A 24-year-old woman presented with polyarthralgia, Raynaud phenomenon, sicca symptoms, and alopecia for 1 year; progressive weakness, numbness, and tingling in all extremities for 5 months; and exertional dyspnea and orthopnea for 1 month. Clinical examination revealed alopecia, maculopapular rashes, pedal edema, raised jugular venous pressure, tachycardia, tachypnea, muffled heart sounds, and bilateral basal crepitations. Neurological examination revealed myokymia in the masseter and temporalis muscles of both sides (Video); symmetric weakness of all 4 limbs involving the distal and proximal muscles equally; weakness of the trunk and neck muscles; hypotonia; global areflexia; and diminished touch, pain, temperature, vibration, and position sense in all extremities (distal more than proximal). She was unable to walk without support. Complete hemogram, liver, and kidney function tests; thyroid profile; and urine routine examination results were normal. Chest radiography showed an enlarged cardiac silhouette. Electrocardiography showed sinus tachycardia and low voltage complexes. Two-dimensional echocardiography showed moderate pericardial effusion. Abdominal ultrasound revealed hepatomegaly. Antinuclear anti–double-stranded DNA, antiribosomal P, and anti–Sjögren syndrome A antibodies were present in her serum. Serum C3 and C4 complement levels were low (36.0 mg/dL and 8.3 mg/dL, respectively [to convert to g/L, multiply by 0.01]). C-reactive protein was elevated (0.6 mg/dL [to convert to mg/L, multiply by 10]). Antiphospholipid antibodies were absent. Direct Coombs test results were negative. Schirmer test results were positive (right eye, 5 mm; left eye, 7 mm). Nerve conduction study showed prolonged distal latency (>150% of upper normal limit), reduced conduction velocity (<70% of lower normal limit), reduced sensory and compound motor action potential (<90% but >80% of lower normal limit), and prolonged F latency (>130% of upper normal limit) in all 4 limbs; absent H reflexes; and temporal dispersion in median, ulnar, and tibial nerves. Electromyography showed myokymic discharges in both masseters (Figure 1; Figure 2; Video). Electromyography–nerve conduction study of facial muscles and blink reflex were normal. Cerebrospinal fluid showed albuminocytological dissociation (7 cells, all mononuclear; protein, 0.11 g/dL [to convert to g/L, multiply by 10]; glucose, 67.03 mg/dL [to convert to mmol/L, multiply by 0.0555]). Magnetic resonance imaging of the brain and spine were normal. A diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) associated with systemic lupus erythematosus (SLE)-Sjögren overlap syndrome was made, and intravenous methylprednisolone (1000 mg/d for 5 days) was given, followed by oral prednisolone (1 mg/kg/d). Intravenous cyclophosphamide therapy (500 mg/m2 monthly for 6 months) was initiated. The patient made a good recovery and the myokymia subsided.