Review of Radiofrequency Ablation in Tonsillectomy

Abstract

The most common disease involving the tonsils among children and adults is chronic tonsillitis. There are different surgical techniques described in literature for the treatment of diseases involving the tonsils. Of these, the most routinely performed and the traditional method is conventional dissection tonsillectomy. The main disadvantage of this method is bleeding and postoperative pain. Radiofrequency ablation is found to overcome this limitation due to its mechanism of action. Both monopolar and bipolar radiofrequency ablation can be used in the surgical management. The effectiveness of monopolar radiofrequency has been proved in different fields of medicine. Hence new studies can be directed in comparing monopolar radiofrequency ablation with other techniques of tonsillectomy.

Introduction

Tonsillectomy is the most common surgery performed by Otorhinolaryngologists all over the world. Different techniques of tonsillectomy are practised across the world with conventional dissection method being the traditional method [1]. Numerous studies have been conducted to compare the efficacy between different techniques with contradictory results for radiofrequency tonsillectomy. Hence this review is done to analyse the effectiveness of radiofrequency ablation with the help of 40 articles published between 2004 and 2021 using Pubmed, Google Scholar and Web of Science with keywords of monopolar radiofrequency ablation, tonsillectomy, tonsil resection, tonsil removal and bipolar radiofrequency ablation. Articles relating to other tonsillectomy techniques, irrelevant articles, reviews or meta-analyses were excluded and 19 articles were selected for reference.

Overview

Cold tonsillectomy methods include dissection and snare method, cryosurgical technique, harmonic scalpel, guillotine method, plasma mediated ablation technique and intra capsular tonsillectomy. Hot tonsillectomy methods include radiofrequency, coblation tonsillectomy, electrocautery and laser tonsillectomy [2]. Different guidelines have been suggested for deciding on tonsillectomy in patients with chronic tonsillitis which includes the American academy of Otolaryngology, head and neck surgery guidelines for tonsillectomy 2011, Pittsburg criteria, Paradise criteria and Sign guidelines [3].

Radiofrequency Tonsillectomy

All thermoablative techniques will result in circumscribed or localized tissue damage, known as thermonecrosis, when exposed to a temperature rise of 65–100 °C. This temperature rise will lead to an irreversible destruction of cells that are eventually degraded by the body, resulting in reduction of tissue size and thereby improving local symptoms [4]. Recently, temperature controlled RF has been found to be more effective and safe for reduction of tonsil. At relatively low temperatures of 40–70 °C, a plasma field is generated at the probe’s surface of RF device which causes tissue ablation. The highly ionised particles present in this plasma field will help to break the molecular bonds of tissue and thereby, reduce the heat dissipation to neighbouring tissues. Whereas, in diathermic devices, temperature greater than 500 °C is generated causing more damage to the local tissue [5]. Heat is generated due to the natural resistance of tissue to the movement of electrons within a RF field (Ohm's Law). This resistance, called impedance, creates heat relative to the amount of current (amps) and time (seconds). With RF, one must consider not only the depth of energy penetration, but also that the soft tissue is made up of multiple layers, including dermis, fat, muscle, and fibrous tissue, all with varying resistance to the movement of RF energy. This mechanism is quite different from the photothermal effect produced by lasers. RF can be monopolar or bipolar. In monopolar RFA, the current spreads from each electrode centrifugally to the periphery, whereas during bipolar RFA the electrical current flows between a pair of electrodes [6]. Hence bipolar effect is more superficial when compared to the deep effect with monopolar. Also, in bipolar RFA, the shape of ablation zone tends to be ellipsoidal and the ablation area is smaller when compared to monopolar which is disadvantageous. Bipolar RFA is often used in liver, kidney and muscle treatments. The thermal injury induced will result in primary and secondary processes which include vascular bed contraction, thrombosis, ischemia and inflammation.

