空鼻症候群

空鼻症候群，简称空鼻症，（Empty Nose Syndrome，缩写：ENS），在耳鼻喉科学中指的是通过过度切除（通常为下鼻甲）后所造成的鼻腔异常及一系列并发症。

患者的症状主要有：感受不到气流（鼻阻力过低及鼻粘膜受损）、鼻腔干燥、嗅觉下降、头疼、精神不济、身体易疲劳、注意力不集中等，时间长了易诱发哮喘和肺纤维化等。

有研究显示，在接受下鼻甲破坏性手术后，20%的患者会患上空鼻症。而中国工程院院士、北京同仁医院院长韩德民教授认为，这个数字有可能更高。

空鼻症候群是一种医源性疾病，完全是可以避免的。

## 主要症状

空鼻症的两大症状为：

- 慢性鼻腔干燥。这一般会导致慢性粘膜炎症及疼痛。慢性发炎可以引致部分粘膜萎缩，有些研究因此称其为“继发性萎缩性发鼻炎”。至少一项大型研究指出，萎缩性鼻炎的症状平均需要7.1年后才会出现。研究还建议医生注意早期症状，并对病患者处方每日自行冲洗和润湿鼻腔。
- 矛盾性鼻阻。患者会感到鼻塞，而由于失去鼻粘膜来回馈气流的感觉，这还会伴随持续且经常出现的窒息感。产生这一感觉的三叉神经的萎缩、粘膜的干涸和化生以及鼻甲切除术后的异常气流运动都可能导致这种症状。中枢神经系统接收不到持续的呼吸感觉，就会产生窒息、呼吸困难的感觉。

其他主要症状还包括睡眠困难和长期疲倦。因为这些慢性症状，所以患者的生活品质会大大降低，并会难以专注、产生焦虑及忧郁。另外可能出现的并发症还包括哮喘和慢性阻塞性肺病。

## 病因

<image>

鼻腔中的鼻甲有着增润、调节温度、过滤空气、控制气流和感应气流等作用。气流进入鼻腔后，会绕过鼻甲，其结构有效提高空气与鼻粘膜的接触面积。鼻甲的功用对鼻部健康极为重要。其结构呈流线体，在处理空气的同时并不阻碍气流。

鼻甲能够保护内鼻粘膜，帮助其休息及再生。正常的成年人鼻腔能够在24小时内处理1万升空气，因此鼻粘膜需要有一定的休息期，才可保证呼吸道上皮的健康。这种间断的休息期称为鼻周期。每3至6小时，血液充盈半边鼻，使其休息和再生；另外一边则不被充盈，进行大部分的呼吸工作。在下鼻甲切除后，鼻周期无法使血液完全充盈受损的一边，因此丧失自然再生的能力。

人类的鼻子一般有三对鼻甲：下鼻甲、中鼻甲和上鼻甲。每一对鼻甲的大小和形状都非常不同，有着各自保护的鼻腔空间。下鼻甲最大，几乎占据整个鼻腔下部，从前部一直延伸到接近鼻咽处。由于下鼻甲处理大部分被吸入的空气，所以一旦被损坏，会对剩余的粘膜有极大的影响。中鼻甲位于下鼻甲之上，大约在鼻腔中部。中鼻甲相对较小，含有嗅觉神经轴突，且保护鼻腔上部，特别是位于顶部的嗅觉神经束以及筛窦和前额窦部分。中鼻甲的损坏对温度、湿度的调节影响不大，但可能会降低嗅觉并影响筛窦和前额窦的健康。上鼻甲最小，是保护嗅球的最后一道防线。

如果损失过多的鼻甲组织，被切除部位周围剩余的粘膜会逐渐发炎、变干、化生，并最终萎缩。鼻子的四大功能将会受到损害：呼吸、防御、嗅觉和产生音韵。这一过程可以持续若干年，使得早期诊断非常困难。患者一般在鼻甲切除术后不久就能感觉到空鼻症的症状。

