Mediastinal shift
| Mediastinal shift | |
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| Left tension pneumothorax with a large, well-demarcated area devoid of lung markings with tracheal deviation and movement of the heart away from the affected side. |
Mediastinal shift is the deviation of the mediastinal structures towards one side of the chest cavity, usually seen on chest radiograph. It indicates a severe asymmetry of intrathoracic pressures.[1] Mediastinal shift may be caused by volume expansion on one side of the thorax ("push forces"), volume loss on one side of the thorax ("pull forces"), mediastinal masses and vertebral or chest wall abnormalities.[2] Another radiologic sign, which is a component of mediastinal shift, is tracheal deviation. Tracheal deviation, with the trachea located in the superior mediastinum, is an indicator of upper mediastinal shift while a shift in the position of the heart, located within the middle mediastinum, represents a lower mediastinal shift.[3][4]
Notable examples of mediastinal shift
Tension pneumothorax
An emergent condition classically presenting with mediastinal shift is tension pneumothorax. In this condition air fills the pleural cavity outside the lung, between the lung and chest wall, causing collapse of the lung. Forces are transmitted to the mediastinum and effectively "push" the mediastinal structures to the opposite, contralateral, side of the chest cavity.[5]
Pleural effusion
Typically a pleural effusion, an accumulation of fluid within the pleural cavity, will "push" the mediastinal structures to the contralateral side of the chest cavity. However, should the mediastinal structures remain midline or "pulled" to the same, ipsilateral, side of a large pleural effusion then underlying lung collapse causing ipsilateral "pull forces" should be suspected. This can occur secondary to a tumor obstructing a bronchus and causing lung collapse.[3]
Hemothorax
Hemothorax, or accumulation of blood in the pleural space can result from trauma or surgical procedures in the chest. This accumulation of blood can grow large enough to compress the lung and push away other structures in the chest, thus causing a mediastinal shift.[6] On a chest x-ray, a hemothorax can appear similarly to a pleural effusion with blunting of the pleural recess and white out of normal lung zones.[7] In the setting of traumatic chest injury, rib fractures are also commonly observed on x-ray. [8]
Masses
Masses such as tumors can also cause compression and displacement of mediastinal structures. There are various mediastinal tumors and they are classified by their location in the chest. Notable examples include include germ cell tumors and lymphomas.[9] Teratomas are a class of germ cell tumors that arise in the chest due to failure of germ cell migration during development. They can expand to large sizes and cause hemopytsis and pleural effusion. Radiographic features of teratomas typically include fluid and fat but also muscle, teeth, and bones inside the mass.[10]
Infection
An infection or inflammation of the mediastinum is referred to as mediastinitis. Etiologies include trauma, esophageal rupture, thoracic surgery, and descending infection from the oropharynx. Notably, post-operative mediastinitis is regarded as the most common etiology. An infection of the thoracic cavity is life threatening and therefore requires urgent diagnosis and treatment.[3] Typical chest x-ray signs include mediastinal widening, pneumomediastinum, and pleural effusion. Computed tomography or magnetic resonance imaging are often used to get a fuller picture of the infection.[3][11]
Fetal conditions
Mediastinal shift may be detected on antenatal ultrasound in certain fetal conditions.[12]
References
- ^ Reed, James C. (2018). Chest radiology: patterns and differential diagnoses (Seventh ed.). Philadelphia, PA: Elsevier. ISBN 9780323510219. OCLC 1012134513.
- ^ "Mediastinal Position". www.meddean.luc.edu. Retrieved 2024-02-21.
- ^ a b c d Khajotia, R. (2012). "Respiratory Clinics: MEDIASTINAL SHIFT: A SIGN OF SIGNIFICANT CLINICAL AND RADIOLOGICAL IMPORTANCE IN DIAGNOSIS OF MALIGNANT PLEURAL EFFUSION". Malaysian Family Physician. 7 (1): 34–36. ISSN 1985-207X. PMC 4170449. PMID 25606244. Cite error: The named reference ":0" was defined multiple times with different content (see the help page).
- ^ Stoddard, Nathan; Heil, Jenna R.; Lowery, David R. (2024), "Anatomy, Thorax, Mediastinum", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30969641, retrieved 2024-02-21
- ^ Jalota Sahota, Ruchi; Sayad, Edouard (2024), "Tension Pneumothorax", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 32644516, retrieved 2024-02-21
- ^ Taghavi, Sharven; Askari, Reza (2024), "Mediastinal Trauma", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30252287, retrieved 2024-03-06
- ^ Salim, Shihas; Ganeshram, Prasanthi; Patel, Amish Dilip; Kumar, Anita A.; Vemuri, Divya; Jeyachandran, Vijay; Rajamanickam, Deepan; Shantha, Ghanshyam Palamaner Subash (2008-10-07). "Unilateral hemothorax in a 46 year old South Indian male due to a giant arteriovenous hemodialysis fistula: a case report". Cases Journal. 1 (1): 225. doi:10.1186/1757-1626-1-225. ISSN 1757-1626. PMC 2567296. PMID 18840271.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Kim, Michelle; Moore, James E. (2020). "Chest Trauma: Current Recommendations for Rib Fractures, Pneumothorax, and Other Injuries". Current Anesthesiology Reports. 10 (1): 61–68. doi:10.1007/s40140-020-00374-w. ISSN 1523-3855. PMC 7223697. PMID 32435162.
- ^ Ghigna, Maria-Rosa; Montpreville, Vincent Thomas de (2021-12-31). "Mediastinal tumours and pseudo-tumours: a comprehensive review with emphasis on multidisciplinary approach". European Respiratory Review. 30 (162). doi:10.1183/16000617.0309-2020. ISSN 0905-9180. PMID 34615701.
- ^ Jilani, Talha N.; Killeen, Robert B.; Siddiqui, Abdul H. (2024), "Mediastinal Cancer", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 30020603, retrieved 2024-03-06
- ^ Sirakaya, Mert. "Mediastinitis | Radiology Reference Article | Radiopaedia.org". Radiopaedia. Retrieved 2024-03-06.
- ^ Colombani, M.; Rubesova, E.; Potier, A.; Quarello, E.; Barth, R.A.; Devred, P.; Petit, P.; Gorincour, G. (February 2011). "Conduite à tenir devant une déviation médiastinale fœtale : une approche pratique". Journal de Radiologie. 92 (2): 118–124. doi:10.1016/j.jradio.2010.12.002. PMID 21352743.
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