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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/02/06 21:34:55」(JST)

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A thymectomy is an operation to remove the thymus. It usually results in remission of myasthenia gravis with the help of medication including steroids. However, this remission may not be permanent.

Surgical approaches

There are a number of surgical approaches to the removal of the thymus gland: transsternal (through the breast bone), transcervical (through a small neck incision), transthoracic (through one or both sides of the chest.)

The transsternal 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. It has been popularized by Joel Cooper. Because of its increased technical demands, it is performed by only a relative few surgeons in North America: Joel Cooper (University of Pennsylvania; Philadelphia, Pennsylvania), M. Blair Marshall (Georgetown University; Washington, DC), Bryan Meyers (Washington University; St. Louis, Missouri), Stephen Cassivi (Mayo Clinic; Rochester, Minnesota), Sudhir Sundaresan (University of Ottawa; Ottawa, Canada), Shaf Keshavjee (University of Toronto; Toronto, Canada), Michael Rutter (Cincinnati Childrens Hospital, Ohio)

Interestingly, there has been no difference in success in symptom improvement between the transsternal approach and the minimally invasive transcervical approach.^[1]

Video assisted approaches have been described.^[2]

Impact of thymic loss

A thymectomy is mainly carried out in an adult. This is because 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.

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.

References

^ 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. //www.ncbi.nlm.nih.gov/pmc/articles/PMC1420904/.
^ 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.

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1. 重症筋無力症に対する胸腺摘出術 thymectomy for myasthenia gravis
2. 重症筋無力症患者に対する麻酔 anesthesia for the patient with myasthenia gravis
3. 重症筋無力症の治療 treatment of myasthenia gravis
4. 胸腺腫および胸腺癌の臨床症状およびマネージメント clinical presentation and management of thymoma and thymic carcinoma
5. 重症筋無力症の病因 pathogenesis of myasthenia gravis

English Journal

Clinical outcome and predictive factors of postoperative myasthenic crisis in 173 thymomatous myasthenia gravis patients.

Li Y1, Wang H1, Chen P2, Chen Z3, Su C4, Luo C5, Feng H2, Liu W2.
The International journal of neuroscience.Int J Neurosci.2018 Feb;128(2):103-109. doi: 10.1080/00207454.2017.1366905. Epub 2017 Oct 2.
PMID 28803488

A bilateral approach to extended thymectomy using the da Vinci Surgical System for patients with myasthenia gravis.

Kawaguchi K1, Fukui T2, Nakamura S2, Taniguchi T2,3, Yokoi K2.
Surgery today.Surg Today.2018 Feb;48(2):195-199. doi: 10.1007/s00595-017-1567-x. Epub 2017 Jul 11.
PMID 28699002

Myasthenia gravis and infectious disease.

Gilhus NE1,2, Romi F3, Hong Y4, Skeie GO3.
Journal of neurology.J Neurol.2018 Jan 25. doi: 10.1007/s00415-018-8751-9. [Epub ahead of print]
PMID 29372387

Japanese Journal

Splenectomy prolongs the effects of corticosteroids in mouse models of autoimmune hepatitis.

Maruoka Ryutaro,Aoki Nobuhiro,Kido Masahiro,Iwamoto Satoru,Nishiura Hisayo,Ikeda Aki,Chiba Tsutomu,Watanabe Norihiko
Gastroenterology 145(1), 209-220.e9, 2013-07-00
… BALB/c mice with disruption of programmed cell death 1 (PD-1^{–/–} mice) that undergo thymectomy 3 days after birth develop a deregulated immune system, have reduced numbers of Foxp3^+ regulatory T cells, and develop fulminant hepatic failure that resembles acute-onset AIH in humans. … [Methods]After thymectomy, BALB/c PD-1^{–/–} mice were treated with dexamethasone before or after induction of AIH; … Neonatal C57BL/6 PD-1^{–/–} mice underwent thymectomy to create a model of chronic AIH. …
NAID 120005315980

Ectopic Cervical Thymoma Accompanied by Goods Syndrome

Nagoya Akihiro,Kanzaki Ryu,Nakagiri Tomoyuki,Inoue Masayoshi,Susaki Yoshiyuki,Inoue Shinya,Okumura Meinoshin
Annals of Thoracic and Cardiovascular Surgery, 2013
… After the intravenous infusion of gammaglobulin, tumor resection and a subsequent video-assisted thoracoscopic extended thymectomy were performed. …
NAID 130003377806

針生検による穿刺経路播種をきたした胸腺腫の1例

岡崎敏昌,塩野知志,安孫子正美,佐藤徹
日本呼吸器外科学会雑誌 27(5), 589-593, 2013
症例は78歳男性．2004年8月前立腺癌経過観察中のCTで前縦隔腫瘍を指摘された．胸部X線で右肺門部に突出する腫瘤影，CTで前縦隔に60×28 mmの石灰化を伴う腫瘤を認め，超音波ガイド下針生検を施行した．胸腺腫との診断が得られ，胸腺摘出術を施行した．術後病理は胸腺腫WHO type ABで正岡II期であった．2008年7月から右前胸部に3 cmの硬い無痛性腫瘤が出現した．CTでは前胸壁に45×1 …
NAID 130003368802