抗γ-氨基丁酸B型受体抗体脑炎合并顽固性低钠血症：小细胞肺癌的临床警示与治疗探索

Anti-γ-aminobutyric acid B receptor antibody encephalitis with refractory hyponatremia: clinical warning and therapeutic exploration in small cell lung carcinoma

摘要:

该文回顾性分析1例68岁女性患者的临床资料。患者以反复癫痫发作、认知功能减退为首发表现，合并顽固性低钠血症。患者血清及脑脊液抗γ-氨基丁酸B型受体（GABABR）抗体均阳性（效价1∶100）。胸部计算机体层成像及正电子发射计算机体层成像提示右肺上叶结节合并纵隔淋巴结肿大，诊断为小细胞肺癌（SCLC，T4N2M0Ⅲb期）。经免疫治疗（静脉注射免疫球蛋白+甲泼尼龙冲击）及抗癫痫治疗后，神经症状改善，但低钠血症有反复，加用口服托伐普坦（15 mg/d）后血钠维持在118.5～138.0 mmol/L。抗GABABR抗体脑炎合并SCLC及顽固性低钠血症的三联征极为罕见。低钠血症可作为早期副肿瘤信号，托伐普坦在抗肿瘤效果有限时，仍可安全有效纠正低钠。

Abstract:

This article performs a retrospective analysis of the clinical data of a female patient aged 68 years. The patient had the initial manifestation of recurrent epileptic seizures and cognitive decline， with the comorbidity of refractory hyponatremia. Anti-γ-aminobutyric acid B receptor （GABABR） antibody was detected in both serum and cerebrospinal fluid， with a titer of 1∶100. Chest computed tomography and positron emission tomography-computed tomography revealed a nodule in the right upper lobe of the lung， with the presence of mediastinal lymphadenopathy. Therefore， the patient was diagnosed with small cell lung carcinoma （SCLC） （T4N2M0 stage Ⅲb）. Neurological symptoms were improved after immunotherapy （intravenous injection of immunoglobulin combined with methylprednisolone pulse therapy） and antiepileptic therapy. However， hyponatremia recurred after treatment； after oral administration of tolvaptan （15 mg/d）， serum sodium was maintained at 118.5 to 138.0 mmol/L. The triad of anti-GABABR encephalitis comorbid with SCLC and refractory hyponatremia is extremely rare. Hyponatremia may be used as an early paraneoplastic signal， and tolvaptan remains safe and effective in correcting hyponatremia even when the antitumor response is limited.