Generalized tonic-clonic seizure after a taser shot to the head

March 17, 2009
Canadian Medical Association Journal

Esther T. Bui, MD, Myra Sourkes, MD and Richard Wennberg, MD
From the Division of Neurology, Krembil Neuroscience Centre, University Health Network, Toronto Western Hospital, University of Toronto, Toronto, Ont.

Correspondence to: Dr. Richard Wennberg, Toronto Western Hospital, Ste. 5W444, 399 Bathurst St., Toronto ON M5T 2S8; fax 416 603-5768; r.wennberg@utoronto.ca

Abstract

During a police chase on foot, a previously well police officer was hit mistakenly by a taser shot meant for the suspect. The taser gun had been fired once, sending 2 barbed darts into his upper back and occiput. Within seconds, the officer collapsed and experienced a generalized tonic-clonic seizure with loss of consciousness and postictal confusion. Subsequent magnetic resonance imaging scans of the head and electroencephalograms were normal. The patient has experienced no recurrence of seizure over more than a year of follow-up. This report shows that a taser shot to the head may result in a brain-specific complication such as generalized tonic-clonic seizure. It also suggests that seizure should be considered an adverse event related to taser use.

The taser stun gun, manufactured by Taser International in Scottsdale, Arizona, is a weapon used increasingly among law enforcement personnel to temporarily incapacitate detainees. Questions have arisen in both the scientific literature and the lay press about the device's safety.1–3 In this article, we report the occurrence of a generalized tonic-clonic seizure in a person who received a taser shot to the head.

Case report

The patient was a previously well police officer in his 30s who took part in a police chase involving a suspected robber. He and a colleague cornered the suspect, who initially appeared to surrender but then attempted an escape. The officer had begun to chase the suspect on foot when he experienced a sudden, severe pain in the back of his head. He later described the moment as feeling like he had been "hit by a bat." He recalled letting out a brief gasp before losing consciousness. He had no recollection of falling to the ground on top of the suspect. Police records indicate that the officer's colleague had fired a taser shot meant for the suspect but that the 2 copper darts had instead struck the officer in the occiput and upper back. The officer had been wearing an armoured vest. Immediately after being shot, he was found by his colleague to be unresponsive and foaming at the mouth. His eyes were rolled upward and he had generalized tonic-clonic movements with apnea lasting for about 1 minute. He did not have urinary incontinence. Postictally, he was initially confused and combative. Emergency medical services personnel were able to restrain him. They recorded a Glasgow Coma Score of 9 within 5 minutes after arrival; 5 minutes later, his score was 13.

The patient's next memory was of being in the emergency department. During this period, he felt as if he were in "a bad dream." As he gradually regained orientation over the next few hours, he became aware of thoracic tightness that was aggravated by deep breaths, and a severe headache. He was monitored overnight, then discharged in stable condition.

The patient had no history of febrile or unprovoked seizures, head injuries, headaches, meningitis or encephalitis. He had no family history of seizures or of other neurologic or psychiatric conditions. His developmental history was normal. He was not taking any medications.

The results of a general physical and neurologic examination were normal. Results of routine blood tests were unremarkable except for an elevated leukocyte count of 12.9 (normal 3.6–11.0) x 109/L 30 minutes after the event (decreasing to 11.2 x 109/L 5 hours later) and an elevated serum creatine kinase level of 580 (normal < 232) U/L.

The patient returned to full-time work 5 days after the incident. He experienced persistent headaches, dizziness, back pain and chest tightness. Magnetic resonance imaging scans of the head (1.5 and 3 Tesla) as well as routine and 24-hour ambulatory electroencephalography were performed 1, 2 and 12 months after the seizure. All findings were normal.

A diagnosis of mild traumatic brain injury (concussion), in addition to provoked seizure, was considered after a neurologic consultation during assessment of the patient at a rehabilitation centre 6 months after injury. A psychiatric consultation 7 months after injury suggested an Axis I diagnosis of adjustment disorder with depressed and anxious mood. Formal neuropsychological testing performed 9 months after injury showed no definite evidence of cognitive impairment in any domain.

