A small asymptomatic Bochdalek hernia in an adult : diagnosis and repair by video-assisted thoracoscopic approach

Makoto Sugita, Motoyasu Sagawa, Tetsuo Hashimoto, and Tsutomu Sakuma

Department of Thoracic Surgery, Kanazawa Medical University, Ishikawa, Japan.
Department of Surgery, Kanazawa Social Insurance Hospital, Ishikawa, Japan.

Key words: VATS, Bochdalek hernia, pulmonary function

ABSTRACT

Using video-assisted thoracoscopic surgery (VATS), the foramen (3 cm in diameter) of Bochdalek was closed by primary suture approximation of the diaphragmatic edges. Pulmonary function tests at postoperative day 8 revealed no significant deterioration compared to the preoperative baseline. Chest computed tomography (CT) performed one year after surgery confirmed no recurrence of the hernia. VATS may be the technique of choice for diagnosis and repair of a small Bochdalek hernia.

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INTRODUCTION

Since the advent and evolution of computed tomography and magnetic resonance imaging (MRI) technologies, asymptomatic Bochdalek hernias are being detected with increased frequency. However, when the hernia contents are small, it is difficult to make an accurate diagnosis. In addition, the choice of treatment remains controversial. Moreover, it is important to minimize the patient's postoperative deterioration in pulmonary function. Here, we report the case of a small asymptomatic Bochdalek hernia in an adolescent. Utilizing VATS, we were able to both diagnose and repair the patient's diaphragmatic defect without compromising his pulmonary function.

CASE REPORT

A 66 year-old asymptomatic man with no significant past medical history and a negative family history was referred to our hospital for surgical treatment of a small round mass in the right chest cavity. The mass was incidentally discovered on chest CT during a medical evaluation at another hospital. No prior CT or chest X-ray was available for comparison. Imaging revealed a rounded mass (3 cm in diameter) located either at S10 of the left lung or in the paravertebral region of the left diaphragm (Figure 1a). The CT attenuation of the mass was consistent with fatty tissue, therefore Bochdalek hernia was highly suspected. However, other pathophysiological conditions could not be completely excluded, so we decided to perform surgical exploration by VATS.

Figure 1a Preoperative chest CT showing the mass in the posterolateral region of the left chest cavity.

In preparation for the procedure, the patient was placed in the right decubitus position, and single-lung ventilation was instituted. Three ports were placed, and a 30-degree thoracoscope was inserted. We observed a yellow rounded mass located at the paravertebral region of the diaphragm. A thin hernial sac was identified, and fully excised using an electric coagulator hook, which concurrently allowed us to confirm the presence of a foramen. After determining that the mass consisted of retroperitoneal fat, we obtained a small portion of the tissue for pathological examination, which later confirmed normal adipose tissue. The retroperitoneal fat tissue was pushed back into the peritoneal cavity. The edges of the defect were approximated using four figure of eight interrupted sutures, and the knots were extracorporeally tied using a knot pusher (Figure 1b). The entire procedure was accomplished using exclusively thoracoscopic techniques, thus eliminating the need to enlarge any of the skin incisions.

Figure 1b Thoracoscopic view showing closure of the diaphragmatic defect by primary suture.

The patient's postoperative course was uneventful. Postoperative pain was managed with epidural anesthesia until postoperative day 2. Pulmonary function tests performed on postoperative day 8 revealed essentially no changes, as described in Table 1. Chest CT was performed both 6 months and one year following surgery, and both showed no evidence of recurrence of the hernia.

DISCUSSION

Thanks to advances in radiological imaging technology, CT and MRI have revealed that the small asymptomatic Bochdalek hernia in adults is not as rare as previously considered.1 When the contents of the hernia are large or consist of abdominal organs, the diagnosis can be made without much difficulty. However, such is not the case when the Bochdalek hernia contains only a small amount of retroperitoneal fat protruding through a narrow diaphragmatic defect. In addition, it is difficult to qualitatively distinguish the protruded retroperitoneal fat from other pathophysiological conditions such as diaphragmatic fat, other diaphragmatic hernias, intrathoracic lipoma, or liposarcoma. With these findings, particularly in the case of liposarcoma with predominantly lipoma-like portions, CT attenuation resembles that of fat tissue2. Therefore, surgical exploration has been strongly recommended, especially when the possibility of liposarcoma cannot be excluded.3

There is some debate over how to manage the diaphragmatic defects associated with such hernias. Controversy exists regarding the surgical approach, the choice of procedure, and method of repair. Thoracic and abdominal approaches have both been described in the literature,4,5 and the thoracic approach has been recently recommended.4 Unlike the abdominal approach, it does not result in any degree of paralytic ileus, nor does it increase the risk of subsequent intestinal obstruction secondary to adhesions. Furthermore, we believe that when the hernia is located in the paravertebral region of the diaphragm, as was the case in our patient, the thoracic approach provides better access than the abdominal approach. As to the choice of procedure, VATS is generally considered to be advantageous over standard thoracotomy for surgical exploration and intervention because it is associated with reduced postoperative pain and respiratory compromise. In spite of this, the impact of VATS on pulmonary function, and its long term efficacy in Bochdalek hernia repair have not been documented yet. However, the advantages of VATS were borne out by our case. Our patient was pain free and receiving no pain medication after postoperative day 3 and pulmonary function tests performed at postoperative day 8 showed a return to preoperative levels (Table 1). With regards to the method of repair, closure of the diaphragmatic defect can be achieved either by primary suture approximation of the diaphragmatic edges or by covering the defect with a mesh. In our case, we chose to utilize primary suture with an interrupted suturing technique. We believe that when the defect is small enough for the foramen to be closed completely without placing too much tension on the repair, primary suture by VATS is not only feasible but also sufficient.

We have periodically followed the patient for over a year since surgery. Chest CTs were taken at 6 months and one year postoperatively. Both showed no sign of recurrence of the hernia. This strongly supports the validity of using VATS to repair a small diaphragmatic defect by primary suture. Using a VATS approach for the diagnosis and repair of a small Bochdalek hernia permits not only complete closure of the hernia but also early recovery of pulmonary function after surgery.

REFERENCES

1. Mullins ME, Stein J, Saini SS, Mueller PR. Prevalance of incidental Bochdalek's hernia in a large adult population. 2001; AJR 177: 363-366.
2. Kim T, Murakami T, Oi H, Tsuda K, Matsushita M, Tomoda K, Fukuda H, Nakamura H. CT and MR imaging of Abdominal liposarcoma. 1996; AJR 166: 829-833.
3. Froehner M, Ockert D, Bunk A, Saeger HD. Liposarcoma of the diaphragm: CT and sonographic appearances. Abdom Imaging 2001; 26: 300-302.
4. Silen ML, Canvasser DA, Kurkchubasche AG, Andrus CH, Naunheim KS. Video-assisted thoracic surgical repair of a foramen of Bochdalek hernia. Ann Thorac Surg 1995; 60: 448-450.
5. Ackroyd R, Watson DI. Laparoscopic repair of a hernia of Morgagni using a suture technique. J R Coll Surg Edinb 2000; 45: 400-402.