Thymectomy
| Thymectomy | |
|---|---|
| ICD-9-CM | 07.8 |
| MeSH | D013934 |
A thymectomy is an operation to remove the thymus. It usually results in remission of myasthenia gravis with the help of medication including steroids.[1] However, this remission may not be permanent. Thymectomy is indicated when thymoma are present in the thymus. Anecdotal evidence suggests MG patients with no evidence of thymoma may still benefit from thymectomy, thus the procedure is (unless and until a much-discussed clinical survey ever reaches a contraindicatory conclusion) commonly prescribed.
Surgical approaches
There are a number of surgical approaches to the removal of the thymus gland: transternal (through the breast bone), transcervical (through a small neck incision), transthoracic (through one or both sides of the chest.)
- The transternal approach is most common and uses the same length-wise incision through the sternum (breast bone) used for most open-heart surgery. It is espoused by surgeons such as Alfred Jaretzki and is the most commonly performed procedure due to its relative simplicity.
- The transcervical approach is a less invasive procedure that allows for removal of the entire thymus gland through a small neck incision
There has been no difference in success in symptom improvement between the transsternal approach and the minimally invasive transcervical approach.[2]
Video-assisted approaches, such as laparoscopic surgery, are increasingly prescribed since the less invasive nature of the procedure strikes a balance with the lack of actual clinical evidence supporting thymectomy in non-thymomal cases.[3]
Impact of thymic loss
A thymectomy is mainly carried out in adults as the thymus loses most of its functional capacity after adolescence, but does retain a small portion of its function during adulthood. This is shown in the decreasing size of the thymus with increasing age after adolescence.[citation needed]
The role of the thymus prior to adolescence is for the processing and maturation of thymocytes, which become T-lymphocytes and are released into the circulation. They then populate the lymphoid organs for storage until needed. Removal of the thymus as an adult has little immediate effect on the immune system as its role has been completed.
Thymic hypoplasia as may be seen in DiGeorge syndrome results in no T-cell education, and therefore a severe compromise in T-cell-mediated and humoral responses.
See also
References
- ^ Müllges, Wolfgang; Stoll, Guido (2019-09-19). "Myasthenia gravis". Der Nervenarzt (in German). 90 (10). Springer Science and Business Media LLC: 1055–1066. doi:10.1007/s00115-019-00798-8. ISSN 0028-2804. PMID 31538208.
Myasthenia gravis (MG) is an autoimmune disorder caused by antibodies against acetylcholine receptors (AChR) or other structural proteins of the neuromuscular junction. This diminishes cholinergic transmission, thus leading to exercise-induced fatigue and sometimes manifest muscle weakness, including the bulbar and ocular musculature. The thymus plays a particular role in the pathophysiology of AChR antibody-positive MG, which can also manifest as a paraneoplastic disorder in the context of a thymoma.
- ^ Calhoun R, et al. (1999). "Results of transcervical thymectomy for myasthenia gravis in 100 consecutive patients". Annals of Surgery. 230 (4): 555–561. doi:10.1097/00000658-199910000-00011. PMC 1420904. PMID 10522725.
- ^ Ng, CS.; Wan, IY.; Yim, AP. (Jun 2010). "Video-assisted thoracic surgery thymectomy: the better approach". Ann Thorac Surg. 89 (6): S2135–41. doi:10.1016/j.athoracsur.2010.02.112. PMID 20493997.