Keywords

Introduction

Diaphragmatic eventration is a rare congenital disorder (incidence <0.05%) that affects the central portion of the diaphragm [1]. It is characterized by a paucity of muscle fibers, while the normal diaphragmatic attachments to the sternum, ribs and spine are not affected [2]. In contrast, diaphragmatic paralysis is an acquired condition in which the muscle fibers might be atrophic, but they are present. Some authors have classified diaphragmatic eventration as congenital or acquired. This is a common misconception , as both pathologies have similar symptoms, physiological impact, and treatment. For this reason, we have chosen to name both diseases “eventration” in this chapter.

Eventration is a diagnosis of exclusion, often asymptomatic in adults, more common in males, and affects predominantly the left hemidiaphragm, although there are cases of right/bilateral involvement reported in the literature. The condition is thought to be caused by abnormal myoblast migration from the third, fourth, and fifth cervical somites into the septum transversum and pleuro-peritoneal membrane [3]. The main symptom that patients experience is dyspnoea, owing to a combination of loss of pulmonary and chest wall compliance and a ventilation/perfusion mismatch [4]. Other non-specific symptoms include epigastric pain, bloating, nausea, and constipation [5]. “Acquired” diaphragm eventration (paralysis) is most commonly seen following heart surgery or in pathologies affecting the phrenic nerve such as intrathoracic tumours and neuromuscular disorders. Symptoms are usually worse in children, who sometimes require mechanical ventilation, because they rely more on their diaphragmatic excursion for respiration due to intercostal muscle underdevelopment and a horizontal orientation of the ribs [6].

Surgical repair can be done either open or minimally invasively using a transthoracic or transabdominal approach, and various techniques such as plication, imbrication, and double breasted suturing have been described. Diaphragmatic plication seems to be the most popular method and has the goal to provide symptomatic relief by improving diaphragmatic function; therefore, surgical treatment is reserved exclusively for symptomatic patients [1].

As diaphragmatic dysfunction reduces the compliance of the chest wall, pulmonary function tests (PFTs) can demonstrate a restrictive pattern [4]. Furthermore, the diaphragm plays a critical role in inspiration, therefore measuring the maximum forced inspiratory flow (FIFmax) is useful, as is assessing pulmonary function tests (PFTs) in both supine and upright positions (when supine the PFTs decrease between 20% and 50%) [7]. Despite the PFTs often being abnormal in patients with diaphragmatic eventration, these changes are not consistent and do not correlate with the severity of dyspnea.

Surgery for diaphragmatic eventration in children is mostly performed to facilitate weaning off ventilatory support [6], and we have excluded the studies looking at outcomes following plication in this group of patients.

PFTs are useful in monitoring changes after treatment and in providing an objective evaluation of improvement in diaphragm and chest wall function [1]. This chapter reviews the potential benefit of unilateral diaphragm plication in adult patients with unilateral diaphragm eventration in improving lung function tests.

Search Strategy

Electronic searches were performed using the PubMEd, Embase and Cochrane Evidence based medicine databases from 1990 to 2019 and used to identify available data on outcomes after diaphragm plication in adult patients with diaphragmatic eventration published in the English language. The index terms used were “unilateral diaphragm eventration AND plication OR surgery AND outcomes OR quality of life OR physiological changes OR results”. Conference abstracts, case reports and studies which included only diaphragmatic paralysis were excluded. The quality of the data was classified using the GRADE system. Table 44.1 shows the PICO terms used to perform the literature search.

Table 44.1 PICO formatted terms for literature search
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Results

Most data on outcomes following unilateral diaphragm plication in adults comes from retrospective analyses of case series. Due to the rare nature of this disease, randomized control studies are not feasible, therefore the level of evidence discussed in this chapter is low. Given the myriad of surgical techniques described in the literature, we have divided the results into two sections based on the approach used.

Outcomes After Open Diaphragmatic Plication

In 1992 Ribet et al. [8] published their outcomes after open (thoracotomy) diaphragmatic plication in a cohort of 24 patients over a period of 20 years, including both adults and children, and suggested that one has to be sure the diaphragm is causing the symptoms before performing the procedure (Table 44.2). Out of the 11 adult patients who underwent open diaphragmatic plication, 6 had decreased respiratory function and in 5 cases the post-operative pulmonary function tests were available and demonstrated an increase in forced vital capacity (FVC) by a mean of 20% and in forced expiratory volume in the first second (FEV1) by a mean of 15%. Interestingly, in 5 cases the diaphragmatic elevation persisted post-operatively, albeit to a lesser extent.

Table 44.2 Outcomes after open diaphragmatic plication (thoracotomy)
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Calvinho et al. [9] retrospectively analyzed outcomes in 20 patients operated between 1988 and 2007 with an average length of follow-up of 59.6 ± 55.1 months. The subjective improvement (dyspnea score) was statistically significant at follow-up (Medical Research Council [MRC] dyspnea scale) improved from a mean of 2.06 ± 0.97 to 1.06 ± 1.14; p = 0.007). Although the PFTs improved post-operatively (FEV1% from 66.2 ± 15.3 to 76.1 ± 20.1 and FVC% from 70.4 ± 16.0 to 78.4 ± 17.3), the differences were not statistically significant. The authors attributed this discrepancy to the small sample size and concluded that subjective improvement is of much more value than the objective data from spirometry.