The patient has not had further seizures since the injury more than 1 year ago. His symptoms of anxiety, difficulties concentrating, irritability, nonspecific dizziness and persistent headaches have not completely resolved. Treatment trials have included amitriptyline 50 mg nightly, topiramate 25 mg nightly, escitalopram 10 mg nightly, almotriptan 12.5 mg as needed and ibuprofen 200–400 mg as needed.


Comments

A taser stun gun is a device designed to temporarily immobilize a human target by delivering a direct-current type of shock through 2 barbed copper darts. The shock causes involuntary muscle contraction. Neuromuscular transmission is thought to be affected primarily at the level of the peripheral motor nerve, although studies have shown that stimulation of the spinal cord may occur with dart penetration as far away as the anterior torso.4,5 The muscle contraction induced by tasers is typically tonic, with retained consciousness, no clonic movements and no postictal confusion.4 The manufacturer's website estimates that a single shot lasts about 5 seconds, delivers 19 pulses per second with a typical charge of 100 microcoulombs per pulse, generates an average net current of 2 milliamperes and has an estimated peak voltage of 1300 volts.6

The data are sparse on how this device may affect the central nervous system. A case has been reported involving intracranial penetration by a taser dart with loss of consciousness for 5 minutes.7 The person who had been struck recovered shortly afterward with a mild headache. No details were reported on whether a seizure occurred, although only 1 of the 2 darts struck the patient.7 Another case report describes cranial penetration by a taser dart (with the second dart found in a hair braid) with transient decreased consciousness; no further details were given.5 Other reports of secondary loss of consciousness related to taser shots have involved only cases of severe traumatic head injuries that resulted from falls during neuromuscular incapacitation.5

The description by witnesses of the event involving our patient is most compatible with a generalized tonic-clonic seizure. The loss of consciousness, clonic movements, foaming at the mouth and postictal confusion experienced by our patient differentiate the episode from the usual transient incapacitation induced by tasers. The taser current that passed to his brain from the dart in the occiput probably provoked the seizure directly, with a mechanism akin to that of seizures induced by electroconvulsive therapy. In electroconvulsive therapy, an initial charge of 38–60 millicoulombs is used, according to therapeutic protocol in the United States.8 It is plausible that a copper dart penetrating the scalp and discharging 95 pulses of 100 microcoulombs each could trigger a generalized convulsion.

Given previous case reports of taser-induced cardiac arrhythmias, one could speculate that an initial induced cardiac arrhythmia and a secondary hypoxic seizure, or convulsive syncope, occurred in our case. Convulsive syncope is believed to result from reticular disinhibition in the brainstem resulting from hypoxia-induced cortical dysfunction.9 However, this mechanism seems unlikely in this case, especially given that the points of impact of the taser darts were over the head and upper back and not the heart.

Even less likely is the possibility that the convulsion was induced by a concussion resulting from the direct physical impact of the darts or impact of the patient's head on the ground. Our patient's prolonged period of unresponsiveness and subsequent postictal confusion is not typical of a concussive convulsion, which is usually characterized by immediate onset and a rapid recovery that takes place over a few minutes.10 On the other hand, we believe that his persistent symptoms after injury may be attributable in part to postconcussion syndrome, presumably secondary to mild traumatic brain injury caused by either the impact of the taser dart or the subsequent fall to the ground during the provoked seizure.

Until now, most reports of taser-related adverse events have understandably concentrated on cardiac complications associated with shots to the chest.2 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.

Footnotes

Une version française de ce résumé est disponible à l'adresse www.cmaj.ca/cgi/content/full/180/6/625/DC1

This article has been peer reviewed.

Contributors: All of the authors were involved in the preparation of this manuscript and approved the final version submitted for publication.

Competing interests: None declared.

