven adult patients of TGN were included in the study and randomly allocated into two groups (CRF and PRF). All procedures were performed operation suite with C-arm fluoroscopic guidance. Both, pre- and postprocedure, the patients were assessed for pain on the Visual Analog Scale (VAS) and Barrow Neurological Institute (BNI) Pain Intensity Scale at 1 week and thereafter at 1, 2, 3, and 6 months. Patients with a BNI score ≥4 after 1 month were considered a failure and offered other modes of treatment. A reduction in VAS score ≥50% and a BNI score <4 were considered as effective. Statistical Analysis: Discreet variables were recorded as proportions, ordinal variables and continuous variables with non-Gaussian distribution as medians with interquartile range, and continuous variables with Gaussian distribution as mean ± standard deviation. Association between ordinal variables was tested by Fisher's exact test/Chi-square test whenever appropriate. Equality of means/median was tested by using paired/unpaired t-test or nonparametric tests depending upon the distribution of data. P ≤ 0.5 was considered statistically significant. Data analysis was performed using STATA version 13.04 windows. Results: Efficacy in terms of decrease in VAS ≥50% at 1 month was 33.33% and 83.33% in the PRF and CRF groups, respectively, which was statistically significant(P = 0.036). Effective reduction in BNI scores at the 7th day, 1 month, and 2 months postprocedure was evaluated and found in 41.67% and 83.33% of patients in the PRF and CRF groups, respectively, which was statistically insignificant (P = 0.089). There was a statistically significant reduction in BNI scores in PRF and CRF group patients at 3 and 6 months (at 3 months, 33.33% and 83.33%, P = 0.036 and at 6 months, 25% and 83.33%, P = 0.012). In the CRF group, mild hypoesthesia was evident in three patients which improved by the end of 1 month while no side effects were seen in the PRF group. Conclusion: CRF is a more effective procedure to decrease pain in comparison to long-duration, fixed voltage PRF for the treatment of idiopathic TGN. Although the side effects are more with CRF, they are mild and self-limiting. Limitation: The limitations of this study were as follows: small sample size and short duration.
Keywords: Conventional radiofrequency, facial pain, pulsed radiofrequency, trigeminal neuralgia
|How to cite this article:|
Agarwal A, Rastogi S, Bansal M, Kumar S, Malviya D, Thacker AK. Radiofrequency treatment of idiopathic trigeminal neuralgia (Conventional vs. Pulsed): A prospective randomized control study. Anesth Essays Res 2021;15:14-9
|How to cite this URL:|
Agarwal A, Rastogi S, Bansal M, Kumar S, Malviya D, Thacker AK. Radiofrequency treatment of idiopathic trigeminal neuralgia (Conventional vs. Pulsed): A prospective randomized control study. Anesth Essays Res [serial online] 2021 [cited 2021 Dec 3];15:14-9. Available from: https://www.aeronline.org/text.asp?2021/15/1/14/325017
| Introduction|| |
Trigeminal neuralgia (TGN), also known as tic douloureux, is a chronic pain disorder affecting one or more branches of the trigeminal nerve. The International Association for the Study of Pain defines it as “sudden, usually unilateral, severe brief stabbing recurrent pains in the distribution of one or more branches of the trigeminal nerve (Vth cranial nerve).” Most of the time onset of the pain is triggered by trivial routine life-sustaining rituals which may work as stimuli. These simple routine which may be a cause of pain onset may include washing, shaving, and smoking, talking, and brushing the teeth. Spontaneous recurrences of the episodes of pain have also been reported.
