Department of Medicine Manipal College of Medical Sciences MEDIASTINAL DISEASES ALOK SINHA Department of Medicine Manipal College of Medical Sciences Pokhara, Nepal

What is mediastinum ? Mediastinum is the space in the middle of the chest between the two pleurae Extends from the sternum to the spine Contains ALL the viscera in the thorax except the lungs

Divisions of Mediastinum Posterior Superior Anterior Middle

Subdivision of mediastinum as seen on cross section . Subdivision of mediastinum as seen on cross section anterior mediastinum (1) middle mediastinum (2) posterior mediastinum (3)

Superior mediastinum Boundary Inferiorly: by the transverse thoracic plane – oblique plane passing posteriorly from sternal angle of Louis to the junction of the 4th and 5th thoracic vertebra Superiorly: line from sternum to T1 Laterally: by the pleurae

Contents Arteries Muscles AORTIC ARCH & its bracnches Brachiocephalic artery Thoracic portions of the left common carotid and the left subclavian veins Innominate veins and Upper half of the superior vena cava Left highest intercostal vein Muscles origins of the Sternohyoid and Sternothyreoid

Nerves Trachea Esophagus Thoracic duct Remains of the thymus phrenic nerve left recurrent laryngeal nerve vagus nerve cardiac nerve superficial and deep cardiac plexuses Trachea Esophagus Thoracic duct Remains of the thymus Some lymph glands

Anterior mediastinum-in front of the heart Bounded in front by the sternum behind by the pericardium at the sides by the pleurae It contains remains of thymus gland origins of the sterno-hyoid, sterno-thyroid, and the triangularis sterni muscles internal mammary glands of the left side lymphatic vessels, and loose areolar tissue

Middle Mediastinum: Contains Heart & pericardium Ascending aorta Lower half superior vena cava with vena azygos opening into it Bifurcation of trachea and two bronchi Pulmonary arteries and veins Phrenic nerves Some lymphatic glands

Posterior Mediastinum: Bounded In front by pericardium and roots of lungs Behind by vertebral column At the sides by the pleurae Contains Descending aorta Oesophagus Azygos veins Vagus Splanchnic nerves Thoracic duct Some lymphatic glands  

Mediastinal diseases 1. Mediastinitis 2. Pneumomediastinum Infection or inflammation in the mediastinum acute Chronic 2. Pneumomediastinum Air in the mediastinum

3. Mediastinal mass Commonly caused by Tumor Cyst Vascular anomaly Lymph nodes

SOME CAUSES OF A MEDIASTINAL MASS Superior mediastinum Retrosternal goitre Thymic tumour Dermoid cyst Lymphoma Aortic aneurysm Anterior mediastinum Pericardial cyst Hiatus hernia through the diaphragmatic foramen of Morgagni

Posterior mediastinum Neurogenic tumour Paravertebral abscess Oesophageal lesion Aortic aneurysm Foregut duplication Middle mediastinum Bronchial carcinoma Lymphoma Sarcoidosis Bronchogenic cyst Hiatus hernia

Trachea and main bronchi SYMPTOMS AND SIGNS - MALIGNANT INVASION OF THE STRUCTURES OF THE MEDIASTINUM Trachea and main bronchi Stridor Breathlessness Cough Pulmonary collapse Oesophagus Dysphagia Phrenic nerve Diaphragmatic paralysis Left recurrent laryngeal nerve Paralysis of left vocal cord giving rise to hoarseness and 'bovine' cough Body_ID: B019082

Sympathetic trunk Superior vena cava Pericardium Horner's syndrome Ptosis Meiosis enopthalmos anhydrosis Superior vena cava Non-pulsatile distension of neck veins Subconjunctival oedema Oedema and cyanosis of head, neck, hands & arms Dilated anastomotic veins on chest wall Pericardium Pericarditis and/or pericardial effusion

Which one is “invasion” and which is “compression” ?