REFERENCES

Stanbrook MB, Hébert PC, Kale R, et al. Tasers in medicine: an irreverent call for proposals [editorial]. CMAJ 2008;178:1401-2.[Free Full Text]

Nanthakumar K, Massé S, Umapathy K, et al. Cardiac stimulation with high voltage discharge from stun guns. CMAJ 2008;178:1451-7.[Abstract/Free Full Text]

Hume M, Dhillon S. Questions hang over taser death. Globe and Mail [Toronto] 2007 Oct. 26; Available: www.theglobeandmail.com/servlet/story/RTGAM.20071025.wtaser1026/BNStory/National/home (accessed 2009 Jan. 7).

Sun H, Webster JG. Estimating neuromuscular stimulation within the human torso with Taser stimulus. Phys Med Biol 2007;52:6401-11.[CrossRef][Medline]

Mangus BE, Shen LY, Helmer SD, et al. Taser and taser associated injuries: a case series. Am Surg 2008;74:862-5.[Medline]

Kroll MW. Cardiac safety. Scottsdale (AZ): Taser International; 2007. Available: www.taser.com/research/Science/Pages/CardiacSafety.aspx (accessed 2009 Jan. 9)

Rehman TU, Yonas H, Marinaro J. Intracranial penetration of a TASER dart. Am J Emerg Med 2007;733:e3-4.

Lisanby SH. Electroconvulsive therapy for depression. N Engl J Med 2007;357:1939-45.[Free Full Text]

Stephenson JBP. Fits and faints. Oxford (UK): MacKeith Press, Blackwell; 1990. p. 41.

McCrory PR, Bladin PF, Berkovic SF. Retrospective study of concussive convulsions in elite Australian rules and rugby league footballers: phenomenology, aetiology, and outcome. BMJ 1997;314:171-4.[Abstract/Free Full Text]

Tasers can cause seizures: report

March 16, 2009
Sue Bailey, THE CANADIAN PRESS

OTTAWA – Stun guns can cause seizures if their tiny electric barbs pierce the scalp and shock the brain, says a new article on the accidental jolting of a police officer.

The unnamed Ontario cop, in his 30s, was chasing a suspected robber when he was hit in the back of the head with a Taser fired by his partner.

Within seconds, the officer collapsed and went into a full-blown seizure – foaming at the mouth – for about a minute, says the article co-written by Toronto neurologist Dr. Richard Wennberg.

What is billed as the first report of its kind on such a phenomenon is published in the Canadian Medical Association Journal released Monday.

The officer had no history of seizures, head injuries, neurological or psychiatric conditions, it says. His developmental history was normal and he was not on medication of any kind.

"Until now, most reports of Taser-related adverse events have understandably concentrated on cardiac complications associated with shots to the chest," the article concludes.

"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."

What appears to be a rare if not isolated case should serve as a cautionary tale, Wennberg said in an interview, especially as Taser use grows.

"In that it hadn't ever been reported before, we felt sort of obligated to report on it in the medical literature so that people would know that for sure this can happen.

"To discharge that amount of electrical current in a region overlying the brain, it didn't seem impossible to me that this could happen in a mechanism similar to giving electroconvulsive therapy or something like that."

Wennberg says stun guns pack about the same jolt used to induce seizures in electroshock therapy. It's a procedure that has had some success in treating severe depression by hitting a kind of reset button in the brain.

"No one has any real idea" why it works, Wennberg said. "It does seem to be kind of like rebooting the system."

The police officer came out of his seizure bewildered and with a severe headache. He was later diagnosed with a concussion, likely from the impact of the dart or from hitting his head after collapsing. He still suffers headaches and has difficulty concentrating 18 months later, Wennberg said.

He has not had any seizures since.

Wennberg said he and two other co-authors of the report searched ``anything that's ever been published in medical literature" and did not find a similar case.

"The data are sparse on how this device may affect the central nervous system," says the article.

Taser International Inc., the Arizona-based maker of the device, specifically 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," spokesperson Peter Holran said in a statement following inquiries by 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 from the Canadian Medical Association Journal.