Burchiel in 2003 classified TGN into two types – type 1 (episodic) and type 2 (constant). Various treatment modalities such as medical management, percutaneous minimally invasive procedures, and surgical management for the treatment of TGN have been practiced over the last few decades. In medical management, various drug combinations have been utilized for effective management of TGN. However, anticonvulsant drug carbamazepine has been the “drug of choice.” TGN poses several complexities in treatment and pain management, and in many cases, the first line of treatment may not be effective; in such cases, the second line of treatment is utilized and the drugs used are lamotrigine, baclofen, phenytoin, gabapentin, oxcarbazepine, pregabalin, etc.,,,,,,
Percutaneous minimally invasive procedures and neurosurgical modalities are treatment options in cases of failed medical management. The various modalities which are applied include: (a) peripheral procedures (target portions of trigeminal nerve distal to Gasserian ganglion More Details), (b) percutaneous procedures (target gasserian ganglion), (c) stereotactic radiosurgery using X-rays or gamma-ray precision beams (targets trigeminal nerve root), and (d) microvascular decompression (MVD). MVD is considered the gold standard surgical treatment. This is a major neurosurgical procedure performed under general anesthesia and poses its own complexity; it may not be suitable in old and debilitated patients. Several other procedures applied for pain management include percutaneous pain interventions such as retrogasserian glycerol rhizolysis, alcohol injection, and cryotherapy. Recently, conventional and pulsed radiofrequency (CRF and PRF) treatments have been practiced with encouraging outcome. Several practitioners have also used percutaneous balloon compression which also provides possible minimally invasive options.,,
CRF selectively destroys the unmyelinated or poorly myelinated nociceptive nerve fibers and spares the heavily myelinated fibers (that serve touch, proprioception, and motor function). The CRF is performed at 60°C–75°C for 45–90-s cycles with a success rate of 83%. Significant dysesthesia or sensory loss was reported in 6%–28% of patients and loss of corneal reflex in 3%–8% of patients with CRF., PRF treatment produces neuromodulatory effect on target neural structure with short bursts of radiofrequency current at 42°C causing microscopic damage to axonal microfilaments and microtubules, with greater changes seen in C-fibers than A-β or A-δ fibers.,
This study was conducted to compare the efficacy of long-duration, fixed voltage PRF with CRF for treatment of idiopathic TGN and assessment of side effects animating from these modalities.
| Materials and Methods|| |
This prospective parallel blinded randomized study was conducted in the tertiary care institute in pain medicine unit, department of anesthesiology, from May 2018 to December 2019 on 27 patients (18–80 years of age) of idiopathic TGN and refractory of medical management. After approval from the institutional ethics committee (IEC NO.68/17, DATED-21.3.18) which follows the Helsinki Declaration (2006), all patients were thoroughly evaluated. Complete medical history was charted out and recorded regarding the site, duration, nature of the disease, treatment medications taken including doses, duration, and side effects. Preintervention pain was scored according to the Visual Analog Scale (VAS) and Barrow Neurological Institute (BNI score) [Table 1]. Patients with severe uncontrolled systemic illness, local infection, coagulation disorder, and secondary TGN were excluded from the study.
The study was registered with the Clinical Trials Registry-India (2019/04/018597). The sample size was calculated according to which we needed 11 subjects in the CRF group and 11 subjects in the PRF group to be able to reject the null hypothesis that the cure rates for both the groups are equal with probability (power) of 0.8. Several other studies have employed a similar approach for sample size calculations. The type 1 error probability associated with the test of this null hypothesis was 0.05. After taking written, informed consent, the patients were randomly allocated into two groups with the use of computer-generated random table numbers which were generated by the statistician; patients were enrolled and assigned by the nursing staff. The participant and the assessor were blinded to the treatment (PRF or CRF). Group 1 patients received CRF and Group 2 patients were given PRF of the gasserian ganglion.
All procedures were conducted in the pain medicine operating suite after securing the intravenous line and vital monitoring. With the patient in the supine position, C-arm fluoroscopy was used to obtain a “submentovertex projection” with a caudal inclination of approximately 30° to visualize the foramen ovale [Figure 1]. After local infiltration with 1% injection lignocaine hydrochloride (Neon Laboratories, India), a 22G, 10-cm SMK radiofrequency cannula (Kimberly-Clark Inc. Worldwide, US) with 5-mm active tip was then directed through foramen ovale to reach Meckel's cave, where gasserian ganglion is located. The position of the RF cannula was confirmed by both lateral and AP fluoroscopic views [Figure 2] and [Figure 3]. After satisfactory sensory-motor stimulation to determine the involved division, in Group 1, CRF lesioning was delivered in three fractions at 60°C, 65°C, and 70°C each for 60 s. In Group 2, PRF was performed at 50 V with pulse delivered at every 20 ms for 10 min with a maximum tip temperature of 42°C, using RF pain management generator (Kimberly Clark Inc. Worldwide, US). Thereafter, patients were monitored and observed for 2 h and then discharged.
