Complex Case

Deep Brain Stimulation
 for Tourette Syndrome

A 25-year-old male with Tourette syndrome presented to Alon Mogilner, MD, PhD, director of the Center for Neuromodulation, and a specialist in deep brain stimulation (DBS) in NYU Langone’s Department of Neurosurgery.

The patient was exhibiting tics, tensing and grunting that were so frequent and severe, and had responded so poorly to conventional treatment, that he couldn’t hold a job or attend classes.

As part of the center’s standard clinical evaluation process, the patient was also seen by Michael Pourfar, MD, an NYU Langone neurologist, co-director of the Center for Neuromodulation and Dr. Mogilner’s clinical partner on all neuromodulation cases. Tourette’s symptoms can usually be controlled with behavioral or pharmaceutical interventions, and tend to lessen in severity over time as children and teenagers reach adulthood, thus rendering DBS a treatment of last resort for Tourette’s. Based on the physician team’s two-pronged assessment and the severity of this patient’s case, it was agreed that he was an appropriate candidate for DBS surgery.

Two weeks prior to the surgery, an MRI was taken of the patient’s head in order to locate the thalamus, the general target area for the stimulation. On the day of surgery, the patient's head was placed inside a frame to provide stereotactic image guidance to the target area. Dr. Mogilner drilled two holes, one on either side of the head, and passed a probe through the skull opening and the brain to the centromedian nucleus of the thalamus, a structure that is part of an abnormal circuit in Tourette syndrome. He then temporarily placed a recording microelectrode—a probe with a tip the width of a strand of hair—into the brain to record the activity of individual neurons. This was done in order to detect the irregular cellular electrical activity known as “bursting”: brief, rapid oscillations superimposed on slower, more regular oscillations. Abnormal bursting activity in the thalamus is associated with Tourette’s, Parkinson’s, chronic pain and other neurological conditions, but not usually with normal brain function. The recording process was repeated with different neurons until Dr. Mogilner and Dr. Pourfar, also present in the operating room during all neuromodulation procedures, had determined the appropriate locale for the final electrode.

case2_4aPreoperative MRI to locate general target area.

Dr. Mogilner then inserted the permanent stimulating device—a tiny cylinder 1.3mm wide, with four attached electrodes. To confirm that the cylinder was in the right location, he applied a voltage through the electrodes and looked carefully for any signs that the stimulation was leading to any facial or other movements from the patient. The patient, who remained awake, was also asked if he felt anything unusual, such as pain, dizziness or double vision. Any such movements or sensations would suggest the device was not in the ideal location, since the goal is to isolate the source of Tourette’s tics without having other effect. No such side effects were detected, so the electrode was left in place. “Finding the right location is like trying to find a tiny region in a small country where the inhabitants speak an unusual dialect of a language,” says Dr. Mogilner. “The MRI and a surgeon’s knowledge of anatomy are like a map of a foreign country. It can get you close, but to know you’re there you have to have to talk to the locals.”

 

case2_4bCT scan after implantation of electrodes.

The day after the brain surgery, the patient underwent a second surgery to implant two pacemakers under the skin in the chest, which were connected to the brain electrodes via extension wires in the neck, and he returned home. Two weeks later he returned to the office so that Dr. Pourfar could program into the device a variety of signal strengths and patterns emitted by different combinations of the implanted device’s four electrodes. That allowed finding the combination of electrodes and signals providing maximum relief from the Tourette’s symptoms. Six weeks later the patient returned for a smaller adjustment. The final result: The tics and other Tourette’s symptoms were reduced by 90 percent in the patient, who is today working and attending part-time classes. “It had been years of hearing that he just needed to wait for the symptoms to become milder,” says Dr. Mogilner. “But after this procedure he was able to reclaim his life right away.”