"Taser International will review the case report of this single incident once available," it said.

Wennberg says the officer's ordeal was indeed a mishap.

"They certainly don't mean for these things to ever be aimed at the head – nor was it meant to be in this case even. But it wouldn't always have to be an accident. I'd be surprised if (a seizure) didn't happen most of the time to people if they actually did get Tasered in the head."

Taser International has steadfastly defended the relative safety of its devices although it stresses that no use-of-force tool is risk-free.

More than 20 Canadians have died after being Tasered. Polish immigrant Robert Dziekanski, who died Oct. 14, 2007 after RCMP officers repeatedly zapped and then pinned him to the floor, is the subject of an inquiry in B.C.

"Specifically in Canada, while previous incidents were widely reported in the media as 'Taser deaths,' the role of the Taser device has been cleared in every case to date," says Taser International.

Canadian researchers dispute taser safety

May 7, 2008
CTV British Columbia

Canadian medical researchers are disputing the theory that stun guns do not cause irregular heart rhythms that are sometimes fatal.

Tests had shown that Taser shock could cause fibrillation -- a very rapid, irregular contraction of muscles fibers -- in any muscle, except the heart.

"Bottom line is we think that assumption is incorrect," said Dr. Paul Dorian, a medical researcher from the University of Toronto. "Under certain circumstances, the Taser electrical discharges can, in fact, cause the heart muscle to beat and to beat very fast."

Dorian and his team shocked six pigs with stun guns looking for signs of ventricular fibrillation (VF) and other adverse heart effects. The results echo a recent Chicago study, where prolonged stun gun shocks caused VF.

Two pigs died in the Chicago study. One pig died of VF in Dorian's study and the other five pigs showed cardiac disturbance.

When it occurs in humans, VF can be lethal, Dorian said.

"When this rapid irregular heart rhythm occurs, the heart doesn't beat effectively," Dorian told CTV News. "No blood is pumped from it, and the victim, unless they get CPR and gets an electrical shock to the heart, will die within 10 minutes."

In response to the Toronto study, manufacturer Taser International said it will present results from three cardiac studies of its own later this month at the Heart Rhythm Conference in San Francisco, California.

"Taser International is dismayed by attempts to present this information as something it is not," the company said in a statement.

"I can understand if they're dismayed," Dorian said. "I'm dismayed as well. Dismayed that we have a technology that potentially can cause harm."

When Victoria police conducted Canada's first Taser trials in 1999, VF was the medical problem they were most concerned about.

But no one was considering the adverse effects of another medical condition caused when muscles are shocked and contract too quickly. High levels of acidity, or low levels of alkalinity in the body fluids, including the blood, can cause acidosis.

"The problem with acidosis is that the organs don't function properly when the acids are present in the blood," Dorian said.

Inspector Darren Laur, who spearheaded the Victoria Taser trial, told CTV News in an email that VF was the only medical concern of their research.

"I was not involved in any studies surrounding acidosis," he wrote.

Ken Stethem, a use-of-force expert from Washington, D.C. said acidosis, which worsens if victims are stunned repeatedly, needs to be considered in the Taser debate.

"These devices being used and backed up by policies that don't limit the number of stuns of the length of the exposure times -- it's hard to believe how that would support public safety," Stethem said.

The officer who is in charge of the Taser program for the Victoria police department told a public inquiry Tuesday that he's uncertain if Tasers cause death.

"I think I would be negligent as a police trainer if I stood up here and said they don't cause death," Constable Mike Massine told inquiry commissioner Thomas Braidwood, a retired B.C. Court of Appeal judge who is conducting the first public inquiry into the controversial use of Tasers.

"I don't know if they do. I don't know if they don't," the officer added. "Maybe there is a correlation, I don't know. I hope when we find out what it is, I hope we find that silver bullet."

Massine said putting a moratorium on Tasers would cause a knee jerk reaction, adding stun guns are a necessary tool for officers facing violent suspects.

