Treatment of tympanic paraganglioma by otoendoscopic

Abstract

Purpose

This study aimed to introduce a novel surgical approach for treating glomus tympanicum and to summarize the associated clinical experience in diagnosis and management.

Methods

A retrospective review was conducted in 16 patients with pathologically confirmed tympanic paragangliomas who underwent radiofrequency coblation-assisted ear surgery via the otoendoscopic transcanal pathway in our hospital from January 2020 to January 2024. The indications and techniques for this surgical treatment were analyzed.

Results

Based on imaging and surgical findings, the 16 patients were classified according to the modified Fisch classification: 4 cases of Type A and 12 cases of Type B. All patients underwent complete tumor resection via the endoscopic transcanal pathway, with no need for preoperative angiography or embolization, and the tumors were completely resected by radiofrequency coblation in continuous irrigation mode during the operation. The tumor did not recur during 1–5 years of follow-up.

Conclusion

This surgical method shows clear efficacy in treating tympanic paragangliomas classified as type A, B1, or B2 by modified Fisch classification, without the need for ossicular chain dissection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00405-026-10143-w.

Introduction

Glomus tympanicum is the most common primary vascular-rich benign tumor of the middle ear, originating from neural crest cells on the promontory. It represents the second most frequent tumor of the temporal bone following vestibular schwannoma [1, 2]. The management of glomus tympanicum primarily involves three modalities: clinical observation, surgical resection, and radiotherapy [3]. The preferred option is complete tumor resection, which is generally performed via the ear canal or postauricular incision under a microscope or endoscope [4, 5]. Given the tumor’s high vascularity, preoperative embolization is often required to avoid intraoperative bleeding [6, 7]. Advances in endoscopic ear surgery have spurred exploration into endoscopic glomus tympanicum resection. The underwater endoscopic technique is mainly used for bone grinding operations to expand the bony external auditory canal¹. Based on this technique, we developed a “continuous irrigating mode (CIM)”. This mode changes the optical transmission medium of the traditional endoscope from air to continuously flowing electrolyte solution (normal saline), thus achieving the integration with radiofrequency ablation technology. It also has the advantages of continuously flushing the surgical field, maintaining a clear view, and reducing thermal damage at low temperature. Although radiofrequency ablation technology has been increasingly widely used in the treatment of various diseases in otolaryngology in recent years, including granuloma [8, 9], laryngeal carcinomas [10], and oropharyngeal tumors [11], there is no electrode specifically designed for ear canal surgery. Therefore, our team designed a special coblation electrode for the continuous perfusion platform. This integrated system, which combines the endoscope’s advantages of high-definition, wide-angle, and flexible operation with the ablative, volume-reducing, and cutting capabilities of low-temperature coblation radiofrequency technology, has been successfully applied in the treatment of vascular-rich tumors of the tympanic cavity. The operation process and treatment results are introduced as follows.

Methods

This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of our hospital (PermittedNO HZXJY-PJ-2024-19). Written informed consent was explicitly obtained from all participating subjects prior to their inclusion in this study. We conducted a retrospective review of 16 patients with pathologically confirmed tympanic paragangliomas who were treated in our hospital from January 2020 to January 2024, including 13 females and 3 males. There were 9 cases with left ear and 6 cases with right ear involvement. The age of the patients ranged from 37 to 59 years old, with a mean age of 45.92 ± 4.94 years; the disease course ranged from 2 months to 10 years, with a mean disease course of 4.94 ± 3.55 years. Inclusion criteria: (1) Pathologically confirmed tympanic paraganglioma; (2) Surgical treatment via otoendoscopy; (3) Tumor confined to the mastoid cavity of the middle ear. Modified Fisch classification: 4 cases of Type A and 12 cases of Types B1 and B2.

Figure 1 shows the preoperative data of a type B1 patient.

Fig. 1.

The clinical data of a patient with modified Fisch type B1. A red pulsatile mass was seen in the inner side of the tympanic membrane on otoendoscopic examination (a); Temporal bone CT in the horizontal plane showed that the mass protruded into the posterior tympanum (b); In the coronal plane, the tumor invaded the inferior tympanum (c); On enhanced MRI, obviously enhanced mass could be seen within the tympanum (d) ; Pure tone audiometry of the patient (e).

The radiofrequency generator used in this study is a mainstream model commonly applied in otolaryngology, sharing the same working principle as previously described [12–15]. It employs continuous saline perfusion to form a plasma layer between the electrodes, where radiofrequency energy excites charged particles to disrupt molecular bonds, which decomposes tissues into low-molecular-weight gases rather than relying on direct cauterization. Plasma energy denatures vascular wall proteins to create a sealed coagulum, while low temperatures prevent vascular rupture, making it particularly suitable for hemostasis of capillaries and small veins. We designed a custom coblation tip (Fig. 2) optimized for transcanal use, which in conjunction with tailored power settings enables precise ablation and hemostasis within the ear canal.