## 诊断

空鼻症的先兆包括：患者感到用鼻子呼吸困难，并有强烈的窒息感、鼻腔干燥感。这些征兆只在鼻甲切除术之后出现，有时甚至在几年后才出现。

患者的鼻腔空间异常大，部分鼻甲丧失。某些患者的鼻粘膜因化生而干燥，其他患者则有呈红色的慢性发炎粘膜。硬化情况各异。由于干燥和过强的气流，剩余的组织很有可能有过度萎缩的情况。

## 预测

有关空鼻症候群的长时间观察和研究很少。因为鼻甲切除术后的继发性病症，所以空鼻症多年来都没有受到正确的判断。比如，剩余的粘膜组织（鼻中隔以及其余的鼻甲）通常会极度萎缩，造成实际的阻塞。

由于缺乏长时间观察，因此目前还没有数据显示多少百分比病患者的症状会迅速或大幅度的好转。该病症的症状是由实际鼻组织缺失、损害所造成的，所以能够自行痊愈的可能性不高。

Eugene Kern博士首次使用“空鼻症候群”这一名词。他认为，缺乏了鼻甲的保护，剩余的鼻粘膜会暴露在未经过滤、未经调节的空气，从而随时间持续消耗和损坏，空鼻症的症状也会因此逐渐恶化。他表示，当鼻甲组织少于某个临界点后，鼻粘膜就无法从每时每刻的消耗中再生。一项在美国进行的试验在几年的时间内观测了242位进行了各种鼻甲切除术的病人，他们在手术后产生了萎缩性鼻炎。在用电脑断层和直接观察这些病人的异常鼻腔结构后，科学家将这种情况命名为“空鼻症候群”。研究强调病症大大降低了病人的生活质量，而且病情有随时间恶化的趋势。这一研究符合19世纪末医学界采纳鼻甲切除术以来空鼻症患者群体的结论。然而一些长期研究却没有发现长期的负面影响。目前争议仍在持续，但医学界倾向于在进行切除术时尽量保留鼻甲组织。

病患者可以在鼻腔表面涂上保护性凝胶或使用盐水喷剂来补充损失了的水分，从而避免粘膜组织萎缩。不过，完全重建下鼻甲才是解决这一病症的最彻底的方法。

有近期报告表示有可能通过在粘膜下注入填充物来重建下鼻甲。报告中的病人人数很少，后续观察的时段也比较短，但报告的结论是正面的。2010年的一项研究指出，通过手术进一步对“空鼻”进行切除可以改善鼻内气流，但无法改变鼻子调节温度、湿度的能力。这些功能将无法逆转。另一项研究表示，一旦受破坏的鼻粘膜使纤毛细胞退化、损失，则连用手术闭合鼻孔也无法使纤毛细胞重新增长。

## 目前的治疗方法

### 非手术治疗

非手术治疗通过保持鼻内湿度，避免感染和刺激，以及保证充分的血液供应，可以保持并改善剩余鼻粘膜的健康。

- 用复方薄荷脑滴鼻液或者替代物保持鼻腔的水分，能缓解一定程度的干燥。
- 用生理盐水进行鼻冲洗。
- 睡眠时使用加湿器。
- 可适当服用维生素B2。
- 多喝水。
- 如果有臭鼻症（萎缩性鼻炎）的情况，则在进行鼻冲洗时加入80毫克庆大霉素。
- 许多空鼻症患者（约50%）会感到疼痛或忧郁，可服用相应的药物。
- 避免剧烈运动，通过一些舒缓的锻炼来保持整体生理健康，避免身体继续衰竭，进一步恶化。

### 手术治疗

Surgical treatment involves narrowing back the over enlarged nasal cavity—either by bulking up the partially resected turbinates with biological implant material (in cases where at least 50% of the inferior turbinate remain from anterior to posterior) or by creating neo-turbinates through submucosal implantation between the submucosa and bone in key locations in the nasal cavity. Of course, in some cases a combined approach is the best choice. The main difficulty with implant surgery is to achieve a long lasting bulk that will not get absorbed over time. Sometimes a procedure has to be repeated several times to get a sustainable result. The most physiological location for an implant is the lateral wall of the nasal cavity, where the inferior turbinate used to project from. An easier location to implant is the septum, but it is less favorable as it is not the natural location of the turbinates and may over obstruct the airflow.