The inquiry, which started Monday in Vancouver, is scheduled to continue until May 23.

With a report from CTV British Columbia's Peter Grainger

Jonathan Kay on the best corporate media department in the world (even if they did get my name wrong)

May 7, 2008
Jonathan Kay, National Post

The people who man the media shop at Taser International Inc. are the aces of the corporate flak world. You write anything — anything — even vaguely skeptical (let alone downright negative, in which case they rattle their legal sabers) about stun guns, and they, er, zap you with an inbox full of electro-spin.

Case in point: my Tuesday column about this week's Canadian Medical Association Journal study on the health risks of being stun gunned, which earned me (or, should I say, "Jay") the note below. True, the guy not only got my name wrong, but also the name of my article (which he seems to have confused with Marni's blog post on the same subject). Still, it's the thought that counts.

Jay,

I read with interest your column entitled “Watch where you put that Taser” which appeared last Friday. As such, I wanted to make certain you had a copy of the official statement issued by TASER International related to the discussion article published in the Canadian Medical Association Journal. The statement is attached below.

Related to the CMAJ article and editorial, TASER International will point out that Dr. Stanbrook’s editorial is based primarily on a 2005 article from the Arizona Republic as his ONLY source that TASER International has “’sponsored research to prove the Taser's safety,’ he continues. ‘Just about all the research, as it turns out.’” Over the three years since that article was written, much of the research by the Governments of the United States, Canada, the United Kingdom, and leading academic and medical institutions has been funded independent of TASER International. To date, there are more than 120 major studies or analysis of TASER devices and TASER technology with more than 80 percent of them funded independent of TASER International. In fact, the US Department of Justice has been a prolific funder of TASER research recently and one of the first to fund human studies.

Finally, I have provided you with a press release issued this morning by TASER International regarding a Summit County, Ohio law suit involving erroneous medical examiner reports in three cases involving TARSER devices. I thought that you find this of interest and relevant.

<<080505 Summit Co OH Lawsuit.doc>>

My best,

Peter

________________________________________________

The following is the official statement of TASER International regarding the Canadian Medical Association Journal article “Cardiac stimulation with high voltage discharge from stun guns”:

The manuscript released today by researchers at the University of Toronto appears to be a discussion paper that offers no new research. Rather it appears to be simply a discussing of prior papers and findings. TASER International is dismayed by attempts to present this information as something it is not.

Most important to note is that the authors of this manuscript themselves, in their conclusion, clearly state that there are “many studies suggesting that stun guns do not affect the heart” and that, “the evidence and studies presented in this review suggest that, in some circumstances, stun guns may stimulate the heart while discharges are being applied. However, there is no conclusive evidence to show whether stun gun stimulation (under certain electrophysiological conditions) can result in cardiac arrhythmias late after stun gun discharge.”

The authors, also in their conclusion, acknowledge that final conclusions should not be drawn solely from the referenced pig studies and call for human studies to be done: “In our view, it is inappropriate to conclude that stun gun discharges cannot lead to adverse cardiac consequences in all real world settings. We believe that the findings that stun gun discharges are able, under specific circumstances, to stimulate the heart should be taken into account in future studies involving people. Whether stun guns can stimulate the heart can only be established if one can record electrical activity in the heart during a discharge, especially when the vector of discharge is directed across the heart. Additional research studies involving people will help to resolve the conflicting theoretical and experimental findings, and they could lead to the design of devices with electrical pulses that cannot stimulate the heart.”

To this point exactly, three human studies on the effects of TASER® electronic control devices will be presented at the Heart Rhythm Society’s Heart Rhythm 2008 , May 14-17, 2008, in San Francisco, CA USA. The studies include:

(Thursday May 15, 2008) Presenting Rhythm in Sudden Custodial Deaths After Use of TASER® Electronic Control Device, Charles Swerdlow, MD, FHRS, Mark W. Kroll, PhD, FHRS, Howard Williams, Mazda Biria, MD, Dhanunjaya Lakkireddy, MD and Patrick J. Tchou, MD. Cedars-Sinai Medical Center, Los Angeles, CA, University of Minnesota, Minneapolis, MN, San Marcos Police Department, San Marcos, TX, University of Kansas Medical Center, Kansas City, KS, Cleveland Clinic, Cleveland, OH.