RFA is an upcoming trend which can be used in various other clinical modalities. RFA is found to have a significant role in the treatment of intractable pericranial neuralgia. In the study conducted by Elsayed et al. RFA was performed at 80 °C for 180 s on different nerves including greater and lesser occipital, supratrochlear and supraorbital nerves for the treatment of pericranial neuralgia. The pain scores were analysed and found to be significantly reduced in patients with RFA. In addition to pain, there was reduction in chronic daily headaches, dizziness and insomnia [7]. RFA is an effective treatment option for benign thyroid nodules and recurrent thyroid cancers [8]. Application of RF current to the tissue causes agitation of ions which in turn results in frictional heat generation around the electrodes resulting in instantaneous protein denaturation and irreversible cell death. An innovative and viable modality of endoscopic RFA can be used for the treatment of gastric antral vascular ectasia, chronic radiation proctitis, malignant biliary strictures and ampullary adenomas with intraductal extension [9]. It is effective for treating the lesions in liver, pancreas, lymph nodes and ablation of celiac ganglia for pain control in pancreatic carcinoma. RF catheter ablation has emerged as an alternative to medical management of tachyarrhythmias in children [10]. Monopolar RFA has been increasingly used for facial skin tightening procedures in Dermatology. The thermal energy produced, heats the dermis and subcutaneous fibrous septa which results in collagen denaturation with subsequent thickening and shortening of collagen fibres. This in turn leads to increased fibroblast activity and new collagen formation, resulting in skin tightening over a period of 4–6 months. [11] In otorhinolaryngology, RFA has been used in palatal, tonsillar and turbinate reduction, taking advantage of its ablative properties. A target temperature of 60–75 °C causes safe and effective submucosal reduction of hyperplastic turbinate in 4–10 s [12].

The advantages of RFA includes: (i) hemostatic, (ii) bacteria free method, (iii) better and faster healing than electrocautery, (iv) cut without exerting any pressure. The limitations include (i) the ablation does not eliminate the crypts of tonsil, (ii) possibility of remnants, (iii) inability to send the tissue for histopathological examination. The use of RF waves provides pin point coagulation with minimal lateral heat and thermal damage, thereby causing less scarring and pain.

Numerous studies have been conducted to assess the efficacy of RFA with other modalities of tonsillectomy and the results were not very consistent. No much study has been conducted to evaluate the effectiveness of monopolar RFA in tonsillectomy.

Studies in Favour of Radiofrequency Ablation

A retrospective study was done by Verma et al. comparing the various techniques of tonsillectomy. In this study, they have compared the efficacy between CD tonsillectomy, microdebrider assisted partial tonsillectomy, coblation, radiofrequency and laser tonsillectomy. This study was conducted with 2500 patients who underwent tonsillectomy with or without adenoid removal over a period of 35 years. 41% of the patients underwent CD tonsillectomy, 39% underwent microdebrider assisted tonsillectomy and in 21% coblation, RF and laser was used. Preoperative hydrocortisone and postoperative antibiotics were given to all patients. They have compared intra operative blood loss and time taken for surgery, postoperative pain, bleeding, dehydration and healing time as well as other complications like vomiting, haemorrhage and hospitalization. Intraoperative blood loss was the least with microdebrider and more with CD. The rate of primary, secondary and tertiary haemorrhage was 5, 6 and 1% respectively with CD method. Least haemorrhage rate and pain was observed with coblation and microdebrider. Decreased risk of primary haemorrhage was observed with bipolar when compared to CD group but the risk of secondary haemorrhage was five times high in bipolar electrodissection. Due to vomiting, bleeding and dehydration, the readmission rate was found to be higher in cases done with CD (4%). This study has concluded that the powered intracapsular partial tonsillectomy using microdebrider is the best method followed by coblation as far as per-operative and post-operative complications are concerned. Also, RF tonsillectomy has added advantage of being coft effective with shorter intraoperative duration and easy to use when compared to laser tonsillectomy. In monopolar RF scarring of the tonsil tissue is produced and thus reduction in size. It is done under local anaesthesia or light sedation with minimum discomfort and usually a day care procedure causing less bleeding with less postoperative pain in comparison to cold steel method [13].

