|Year : 2020 | Volume
| Issue : 2 | Page : 142-148
Distal versus proximal pulsed radiofrequency for treating trigeminal neuralgia
Ahmed Sobhi M.E Hegab1, Osama M Baha’a Khidr2
1 Department of Anesthesia, Faculty of Medicine, Zagazig University Hospitals Zagazig, Egypt
2 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Sinai University, Sinai, Egypt
|Date of Submission||06-May-2019|
|Date of Acceptance||18-May-2019|
|Date of Web Publication||27-Jun-2020|
MD, PhD Ahmed Sobhi M.E Hegab
Department of Anesthesia, Faculty of Medicine, Zagazig University Hospitals, Zagazig, Sharkia 44519
Source of Support: None, Conflict of Interest: None
Aims The aim of this study was to evaluate and compare percutaneous distal pulsed radiofrequency (DPRF) and proximal pulsed radiofrequency (PPRF) for the trigeminal nerve in the management of trigeminal neuralgia (TN).
Patients and methods We conducted a prospective clinical trial including 20 patients with recent TN (3–6 months). The patients were randomized into two groups: DPRF (n=10) and PPRF (n=10). Patients were clinically followed up for 1 year and pain intensity was assessed at 3, 6, 9, and 12 months after the procedure using the visual analog scale (VAS).
Results The percentages of patients with satisfactory pain relief (50–80% pain relief) were 30% at 3 months, 40% at 6 months, and 40% at 12 months in DPRF group. However, in PPRF group, the percentages of patients who showed excellent pain relief (≥80% pain relief) at 3, 6, and 12 months were 50, 50, and 40%, respectively, whereas the percentages of patients with satisfactory pain relief (50–80% pain relief) at 3, 6, and 12 months were 40, 30, and 60%, respectively. Comparing the VAS score at 1, 3, 6, and 12 months did not show any significant difference between the two groups. In both groups, there was a significant decrease in VAS score after 1, 3, 6, 9, and 12 months compared with the preprocedure score (P<0.001).
Conclusion PRF treatment is a safe, effective, well-controlled procedure for the treatment of TN. There was no significant difference between DPRF and PPRF procedures. DPRF is a simple, safe, and effective procedure before the attempt to do the intracranial procedure.
Keywords: pulsed radiofrequency, trigeminal neuralgia, visual analog scale
|How to cite this article:|
Hegab AM, Baha’a Khidr OM. Distal versus proximal pulsed radiofrequency for treating trigeminal neuralgia. Res Opin Anesth Intensive Care 2020;7:142-8
|How to cite this URL:|
Hegab AM, Baha’a Khidr OM. Distal versus proximal pulsed radiofrequency for treating trigeminal neuralgia. Res Opin Anesth Intensive Care [serial online] 2020 [cited 2020 Aug 5];7:142-8. Available from: http://www.roaic.eg.net/text.asp?2020/7/2/142/287991
| Introduction|| |
Trigeminal neuralgia (TN) is characterized by recurrent episodes of unilateral electric shock-like pains, abrupt in onset and termination, in the distribution of one or more divisions of the trigeminal nerve that typically are triggered by innocuous stimuli . The trigeminal nerve has three major divisions: ophthalmic V1, maxillary V2, and mandibular V3. It starts at the midlateral surface of the pons, and its sensory ganglion (Gasserian ganglion) resides in Meckel cave in the floor of the middle cranial fossa. Most cases of TN may be caused by compression of the nerve root, usually within a few millimeters of entry into the pons . Compression by an aberrant loop of an artery or vein is thought to account for 80–90% of cases . It is one of the most common causes of facial pain, with a prevalence of four TN cases per 100 000 persons . The male to female ratio of TN ranges from 1 : 1.5 to 1 : 1.7 . This female predominance may be related to the increased longevity of women compared with men. Approximately 90% of patients have their initial symptoms after the age of 40 years .
In the International Classification of Headache Disorders, Third Edition (ICHD-3), TN is divided into classic (or classical) TN, secondary TN, and idiopathic TN . TN is typically unilateral. However, the pain may be bilateral, though rarely on both sides simultaneously . The pain distribution most often involves the maxillary and/or mandibular subdivisions of the trigeminal nerve .