The underlying rationale of surgery is to restore the natural inner nasal geometrical contours of the nasal passages of air (the inferior, middle, and superior meatuses), as much as possible, to mitigate the airflow just enough to restore normal rates of inner nasal humidity and temperature that will allow the mucosa to recuperate and sense the airflow well enough. It is paramount to do so while trying to restore the normal aerodynamics of the airflow in the nose, otherwise nasal obstruction will occur.

Pre-surgical planning has a tremendous impact on the success of the procedure. The surgeon is advised to perform a cotton test prior to the implantation: the surgeon places saline soaked chunks of cotton wool at the pre-planned site of implantation to simulate the implant. By doing so, he restricts and normalizes the nasal airflow patterns. This restores nasal aerodynamics. By trying different locations in accordance to the patient's feedbacks regarding the quality of his breathing and other ENS symptoms, it is possible to pinpoint the exact placement for the implants and their estimated shape and size.

Turbinate tissue is unique and there are no potential donor sites in the body from which to harvest similar tissue. However, in the nose, form equals function. It is therefore possible to restore some function by restoring the natural contours and proportions of the nasal passages:

It is possible to create an artificial look-alike structure of a turbinate in the nasal cavities, and thus to regain some of the nose's capabilities to adequately resist, streamline, heat, humidify, filter, and sense the airflow.

- A video demonstrating lateral wall implantation to create a bulk of tissue that will simulate the shape and function of the resected inferior turbinate.

### Implant materials

<image>

The bulking up of the sub-mucosa and mucosa to create a neo-turbinate structure can be achieved through implanting some supporting material between the bone/cartilage and also into the submucosal layer. Many materials have been tried over the past 100 years. In most cases this operation was used to restore heat and humidity to atrophic noses.

Generally speaking, the implant materials can be divided into 3 groups:

- autografts: bone, cartilage, fat, etc. from one site to another in the same patient. The problems here are relative shortage of tissue, and long term studies have shown high absorption rates in the nose. A Chinese study reported long-term success using iliac bone autografts.
- foreign materials: such as fibrin glue, Teflon, Gore-Tex, and plastipore, which solve the problem of shortage of autografts, are easy to shape and do not tend to get absorbed. However they have a high extrusion rate, and sometimes cause infection. A case study of good retention of hydroxyapatite cement in one patient has been reported in 2000, but the follow-up was only 1 year long.
- allografts: In the last two decades scientists have been able to harvest and remove away genetic markers of some basic human tissues (like skin dermis) from donors, and thus supplying a human natural implant material which does not stimulate the immune system to reject it. A good example for such material is acellular dermis (brand named "Alloderm"). It does not get rejected and in most areas retains most of its volume over long periods.

The ideal implant material, other than real original turbinate tissue should be something with low extrusion and rejection rates, minimal infection risk, and—very importantly—that will provide a strong and endurable enough structure and at the same time allow good permeability for blood vessel incorporation, which seems to be the key against long term absorption.

## 其他图像

<image>

- 下鼻甲移除术后产生的空鼻症

<image>

- 移除所有鼻甲后的右侧壁图

<image>

- 鼻腔解剖结构图

## 外部链接

- Empty Nose Syndrome Association (More symptoms, and a turbinates tutorial on life threatening risks in ENS)
- Dr. Houser's tutorial pages on ENS
- Internet support forum for ENS sufferers
- "Sniffing At Empty Nose Idea" (Aaron Zitner, The Los Angeles Times, 2001)
- Dr. Dondè's pages on ENS not surgical treatment by platelet grown factor