Since the Japanese Society of Broncho-esophagology was founded in 1950, there have been only a few reports on mediastinal disease. In this article, I would like to review the following issues: the development of the diagnostic modalities and management of mediastinal disease, mediastinal emphysema, anterior mediastinal tracheostomy and video assisted thoracoscopic surgery on mediastinal tumors.

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Diagnostic imaging techniques for mediastinal tumors include plain chest radiography, chest tomography, CT, andiography, MRI and radioisotope. When mediastinal diseases are suspected on chest radiographs, we take CT and MRI of our patients and make a final diagnosis. MRI appears particularly suitable for the evaluation of the mediastinum because of the high contrast resolution attainable for soft tissue, multiplane and multisequence imaging. In addition, MRI requires no intravascular contrast medium for distinct delineation of masses from mediastinal vessels.
While MRI and CT provide essentially identical information in most patients, we think that CT should be used as the primary modality and MRI reserved for equivocal or difficult cases in which precise definition of the anatomic relationships is required to guide surgery. Tissue differentiation is higher with MRI than with CT, so MRI can be manupulated to provide unique diagnostic information and thus play a useful adjunct role in problem solving.

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To evaluate diagnostic imaging of the mediastinum, 3D CT reconstruction images of 13 cases were made. These included 10 cases of mediastinal tumor (1 mediastinal goiter, 2 thymoma, 1 invasive thymoma, 1 thymic cyst, 1 bronchial cyst, 1 malignant lymphoma, 3 neurilemmoma) and 3 cases of mediastinal invasive lung cancer (1 Pancoast tumor, 2 SVC invasion). The authors used a “slip-ring” system CT scanner, CT-W2000 Volume Scan (HITACHI). Collimation was set at 5mm, and the table speed at 5mm/sec.
3D CT angiography with rapid intravenous infusion of contrast media clearly revealed the great vessels in the mediastinum, atrium and ventricle. 3D CT aerographic images enabled visualization of the trachea and extrapulmonary bronchus, as in bronchography. A cinical application for 3D CT imaging was plainly shown to be useful for precise tumor localization and examination of adjacent mediastinal structures.
Especially, 3D CT images show a diagnostic capability for direct lung tumor invasion into the superior caval vein, vertebra and ribs. The radiological anatomy of the mediastinum as shown by 3D CT was not exceedingly complex, and there should not be a radiological “blind spot.”
We believe it is possible to perform preoperative simulation surgeries using 3D CT diagnostic imaging, which will also be useful in a mediastinal teaching tool for thoracic surgeons.

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High resolution and real-time sonographic scanning not only permit observation of the relative movement of lesions and neighboring structures, but also provide information on the characteristics of tissues, aiding in the differentiation of vessels from solid masses etc. However, the value of ultrasonography for the evaluation of the mediastinum is limited by bone structures and air. To solve this problem, transesophageal endoscopic ultrasonography has been introduced. This technique is based on the fact that the limitation of the echo penetration by bone and air using the transthoracic approach is markedly reduced by the transesophageal approach. In this article, we address the usefulness of transesophageal endoscopic ultrasonography as an imaging modality for the mediastinum.

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The Mediastinum is one of the most important locations in the human body, though this is not widely recognized because of its miscellaneous nature. Mediastinoscopy is an endoscopy to the mediastinum. It is used to find the mediastinal metastasis of lung cancer. The mediastinoscopic findings can be applied to know the operability of lung cancer. Thoracoscopy is also used in diagnosing mediastinal disease. Endoscopic vision using a thoracoscope is better than mediastinoscopy. Thoracoscopy, therefore, is used in preference to mediastinoscopy to diagnose mediastinal lesions when both are possible. Endoscopic surgery is a better treatment than open thoracotomy, but we must not depend on it since it can lead to complication.

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It is well known that hoarse voice can be produced during the course of any laryngeal lesion. One possible cause is recurrent nerve paralysis due to various pathological conditions. Among various etiologies, our clinical statistics indicate that the incidence of hoarseness due to mediastinal pathology is 2.6%. As for treatment, glottal incompetence should be corrected and various methods have been proposed for this purpose. From our experience, arytenoid rotation and intracordal injection give the best results. However indication for each technique should be considered carefully.

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Seventeen patients with tracheobronchial stenosis due to mediastinal disease were treated. These were twelve males and five females and ranging in age from 23 to 77 years. Diseases included esophageal carcinoma in 8, mediastinal tumor in 5 (2 intrathoracic goiter, 1 teratoma, 2 germ cell tumor), metastatic lymphadenopathy in 3 (2 breast cancer, 1 thyroid cancer), and aortic aneurysm in 1. The stenotic site was the intrathoracic trachea in 10, the right main bronchus in 2, and the left main bronchus in 5.
Irradiation by a YAG laser and insertion of a T-tube for tracheobronchial stenosis due to esophageal carcinoma was very useful for improving dyspnea. In cases of benign mediastinal tumor and aortic anerysm, tracheal stenosis was diminished by surgical treatment.

