CHAPTER 19 Diaphragmatic Eventration

and Paralysis

Li Guang Hu, Liu Wei, and Jean Deslauriers

Diaphragmatic eventration (Box 19-1) is an anomaly that can be defined as a permanent elevation of part or of an entire hemidiaphragm without loss in the continuity in the pleuroperitoneal layers. It is characterized by normal peripheral muscular insertions of the diaphragm but marked decrease in muscular fibers in the eventrated part, which has the appearance of a thin, trans-lucent membrane. It is generally thought that diaphragmatic eventration is a congenital anomaly resulting from an incomplete migration of myoblasts during the fourth week of embryologic development. It has a marked left-sided predominance and does not generally result in para-doxical diaphragmatic motion.

Diaphragmatic paralysis is usually an acquired disorder in which the diaphragm, even if somewhat atrophic, is still muscular. It may manifest in childhood or adulthood and can be associated with phrenic nerve involvement. In many cases, especially in the adult, the exact cause of diaphragmatic paralysis will remain unexplained despite extensive investigation and follow-up.

Diaphragmatic herniation, with or without a hernia sac, involves the loss of continuity in one or more of the layers constituting the diaphragm.

Step 1. Surgical Anatomy

The mature diaphragm is a dome-shaped muscle that is anchored to the bony structures of the thorax and is considered the most important inspiratory muscle. When it contracts, the dome moves inferiorly and becomes flattened, thus decreasing the intrathoracic pressure and allowing air to be taken into the lungs. The muscular parts that originate from the lower six ribs bilaterally, the posterior aspect of the xiphoid, and the external and internal arcuate liga-ments unite at the central tendon. As such, the diaphragm should be viewed as a single muscular unit with two halves.

The diaphragm receives its motor supply through the phrenic nerves, which are formed at the lateral border of the anterior scalenus muscles, chiefly from the C4 nerve roots but with contributions from the C3 and C5 nerve roots. From there, the phrenic nerves enter the superior mediastinum between the ipsilateral subclavian artery and innominate vein and pass anterior to the pulmonary hilum along the pericardium. It is at that level that they are most susceptible to surgical injury, which may result in complete paralysis and eventual muscular

200

Chapter 19 Diaphragmatic Eventration and Paralysis 201

atrophy of the corresponding half of the diaphragm. The right phrenic nerve reaches the diaphragm lateral to the inferior vena cava, and the left phrenic nerve joins the diaphragm lateral to the left border of the heart. They both divide into several terminal branches whose anatomy delineates safe areas in the diaphragm where incisions can be made without creating loss of diaphragmatic function.

Arterial supply to the diaphragm is through the pericardiophrenic and intercostal arteries; venous drainage is through the right and left inferior phrenic veins, which drain medially into the inferior vena cava.

BOX 19-1. Terminology

EventrationCongenital in originCan be total or partial (anterior, posterolateral, medial)Characterized by normal muscular insertions and thin membranous abnormal eventrated area

Predominantly left-sidedParalysisNearly always acquiredCharacterized by atrophic muscleCan occur with or without phrenic nerve involvementHerniaInvolves loss of continuity of one or more of the layers constituting the diaphragm

202 Section II Thoracic Benign

Step 2. Preoperative Considerations

In the adult population, symptoms related to an elevated diaphragm are predominantly respiratory, mainly dyspnea, cough, and retrosternal discomfort. The diagnosis can usually be made on standard posteroanterior chest films (Fig. 19-1A) which show a diaphragm in higher position than normal, forming a round, unbroken line arching from the mediastinum to the costal arch laterally. Often the mediastinum will be shifted toward the unaffected side. If there is diaphragmatic paralysis, paradoxical motion can be observed on fluoroscopic examination. Although seldom done, diagnostic pneumoperitoneum might be useful to dis-tinguish between an elevated diaphragm and frank herniation (see Fig. 19-1B). Computed tomography (CT) scanning and ultrasonography are not particularly helpful in differentiating between an elevated diaphragm and true herniation, but magnetic resonance imaging (MRI) allows one to acquire high-quality images in several planes, which provides a better evalua-tion of the entire diaphragm.

The most important preoperative considerations (Box 19-2) in patients with an elevated hemidiaphragm are to rule out a diaphragmatic hernia or thoracic (pulmonary or mediastinal) malignancy affecting the phrenic nerve, to document by pulmonary function studies and exercise testing the respiratory consequences of the elevated diaphragm, and finally to estab-lish clearly the indication for surgery. This should be done with the understanding that most cases of eventration diagnosed in adults should be treated conservatively unless severe dyspnea that interferes with normal activities, orthopnea, or gastrointestinal symptoms are clearly related to the high position of the diaphragm. Indications for surgery in adults are thus uncommon, and the surgeon must be cautious before recommending plication for respiratory or digestive symptoms thought to be secondary to an elevation of the diaphragm.

Step 3. Operative Steps

The objective of the procedure of diaphragmatic plication is to immobilize the diaphragm in a lower, relatively flat position (see Fig. 19-1C) to reduce lung and mediastinal compression. This can be done through an open posterolateral approach, video-assisted techniques, or a laparoscopic abdominal approach. For all these procedures, gastric decompression with a nasogastric tube is mandatory.

Chapter 19 Diaphragmatic Eventration and Paralysis 203

BOX 19-2. Important Preoperative Considerations in Patients with Diaphragmatic Eventration and Paralysis

Rule out a diaphragmatic herniaRule out a thoracic malignancy affecting the phrenic nerveDocument the respiratory consequences of the elevated diaphragmEstablish a clear indication for surgical repair

Figure 19-1

A B C

204 Section II Thoracic Benign

1. Open Posterolateral Approach

The operation is carried out through a seventh interspace posterolateral thoracotomy. The lung and mediastinum are first examined to rule out unsuspected pathological processes, and the diaphragm is then plicated in successive layers until it becomes taut. This should be done with heavy interrupted silk sutures often reinforced with Teflon pledgets to prevent tearing. The direction of the plication is determined by the axis of the eventration, which is generally transverse rather than anteroposterior.