(Friday May 16, 2008) Can Electrical-Conductive Weapons (TASER®) alter the functional integrity of pacemakers and defibrillators and cause rapid myocardial capture? Dhanunjaya R. Lakkireddy, MD, Mazda Biria, MD, Esam Baryun, MD, Loren Berenbom, MD, Rhea Pimentel, MD, Martin P. Emert, MD, Kevin Kreighbaum, RN, Mark W. Kroll, PhD and Atul Verma, MD. Mid America Cardiology @ University of Kansas Hospital, Kansas City, KS, University of Minnesota, Minneapolis, MN, Southlake Regional Health Center, Toronto, ON, Canada.

(Friday May 16, 2008) Echocardiographic Evaluation of Human Transcutaneous TASER® Application Along the Cardiac Axis, Jeffrey D. Ho, MD, Donald M. Dawes, MD, Robert F. Reardon, MD, Anne L. Lapine, MD, Jeremy D. Olsen, MD, Benjamin J. Dolan, BA and James R. Miner, MD. Hennepin County Medical Center, Minneapolis, MN, Lompoc District Hospital, Lompoc, CA.

The Heart Rhythm Society is the international leader in science, education and advocacy for cardiac arrhythmia professionals and patients, and the primary information resource on heart rhythm disorders. Its mission is to improve the care of patients by promoting research, education and optimal health care policies and standards.

EDITORIAL: Tasers do affect the heart

May 3, 2008
The Globe and Mail

The case for a moratorium on police use of tasers in Canada has been immeasurably strengthened by a group of cardiologists and research scientists from the University of Toronto. They have exploded police and manufacturer claims that the taser does not affect the heart and therefore does not cause fatal heart problems. With taser use growing rapidly - the Mounties alone use them more than 20 times a week - a study by the University of Toronto researchers published in the latest issue of the Canadian Medical Association Journal should be bedside reading for legislators across Canada.

The issue of taser safety has been dominated by questionable science, a point made inadvertently by RCMP Commissioner William Elliott and Alberta Solicitor-General Fred Lindsay when they were voluntarily tasered on Thursday. The idea was to demonstrate that the electric stun gun's effects wear off almost as soon as the five-second zap ends. Step right up, ladies and gents. This is the science of the snake-oil salesman.

It would take more than one William Elliott for an effective experiment, and some of them would have to be on psychotropic drugs, or have a weak heart, or be in the anxious, sweating, breathless state police call "excited delirium."

Especially key, the gun's electrical charge would have to fall across the heart - what the University of Toronto professors call "the worst-case scenario" - and not just across the abdomen. And perhaps Mr. Elliott would afterward volunteer to have a 100-kilogram officer press a knee on his exhausted windpipe. (Respiratory exhaustion, not just heart problems, may be behind some of the taser-related deaths.) Then it would simulate the real world - the world in which Robert Dziekanski was fatally tasered by the Mounties at the Vancouver airport in October.

This is not to deny that the taser has benefits. In Brampton, Ont., this week, police saved a man's life by zapping him after he took a knife to his own neck. But police are permitted to use tasers where serious physical harm is not at issue, in part because they assume it is risk-free.

As the CMAJ study shows, this assumption is wrong. "New and independent research, both epidemiologic and biological, into whether tasers can kill is essential to settle this issue," the journal says in an accompanying editorial. The safety of tasers is a live issue.

Police don't believe it. To them, "tasers do not kill" has become a mantra; no matter how many people die (20 in Canada in the past five years), the mantra does not change. Not even Mr. Dziekanski's death prompted Mr. Elliott and his outfit to question the official line. On what does that line rest? Largely on a few studies of tasers' effects on pigs, and on coroners' inquests that have not directly blamed the taser for deaths.