For all patients with suspected TN or patients with recurrent attacks of pain limited to one or more divisions of the trigeminal nerve and no obvious cause such as herpes zoster, neuroimaging is mandatory to help distinguish classic TN from secondary TN. Neuroimaging of the brain can be done with MRI or computed tomography, though MRI with and without contrast is much preferred because its higher resolution enables imaging the trigeminal nerve and small adjacent lesions .
There are many methods to treat TN, including drug therapy, nerve blockade, and surgical treatments such as radiosurgery (mainly gamma knife therapy), radiofrequency (RF) of the Gasserian ganglion, and microvascular decompression . To our knowledge, pharmacologic therapy is the first-line initial treatment for most patients with classic TN and patients with idiopathic TN. Despite its adverse effect, carbamazepine is the best treatment for classic TN and is established as effective. However, RF treatment of the Gasserian ganglion may be an alternative option for patients who are refractory to medical therapy ,. Pulsed radiofrequency (PRF) treatment is defined as the delivery of short pulses of RF via a needle tip to avoid thermal lesions . This technique had been performed for various other conditions and has been shown to be effective and safe. The role of PRF in treating TN has been described but has not been well studied. The aim of this study was to evaluate and compare percutaneous distal pulsed radiofrequency (DPRF) and proximal pulsed radiofrequency (PPRF) for the trigeminal nerve in the management of TN.
| Patients and methods|| |
A comparative interventional, prospective, clinical trial was carried out in the Pain Management Unit of Anesthesia Department of Faculty of Medicine, Zagazig University. The institutional review board approved the study. Written informed consent was obtained from all individual participants included in the study.
Eligible patients had complained of TN (3–6 months) with past history of administration of medication without improvement for 3–6 months, were aged from 40 to 65 years from both sex, and did not have any significant medical disorder.
We excluded patients with local infection at the site of needle insertion, a generalized neurological disorder such as tumor and all secondary TN, coagulopathy blood disorder (low platelet count), a previous history of mental disorders and drug abuse, high intracranial pressure, and a history of microvascular decompression (MVD), balloon compression, RF treatment, or glycerol injection.
Approximately 84 patients who came to the outpatient clinic of Pain Management Unit of Anesthesia Department of Faculty of Medicine, Zagazig University, from March 2016 to May 2017, complaining of a sharp, dull, bilateral, unilateral, continuous, stabbing, lancinating, tenderness, discomfort, diffuse, and radiating pain into the neighboring structures (eyes, ears, and temples) were included in this study. They also had otolaryngological symptoms (earache and hearing impairment), burning, aching, and paroxysmal shooting that extended from below eye to the corner of the mouth. Of 84 patients, 36 patients were not complaining of TN after examination by an ENT physician and a neurologist. The MRI reports revealed local causes like vascular compression and mass involving the trigeminal nerve in 17 patients, so these patients were excluded. After discussion and explanation of the PRF procedure with the remaining patients, 20 patients accepted to participate in the trial. Then patients were divided randomly into two groups: DPRF (n=10) and PPRF (n=10).
For all the included patients, MRI examination, physical examination, nutritional assessment, and laboratory investigations (complete blood counts, bleeding time, coagulation time, prothrombin time, liver and kidney function profile, and blood glucose level) were done. The preanesthetic examination included airway, heart, lungs, vital signs, oxygen saturation, height, and weight of the patients. Dexamethasone (4 mg intravenous) was started at the night before the operation to decrease postoperative edema.
In the operating theater, the patients were placed in a supine position with a pillow beneath their shoulders to hyperextend the neck. Sedation was performed by use of fentanyl, 1 µg/kg, and midazolam, 0.05 mg/kg before local anesthesia infiltration. Then the injection of propofol was done, 0.75 mg/kg shots, using a needle.
For DPRF group, a dead lateral view of the skull base was used by rotating the C-arm laterally to guide the needle tip till the lateral pterygoid plate, a dead anterior posterior view to ascertain the depth of penetration of the needle tip till the lateral pterygoid plate. The needle was inserted (PRF needle Neurotherm 22–100–5 mm active tip, curved) at the midpoint of the lower margin of the zygomatic arch at the mandibular notch and advanced perpendicularly until it contacted the lateral pterygoid plate. In case of the maxillary nerve, the needle was withdrawn slightly and then advanced cephalo-anteriorly 1 cm to enter the pterygopalatine fossa ([Figure 1]). For mandibular nerve cases, the needle was withdrawn and then redirected posteriorly just behind the posterior border of the lateral pterygoid plate.
