A systematic review of Twiddler's syndrome: a hardware-related complication of deep brain stimulation.

Twiddler's syndrome (TS) is a hardware-related complication of deep brain stimulation which has not been well documented and is probably underreported. The objective of this study is to comprehensively describe TS by systematically reviewing the related literature. The methods include selecting the eligible studies based on the inclusion and exclusion criteria. Data about studies and TS were collected. A descriptive statistical analysis of the extracted data was performed. We found 18 eligible studies describing 23 patients with TS. The mean age of the 23 patients was 61.4 ± 15.9 years (range, 16-79 years.). The percentage of TS in the female population was 91.3% (females: 21/23). The incidence of postoperative TS was 1.4% (6 out of 437) per patient and 1.1% (8 out of 709) per extension wire. The mean time to clinical presentation was 9.9 ± 10.3 months (range, 0.5-36 months). Nineteen of the twenty-three patients presented with a rebound of previous symptoms. Twelve of the twenty-three patients had high impedance at the postoperative checkup of the DBS system. A plain X-ray indicated twisted extension wires in almost all these patients. All patients meeting the definition of postoperative device-related TS underwent revision surgery. TS is more prevalent in females. Based on the typical clinical symptoms (rebound of the previous symptoms, high impedance, and X-ray demonstration), the differential diagnosis can often be straightforward. TS should thus be taken into consideration when attempting to explain or rule out hardware malfunction. The timely recognition and proper revision of TS can prevent further serious damage.