Muthusamy Preetha, Matte Geneviève, Kosmorsky Gregory, Chémali Kamal R
Neuromuscular Department, Cleveland Clinic, Ohio 44004, USA.
Neurologist. 2011 Mar;17(2):86-8. doi: 10.1097/NRL.0b013e3181f83870.
Myasthenia gravis is an autoimmune disease, which commonly presents with extraocular muscle weakness, eyelid ptosis, bulbar dysfunction, and proximal limb weakness. We report an unusual differential diagnosis for myasthenia gravis.
A 56-year-old woman presented with worsening blurry vision, double vision, eyelid droopiness, slurred speech, and fatigable limb weakness, worsening over a 6-month period. On neurological examination, she showed dysarthric speech, ptosis, and proximal limb weakness with preserved reflexes. Myasthenia gravis was considered strongly, but serological and electrodiagnostic testing did not confirm the diagnosis of myasthenia gravis. At subsequent visits, the patient developed headaches and downbeating nystagmus, and a magnetic resonance imaging of the brain showed a Chiari type I malformation.
Chiari type I malformation is an unusual differential for sero-negative myasthenia gravis. Magnetic resonance imaging of the brain, carried out in patients with all classical signs and symptoms of myasthenia gravis, helps identify this anomaly. Headaches, although a classic feature of Chiari type I malformation, need not be an early manifestation. Eyelid ptosis as a manifestation of Chiari malformation has not been reported in the literature.
重症肌无力是一种自身免疫性疾病，通常表现为眼外肌无力、眼睑下垂、延髓功能障碍和近端肢体无力。我们报告一例重症肌无力不常见的鉴别诊断病例。
一名56岁女性出现视力模糊、复视、眼睑下垂、言语不清和肢体易疲劳性无力症状，且在6个月内逐渐加重。神经系统检查发现她存在构音障碍、眼睑下垂和近端肢体无力，但反射正常。高度怀疑为重症肌无力，但血清学和电诊断测试未确诊。在随后的就诊中，患者出现头痛和下跳性眼球震颤，脑部磁共振成像显示为Ⅰ型Chiari畸形。
Ⅰ型Chiari畸形是血清学阴性重症肌无力不常见的鉴别诊断疾病。对具有重症肌无力所有典型体征和症状的患者进行脑部磁共振成像检查，有助于识别这种异常情况。头痛虽是Ⅰ型Chiari畸形的典型特征，但不一定是早期表现。文献中尚未报道过以眼睑下垂作为Chiari畸形表现的病例。