Fig. 2.

Radiofrequency coblation devices for otological use. (a). Main unit panel (b). Otological coblation probe (connected to the main unit) (c). Close-up of b (d). Close-up of the four tip types in c (e). Close-up of the tip in d

Under continuous saline irrigation, the otoendoscope facilitates low-temperature coblation. This process devascularizes the tumor surface and leads to tumor shrinkage. Minor bleeding is washed away by the flowing saline, maintaining a clear operative field for subsequent hemostasis and ensuring surgical fluency. The device shares the same principle as other coblation systems [12–15]but features downsized instruments optimized for otological applications.

Continuous saline irrigation during endoscopic ear surgery enables low-temperature plasma coblation, which acts on the tumor surface to induce devascularization and tumor shrinkage. Minor hemorrhages are washed away by the continuous saline flow, maintaining a clear surgical field for subsequent hemostasis and ensuring smooth surgical procedures. The device shares the same principle with other plasma coblation systems [12–15], but features smaller instruments that are better adapted for otological applications.

Operation metod

Surgery was performed under general anesthesia with the patient supine and the affected ear upward. After routine disinfection and draping, a waterproof film covered the operative field. An endoscopic transcanal approach was used with continuous saline perfusion. A portal incision was made 6 mm from the tympanic ring at the 1-o’clock position, extending to 6-o’clock. The external auditory canal skin flap was carefully incised and elevated toward the tympanic membrane, with the flap lifted below the fibrous tympanic ring and above the chorda tympani nerve. The tympanic membrane flap was separated from the malleus handle, placed anteriorly in the canal, and fixed to maximize tumor exposure.

A self-designed disposable bipolar radiofrequency coblation electrode was used at power level 2 in coag mode on the tumor surface to induce devascularization, causing the bright red mass to blanch, shrink, darken, and carbonize. Following surface debulking, the tumor was systematically resected in an anterior-inferior-posterior-superior sequence. The vascular pedicle on the promontory-facing tumor surface was identified and occluded, halting blood supply and reducing subsequent bleeding. By leveraging​ the endoscope’s wide-angle view, the refractive properties of water, and the tumor retraction after radiofrequency application, the surgeon could resect​ tumor extensions into the Eustachian tube and the inferior, posterior, and superior tympanum without extensive bone removal or ossicular chain sacrifice.

The following screenshots (Fig. 3) and the video show the surgical procedure.

Fig. 3.

Surgical procedure. a-b. Following tumor exposure, the external auditory canal tympanic membrane flap was fully mobilized, and the tympanic membrane was completely separated from the handle of the malleus. c-d. An insulating membrane was used to protect the external auditory canal tympanic membrane flap. Using the coagulation mode of coblation electrode, the tumor surface was cauterized, leading to tumor shrinkage and devascularization. e-f. After tumor volume reduction, a space between the tumor and the ossicular chain, posterior tympanum, and inferior tympanum was obtained. The tumor outside the visual field was retracted into the tympanum to achieve direct visualization under otoendoscopy. g-h. Since the tumor did not extend medially to the ossicular chain or into the superior tympanum, removal of the incus was unnecessary. After contraction along the periphery of the tumor, coagulation and cauterization of the medial surface of the tumor was continued (devascularization). i-j. The blood supply near the Jacobson's nerve on the promontory surface was interrupted by cauterization, and the potential blood supply near the inferior tympanum and Eustachian tube was addressed. k-l. The tumor tissue that extended into the Eustachian tube was debulked, pulled back to the tympanic cavity, and the vascular pedicle on the medial side of the tumor was finally cut off. m-n. With the tumor entirely removed, the anatomy of the tympanic cavity was exposed. o. The external auditory canal tympanic membrane flap was restored to its original position. Note: For large tumors that are tightly adherent to the tympanic membrane, the coblation surgical electrode can be utilized after tumor exposure by lifting the tympanic ring to reduce the tumor volume, inducing retraction. Moreover, under continuous irrigation, the space between the tumor and the tympanic membrane becomes more clearly visible, thereby aiding in the preservation of the integrity of the tympanic membrane. To prevent accidental injury of the tympanic membrane flap caused by the electrode, a silicone insulating membrane can be used as a protective barrier when the flap is reflected anteroinferiorly . When treating hypervascular tumors, slight bleeding may occur even with the use of radiofrequency coblation. In such cases, it is advisable to increase the irrigation flow to maintain a clear surgical field