Balci et al. [10] compared outcomes according to etiology and patch use. In their cohort of 28 patients, 18 cases were secondary to previous operation/disease, 8 were idiopathic, and 2 were post-traumatic. They observed that the patients with a congenital/idiopathic etiology (true eventration) were younger, had a higher diaphragm, were operated sooner after the onset of symptoms, and had better preoperative FEV1 values. In terms of surgical technique, there was no statistically significant difference between open diaphragmatic plication and open diaphragmatic plication and patch. Of note, none of the patients who had the diaphragmatic plication and patch had a post-operative diaphragmatic event; in the plication only group, one patient had an ipsilateral diaphragmatic hernia and one patient developed a recurrence.

Another study by Evman et al. [11] compared mid-term clinical outcomes of open accordion plication vs. open double breasted plication in 42 symptomatic patients with eventration and paralysis. The PFTs and the dyspnea scores (MRC) improved significantly, but there were no statistical differences between the groups. The postoperative increases in FEV1 and FVC were greater than 20% and persisted at 2 years. Although the double breasted technique significantly improved the caudal shift of the diaphragm, this difference did not translate to an increased improvement in pulmonary function tests compared to accordion plication.

Shah et al. [12] retrospectively analyzed 38 patients who underwent surgery for true diaphragmatic eventration over 11 years. They also noted a statistically significant improvement in PFTs and dyspnea score at 6 months post-operatively. Furthermore, they reported a 5.2% 30-day morbidity rate due to surgical emphysema and surgical site infection and a 2.6% 30-day mortality (one patient died due to a fatal arrhythmia).

Outcomes After Minimally Invasive Diaphragmatic Plication

There are only a few studies analyzing outcomes after minimally invasive (VATS or laparoscopy) plication in patients with diaphragmatic eventration. Most are retrospective with the exception of that led by Moroux and colleagues [13], who performed VATS plication in 12 patients with unilateral diaphragmatic eventration and prospectively analyzed the results over an 11 year period. Subjective and objective functional improvement as well as radiological improvement were observed in all patients and persisted long term (Table 44.3.).

Table 44.3 Outcomes after minimally invasive diaphragmatic plication (VATS or laparoscopic)
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Groth et al. [14] retrospectively evaluated the short and mid-term results following laparoscopic diaphragmatic plication for symptomatic, unilateral diaphragmatic paralysis and eventration. Their study included 25 patients and showed significant improvement in respiratory quality of life and pulmonary function test results. Unlike other studies , they included the FIFmax in the analysis and found that the improvement 1 year after plication did not reach statistical significance. After investigating the reason behind this discrepancy, they found that one patient resumed smoking after the 1-month postoperative visit. When analyzing the cohort’s 1-year PFT data after excluding this patient, they found significant improvements in FVC%, FEV1%, and FIFmax% at 1 year after laparoscopic diaphragmatic plication.

Rombolá and coworkers [15] observed the clinical respiratory and spirometric effects of video-assisted mini-thoracotomy diaphragmatic plication (VAM-TDP) in the treatment of diaphragmatic eventration. Eighteen symptomatic patients were included and significant clinical and spirometric improvement persisted up to 1 year post-operatively. They reported no perioperative mortality, but five of their patients had postoperative complications (two required non-invasive ventilation, one had a small hepatic hematoma , and two had postoperative ileus).

In summary, both open and minimally invasive approaches yield similar clinical and functional results. The complication rates after open plication are reported as high as 14.3% in one study [10] and 5.2% in another [12], while in minimally invasive plication Groth et al. [14] and Rombola et al. [15] reported that 25% and 27%, respectively, of their cohorts developed a postoperative complication. In contrast, Evman et al. [11] reported no complications in their cohort of 42 patients undergoing open diaphragm plication as did Moroux et al. [13] in their 12 patients who underwent VATS diaphragm plication. The reported complications are similar in all studies and include (but are not limited to) dyspnea, respiratory failure requiring non-invasive ventilation or endotracheal intubation, prolonged drainage, surgical site infections, stroke, and atrial fibrillation. Although the complication rates for minimally invasive diaphragm plication seem to be higher, these results need to be interpreted with care as these studies are retrospective and include different techniques, number of patients , methodology, and reporting.

The post-operative length of stay seems to be similar in both types of approach, ranging between 2 to 15 days across the studies involving open procedures [8,9,10,11,12] and 1 to 15 days in VATs studies [13,14,15]. However, these results need to be interpreted with caution, as the studies looking into outcomes after open plication involve more patients and have a more variable follow-up period than those studying the outcomes after VATs.

Conclusions and Recommendations

The results of the aforementioned studies should be interpreted with care, as the diagnosis of eventration is often confused with diaphragmatic paralysis. Both open and minimally invasive approaches offer similar clinical and spirometric improvement. However, there is no level 1 evidence comparing the approaches. Diaphragmatic plication is recommended for symptomatic patients with diaphragmatic eventration, as it provides durable improvement in both lung function and symptoms.

Recommendations

  • Diaphragmatic plication is indicated in symptomatic patients with diaphragm eventration (evidence quality low; weak recommendation).

  • Minimally invasive and open techniques have similar outcomes, thus an approach with which the surgeon is familiar should be adopted (evidence quality low ; weak recommendation).

A Personal View of the Data

In our opinion, as with diaphragmatic paralysis, respiratory capacity improvement is likely to occur following repair of eventration at the abdominal-rib cage level in both the operated and contralateral sides, with restoration of synchrony of chest wall movements. These dynamic improvements are not captured by simple spirometry [16]. We prefer a thoracoscopic approach to diaphragmatic plication, as mid-term and long term results are similar to other approaches, and the potential for chronic pain is low in our experience. While VATS and laparoscopic approaches have become more popular, a comparative study with open techniques is warranted.