In the flag plication technique, two Babcock clamps are used to raise the eventrated dia-phragm, and the created fold is fixed at its base with U-shaped heavy silk sutures (Fig. 19-2A). This plicated area is then folded and resutured close to the intercostal insertion of the diaphragm by one or several rows of additional stitches (see Fig. 19-2B).

In the accordion plication technique, the eventrated diaphragm is pulled in a radial direc-tion, and folds are created by placing full-thickness sutures in the anterolateral to postero-medial direction (Fig. 19-3A). In this manner, the diaphragm can be plicated with as many rows of sutures as necessary to tighten it (see Fig. 19-3B).

Other techniques that can be carried out through an open thoracotomy include mechanical stapling of the base of the eventration, incising the eventration and folding it onto one side, or plicating the fold with U-shaped sutures placed over one or two right-angle clamps. With this last technique, the created semilunar fold is laid down and sutured again to reinforce the thinnest portion of the eventration, usually its anterior part.

Chapter 19 Diaphragmatic Eventration and Paralysis 205

A BFigure 19-2

Figure 19-3 A B

206 Section II Thoracic Benign

2. Plication by Minimally Invasive Thoracoscopic Technique

This procedure, originally described by Mouroux, is carried out through two 5-mm thora-coports and a mini-thoracotomy made over the ninth intercostal space for the suturing of the diaphragm (Fig. 19-4A). The eventrated diaphragm is first pushed down toward the abdomen (see Fig. 19-4B), and the created transverse fold is closed with a back and forth continuous suture beginning at the periphery of the diaphragm down to the cardiophrenic angle (see Fig. 19-4C).This is followed by a second row of continuous suture burying the first suture line (see Fig. 19-4D). It is to be noted that the presence of extended pleuropul-monary adhesions is generally considered a contraindication to videothoracoscopic plication.

3. Laparoscopic Plication

This technique for left-sided eventrations, which was described by Httl, is done with the patient in a 30-degree reverse Trendelenburg position where the surgeon is positioned between the legs of the patient. The redundant diaphragm is pulled down and plicated with 12 to 15 U-type sutures inserted from the left dorsal portion of the diaphragm to its ventral medial portion.

Chapter 19 Diaphragmatic Eventration and Paralysis 207

A B

C D

Port 15th ICS

Port 25th ICS

9th ICS

Figure 19-4

208 Section II Thoracic Benign

Step 4. Postoperative Care

The postoperative care of these patients is usually fairly straightforward with placement of one chest tube, which is removed within 48 to 72 hours of the operation, and a nasogastric tube, which is kept in place until abdominal peristalsis has resumed (normally within 24 hours).

Step 5. Pearls and Pitfalls

In adults, diaphragmatic eventration rarely requires surgical correction, except when respira-tory or digestive symptoms are clearly related to the abnormality and other causes of elevated hemidiaphragm have been ruled out. In selected patients, however, there is evidence that diaphragmatic plication will provide substantial and long-lasting benefits in terms of improv-ing symptoms and lung function. The possibility of performing these operations by less invasive techniques, such as video-assisted thoracoscopy, may lead to new interests in these disorders and their surgical treatment.

Chapter 19 Diaphragmatic Eventration and Paralysis 209

Suggested Readings

Graham DR, Kaplan D, Evans CC, et al. Diaphragmatic plication for unilateral diaphragmatic paralysis: A 10-year experience. Ann Thor Surg 1990;49:248-252.

Httl TP, Wichmann MW, Reichart B, et al. Laparoscopic diaphragmatic plication. Surg Endosc 2004;18:547-557.Lai DTM, Paterson HS. Mini-thoracotomy for diaphragmatic plication with thoracoscopic assistance. Ann Thorac Surg

1999;68:2364-2365.Mcnamara JJ, Paulson DL, Urschel HC, et al. Eventration of diaphragm. Surgery 1968;64:1013-1021.Merendino KA, Johnson RJ, Skinner HH, et al. The intradiaphragmatic distribution of the phrenic nerve with particular reference to the

placement of diaphragmatic incisions and controlled segmental paralysis. Surgery 1956;39:189-198.Mouroux J, Padovani B, Poirier NC, et al. Technique for the repair of diaphragmatic eventration. Ann Thorac Surg 1996;62:905-907.Mouroux J, Venissac N, Leo L, et al. Surgical treatment of diaphragmatic eventration using video-assisted thoracic surgery: A prospective

study. Ann Thorac Surg 2005;79:308-312.Piehler JM, Pairolero PC, Gracey DR, et al. Unexplained diaphragmatic paralysis. J Thorac Cardiovasc Surg 1982;64:861-864.Schumpelik V, Steinan G, Schlper I, Preschner A. Surgical embryology and anatomy of the diaphragm with surgical applications. Surg

Clin North Am 2000;80:213-239.Thomas TV. Congenital eventration of the diaphragm. Ann Thorac Surg 1970;10:180-192.Wright CD, Williams JG, Ogilvie CM, et al. Results of diaphragmatic plication for unilateral paralysis. J Thorac Cardiovasc Surg

1985;90:195-198.

Diaphragmatic Eventration and ParalysisSurgical AnatomyPreoperative ConsiderationsOperative StepsOpen Posterolateral ApproachPlication by Minimally Invasive Thoracoscopic TechniqueLaparoscopic Plication

Postoperative CarePearls and PitfallsSuggested Readings