Most reports of Taser-related side-effects have concentrated on cardiac complications. (Toby Talbot/Canadian Press/AP)

A police officer who was mistakenly hit in the head by a stun gun suffered seizures, Canadian doctors reported on Monday.

The officer was in his 30s and previously in good health. He was hit by a Taser shot meant for a suspect involved in a police chase, Dr. Richard Wennberg and co-authors from Toronto Western Hospital and the University of Toronto reported in the Canadian Medical Association Journal.

"Until now, most reports of Taser-related adverse events have understandably concentrated on cardiac complications associated with shots to the chest," the study's authors said in their case report.

"Our report shows that a Taser shot to the head may result in brain-specific complications. It also suggests that seizure should be added to the list of Taser-related adverse events."

Taser stun guns are manufactured by Taser International Inc. in Scottsdale, Ariz. and are used by law enforcement personnel to incapacitate people with an electric shock.

The stun gun was fired once, sending two barbed darts into the officer's upper back and back of the head, according to police records.

The report didn't specify what police force the man was from.

Not the usual symptoms

After the officer was hit, he collapsed, lost consciousness and was not breathing, the doctors reported.

His eyes rolled upward, he was foaming at the mouth and his arms and legs jerked for about one minute. He was confused for several minutes.

These symptoms distinguish the episode from the usual, short-term incapacitation induced by stun guns, the researchers said.

Wennberg said stun guns pack about the same jolt used to induce seizures in electroshock therapy, which is used to treat severe depression.

A neurological assessment of the patient diagnosed mild traumatic brain injury and post-concussion syndrome related to the head impact from the Taser shot or falling to the ground during the seizure.

The patient has not had any more seizures since the incident more than one year ago.

He continues to have symptoms of anxiety, difficulties concentrating, irritability, dizziness and persistent headaches, the researchers said in describing his treatment.

Company warns of seizure risk

Taser International warns that stun guns should not target the head.

"We do, both in training and warnings, make mention that the head should not be targeted," spokesman Peter Holran said in a statement to the Canadian Press.

"Taser International is aware of a few incidents during training in which an officer experienced a seizure following a hit by a Taser device."

Those incidents were not written up in medical reports. But the company's document Product Warnings: Law Enforcement clearly warns against targeting sensitive areas such as the head and further states that the risk of a seizure "may be heightened if electrical stimuli or current passes through the head region."

The company said it did not receive an advance copy of the case report, and will review it.

With files from Canadian Press