CT-guided percutaneous ethanol injection of the thymus for treatment of myasthenia gravis

This study was designed to validate the therapeutic effectiveness of CT-guided percutaneous ethanol injection of the thymus for the treatment of myasthenia gravis.

The subjects were 45 patients with myasthenia gravis. The diagnosis was determined by the patients' histories, physical findings, neostigmine tests, and morphologic changes. According to the Osserman classification, the 45 patients with myasthenia gravis were classified as stage I (n = 26), stage III (n = 13), and stage IV (n = 6). A 21- or 22-gauge needle was inserted into the thymus under CT guidance, and then ethanol was injected step by step until it was distributed throughout the whole thymoma, the hyperplasia of the thymus, or the normal thymus. The amount of ethanol injected ranged from 2 to 13 mL, with a mean of 7 mL.

CT follow-up at 3-4 weeks showed that the thymus or thymoma was completely or mostly necrotized. CT follow-up at 3 months showed that the vertical, transverse, and anteroposterior dimensions of the thymus in all 45 myasthenia gravis patients decreased by 59.2%, 68.6%, and 73.2%, respectively, compared with those before percutaneous ethanol injection treatment. The therapeutic effect was observable clinically 2 days after treatment in 44 patients, including 36 patients who were able to open their eyes after treatment. A 5-year follow-up study showed that the condition markedly improved in 35 patients, improved in nine patients, and failed to improve in one patient who did not respond to the treatment. After treatment, 37 patients presented with low-grade fever (range, 37.3-37.7 degrees C; mean, 37.5 degrees C), which resolved 3 days later without treatment; all 45 patients complained of mild retrosternal pain after ethanol injection.

The therapeutic effect of CT-guided percutaneous ethanol injection into the thymus of patients with myasthenia gravis is definite. This procedure is safe and has low morbidity. CT-guided percutaneous ethanol injection is a minimally invasive alternative treatment for myasthenia gravis.