Laser Excision of Glomus Tympanicum (Transcanal Approach)

Case Overview

Tympanomastoid paragangliomas (TMPs), or “glomus tympanicum” as they are more commonly known, are tumors that arise from paraganglia that lie along Arnold’s nerve (auricular branch of X) and the Jacobson’s nerve (tympanic branch of the IX) and often are associated with a dense vascular network.¹² Typically, these tumors are benign and slowly growing over the years.³ The annual incidence of glomus tympanicum is estimated to be around 1 in 1.3 million people annually.⁴ Pulsatile tinnitus and conductive hearing loss are frequently observed as presenting symptoms of this tumor. Complete surgical resection is a frequently employed therapeutic approach in such instances. The approach is determined by the tumor’s location, size, and existence of vascular encasement. 

Table 1. Modified Fisch and Mattox classification

Multiple approaches and strategies exist for the resection of glomus tumors including the transcanal approach, postauricular approach, canal wall-up mastoidectomy with posterior tympanotomy, and facial recess tympanotomy, and subtotal petrosectomy with middle ear obliteration. These surgeries have been commonly performed using either microscopic or endoscopic visualization.⁴

Because of the rich network of vascular spaces within the fibrous septa, biopsy and surgery of these lesions are associated with profuse hemorrhage with little tendency for spontaneous arrest of the bleeding as the vascular spaces lack contractile elements. A Potassium Titanyl Phosphate (KTP) laser was decided to be utilized to target the tumor's blood supply, as it showed to be successful for glomus tympanicum tumors with no complications and good long-term results.⁵ The KTP laser produces light at a wavelength of 532 nm,⁶ which corresponds to one of the absorption peaks of hemoglobin and can, therefore, provide excellent coagulation of vascular structures and has been successfully used in excision of glomus tympanicum tumors.⁵

The microscopic transcanal surgical approach, introduced in the 1960s, offers a minimally-invasive way to access the middle ear. This technique provides two-handed manipulation, binocular vision, and excellent stereoscopic views without the need for postauricular or endaural skin incision, therefore shortening surgery duration and minimizing postoperative pain, bleeding, and tissue scarring.^7,8 With its superior 3D visualization, it's well-suited for various otologic surgeries, including tympanoplasty,⁹ ossiculoplasty,¹⁰ glomus tympanicum treatment,¹¹ labyrinthectomy,¹² neurectomy,¹³ and cochlear implantation.¹⁴ If an endoscope is unavailable, the microscope remains the preferred tool for these procedures due to its versatility and effectiveness.

The provided video offers a detailed and systematic representation of the laser excision of the glomus tympanicum using a transcanal approach. The patient, a 61-year-old female, presented with pulsatile tinnitus involving her right ear, without any prior history of ear issues. Upon examination, a vascular-appearing mass behind the eardrum was discovered. This finding was consistent with a small glomus tympanicum. The patient elected to undergo surgical removal of the tumor. The procedure was performed with the patient awake but sedated. Initially, the ear was adequately irrigated, and a Povidone-iodine solution was applied to the ear canal. Debris, wax, and irrigation were removed from the external canal. Subsequently, the procedure transitioned to the microscope. During the procedure, the patient exhibited slight movement, prompting consideration of alternative measures such as taping her head. A solution of 1% lidocaine with 1:40,000 epinephrine was prepared and administered around the meatal skin to ensure thorough coverage. The ear canal was dilated then with a speculum. The process of dilation additionally facilitated the medial movement of the anesthetic into the subcutaneous canal. The loose epithelium was cleaned, and the area was wiped for better visibility.

Upon closer examination, a small glomus tympanicum was observed on the promontory, located just behind the eardrum. A subsequent administration of injection at the level of the bony cartilaginous junction was performed, specifically targeting the vascular strip. As the injection progressed, blanching of the vessels onto the short process of the malleus was observed. Following that, a tympanomeatal flap incision was made. The annulus, identifiable as a white band at the 6-o’clock position of the eardrum, served as the reference point for the incision. The incision began just lateral to the annulus and extended into the canal, resulting in the formation of a tympanomeatal flap approximately 8 mm in length.