But the CMAJ study from the University of Toronto researchers found major weaknesses in the pig studies, and clear evidence, both in a study they did on pigs and in pig studies they reviewed, that the heart could be affected when the gun's two barbs struck in such a way that the electricity passed through the heart (without the barbs actually penetrating the heart). In one study, researchers opened a pig's chest when it was zapped and observed that the heart was affected. The stun gun could cause the pigs to abruptly lose their blood pressure. Two pigs died immediately after the stun-gun discharge in the study. As for the inquests, the CMAJ makes no reference to them, but in an interview, co-author Paul Dorian said that "as a scientist, I'm sympathetic to the difficulty of ascribing cause with very limited information." His study concludes: "It is inappropriate to conclude that stun gun discharges cannot lead to adverse cardiac consequences in all real world settings." But that is exactly the police conclusion.

Whom is the public to believe, Mr. Elliott and Mr. Lindsay, who faced the taser's barbs, or medical scientists who specialize in the heart? The answer seems obvious.

Police guidelines for taser use are based on faulty assumptions. A temporary suspension of taser use would allow for those guidelines to be rewritten to reflect the weapon's real world risks.

Canadian medical journal calls for independent studies on taser safety

May 1, 2008
The Canadian Press

OTTAWA — A scathing editorial in the latest Canadian Medical Association Journal says the safety of Taser stun guns must be studied independently. The journal blasts Taser International, which makes the powerful weapons, for funding much of the research used to support the safety of Tasers. It reviews existing scientific studies and says there's an urgent need for new and unbiased research.

More than 300 people in North America, including 20 in Canada, have died soon after being Tasered. The electronic guns are overwhelmingly popular with police, who say they avoid injuries to suspects and officers. The medical association says Taser International has aggressively challenged researchers and coroners who've raise safety concerns.

Tasering could affect heartbeat, Toronto researchers find

May 1, 2008
Sharon Kirkey, Canwest News Service

Despite the theory that stun guns don't harm internal organs such as the heart, Canadian researchers are reporting that, in fact, research suggests stun gun discharges are able to stimulate heart muscle under certain circumstances.

"In our view it is inappropriate to conclude that stun gun discharges cannot lead to adverse cardiac consequences in all real-world settings," Dr. Kumaraswamy Nanthakumar, of the University of Toronto, and colleagues report in the Canadian Medical Association Journal, published online Thursday.

The researchers studied a total of 150 discharges in six anesthetized pigs and found that 74 of the discharges resulted in stimulation of the myocardium, or heart muscle.

"We took care to ensure that the gun barbs did not pierce deep into the tissue," the researchers reported, just days before a B.C. inquiry into the death of Polish immigrant Robert Dziekanski is set to begin. Dziekanski was Tasered by the RCMP last October after he began behaving erratically in a secure area of Vancouver airport, and died shortly after.

The researchers from the University of Toronto and two Toronto hospitals found that the positioning of the barbs, which transmit the electrical impulses from the device, played a key role. Placing them across the chest, nearest the heart, simulated "the worst-case scenario of creating a current vector that directly passes through the heart," the researchers reported.

If the barbs were placed away from the chest and across the abdomen, none of the 56 test discharges stimulated the heart, "suggesting that the location of the barbs had a crucial influence on stimulating the heart."

In one study, the pigs' blood pressure was suddenly lost after a stun gun, such as a Taser, was discharged. In another study, two animals died from ventricular fibrillation - rapid, uncontrolled contraction of the heart - immediately after being Tasered.

"This suggests that sufficient current density was produced by the stun gun to stimulate the heart, which, according to theory, should not and could not occur."

"Three different studies involving pigs, one of which was performed by us, have shown that a stun gun discharge can stimulate the heart,"Nanthakumar noted.