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Acute mediastinitis is a life-threatening condition with a mortality rate of 30-40%. To discuss the pathophysiology of this disease, the authors reported the details of esophageal perforations experienced in our institute and reviewed the literature.
Eight cases of esophageal perforation, six men and two women, with a mean age of 48.3 years, were reported. There were five spontaneous perforations, and two iatrogenic perforations. The remaining one occurred from the rupture of the esophageal diverticulum. By plain chest X-ray films, mediastinal emphysema and pleural effusion were detected in 62.5% and 75%, respectively. Esophagography and endoscopic examination were diagnostic in 100% of the cases. In all but one case, the locations of the perforation were in the lower portion of the esophagus. All of the cases were treated surgically. One case died of the exsanguination of a hemorrhagic duodenal ulcer in hospital.
Nowadays, acute mediastinitis after cardiovascular surgery is the most common cause of acute mediastinitis whereas 90% of nonsurgical mediastinitis occurs from esophageal perforations. Descending necrotizing mediastinitis is a rare condition, but its mortality rate remains high. The pathogenic bacteria and pathways of the infectious extension are different for each source of acute mediastinitis. Therefore, appropriate therapeutic modalities, including antiseptic therapy and operative procedures, should be selected.
To decrease the mortality rate of this disease, immediate diagnosis and therapy are advocated.

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A retrospective analysis was done of 38 patients with lung cancer invading the mediastinal organs (T4) as confirmed post-surgically.
The average patient age was 56.2 years, and the majority were male (37/38). 32 of 38 tumors were squamous cell carcinoma; 3 were adenocarcinoma; and 3 were large cell carcinoma. There were 3 N0, 10 N1 and 25 N2 disease. 36 of the patients were M0.
The 3 and 5 year survival rates of the 38 patients with T4 lesions were 23.9% and 14.9%, respectively, this was significantly lower than these of 57 patients with T3 tumors, which were 39.3% and 36.3%, respectively (P<0.05).
Cell-type did not make any significant difference in the patients' survival.
Patients with N1 lesions tended to survive longer than those with N2 lesions.
The survival rate of patients with tumors invading a single mediastinal organ was significantly better than that of patients with tumors invading more than two mediastinal organs, 31.1% vs. 8.3% at 3 years and 22.2% vs. 0% at 5 years (P<0.01).
Patients with tumors invading the heart and great vessels showed a better survival rate than those with tumors invading the trachea, tracheal bifurcation or the esophagus (P<0.01).
The survival rate of patients with tumors presumably resected in a complete fashion was significantly better than that of patients with tumors resected incompletely, 19.8% vs. 0% at 5 years (P<0.01).

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The operative procedures for lymphadenectomy and its postoperative results in relation to a number of positive nodal involvements were discussed. For advanced cases, lymphadenectomy is commonly performed in three areas (mediastinum, abdomen and cervical areas). In particular, lymphadenectomy in the upper mediastinum seems to be important. Bilateral recurrent nerve nodes should be dissected in almost all cases. However, dissection of the lymph nodes around the brachiocephalic artery should be avoided for poor risk patients to prevent postoperative pulmonary complications. The five-year survival rate of cases without any lymph node involvement was 70%, that of patients with 1-3 positive nodal involvements was 31%, and that of patients with 4 or more positive nodes was 11%, with significant differences between each group. Cases having fewer metastatic lymph nodes showed better long-term results following the operative procedures.

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The representative malignant mediastinal tumors are 1) thymic epithelial tumors, 2) undifferentiated germ cell tumors, 3) malignant lymphoma, and 4) neuroblastoma. Thymic epithelial tumors include thymoma, thymic cancer, and thymic carcinoid. As the latter two tend to metastasize more frequently than thymoma, they require resection of regional lymphnode and adjuvant therapies. Prognosis for germ cell tumors is improved with intensive chemotherapy.
Malignant lymphoma has different types, which have different behaviors and responses to chemotherapy. Considerations of these differences are necessary in the treatment of these tumors.
Neuroblastoma is now treated systematically, i. e., stages I and II undergo initial surgery, and stages III and IV undergo preoperative chemotherapy. The prognosis for neuroblastoma is now excellent.

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The hypopharyngeal constrictor muscle consists of the thyropharyngeal (TP) and the cricopharyngeal (CP) muscles. The CP muscle continuously contracts as an upper esophageal sphincter. It relaxes only when the TP muscle contracts at the pharyngeal swallowing stage.
The authors investigated histochemical properties of the canine TP and CP muscles. Acetylcholine esterase stain showed that neuromuscular junctions of the CP muscle distribute more widely in the horizontal plane than those of the TP muscle. The glycogen depletion test suggested that the CP muscle fibers are innervated by the ipsilateral pharyngo-esophageal branch of the vagal nerve, and that they mostly terminate around the mid-line, with only some reaching the contralateral side. Adenosine triphosphatase stain showed that type 2 fibers were predominant in the TP muscle, and that type 1 fibers were predominant in the CP muscle.

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White lesions of the laryngeal mucosa should be carefully treated because they are usually precancerous or carcinoma when seen to be histopathologic. We classified 71 inpatients suffering from white lesions of the vocal fold who had been receiving treatment within our department for 9 years (from November 1981 to November 1990) into three groups (hyperplasia, dysplasia and carcinoma) and then compared the clinical characteristics of each and observed the malignant changes and the number of recurring cases. The results can be summarized as follows.
1) White lesions of the vocal folds were mainly seen among males in their seventh decade.
2) Among our cases, 90.1% were smokers, and most of the cancer patients had smoked for more than 30 years.
3) In the case of the carcinoma group, the site of the lesions was mainly in the anterior one third of the vocal fold.
4) In terms of gross appearance, the hyperplasia and dysplasia groups had mainly white patches, while the carcinoma group had mainly a white mass.
5) For the initial treatment, one patient was treated with only excision, 5 patients were treated with radiotherapy alone; 47 patients were treated only with CO₂ laser vaporization; and 18 patients were treated with radiotherapy in a addition to laser.
6) Recurrence was mainly seen in cases of dysplasia, indicating a malignant change.

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