Patients

All consecutive CFS patients (27–65 years old; 5 men, 1 woman) followed up in our outpatient clinic were recruited, and their demographic, clinical, and laboratory data were recorded (Table 1). CFS was defined by the presence of muscle cramps and fasciculations in the upper and lower limbs on the neurological exam. None of the patients had any electrolyte disturbance, another neuromuscular disorder, or clinical and electrophysiological evidence for anterior horn disease or another autoimmune disease. Cranial magnetic resonance imaging (MRI) was normal in all patients. They were screened for occult malignancy with thorax and abdominal computerized tomography (CT), tumor markers, and fludeoxyglucose positron emission tomography (Cases 1 and 5), and none of the patients were found to have a tumor. The study was approved by the Institutional Review Board, and all patients gave their consents.

Clinical, electrophysiological, and serological features of CFS patients

M: male; F: female; CBZ: carbamazepine; PRG: pregabalin; DTR: deep tendon reflexes; ↑: increased, vibration; ↓ LL: reduced vibration sense in the lower limbs; OAS: other autonomic symptoms; VGKC: uncharacterized voltage gated potassium channel antigens; CASPR2: contactin-associated protein-like 2; IST: immunosuppressive treatment; SSR: sympathetic skin response; RRIV: R-R interval variability; NCSs: nerve conduction studies; ADs: after-discharges; N: normal