The government on Friday approved a new therapy for the severely depressed who have run out of treatment options: a pacemaker-like implant that sends tiny electric shocks to the brain.
The Food and Drug Administration’s clearance opens Cyberonics Inc.’s vagus nerve stimulator, or VNS, as a potential treatment for an estimated 4 million Americans with hard-to-treat depression — despite controversy over whether it’s really been proven to work.
“These are patients pretty much at the end of the line in terms of what treatment options are available to them,” said FDA medical device chief Dr. Daniel Schultz, who said he personally was persuaded by Cyberonics’ research despite initial skepticism within his agency.
The pacemaker-like implant has been sold since 1997 to control intractable epilepsy, a much smaller market.
A generator the size of a pocket watch is implanted into the chest. Wires snake up the neck to the vagus nerve, delivering tiny electric shocks through that nerve and into a region of the brain thought to play a role in mood.
Cyberonics began a 200-patient study to see whether VNS could treat depression patients not adequately helped by other therapies. An FDA review last year found no difference after three months of implant treatment. Cyberonics argued that a year later, a significant number of the VNS recipients had had their depression ease.
That yearlong follow-up hadn’t been done according to standard scientific procedures — it wasn’t a randomized controlled study — and thus critics questioned its validity.
Cyberonics continued to track the VNS recipients, and two years later a third of patients in the original study had experienced some response and between 17 percent and 20 percent were in remission, Schultz said, evidence he ultimately found persuasive.
Still, critics have complained that without a comparison group, it’s unclear if the implant really helped or the depression eased for some other reason.
Schultz said there are some safety warnings. The chief risk: More than half of patients in the depression study experienced at least temporary voice alterations — a hoarseness or raspiness, or voice “breaks” — that seem to persist in a significant number, he said.
Other complications include difficulty breathing or swallowing, he said. Deaths have been reported among some epilepsy patients who have a VNS implant, but Schultz said there was no sign of increased deaths in the depression study.