|Figure 1: Fluoroscopic view showing “foramen ovale in submentovertex” view (black arrow)|
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Pain and treatment outcome was assessed by VAS and BNI scores after the intervention. Side effects and complications related to the technique (facial dysesthesia, corneal anesthesia, and masseter muscle weakness) were recorded. Patients with a BNI score of ≥4 after lapse of 1 month were considered a failure and were advised alternative modes of treatment. A reduction in VAS scores ≥50% was considered as an effective treatment, and a BNI score <4 was considered effective.,
Discreet variables were recorded as proportions, ordinal variables and continuous variables with non-Gaussian distribution as medians with interquartile range, and continuous variables with Gaussian distribution as mean ± standard deviation. Association between ordinal variables was tested by Fisher's exact test/Chi-square test whenever appropriate. Equality of means/median was tested by using paired/unpaired t-test or nonparametric tests depending upon the distribution of data. P ≤ 0.5 was considered statistically significant. Data analysis was performed using Statistical package for the Social Sciences-21, Chicago, Illinois, USA.
| Results|| |
Twenty-seven patients of TGN who were refractory to medical management (BNI ≥ 4) were enrolled in the study. Three patients did not complete the specified follow-up, thus only 24 patients were included in the final statistical analysis.
The cohort included 11 males and 13 females. Age varied from 34 to 74 years (mean age: 54.91 ± 10.29 years). The territorial involvement included ophthalmic nerve in 8 patients, maxillary nerves in 10 patients, and mandibular nerve in 12 patients. Nine patients had single nerve root involvement while 15 patients had multiple nerve root involvement, the most common involvement was of V2 and V3 divisions (33%) followed by V1 and V2 (25%), and all three divisions V1, V2, and V3 were in involved in 4% of patients [Figure 4]. Right side (n = 13) was more frequently involved than the left (n = 11); none of the cases in this cohort had bilateral involvement. Both the groups were comparable in terms of demographic data [Table 2]. The mean disease duration was 5.8 years and 5.44 years in the CRF and PRF groups, respectively, which was insignificant (P = 0.86). The preprocedure mean BNI scores were 4.41 ± 0.05 in both the CRF and PRF groups which were comparable. After the procedure, at the 7th day, 1 month, and 2 months, the percentage reduction in BNI score was seen in 41.67% and 83.33% of PRF and CRF group patients, respectively, which was statistically insignificant (P = 0.089). There was a statistically significant reduction in BNI scores in PRF and CRF group patients at 3 and 6 months (at 3 months, 33.33% and 83.33%, P = 0.036 and at 6 months 25% and 83.33%, P = 0.012) [Table 3]. In Group CRF, mild hypoesthesia was evident in three patients at 7 days which improved by 1 month. The mean baseline VAS scores were 9.16 in both the groups. After procedure at 7 days, effectiveness in terms of VAS score was 50% and 83.33% in the PRF and CRF groups, respectively, and was statistically insignificant (P = 0.193). Statistically significant improvement was seen in VAS after 1 month which stayed like that till the end of study at 6 months (at 1 month, 33.33% and 83.33%, P = 0.036; at 2 months, 41.67% and 91.67%, P = 0.027; at 3 months, 33.33% and 83.33%, P = 0.036; and at 6 months, 25% and 83.33%, P = 0.012, respectively, for the PRF and CRF groups) [Table 4].
|Table 2: Patient demographics data are represented as mean±standard deviation, n (%) and ratio|
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|Table 3: Effectiveness in terms of barrow neurological institute throughout follow up period|
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|Table 4: Effectiveness in terms of visual analogue scale throughout follow up period|
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Mild hypoesthesia was seen in three patients in the CRF group at 7 days which persists for 1 month, and no hypoesthesia was seen with PRF at any stage of treatment [Table 5]. No other side effect as masseteric weakness, corneal abrasion, and anesthesia Dolorosa was seen in any patient in both the groups.