The team cautions that a human's chest is different from that of a pig, and that "one should be prudent in extrapolating data from animals to humans because of this fact." Still, most of what's known about cardiac defibrillation comes from studies in animals, not humans.

In an accompanying editorial, CMAJ deputy editor Dr. Matthew Stanbrook says deaths occurring in association with Tasers "make the safety of these devices a public health issue."

He says police should share information about their use, and that information that should be analyzed by independent researchers, "on the principle that the assertion that Tasers have saved lives of police and suspects alike, while plausible, should be proven, not merely asserted as fact."

"New and independent research, both epidemiologic and biological, into whether Tasers can kill is essential to settle this issue."

More than 300 deaths following stun gun use have been documented, 20 of them in Canada.
The devices are used to physically incapacitate a person by discharging controlled electric energy into the body.

The Toronto researchers found no conclusive evidence to show whether stun guns can cause erratic heartbeats sometime later, after the stun gun discharge is complete.

CBC Documentary - Taser Deaths

In a Radio-Canada/CBC in-depth documentary on Tasers, produced by Frederic Zalac and aired nationally on Canadian television at the end of last year, the conclusions of recent independent medical reviews of Tasers were revealed which raised some very serious questions about the lethality of Tasers.

The documentary, in which I very enthusiastically participated, is about 20 minutes in length and is available online at CBC News. Scroll down and click on (or search for) “Taser Deaths”.

Highlights include:

Dr. Stanley Nattel, Cardiologist at the Montreal Heart Institute, Director of the Paul-David Chair in Cardiovascular Electrophysiology and leading cardiology researcher at the University of Montreal, and an associate professor at McGill University, analyzed a study performed at the University of Toronto (see below) and concluded that “A rapid rhythm induced by a Taser, called a Ventricular Tachycardia, may not cause very severe symptoms and particularly if the person is very excited, frightened, etc., they might not even notice it. But that kind of rhythm can eventually what we call “degenerate” to Ventricular Fibrillation, which is an even faster and irregular rhythm that is rapidly lethal.”

Dr. Nattel said further that “the way in which the Taser causes death is by provoking a very rapid, irregular heart rhythm, and that doesn’t leave any traces in the body. So basically if you don’t see anything there, you don’t know what the cause is and it could be a lethal dose of drugs or it could be an extreme mental stress or it could be the Taser. I don’t think it’s possible to differentiate those possibilities in most cases.”

An independent study in Canada on the effects of Tasers on pigs was performed at the University of Toronto by Kumaraswamy Nanthakumar, MD; Ian Billingsley, MD, Stephane Masse, MASc, Paul Dorian, MD, Douglas Cameron, MD, Vijay S. Chauhan, MD, Eugene Downar, MD and Elias Sevaptsidis, DEC. This study injected into pigs a substance that mimics the adrenaline rush that would be experienced during a stressful arrest by police or a cocaine high. The pigs were then shocked with Tasers. The study found that, in circumstances of increased adrenalgenic stress, arrythmias (irregular heart rhythms) were caused and, in some cases, were lethal. (Journal of the American College of Cardiology)

In the U.S., Dr. John Webster, Biomedical Engineer, University of Wisconsin tried to duplicate the situation that would occur with humans … and “we got very different results. I don’t think that they’re non-lethal weapons but I think that there’s a probability, albeit small, that the Taser could electrocute a person.”

When asked by Radio-Canada reporter, Frederic Zalac, what he would do if a study showed there was a risk, Taser International spokesperson Steve Tuttle answered by saying, “We would have an obligation to disclose that to our customers and to the public. That’s pure and simple.”

To the best of my knowledge, Taser International has never disclosed these results to its customers or to the public.

Cardiac Electrophysiological Consequences of Neuromuscular Incapacitating Device Discharges

Full study

Cardiac Electrophysiological Consequences of Neuromuscular Incapacitating Device Discharges

CONCLUSIONS: In an experimental model, NID discharges across the chest can produce cardiac stimulation at high rates. This study suggests that NIDs may have cardiac risks that require further investigation in humans.