Clinical effect of CO₂ laser resection of the epiglottic cyst under micro-laryngoscope suspension

Abstract

Background

Epiglottic cysts are common diseases and have multiple morbidity, and traditional surgery causes intraoperative bleeding and postoperative recurrence.

Objective

To investigate the therapeutic effect of CO₂ laser resection on epiglottic cyst when compared with traditional surgery.

Method

Eighty patients with epiglottic cysts were randomly enrolled into the CO₂ laser group (44 patients) and the high-frequency electrocautery group (36 patients).

Results

The CO₂ laser group had a shorter operation time, less blood loss and fewer intraoperative ruptured cysts (p < .05). The duration of sore throat and the time before wound redness and swelling subsidence in the CO₂ laser group were significantly shorter than those in the high-frequency electrocautery group (p < .05). Within one year after the operation, the incidence of epiglottic scar contracture in the CO₂ laser group was significantly lower than that in the high-frequency electrocautery group (p < .05).

Conclusion

The CO₂ laser group has the advantages of minimally invasive, less bleeding, short operation time and less postoperative complications, and it is worthy of applying as clinical routine to treat epiglottic cysts.

Chinese Abstract

背景：会厌囊肿是常见病, 发病率高, 传统手术导致术中出血和术后复发。

目的：比较CO2激光切除会厌囊肿与传统手术的治疗效果。

方法：80 例会厌囊肿患者随机纳入 CO2 激光组（44位患者）和高频电灼组（36 位患者）。

结果：CO2激光组手术时间更短、失血量更少、术中更少发生囊肿破裂(p < .05)。CO2 激光组的喉咙痛持续时间和伤口红肿消减前的时间明显短于高频电灼组（p < .05）。术后1年内, CO2激光组会厌瘢痕挛缩发生率明显低于高频电灼组 (p < .05)。

结论：CO2激光组具有微创、出血少、手术时间短、术后并发症少等优点, 值得临床推广应用来治疗会厌囊肿。

Keywords:

• CO₂ laser
• suspension micro-laryngoscope
• epiglottic cyst
• high-frequency electrotome

Introduction

Epiglottisa leaf-like structure in the upper and anterior part of the larynx is composed of epiglottic cartilage and mucous membrane. It is behind the hyoid bone and the root of the tongue, above the front of the laryngeal entrance. Due to the unique structure of epiglottis, especially abundant peripheral blood vessels and nerves, its physiological conditions will affect the function of respiration and swallow. Epiglottic cyst, a special type of laryngeal cyst, is a kind of cyst under epiglottic mucosa, which is a common disease in the Department of Laryngology. It is caused by inflammation, mechanical stimulation or trauma that causes blockage of the mucous ducts of the epiglottis mucosa and the inability of the glands to expel retention. In benign laryngeal masses, the disease’s incidence is 4.3%–6.1% [1]. Cysts usually occur on the lingual surface, vallecula and edge of the epiglottis. There is not any noticeable symptom when cysts are small. Nevertheless, a feeling of foreign body sensation and obstruction sensation in the pharynx may appear when they become large. Complicated with infection, local pain and discomfort are inevitable, and even dyspnea will be caused when it is serious [2–4]. The primary treatment is surgical resection, and the operation requires complete removal of the cysts, good hemostasis, meanwhile minimum damage to the surrounding tissue and most negligible adverse effects on patients after procedure. Traditional surgical treatment is mainly forceps incision prone to intraoperative bleeding and postoperative recurrence. Added to the particular structure of epiglottis, the throat of the patient suffers an extensive injury, which is difficult to recover. Thus, forceps incision is not often used clinically now. With the continuous development of medical technology in China, the treatment of epiglottic cyst has become diversified, including high-frequency electrotome resection, microwave treatment, radiofrequency, uncovering method, and low-temperature plasma and CO₂ laser resection. Among them, CO₂ laser resection is an essential means of treatment, which has been gradually used in the treatment of benign and malignant laryngeal diseases since the 1990s in China. Due to the rapid development of microtechnology, CO₂ laser resection of cyst under suspension laryngoscope has been more and more widely used in the surgical treatment of laryngeal lesions in recent years. It has advantages over clearer vision, more accurate laser resection, better hemostasis, which is beneficial to remove the cyst wall thoroughly, minimize damage to normal tissue, and recovery rapidly after operation, which results in an excellent therapeutic effect [5,6]. This study applies two technique of microlaryngo-surgery under suspension laryngoscopy and CO₂ laser resection involved in the treatment of patients with epiglottic cysts, and figures out which one can lead a better efficacy.

