An unusual case of deep brain stimulation-induced insomnia.

Cervical dystonia (CD) is the most common adult-onset focal dystonia. Non-motor symptoms, such as insomnia, can greatly impact the quality of life in CD patients. CD can be treated with deep brain stimulation (DBS) of the globus pallidus pars interna (GPi) although its effect on sleep is not yet fully understood. Here, we report a case of a 66-year-old female patient with cervical dystonia, who developed an unusual form of insomnia following her DBS surgery. Our patient reported recurrent episodes of visual symptoms (flashing lights), which would often wake her up at night. Following surgical revision of the extension wire, these visual symptoms completely resolved. This case provides an example of impedance oscillations caused by pressure on the pillow, which resulted in irregular delivery of current (according to Ohm's law) and recruitment of optic tract fibers secondary to excessive current.