Applying electricity to the brain with deep-brain stimulation could ease Parkinson’s disease, pain, depression, and more.
A Switch for the Brain
The video is brief, just a couple of minutes, but it’s reality TV as riveting as anything you’ll ever see. A man in his mid-50s, affable, articulate, faces the camera and talks a bit about a medical procedure he’s had. He holds in his hand what looks like a remote control. “I’ll turn myself off now,” he says mildly. The man presses a button on the controller, a beep sounds, and his right arm starts to shake, then to flap violently. It’s as if a biological hurricane has engulfed him, or perhaps it’s that his arm is made of straw and some evil sprite is waving it about. With effort, the man grasps the malfunctioning right arm with his left hand and slowly, firmly, subdues the commotion, as if he were calming a child in the throes of a temper tantrum. He’s breathing hard, and it’s clear he can’t keep it up much longer. With an almost desperate gesture, he reaches out for the controller and manages to press the button again. There’s a soft beep, and suddenly it’s over. He’s fine.
Composed, violently afflicted, then composed again. All with the flick of a switch. As before-and-after moments go, this one is potent, verging on the miraculous. It’s the kind of thing you’d expect to witness under a revival tent, not in the neurology ward of a British hospital. Once you’ve seen it, you’ll have an indelible image of Parkinson’s disease. The word “tremor” doesn’t convey what can happen to people—the way they are thrashed and harassed by their own bodies. But this scene, involving a patient of ours, informs viewers about more than a disease; it’s a vivid window onto a powerful medical technology known as deep-brain stimulation (you can watch the video at www.kringelbach.dk/nrn).
Sudden, radical transformation is the hallmark of deep-brain stimulation. The treatment, essentially a pacemaker for the brain, consists of a deceptively simple two-part device. A surgeon threads one or two thin wires into carefully selected locations deep within the brain, then inserts a small battery just underneath the skin near the collarbone. Pulses of electricity travel from the battery to four electrodes situated at the tip of each wire. The effects are instantaneous, usually appearing while the patient is still on the operating table—the quieting of a tremor, the ability to walk again or, in some patients with otherwise treatment-resistant depression, a renewed energy for life.
