Twiddler (or Not) Syndrome: Questioning etiology for an uncommon form of hardware malfunction in deep brain stimulation

BACKGROUND: Hardware failure or malfunction after deep brain stimulation is an infrequent but costly occurrence with currently available systems. CASE DESCRIPTION: The authors present the case of a 65-year-old female patient with predominantly tremoric Parkinson's disease who, 4 months after bilateral subthalamic nucleus stimulation with very good clinical results, began to display signs of recurrent disease and an increasingly smaller response to stimulation. Radiological studies, changes in electrode impedance and surgical findings and results established the diagnosis of Twiddler syndrome. Close patient follow-up, lack of a psychiatric history and physical examination findings were, however, contrary to the previously described causative mechanism. CONCLUSION: The clinical and radiological setup of Twiddler syndrome must be readily recognized. Its causative mechanism should remain under discussion, and intraoperative technical details may help to explain its occurrence.