|Figure 1 Radiograph showing final needle position for distal maxillary nerve pulsed radiofrequency in anterior posterior and lateral views.|
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For PPRF group, the classic Hartle technique was used to reach the Gasserian ganglion. The C-arm, fluoroscopy, was adjusted in a posteroanterior fashion and rotated caudocranially (caudocranial by 30–50°) with slight obliqueness (10–30°) to visualize the foramen oval. The PRF needle (Neurotherm 22–100–5 mm active tip, curved) was inserted was 2–3 cm from the corner of the mouth. The tunnel view technique for the needle path was done to ‘bring the foramen oval to the entry point’ by the C-arm in a caudocranial orientation. The final proper position of the needle tip is just past the angle formed by the petrosal ridge of the temporal bone and the clivus ([Figure 2]).
|Figure 2 Radiograph showing final needle position in PPRF group by lateral and oblique views. PPRF, proximal pulsed radiofrequency.|
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[Figure 3] showed the needle entry point of the two groups.
|Figure 3 Radiograph showing needle entry point for (a) DPRF and (b) PPRF. DPRF, distal pulsed radiofrequency; PPRF, proximal pulsed radiofrequency.|
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The patients were kept awake, and sensory stimulation was performed at 50 Hz. Patients experienced electrical stimulation at the distribution of stimulated nerve when the potential reached 0.1–0.3 V. Motor stimulation produced jaw movement at 2 Hz with a potential of 0.2–0.6 V. The accuracy of the needle tip optimal site was confirmed by adjusting the depth and direction of the needle tip according to the patient’s response. PRF was done in both groups for 12 min at 60 V, with a pulse width of 20 ms and a pulse frequency of 2 Hz. The cut-off needle tip temperature was set at 42°C. At the end of the procedure, dexamethasone 4 mg was administered through the PRF needle.
All patients completed the steroid regimen which consists of dexamethasone ampule 4 mg intravenous twice a day on the day of surgery, 2 mg twice a day on the second postoperative day, and 1 mg on the third postoperative days. Patients in the two groups were clinically followed up for 1 year, and pain intensity was assessed at 3, 6, 9, and 12 months after the procedure using the visual analog scale (VAS).
Statistical analyses were performed using the statistical software program, SPSS, for Windows, version 25.0 (SPSS, Chicago, Illinois, USA). Data are presented as mean±SD. For quantitative variables, parametric independent t test was used for comparison in case of Gaussian distribution, whereas the Mann–Whitney U test was used for non-Gaussian distribution. For categorical variables, Fisher’s exact test was used. For all tests, a P value of 5% or less at a two-sided test was considered statistically significant.
| Results|| |
The present study included 20 patients (11 males and nine females) with TN as a final diagnosis with severe pain in the distribution of mandibular, maxillary, or both nerves for 3–6 months, which occurs in paroxysms with history of unsuccessful medical treatment. Patients’ characteristics are summarized in [Table 1].
The patients were classified into two groups: group 1 (n=10) received DPRF and group 2 (n=10) received PPRF. Nine patients in DPRF group received the same preoperative dose of medication for 2 weeks postoperatively as a routine work, and gradually complete withdrawal of the medication was done. Only one patient experienced recurrent TN pain after 3 months, and then he was submitted to another DPRF session with 2 weeks of postoperative medication.
In PPRF group, eight patients received the same preoperative dose of medication for 2 weeks as a routine work, and gradually complete withdrawal of the medication was done. However, two patients experienced recurrent TN pain after 6 months, and they were subjected to another PPRF session with 2 weeks of postoperative medication.
In both groups, there was a significant decrease in VAS score after 1, 3, 6, 9, and 12 months compared with preprocedure score (P<0.001, [Figure 4]).
|Figure 4 Change in the VAS score through the study periods in the two groups. VAS, visual analog scale.|
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In DPRF group, excellent pain relief was reported for six patients after 1, 3, 6, 9, and 12 months after the procedure. The percentages of patients who showed excellent pain relief (≥80% pain relief) at 3, 6, and 12 months were 60%. The percentages of patients with satisfactory pain relief (50–80% pain relief) at 3, 6, and 12 months were 30, 40, and 40%, respectively. Only one patient reported unsatisfactory pain relief after 3 months. In PPRF group, the percentages of patients who showed excellent pain relief (≥ 80% pain relief) at 3, 6, and 12 months were 50, 50, and 40%, respectively, whereas the percentages of patients with satisfactory pain relief (50–80% pain relief) at 3, 6, and 12 months were 40, 30, and 60%, respectively. Only one patient reported unsatisfactory pain relief after 3 months and two patients after 6 months. Comparing the VAS score at 1, 3, 6, and 12 months did not show any significant difference between the PPRF group and DPRF group ([Table 2]).