Material and method

General data collection

A total of 80 patients with epiglottic cysts treated at Department of Otolaryngology were admitted, from January 2018 to December 2020. The average age of the patients was 46.1 ± 13.1 years old, the mean course of the disease was 2.48 ± 1.42 years and the size of the cysts ranged from 0.3 cm × 0.5 cm × 0.5 cm to 1.4 cm × 1.5 cm × 2.0 cm. Clinical data are listed in detail in Table 1.

Table 1. Comparison of general data.

Item	CO2 laser (n = 44)	High-frequency electrotome (n = 36)	χ^2	p
Gender
Male	15	12	0.6712	0.4126
female	29	24
Age
<46 years old	22	14	0.1506	0.6980
≥46 years old	22	22
Course of disease
<2.5 years	36	28	0.2020	0.6531
≥2.5 years	8	8
Onset condition
Initial	39	27	2.550	0.1103
Recurrent	5	9
Cyst location
Epiglottic vallecula	9	8	0.1652	0.9207
Epiglottis lingual surface	24	18
Epiglottis edge	11	10
Quantity
Single	35	26	0.5864	0.4438
Multiple	9	10

Inclusive criteria: (1) All patients with epiglottis mass were confirmed by laryngoscopy; (2) All patients were diagnosed with benign lesions by histopathological examination; and (3) All cases were voluntary, signed informed consent and had complete clinical data. Exclusion criteria: (1) patients with pacemakers; (2) pregnant and lactating women; (3) patients with a recent history of herpes virus infection; (4) patients with cardiopulmonary insufficiency.

Surgical equipment

Lumenis CO₂ Laser Surgery System (LUMENIS AcuPulse 40, USA), operating microscope (Moller, Germany), Dilatation laryngoscope, and laryngeal microinstrument (Tonglu, Zhejiang, China), high-frequency electrotome ((ValleylabTm ForceTm2-8PCH, USA).

Operation method

All the patients were performed under general anesthesia induced by intubation through the mouth. Two groups were divided via CO₂ laser group and high frequency electrotome group. The operation is conventional according to clinical operative routine.

Observation indices

(1) The results of preoperative and postoperative laryngoscopy and postoperative pathological examination were collected. (2) Intraoperative data were collected, such as operation time (from the insertion of the laryngoscope to the withdrawal of the laryngoscope), bleeding volume and the number of cysts ruptured. (3) Postoperative data were collected, such as visual analogue scale (VAS) score at one day, duration of sore throat, regression time of the red and swollen wound, and time of albuginea falling off. (4) One month after the operation, the mucosa of the epiglottis was observed by laryngoscope, and three months after the operation, the curative effect of all patients was evaluated, and the evaluation criteria were as follows: Cure: the symptoms disappeared completely, the cyst was completely removed, the wound healed well, and the surrounding tissue structure (epiglottic cartilage, epiglottic vallecula, root of the tongue) was normal; Effective: the symptoms were slightly relieved, the cyst was completely removed, the wound was healed, and the surrounding tissue structure was affected; Invalid: no remission of symptoms, or recurrence of cyst in situ. Total effective rate = (cure + effective)/number of people * 100%. (5) The incidence of complications and recurrence was recorded within one year after the operation.

Statistical analysis

SPSS 20.0 software was used for statistical analysis. The data of this study were in accordance with the normal distribution, so the measurement data were expressed by $\overline{\mathrm{X}}$± s’ and compared by t test. The counting data were expressed by ‘%’and compared by χ² test. The difference was statistically significant when p < .05.

Results

Results of laryngoscopy

Preoperative laryngoscopy showed chronic mucosal congestion, epiglottis congestion, huge spherical smooth protrusion on the lingual surface of the epiglottis, without any ulceration or bleeding. The day after the operation, the epiglottis was slightly swollen, but the cartilage was not exposed or injured (Figure 1). One month after the operation, the mucosa of the epiglottis was slightly uplifted with a smooth surface (Figure 2).

Figure 1. Results of laryngoscopy and intraoperative images.

Figure 2. One month after the operation, the mucosa of the epiglottis lingual surface returned to normal.

Postoperative pathological results

Pathological sections were performed for HE stains, and the pathological diagnosis result was epiglottic lymphoepithelial cyst (Figure 3).

Figure 3. Pathological results. On optical microscopy, the cyst wall is filled with inflammatory cells such as neutrophils.

Comparison of intraoperative conditions

There were statistically significant differences in operation duration, bleeding volume, and the number of intraoperative cyst ruptured between the two groups (p < .05) which showed a shorter time for operation, less blood loss and fewer raptured cysts in the CO₂ laser group (Table 2).

Table 2. Comparison of intraoperative conditions.