Results

Based on imaging and surgical findings, the 16 patients were classified according to the modified Fisch classification: 4 cases of type A, 10 of type B1, and 2 of type B2. All patients underwent complete tumor resection via the endoscopic transcanal pathway, with no need for preoperative angiography or embolization. The tumors were completely resected by radiofrequency coblation under continuous irrigation during the operation. Postoperatively, tympanic membrane perforation occurred in three patients, all of whom underwent successful repair using conchal cartilage grafts. The remaining patients maintained intact tympanic membranes. None of the patients required ossicular chain removal. Tinnitus resolved in all patients after surgery. Three patients with normal preoperative hearing had no change in hearing after surgery, and the 6 patients with conductive hearing loss​ showed an average improvement of​ of 17 dB HL in air-conduction hearing threshold after surgery. In 7 patients with mixed hearing loss, air-conduction hearing thresholds improved by about 15 dB HL after surgery, and bone-conduction hearing thresholds remained unchanged. The patients were followed up for 1 to 4 years, during which no recurrence was observed on clinical and imaging examinations.

The tympanic membrane image, temporal bone HRCT, and audiologic examination results of the patient 1 year after surgery in Fig. 1.

Figure 4 shows the tympanic membrane image, temporal bone HRCT, and audiologic examination results of the patient 1 year after surgery in Fig. 1.

Fig. 4.

Result

The clinical results are in Table 1.

Table 1.

Clinical results

Discussions

Surgical resection remains the primary treatment for tympanic paraganglioma. However, the procedure can be challenging due to the tumor’s high vascularity and proximity to vital anatomical structures. The surgical route should be selected based on the location and extent of the tumor, and bleeding should be effectively controlled during the operation, so that the tumor can be completely resected while protecting the facial nerve, stapes, and other vital structures. According to current mainstream practices, Fisch type A tumors can be excised via the ear canal, while Fisch type B tumors typically require an open or intact-wall mastoidectomy to ensure complete resection. When the tumor extends medially to the ossicles, meticulous dissection is necessary, and removal of the incus or even the malleus may be required to achieve complete resection. Tympanic paragangliomas are highly vascularized tumors, which makes intraoperative bleeding a common issue that can compromise visualization of the surgical field and increase the risk of serious complications. Therefore, controlling bleeding is essential. Effective control of bleeding hinges on addressing the tumor base as a priority. The base’s precise location can be determined by evaluating the tumor’s mobility. Employing strategies like intermittent bipolar coagulation, gelatin sponge application, and adrenaline-soaked saline gauze can substantially mitigate bleeding. Furthermore, optimizing surgical efficiency to reduce both the duration of the procedure and the time of continuous bleeding is important during tumor removal. In their study, Salem et al. [16, 17] demonstrated that the use of a Coblation probe (Procise™ MLW Wand) facilitated complete tumor excision with bony canal (BC) preservation, auditory capacity (AC) enhancement, and effective hemostasis. Nevertheless, their approach highlighted a technical constraint: the limited flexibility of the 4-mm rigid endoscope and the 3.5–4.5 mm probe within the external auditory canal. This inherent limitation raises concerns regarding the efficacy and safety of instrument manipulation in anatomically challenging regions, including the posterior tympanic cavity and areas medial to the ossicular chain, where precise dissection is paramount to avoid iatrogenic injury to vital structures.

In recent years, otoendoscopic surgery has developed rapidly and its scope of application has been gradually expanded. Since Marchioni [18] first used otoendoscopy to remove tympanic tumors, an increasing number of studies have reported the endoscopic removal of A1-B1 tympanic paragangliomas [4, 19–21]. However, during the one-handed endoscopic operation, the control of bleeding is a major challenge in its application for paraganglioma resection. Killee et al.²⁰ reported that 21% of endoscopic tympanic paraganglioma resections were converted to microscopic tumor resection due to difficulty in controlling bleeding. Fermi et al.¹⁹ introduced the “two-person three-hand” technique to address intraoperative bleeding. Nonetheless, the confined space of the ear canal requires the concurrent use of multiple instruments, and the technique relies heavily on precise collaboration between the surgeon and assistant. These inherent difficulties significantly heighten the technical demands of endoscopic resection for tympanic paragangliomas. In this study, the operations were performed with a continuous irrigation platform integrated with ear otoendoscopy, using saline as the medium alongside a self-designed radiofrequency coblation surgical electrode dedicated for endoscopic use. This innovative approach allowed for meticulous low-temperature plasma operations under endoscopic control, effectively tackling the issue of tumor devascularization. The radiofrequency application to the tumor surface resulted in a significant reduction in tumor volume. As the tumor’s growth center in tympanic paragangliomas is located on the promontory surface, the tumor extensions into the surrounding tympanic cavity could be retracted into the endoscopic field of view following volume reduction. Moreover, the wide-angle visualization provided by the endoscope, combined with the refractive effects of water, further expanded the observable range, making it feasible to achieve precise and complete resection of type B2 tympanic paragangliomas via the transcanal pathway under endoscopic guidance. In this study, all 16 patients achieved complete tumor resection using the endoscopic technique, without extensive removal of the bony ear canal or ossicular chain even in the cases with modified Fisch type B tumors.

