Transcanal Endoscopic Excision of Glomus Tympanicum in can tho Ent Hospital: Three Cases Report

Glomus tympanicum (GT) is a highly vascular, benign, and slow-growing tumor of the middle ear. It can be confused with other common ear diseases such as acute middle ear infection, otitis media with eﬀ usion, ear trauma… It is accurately diagnosed by history and endoscopy. CT scan showing: the presence of eroding jugular bulb is the most important thing to distinguish glomus tympanicum and glomus jugulare and assess the extension of the tumor to make good surgical planning. We present here the three cases in Can Tho ENT hospital: where total excisions were achieved trans-canal endoscopically without embolization. These procedures were safe, quick, and eﬀ ective due to the better visualization of the surgical ﬁ eld with the endoscope.


Introduction
Glomus tumors, also known as non-chromaf in cell paraganglioma, arise from the neural crest cells [1].They are rare tumors, representing less than 0.5% of all head and neck tumors [2].Glomus tumors are classi ied into types depending on where they begin to grow: tympanicum, jugulare, glomus vagale, or carotid body.In this article, we just discuss glomus tympanicum [2][3][4].It is a highly vascular, benign, and locally invasive tumor of the middle ear usually originating along the tympanic (Jacobson's) or auricular (Arnold's) nerve.It is the most common primary neoplasm of the middle ear and the second most common tumor of the temporal bone [1,5,6].

Methods
From 2021 to 2022, there were three cases of glomus tympanicum tumors operated by trans-canal endoscopic excision in Can Tho ENT hospital.All of the cases are female and aged from 44 to 60 years old.
-Hearing test: showed moderate mixed hearing loss.
-Grade De inition (Glasscock-Jackson Classi ication) [1,2]: 1. Tumor margins are completely visible on otoscopy 2. Tumor ills the middle ear 3. Tumor ills the middle ear and the mastoid 4. The tumor extends through the tympanic membrane and into the external ear canal.
Classi ication of the tumor helps make a good plan and choose the proper surgical approach by trans-canal endoscopy or microscopy.

Case 1
A 44-year-old female patient presented to us with a history of pulsatile tinnitus, aural fullness, and progressive rightsided hearing loss over 7 months.She was treated in some clinics but no relief.There was no history of ear discharge, ear pain, or any other symptoms Figures 1-3 -Procedure: we started with a trans-canal endoscopic approach with a 0 0 scope.After adrenaline was injected and the tympanomeatal lap was elevated using a round knife, the pulsatile mass immediately came into view.The tumor illed the mesotympanum and hypotympanum with its base originating from a vessel at the promontory.It was completely removed with forceps which led to bleeding, and controlled by compressing with an adrenaline cotton ball.The tumor was successfully removed completely in two hours.After surgery, the patients have no more pulsatile tinnitus and their hearing level were improved Figure 4.

Case 2
A 59-year-old female patient presented to us with a history of pulsatile tinnitus and progressive left-sided hearing loss for nearly 2 years Figures 5,6.
-Hearing test: audiogram showed mild conductive hearing loss of 37dB and tympanometry had a sine graph shape.
-Procedure: similar to case 1 but we were more careful when assessing the tumor in the hypotympanum to prevent bleeding.A 46-year-old female patient presented to us with a history of pulsatile tinnitus, ear pain, progressive right-sided hearing loss, headache, and runny nose over 4 months.The patient was diagnosed with acute otitis media rhinosinusitis.After taking some assessments, she was diagnosed with glomus tympanicum Figures 7,8.
-Hearing test: audiogram showed average conductive hearing loss of 50dB and tympanometry had a sine graph shape.
-Procedure: The endoscopic trans-canal modi ied canalwall-down mastoidectomy.We opened the attic by curetting the scutum and open the antrum by drilling the superior bony canal wall.After that drilled the canal wall down partially to exposure of the tumor clearly.
The tumor illed the epitympanum, mesotympanum, and hypotympanum and surrounded the ossicular chain.We had to remove the incus to excise the whole tumor.After surgery, the hearing level decrease, and need to perform ossiculoplasty Figure 9.

Discussion
The principle of operating on the glomus tympanum by trans-canal endoscopic excision is preventing from rupturing the tumor.We slowly exposed the entire margin of the tumor from the surrounding structure with an adrenaline cotton pad and try to protect the facial nerve and ossicular chain [7].Then we removed the whole tumor from its origin over promontory.The cons of the endoscopic is dif icult to observe the structures in the surgery site when excessive bleeding [7,[12][13][14][15].

Conclusion
The surgical approach should be chosen according to the extension and the size of the glomus.We found that a total endoscopic excision can apply for Glasscock-Jackson type I, II, and type III with diploic or sclerotic mastoid.The development of this surgical technique provides better exposure and access, therefore leading to safe, quick, and effective tumor removal without sutures or canaloplasty.

Figure 1 :
Figure 1: A red pulsatile mass was observed under the entire of the tympanic membrane.

Figure 2 :
Figure 2: Audiogram with moderate mixed hearing loss 45dB and tympanometry had a sine graph shape.

Figure 3 :
Figure 3: A tumor in the tympanic cavity and hypotympanum, not spread to the mastoid and does not erode the jugular bulb.

Figure 4 :
Figure 4: Endoscopic view of tumor removal of case 1.

Figure 5 :
Figure 5: A red pulsatile mass was observed under the inferior half of the tympanic membrane.

Figure 6 :
Figure 6: Showing tumor in the tympanic cavity and spread to the hypotympanum close to the carotid artery but not eroding it.

Figure 8 :
Figure 8: A tumor in the tympanic cavity and hypotympanum, epitympanum, antrum and no eroded jugular bulb.

Figure 9 :
Figure 9: Endoscopic view of tumor removal of case 3.