Group	Operative duration ($\overline{\mathrm{X}}$ ± s min)	Blood loss ($\overline{\mathrm{X}}$ ± s mL)	Number of ruptured cysts during operation (n)
			With rupture	Without rupture
CO2 laser group	15.37 ± 2.16	3.23 ± 0.43	3	41
High-frequency electrotome group	21.68 ± 4.33	8.21 ± 1.02	8	28
t/χ^2	8.416	29.24	3.926
p value	<0.0001	<0.0001	0.0465

Comparison of postoperative conditions

One day after the operation, there was no significant difference in VAS score between the two groups (p > 0.05). However, the duration of sore throat and the regression time of red and swollen wound in the CO₂ laser group were significantly shorter than those in the high-frequency electrotome group (p < .05) (Table 3).

Table 3. Comparison of postoperative conditions.

Group	VAS score	Duration of sore throat ($\overline{\mathrm{X}}$ ± s d)	Time of wound redness and swelling regression ($\overline{\mathrm{X}}$ ± s d)	Time of tunica albuginea falling off ($\overline{\mathrm{X}}$ ± s d)
CO2 laser group	3.15 ± 1.26	2.95 ± 0.33	2.56 ± 0.45	24.83 ± 3.57
High-frequency electrotome group	3.39 ± 1.12	4.07 ± 0.38	3.74 ± 0.41	27.01 ± 3.19
t/χ^2	0.4564	13.91	11.93	2.800
p value	0.6494	<0.0001	<0.0001	0.0065

Efficacy evaluation

Three months after the operation, the total effective rate of the CO₂ laser group was slightly higher than that of the high-frequency electrotome group, and the recurrence rate was slightly lower than that of high-frequency electrotome group. Still, the differences were not statistically significant (p > 0.05) (Table 4).

Table 4. Comparison of therapeutic effects.

Group	Markedly effective (n)	Effective (n)	Ineffective (n)	Number of recurrences (n)	Total effective rate (%)	Recurrence rate (%)
CO2 laser group	40	3	1	1	97.73	2.27
High-frequency electrotome group	28	3	3	2	91.18	8.82
χ^2					0.1490	0.6756
p value					0.6995	0.4111

Complications

Within one year after the operation, the contracture incidence of epiglottic scar in the CO₂ laser group was significantly lower than that in the high-frequency electrotome group (p < .05). There was no significant difference in the total incidence of complications between the two groups (p > 0.05) (Table 5).

Table 5. Incidence of complications.

Group	Cicatricial contracture of epiglottis (n (%))	Conglutination of vocal cords (n (%))	Active hemorrhage (n (%))	Deformation and defect of epiglottic cartilage (n (%))	Total incidence (n (%))
CO2 laser group	3 (6.82)	1 (2.27)	1 (2.27)	0 (0.00)	5 (11.36)
High- frequency electrotome group	8 (22.22)	0 (0.00)	1 (2.78)	0 (0.00)	9 (25.00)
χ^2	3.926	0.8285	0.0207	–	2.550
p value	0.0465	0.3627	0.8855	–	0.1103

Discussion

In this study, patients with epiglottic cysts were treated with CO₂ laser or high-frequency electrotome under the suspension laryngoscope microscope, and the curative effects of the two methods were compared. The results showing that the CO₂ laser group had a shorter operation duration, less intraoperative blood loss and fewer intraoperative ruptured cyst, indicated that that the CO₂ laser group performed better in the field of security. Moreover, the duration of sore throat and the regression time of red and swollen wound in the CO₂ laser group were significantly shorter than those in the high-frequency electrotome group (both p < .05). Three months after the operation, the total effective rate of the CO₂ laser group was slightly higher than that of the high-frequency electrotome group, and the recurrence rate was slightly lower than that of the high-frequency electrotome group. Although there was no significant difference between the two groups (both p < .05), the above results hinted the exact effect of CO₂ laser resection, and the postoperative recovery of patients was better to a certain extent. In addition, from the follow-up records within one year after the operation, we can know that there was no significant difference in the total incidence of complications between the two groups (p > 0.05), but the incidence of epiglottic scar contracture in the CO₂ laser group was significantly lower than that in the high-frequency electrotome group (p < .05), indicating that CO₂ laser resection technology has significant advantages in preventing postoperative epiglottic scar contracture.