Following the incision, the flap was carefully elevated using the round knife, ensuring it was positioned directly on the bone to prevent any potential damage. The procedure was meticulously performed under continuous suction and with precise instrument control. While the flap was still being elevated, focus was being placed on getting beneath the annulus. It was possible to see the annular ligament, which was visible as a distinct white band, especially medially. The next step involved incising the mucosal layer beneath the annulus to further elevate the flap. With the assistance of a large round knife, the flap was elevated out of the annular groove, revealing structures such as air cells, the promontory, and the round window. A cotton ball soaked in epinephrine solution helped with hemostasis and kept the flap's corner anterior. The tumor was exposed through an elevated tympanomeatal flap.

The laser equipment was being set up for use, with changes made to the power and pulse duration settings. The KTP laser was used on the ultrapulse setting at 2000 Hz to treat the lesion's base, which showed vascular supply. Once the vessels had been adequately addressed, the lesion was grasped with cupped forceps and gently avulsed from the promontory. Following tumor removal, the laser was used to eliminate any remaining cells at the tumor's base. A request for a small piece of hydrogel wound dressing was made, and once obtained, it was carefully placed over the treated area. Additional pieces of injectable bioresorbable packing were requested to ensure complete coverage. The tympanomeatal flap was unrolled from the anterior canal and returned to its preoperative position. Care was taken to ensure no skin edges were rolled under, particularly at the incision site. Next, Bacitracin ointment was applied to the ear canal and over the surface of the eardrum. This ointment helps to hold the flap in place and promotes healing. To provide additional protection, a cotton ball and adhesive bandage were requested. The flap is expected to heal in about a week or two. The procedure concludes once the ointment has been applied.

Discussion

The algorithm for the surgical approach to glomus tympanicum is determined by the tumor’s location, size, and the presence of vascular encasement. Sanna M et al. suggest formulating the surgical strategy using the Fisch and Mattox classification.

Class A1 tumors can be safely removed via a stapedectomy-type transcanal approach. For Class A2 tumors, the retroauricular-transcanal approach and its modified procedure (glove finger flap technique), which allows for wider exposure through the ear canal, is considered the best. To obtain adequate access for Class B1 tumors, the optimal method is CWUM with posterior tympanotomy. In Class B2 tumors, posterior tympanotomy is extended inferiorly toward the hypotympanum, and a retrofacial tympanotomy is added. For Class B3 tumors, a subtotal petrosectomy with middle ear obliteration should be considered. If the tumor is found intraoperatively to involve the jugular bulb, the surgeon can attempt to dissect the tumor. If a dissection plane cannot be identified, the surgery should be stopped. An infratemporal approach should then be considered, following patient consent and necessary preoperative evaluations such as angiography and embolization. Literature reviews indicate that complete removal of glomus tympanicum tumors is achievable in 94—100% of Class A and B cases, with recurrence rates reported between 0% and 5%.^6,15

Laser allows for a minimally-invasive approach performed through the ear canal, reducing the need for larger approaches. It provides minimal bleeding during surgery, which ensures good visualization. Additionally, the laser provides precise control, allowing for the targeted removal of the tumor while preserving surrounding structures. Many studies and case reports show a very low rate of recurrence after laser surgery. Endoscopic techniques combined with KTP laser offer enhanced visualization of the surgical field.^1,5,6,15

The KTP laser is suitable for tumors confined to the middle ear that do not involve extensive bony structures. Tumors that fill the mesotympanum and hypotympanum but do not extend beyond the jugular bony plate are ideal candidates.⁶ It is also very important for the surgeon to be trained in laser use to avoid complications. The possible transmission of energy through the round window into the cochlea can lead to hair cell damage and consequently to SNHL. Moreover, imprecise work may lead to thermal injury of middle ear structures.^1,5,6,15

A comprehensive understanding of the anatomy and competence in laser manipulation is imperative in the context of this surgical procedure. Complete excision of the lesion was achieved without the need for bony removal and with minimal blood loss. The application of minimally-invasive approaches in otologic surgery, including the management of middle ear tumors like glomus tympanicum tumors, represents a promising advancement in the field, potentially improving surgical outcomes and patient recovery. Despite its numerous advantages, this method is still not routinely performed by otologic surgeons. Since this minimally-invasive technique is more challenging, there is a need for educational materials and extensive training for it to be widely adopted by otologic surgeons.⁸

Statement of Consent

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.