Benign tumours and cysts: Frequently diagnosed on unrelated X ray of the chest Do not invade vital structures May cause symptoms by compressing Trachea Superior vena cava

Malignant mediastinal tumours: Can be due to invade as well as compress bronchi & lungs Can be due to Mediastinal lymph node metastases Lymphomas & leukaemia Malignant thymic tumours Aortic and innominate aneurysms have destructive features resembling those of malignant mediastinal tumours

INVESTIGATIONS !

1. Radiological examination Benign mediastinal tumour sharply circumscribed opacity situated mainly in mediastinum often encroaching on one or both lung fields Malignant mediastinal tumour no clearly defined margin general broadening of the mediastinal shadow CT (or MRI) is the investigation of choice for mediastinal tumours

Liposarcoma

2. Endoscopic investigation: Bronchoscopy may reveal a primary bronchial carcinoma causing mediastinal tumour by secondary lymphatic spread

Posterior mediastinum can be imaged by 3. Ultrasonography Posterior mediastinum can be imaged by Transoesophageal ultrasound Needle biopsies of lymph node masses may be obtained under USG through endoscope

4. Surgical exploration 1. Mediastinoscopy: tissue from enlarged lymph nodes in ant. mediastinum can be removed for histological examination 2. surgical exploration of the chest with removal of part or all of the tumour often required to obtain a histological diagnosis

Management Benign mediastinal tumours removed surgically because Most produce symptom sooner or later Cysts may become infected Neural tumours may undergo malignant transformation Low operative mortality in absence of Coexisting cardiovascular disease COPD Extreme age

MEDIASTINAL INFECTIONS

Acute Mediastinitis Most cases are due to: 1. Oesophageal perforation spontaneously (Mallory weiss syndrome) complication of esophagoscopy Acutely ill with chest pain and dyspnea Treatment is surgical exploration of the mediastinum with primary repair of the esophageal tear and drainage of the pleural space and the mediastinum

2. After median sternotomy for cardiac surgery Presentations with sepsis or widened mediastinum Treatment includes immediate drainage & debridement parenteral antibiotic therapy mortality still exceeds 20%.

Chronic Mediastinitis Ranges from Granulomatous inflammation of lymph nodes to Fibrosing mediastinitis Due to TB Histoplasmosis & other fungal infections Sarcoidosis Silicosis

Patients with fibrosing mediastinitis usually have compression of superior vena cava large airways phrenic or recurrent laryngeal nerve paralysis pulmonary artery or proximal pulmonary veins Other than antituberculous therapy for tuberculous mediastinitis, no medical or surgical therapy has been demonstrated to be effective for mediastinal fibrosis

Pneumomediastinum

Gas in the interstices of the mediastinum Causes are: (1) alveolar rupture with dissection of air into the mediastinum (2) perforation or rupture of the esophagus, trachea, or main bronchi (3) dissection of air from the neck or the abdomen into the mediastinum

Excessive coughing Repeated bearing down to increase abdominal pressure (such as pushing during childbirth or a bowel movement) Sneezing Vomiting Rapid rises in altitude, SCUBA diving Tearing of the esophagus Tracheal tear Use of vevtilator Using inhaled recreational drugs such as crack cocaine

Symptom Severe substernal chest pain With radiation into the neck and arms Pain may worsen on breathing or swallowing With which disease it is likely to be confused ?

Physical examination reveals Subcutaneous emphysema in suprasternal notch small bubbles of air is felt under the skin of the chest, arms, or neck Hamman's sign (crunching or clicking noise synchronous with the heartbeat and best heard in the left lateral decubitus position) Diagnosis is confirmed with chest X ray

Pneumomediastinum

A previously healthy 18 year old male had chest pain of sudden onset. Heart sounds were normal but crunching and clicking sounds were heard over the left sternal border An ECG was normal

Usually no treatment is required Mediastinal air will be absorbed faster if the patient inspires high concentrations of oxygen Compression can be relieved with needle aspiration Surgery for tracheal or esophageal tear