[Prognostic factors of myasthenic crisis after extended thymectomy in patients with generalized myasthenia gravis].

ABSTRACT

OBJECTIVE: To investigate the prognostic factors of myasthenic crisis after extended thymectomy in patients with generalized myasthenia gravis (MG). METHODS: Extended thymectomy was performed on 176 patients with generalized MG, 74 males and 102 females, aged 4 - 67, of which 36 experienced postoperative myasthenic crisis and required prolonged mechanical ventilation. The relations among the age, sex, preoperative course of disease, pathologic type of thymus, Osserman classification, history of infection during 1 month preoperatively, history of myasthenic crisis 1 month preoperatively, thymoma, preoperative daily dose of pyridostigmine, preoperative steroid use, operation time, intra-operative blood loss, and intra-operative pleura injury and postoperative myasthenia crisis were analyzed. RESULTS: Univariate analysis showed that bulbar symptoms (OR = 8.494, P = 0.001), history of myasthenic crisis 1 month preoperatively (OR = 5.667, P = 0.000), thymoma (OR = 2.147, P = 0.047), Osserman types III and IV (OR = 0.459, P = 0.000), history of infection during 1 month preoperatively (OR = 3.30, P = 0.038), large pre-operative dose of pyridostigmine (OR = 1.019, P = 0.001), long operation time (OR = 1.012, P = 0.034), and more blood loss (186 ml +/- 163 ml) (OR = 1.004, P = 0.012), were all prognostic factors or postoperative myasthenic crisis. However, multivariate logistic regression analysis revealed that preoperative bulbar symptoms (OR = 7.709, P = 0.003), history of infection during 1 month preoperatively (OR = 4.582, P = 0.037), history of myasthenic crisis 1 month preoperatively (OR = 4.526, P = 0.001, large pre-operative dose of pyridostigmine (OR = 1.016, P = 0.001) were prognostic factors of postoperative myasthenic crisis. CONCLUSION: Preoperative bulbar symptoms, history of preoperative myasthenic crisis, history of preoperative infection, and large preoperative dose of, pyridostigmine are all independent influencing factors of postoperative myasthenic crisis. Ample preoperative care may prevent postoperative myasthenic crisis in the patients with such factors.