Analgesic consumption especially carbamazepine was reduced gradually after 1–2 months and completely stopped in the patients of both DPRF and PPRF groups.
Regarding this procedure’s complications, in PPRF group, two patients experienced intraoperative and postoperative facial edema and two other patients showed aspiration of blood using plastic syringe during procedure which was managed by application of ice packs immediately. However, in DPRF group, we did not report any intraoperative or postoperative complications.
| Discussion|| |
To our knowledge, PRF is a recent method for treatment of TN. In this study, 60% continued to report satisfactory pain relief after 12 months of PPRF treatment and 40% in DPRF. This may mean that good pain relief at 6–12 months after PRF treatment may predict for long-term pain relief using PRF. These results were similar to those previously reported in the literature ,. In 2004, Lopez et al.  conducted a systematic review to systematically identify all of the studies reporting outcomes and complications of ablative techniques for treatment of TN and concluded that RF offers the highest rates of complete pain relief. Furthermore, Chua et al.  conducted a retrospective study including 36 consecutive patients who underwent DPRF treatment for TN, for 6 min at 45 V at a pulsed frequency of 4 Hz and a pulse width of 10 ms and revealed that the percentages of patients who showed excellent pain relief (>80% pain relief) at 2, 6, and 12 months were 73.5, 61.8, and 55.9, respectively. The percentages of patients showing satisfactory pain relief (50–80% pain relief) at 2, 6, and 12 months were 14.7, 17.6, and 17.6%, respectively, and those of patients showing less than satisfactory pain relief (<50% pain relief) at 2, 6, and 12 months were 11.8, 20.6, and 23.5%, respectively. In our study, the percentages of patients in DPRF group who showed excellent pain relief (≥80% pain relief) at 3, 6, and 12 months were 60%. The percentages of patients with satisfactory pain relief (50–80% pain relief) at 3, 6, and 12 months were 30, 40, and 40%, respectively. Only one patient reported unsatisfactory pain relief after 3 months.
Either PRF or CRF can be used to treat TN. Erdine et al. , conducted a randomized, double-blinded study to evaluate the effect of pulsed PRF in comparison with conventional RF in the treatment of idiopathic TN including 40 patients. The VAS score decreased in only two of 20 patients from the PRF group and pain recurrence occurred 3 months after the procedure. Erdine and colleague concluded that PRF is not an effective method of pain treatment for idiopathic TN. This study found that the outcome in patients treated with PRF was better than that in the study by Erdine and colleagues. This study reported that four patients had long-term excellent outcome and four patients had long-term satisfactory outcome and two patients required more than one session of PRF treatment. The reason for this may be owing to the neuromodulatory mode of action of PRF with increased time (12 min) and increased volt used in PRF (60 V) compared with the study by Erdine and colleagues, which does not produce immediate paresthesia as in RF thermocoagulation.
However, the effects of treatment on different branches of the trigeminal nerve were not the same between the different treatment methods . Savas and Sayin , reported that, in normal circumstances, the complication rate of PRF is ∼3.8%. To reduce the complications, it is necessary to confirm the puncture depth and the accurate location of the foramen oval.
Kanpolat et al.  performed the largest study till now that included 1600 patients who had undergone percutaneous RF trigeminal rhizotomy over a period of 25 years. The complications reported in this large study were decreased corneal reflex (5.7%), dysesthesia (1%), weakness and paralysis of the masseter muscle (4.1%), weakness and paralysis of the masseter muscle (4.1%), anesthesia dolorosa (0.8%), weakness and paralysis of the masseter muscle (4.1%), and temporary paralysis of the third and fourth cranial nerves (0.8%) . In the present study, two patients experienced facial edema and two other patients showed aspiration of blood during procedure, and no patients reported any procedure-related complications.
| Conclusion|| |
In conclusion, RF treatment is a safe, effective, and well-controlled procedure for the treatment of TN. It also may be used successfully as a first-line treatment for TN cases to avoid unpredicted systemic adverse effects of drugs.
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]