| Discussion|| |
Twenty-seven patients of TGN who were refractory (BNI ≥4) to pharmacological treatment were included in this study. Three patients did not complete follow-up, so only 24 patients were included in the study. The demographic data of our study is comparable in both PRF and CRF groups in reference to age, sex and side of involvement. Maxillary (V2) and Mandibular (V3) divisions were more commonly involved in our patient population. Our demographic data is comparable to systematic review done by de Toledo et al. The mean baseline BNI scores and VAS scores in our study were 4.41 and 9.16, respectively, in both the CRF and PRF groups. At 7 days postintervention, effectiveness in terms of BNI score was 41.67% and 83.33% in the PRF and CRF groups, respectively, which was statistically insignificant (P = 0.089). Statistically significant BNI improvement was shown after 3 months postprocedure to values of 33.33% and 83.33% (P = 0.036) in the PRF and CRF groups, respectively, which further improved to 25% and 83.33% (P = 0.012) at 6-month duration. In the PRF group, gradual diminution in effectivity was shown by BNI score was 41.67%, 41.67%, 41.67%, 33.33%, and 25% at 7 days, 1 month, 2 months, 3 months, and 6 months, respectively, and early relapse was evident in the PRF group after 2 months of the procedure.
Side effects in terms of mild hypoesthesia were seen in three patients in CRF which recovered in 6 weeks. No side effects were seen with the PRF group.
On reviewing the literature for the management of TGN regarding CRF and PRF, many studies and many hypotheses had been given by different authors. Kanpolat et al. found CRF to be effective in a study of 1600 patients, with pain relief in 1561 patients (97.6%), though recurrence was observed in 123 patients (7.7%); they concluded that CRF is an effective and safe procedure in TGN.
In 2007, Erdine et al., in their landmark study, evaluated the effect of PRF in comparison to CRF. They used PRF for 120 s at 45 volts with temperature not exceeding to 42°C. They concluded that unlike conventional radiofrequency, PRF is not an effective method of pain treatment for TGN. In contrary to Erdine et al. findings, Chua et al. in 2012 retrospectively studied 36 patients who underwent PRF reported excellent pain relief with PRF treatment for idiopathic TGN. On comparison of both these landmark studies, we found that Chua et al. have used much longer duration of PRF, i.e. 6 min (vs. Serdar Erdine et al., who used 120 s of PRF) at 45 V at 42°C. Similarly, Fang et al., in 2015, performed high voltage PRF in 26 patients and found out significant improvement in a Numeric Rating Scale (NRS) in 18 (69%) patients, and none of them suffered a recurrence. Among these 18 patients, NRS was 0 in 13 patients, and they stopped the usage of carbamazepine; 5 patients achieved NRS relief >50% and 8 patients (31%) failed to respond to treatment 1 month postoperatively. The contrasting findings of these noteworthy research works by Serdar Erdine et al., Chua et al., and Fang et al. became the basis of our study. In various previous studies, different methods for increasing the effectiveness of PRF in TGN were proposed. To increase the efficacy of PRF, Chua et al. proposed increasing the duration of treatment while Luo et al. suggested that increasing output voltage. Therefore, in an attempt to get the maximum effect of PRF, we combined all the parameters of PRF settings described in the previous literature,,, and compared it with standard treatment CRF for our prospective randomized study.
Jae Hun Kim et al. compared long-duration (360 s) PRF treatment with CRF and reported that CRF had a longer duration of pain relief in comparison to the PRF group, though the reported incidence of complications in the CRF group (46.4%) was higher than that in the PRF group (3.8%) (P < 0.05). However, even after optimizing these parameters also, our findings were similar to Erdine et al. and Kim et al., that is, PRF treatment has lower effectiveness. In our study also, gradual diminution in effectivity was shown by BNI scores at 7 days, 1 month, 2 months, 3 months, and 6 months, respectively, to be 41.67%, 41.67%, 41.67%, 33.33%, and 25% showing early relapse in the PRF group after 2 months, similar to Abd-Elsayed et al. who also found relapse in 57% of patients within 6-month follow-up after PRF.
| Conclusion|| |
Comparative evaluation reveals that long-duration, fixed voltage PRF treatment is not as effective as CRF treatment for TGN. One of the pertinent findings was that there was an early relapse even in those patients where PRF treatment was considered successful initially. No side effects were observed with PRF treatment, while the patient treated with CRF had mild and self-limiting side effects. It was thus concluded that CRF is a more efficacious modality than long-duration, fixed voltage PRF in treatment of TGN with negligible side effects.
The limitations of this study were as follows: small sample size and short duration.
- Minimally invasive intervention radiofrequency ablation in TGN
- CRF better with minimal side effects
- Long-duration PRF early relapse with less effectivity.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]