Although epiglottic cysts are generally benign tumors, however, larger epiglottic cysts can stimulate the sensory nerves of the pharyngeal and laryngeal mucosa, causing persistent foreign body sensation and blockage sensation [7]. If the cyst is infected or suffers external force and enlarges suddenly, it can lead to unclear speech, pain, irritating cough, even poor swallowing and obstruction. In severe cases, it can lead to asphyxia or even sudden death. Therefore, for a sizeable epiglottic cyst or apparent symptoms of the cyst, surgery is recommended. For small cysts (such as mung bean size), conservative treatment and regular reexamination by laryngoscope should also be accepted to avoid the risk of cyst enlargement. Epiglottis is a unique structure and is peculiar in two ways. For one thing, the epiglottic blood supply comes from the superior laryngeal artery. Its branches form arterial loops near the vallecula epiglottica or aryepiglottic plica, and then send out two to five branches to walk in the vallecula epiglottica, the root of the epiglottis, the lateral edge of epiglottic cartilage and quadrilateral membrane, and distribute in the mucous membrane of the glossal and larynx surface of the cartilage. This particular blood supply is straightforward to cause epiglottis surgery bleeding; once the intraoperative bleeding is excessive, it will seriously endanger the life of patients [8–10]. Furthermore, epiglottis submucosal tissue is thin and loose, rich with nerves and sensitivity. Intense stimulation can easily lead to congestion, swelling, even laryngeal edema and spasm. In addition, epiglottic cysts grow in the deep and narrow laryngeal cavity. The above factors make the surgical treatment of epiglottic cysts more difficult, which is also a challenge for surgeons. Therefore, it is crucial to choose an appropriate treatment method that can shorten the operation duration, reduce blood loss, obliterate the cyst, reduce the injury to patients and accelerate the postoperative recovery.

At present, there are many options for the surgical treatment of epiglottic cysts, such as electrosurgical resection, microwave cauterization, radiofrequency ablation, low-temperature plasma ablation, and CO₂ laser resection [9,11–13]. The commonly used method is to clamp the cyst with laryngeal forceps under a suspension laryngoscope, and then use an electrotome to remove the cyst along the base of the cyst wall. Conventional electrosurgical resection works with high temperature, and sometimes the cyst wall will be burned or damaged, leading to cyst fluid flowing out cyst wall collapse, and cyst boundary uncleared. Moreover, the blade is easy to adhere to the surrounding tissue, causing bleeding when it is pulled out, and the tissue is carbonized seriously when it is clotted again, which not only makes it difficult to altogether remove the capsule wall but also burns the surrounding normal tissue. In addition, laryngeal forceps and electric knives are operated in a small space of laryngoscope. Due to the small room, the instruments often ‘fight’ with each other, which is easy to block the surgical field of vision. And it makes it difficult to achieve fine and accurate operation. As a result, the procedure is more traumatic, and bleeding is relatively more. Patients often complain of obvious pharyngeal pain after the operation, and some patients even have epiglottic cartilage damage [7,14]. The CO₂ laser is a kind of infrared mid-infrared emitted by the molecular gas laser, with a wavelength of 10.6 μm. It is an invisible light and has heat, pressure, and electromagnetic effects. Since the 1990s, the CO₂ laser has been widely used in minimally invasive surgery for benign and malignant diseases of the larynx and pharynx. Its working principle is CO₂ laser produces a beam with a diameter of 0.4–2.0 mm, which can gasify and cut on the lesion and certain pressure generated during the operation can gasify and cut on the lesion and condense the blood exposed at the incision. Even if the diameter of the bleeding point is less than 0.5 mm, using a microscope, a CO₂ laser can burn and stop bleeding in time. At the same time, the blood vessels around the wound can be closed by thermal coagulation to achieve simultaneous cutting and hemostasis, which can considerably significantly shorten the operation time. In addition, under the magnification of the microscope, the boundary and vascular stria of the diseased tissue can be displayed very clearly. By accurately selecting the laser power, spot diameter, action time, and other parameters, satisfactory delicate operation can be carried out. Large blood vessels can be sealed with a light spot in advance. The operation field is clear and clean, which avoids the risk of bleeding in the operation area, unclear vision, and easy residual cystic wall in traditional operation. Compared with the expected standard operation procedure, it is more thorough and less likely to recur and has achieved good results [15,16]. Moreover, the high-temperature laser cutting also reduces the incidence of wound infection in patients; patients do not need antibiotics after surgery, reducing the risk of antibiotic abuse. There are many advantages to CO₂ laser to remove epiglottic cysts under the suspension laryngoscope microscope, worthy of promotion and application. However, there is a lack of research reports in China.

In conclusion, CO₂ laser resection of the epiglottic cyst under suspension laryngoscope microscope has the advantages of minimally invasive, less bleeding, short operation duration, and less postoperative pain, and can be used as a better choice for the treatment of epiglottic cyst in hospitals with adequate conditions.

Disclosure statement

The authors have no conflicts of interests to disclose.