For B2 tumors that do not extend beyond the posterior aspect of the facial nerve, bony removal is unnecessary (although bone drilling is feasible in this mode). Radiofrequency-induced devascularization shrinks the tumor, and combined with the wide-angle view of the otoendoscope and refractive properties of water, B2 tumors with mastoid infiltration can be resected through a sequence of debulking, retraction, and further debulking.

Effective hemostasis is a cornerstone of successful endoscopic ear surgery (EES) for paraganglioma. Due to the highly vascular nature of glomus tympanicum tumors, especially when the tumor is close to or attached to the internal carotid artery (ICA), how to effectively control bleeding during endoscopic glomus tympanicum resection is particularly important¹. Consequently, significant research efforts have been devoted to developing improved hemostatic techniques. For instance, Takata [22], Surmelioglu [23], Fermi [20] etc., used endoscopic bipolar electrocoagulation for hemostasis. Takata²¹ proposed that severe bleeding should be switched to microscopic two-handed electrocoagulation hemostasis. Julia E [24] used KTP laser, and Quer-Castells [16] used blue laser. These methods can both shrink the tumor and stop bleeding. However, there are the following shortcomings: (1) Poor effect on massive bleeding; (2) Both will generate heat, and surrounding important tissues (inner ear, facial nerve, etc.) will be damaged by high temperature; (3) Inconvenient to use under otoendoscopy, especially for bleeding from tumor tissues in peripheral corners, making effective hemostasis challenging in these areas; (4) The laser hemostasis effect is not ideal. The technique described in this study addresses these limitations effectively. The coblation probe itself has a low temperature, and continuous perfusion will not increase the tissue temperature; excellent hemostasis is achieved, often resulting in a nearly bloodless surgical field. The coblation technique is relatively straightforward to perform providing bloodless field and minimal tissue damage. The intraoperative blood loss was significantly less in the coblation method than the dissection and snare method [14, 15]; the probe tip has a certain angle, which can facilitate the resection of marginal lesion tissues and control a larger range of bleeding.

In terms of ease of use, the thin rod and angled coblation probe are more convenient to use. Lasers are more easily interfered by endoscopes and other instruments in the narrow ear canal. The tip of the bipolar electrocoagulation does not have an angle and is wider, affecting the use. Relatively speaking, the coblation probe is more convenient, the surgery is smoother, and the resection is more effective.

The “continuous irrigating mode (CIM)“ [25] changes the optical transmission medium of the traditional endoscope from air to continuously flowing electrolyte solution (normal saline), thus achieving the integration with radiofrequency ablation technology. It also has the advantages of continuously flushing the surgical field, maintaining a clear view, and reducing thermal damage at low temperature.

This method still cannot effectively control a large amount of acute bleeding. If a similar situation occurs during the operation, the surgical method should be changed; this method requires multiple sets of hardware systems, including an endoscopic system, a continuous perfusion system, and a coblation system. If a medical institution does not have these equipment adjustments, this operation cannot be carried out. Future research will focus on the integration of the device to enhance its user-friendliness, while also exploring its potential application for the treatment of larger tympanic body tumors.

Conclusions

The integration of continuous irrigating mode and radiofrequency coblation technology under otoendoscopy allowed for effective devascularization of the highly vascular tumors in the middle ear. CIM quickly cleared any minor bleeding, maintaining a clear surgical field, which greatly improved the visibility and efficiency of the otoendoscopic procedure. The low-temperature environment provided by the water shielded critical structures such as the cochlea and facial nerve from thermal damage caused by the radiofrequency, increasing the safety of the surgery. The excellent tumor volume reduction effect of the radiofrequency, along with wide- and multi-angle endoscopic visualization, minimized the need for extensive bone drilling and ossicular chain removal, ensuring precise and minimally invasive treatment. Otoendoscopic transcanal coblation-assisted surgery for glomus tympanicum is safe, effective, minimally invasive. With its broad application potential, this technique is worthy of widespread adoption and promotion.

Supplementary Information

Below is the link to the electronic supplementary material.

Funding

The authors have no funding, financial relationships, or conflicts of interest to disclose.

Declarations

Competing Interests

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.