Last year, futurist Elon Musk announced a new project: a medical research company called Neuralink set to develop a new generation of brain implant devices—which may, among other things, help us in the coming AI apocalypse. But evil robots aside, the devices first have to face a more nefarious foe: lightning.

Doctors in Slovenia report that a 66-year-old woman with an existing brain implant experienced a close call with the device after lightning struck her apartment building. The strike ruined the woman’s television and air conditioning unit and managed to switch off her brain implant. Luckily, the woman and her device were not otherwise harmed.

But in a report published this week in the Journal of Neurosurgery, the doctors say the situation could have easily been much worse, possibly zapping her brain or destroying her implant. They call for more precautions, such as surge protectors, as well as better awareness of the risks of lightning strikes with such implants—or deep brain stimulation (DBS) devices.

“In the future, DBS manufacturers’ safety recommendations should specifically mention the possibility of hazards from naturally generated electromagnetic interference, such as during thunderstorms,” they conclude.

DBS devices, such as the woman’s, are increasingly used to help treat neurological conditions like Parkinson’s, tremors, muscle spasms, epilepsy, and obsessive compulsive disorders. The devices work by placing electrodes in specific areas of the brain to deliver electrical impulses that are thought to help regulate aberrant electrical signals there—although it’s still unclear how exactly this works. The devices’ electrical impulses are generated by a pacemaker-like pulse generator implanted in the chest or torso, connected by wiring and powered by a battery. Some pulse generators’ batteries—including the woman’s—can be paired with an antenna-equipped recharger system that itself is charged using a standard wall plug.

Boom goes the DBS device

Luckily, at the time of the thunderstorm, the woman wasn’t charging her pulse generator or charging the recharger system, so none of her equipment was damaged. But the tremor in her neck—which the brain implant was effectively treating—returned about an hour after the storm. When she checked her device, she realized it wasn’t on and went to a clinic, fearing her device had been fried by the jolt.

Doctors there discovered that the implant was simply turned off and not harmed by the electrical blitz. They speculated that a safety system in her device (the Activa RC neurostimulator by Medtronic) kicked in during the storm, sensing the electromagnetic disturbance, and caused it to turn itself off. While this is a good fail-safe for the device, it could be devastating for patients who suddenly have debilitating symptoms return unexpectedly when their implants shut off.

The doctors call for DBS device users to always use surge protectors for the recharging systems, to avoid charging during thunderstorms, and to be aware of the risks from strong electrical magnetic interference, such as that from lightning, electrical substations, and MRI units. They note a case where a patient with a DBS device to treat Parkinson’s disease suffered “serious, permanent neurological injury” after their DBS electrode heated up during an MRI scan.

The warnings and cautionary tales will certainly have more juice as these types of devices become even more common—and expand in purpose. For now, Musk expects Neuralink’s proof-of-concept devices to be similar DBS devices to the woman's—that is, devices that use electric impulses to treat conditions such as depression and epilepsy. But his vision for the future is to create mesh-like interfaces—or neural laces—that wire up human brains directly to computers. These will help us do things like download thoughts and, perhaps, defend against wicked AI.

Journal of Neurosurgery, 2018. DOI:10.3171/2017.12.JNS172258 (About DOIs).