A clinical study on the influence of RF surgery on the architecture of the palatine tonsils was conducted by Plzak et al. Here the study was conducted among 83 adult patients with tonsillar hypertrophy and sleep disordered breathing under local anaesthesia. Celon Lab ENT device was used for bipolar RFA set at 7 W with 3–5 punctures on the tonsil. An ovoid shaped model was used to calculate the tonsillar volume using measurement of three tonsillar dimensions with the help of ultrasound. Five patients underwent cold steel tonsillectomy 6–8 months after RFA. Average volume of tonsil before and after surgery was 4.4 ml and 2.6 ml with 38% volume reduction. Histopathology of the removed specimen showed normal architecture without any fibrosis or scarring. They have concluded that RF tonsillectomy is effective for submucosal volume reduction of tonsillar hypertrophy with less postoperative complications [14]. The study done by Chinmona et al. comparing radiofrequency tonsillectomy, thermal welding and cold knife tonsillectomy in children showed that radiofrequency excision is associated with less bleeding and intraoperative duration. Postoperative pain was however found to be less with patients who underwent cold knife tonsillectomy [15].

Blumen et al. has used transcervical approach for radiofrequency ablation of lingual tonsils. Here patient is placed in supine position and electrodes are introduced transcervically after localisation of lingual artery and hypoglossal nerve using USG doppler. Fluoroscopy is used to localise the stylet and radiofrequency is applied at various heights to the lingual tonsil and base of tongue. This approach reduces the risk of infection and chances of difficult intubation with disadvantage of retaining persistent tonsillar tissue [16].

Studies Against Radiofrequency Ablation

In the study conducted by Aksoy et al. RF and monopolar electrocautery tonsillectomy were compared in terms of intraoperative duration, postoperative pain, wound healing and intraoperative and postoperative haemorrhage. A prospective, randomized double blind study was conducted on 50 patients above the age of 10 years. Preoperatively, all patients were given routine antibiotic, analgesic and dexamethasone. One tonsil was removed using RF set at 6 W with cutting and coagulation mode. The other tonsil was removed using monopolar electrocautery set at 20–35 W with cutting mode. Postoperatively, oral antibiotics and analgesics were given for 10 days. The intraoperative duration was found to be longer with RF although the p value was not significant (0.034). Postoperative pain was assessed using VAS and no significant difference was noticed between the two methods with regards to intraoperative and postoperative haemorrhage and pain. Wound healing was assessed on the basis of oedema, erythema and fossa whitening on postoperative day 1, 5, 10 and 14. Wound healing was found to be better with monopolar electrocautery with p value < 0.001. Hence the study concluded that monopolar electrocautery tonsillectomy appeared to be superior to RF in relation to surgical duration and postoperative healing with no significant difference in postoperative pain [17].

Numerous studies have been described in literature explaining the postoperative risk of Horner’s syndrome following tonsillectomy which is often temporary. The pathology attributed to this is due to the direct penetration of local anaesthesia into the sympathetics [18]. But Kucur et al. has reported a case of Horner’s syndrome post tonsillectomy done with Monopolar probe at 15 J. The proposed mechanism of action is due to deeper penetration of probe causing direct thermal damage to the sympathetic plexus or due to postoperative inflammation and edema causing pressure damage on sympathetic plexus. The symptoms were however temporary and resolved with usage of steroids [19].

Conclusion

Radiofrequency ablation works by causing local tissue damage and thermonecrosis within a short duration. Due to vascular contraction and thrombosis, it causes less bleeding and postoperative pain. Thus, radiofrequency tonsillectomy is associated with less morbidity and mortality. Monopolar radiofrequency may also be equally beneficial to bipolar in terms of postoperative bleeding, pain and is more cost effective. But due to its deep local tissue penetration, there is a risk for postoperative complication like Horner’s syndrome. This necessitates the need for reconsideration of Monopolar radiofrequency tonsillectomy. Hence further experimental studies should be conducted in animal models to evaluate its local complications. However, bipolar radiofrequency tonsillectomy can be considered as a cost effective alternate with less complications when compared to other techniques.