Apr 06 09 05:53p

A

Shari Damm

519 735 9919

p. 2

Generalized tonic-donie seizure after a taser shot
to the head
Esther T. Bui MD, Myra Sourkes MD, Richard Wennberg MD

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During a pol ice 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 Int o his upper back and occiput. Within seconds, the
off ice r co llapsed a nd experienced a generalized tonic·
clonic seizure with lo ss of consciousness and postictal confusion. Subsequent magnetic resonance imaging scans of
the head and electroencephalograms were normal. The
patien1 has experienced no recurrence of se izure over
more than a year of follow-up. This report sh ows that a
taser shot t o the head may result in a braln~peclfk complication such as generalized tonk-donie seizure. It also
suggests that seizure should be considered a n adverse
event related t o taser use.
Une version fran<;ai~e de ce resume est disp oniblo
www..:maj.c~/cg i/conu:nllfullfi80/6/625/DC I

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CMAJ 200!1;180(6}:625-(t

he tnscr s tun gun, mnnufnetured by Taser I nternational in Scottsdale, Arizona, is a weapon used increasingly among law enforcement personnel to tem·
pornrily incapacitate d etainees . Questions have arisen in bo th
the scientific literature and the Jay press about the device 's
satety. 1•1 In this article, we report the occurrence of a general·
ized tonic-clonic seizure in a per.~on who received a taser sh01
to lhe head.

T

Case report
The p atient was a previously well police officer in his 30s
who took pllit in a police chase involving a suspected robber.

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He and n colleague cornered the s uspect, who initially ap·
peared to surrender but then attempted an escape. The officer
had begun to chase the suspect on foot when he experie nced a
sudden, severe pain in the back of his head. He later de ~cribcd
the moment us feeling like he had been "hit by a bat" Herecalled letting o ut a brief gasp before losing conscioutmess. He
had no recollection of fa lling to the ground on top of the suspcct. Police records indicate tha t the officer' s colleague had
fired u tascr ~hoi meant for the s uspect but that the 2 copper
darts had instead struck the officer in the occiput and upper
back. The officer had been wearing an ar moured vest. Jmmc-

CMAJ

diatcly after being shot, he was found by his colleague to be
unresponsive and foaming at the mouth. His eyes were rolled
u pward and he had generalized tonic-clonic movements with
apnea lusting for about 1 minute. He did not hnve urinary in·
conlinencc. Postictally, he wus initially confused and combative. Emergency medical services personnel were able to rc·
s train him. T hey recorded a Glasgow Coma Score of9 witltin
5 minutes after arrival; 5 minutes later, his score was l 3.
The patient's next memory was of being in the emergency
deparlmcnt. During this period, he felt as if he were in "a bud
dream." As he gradually regained orientation over the next
few hou rs. he became aware of thoracic tigh tness tbat wns aggravated by deep breaths, and a severe headache. He was
mo nitored overnight, th en d ischarged in stable condition.
The patien t had no hi story of febrile or u nprovoked
seizures, head injuries, headaches, menlngilis or encephalitis.
He had no family hi~tory of seizures or of other neurologic or
psychiatric conditions. His developmental history was nor·
mlll. Be was not taking any medications.
The results of a general physical and n eurologic Cl'arnination were normal. Results of routine blood tests were unremarkable except for em elevated leukocyte count of 12.9 (normal 3 .6-J 1.0) x 10'/l.. 30 minutes after the event (decreasing
to J 1.2 x I o•!L 5 hours later) and an elevated se.mm 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, dizzi ness. back
pain and che.~L tightness. Magnetic resonance imaging scans
of the head (1 .5 nod 3 Tesla) ns well as routine and 24-hour
ambulatory electroencephnlogr.lphy were performed l, 2 and
12 months after tbe seizure. All findings were normal.
A diagnosis of mild traumatic brain injury (concussion), in
addition to provoked ~eizure, was considered after a neurologic consultation during assessment of the patient at a reha·
bilita.tion centre 6 months after injury. A psychiatric cons\Jltotion 7 months after injury suggested an Axis 1 diagnosis of
adjustment disorder with depressed and aox:ious moor!. Formal ncuropsychologicnl testi ng performed 9 months after
injury showed no definite evidence of cognitive impairment
in ony domain.
From the Division of Neurology, Krembil Neurosdence Centre, University
Heolth Network. Toronto Western Hospital_ University of Toronto ,
Toronto, Ont.

• MARCH 17, 2009 • 180(6)

0 lODi Canadf.an Medic;. I Au oci;allon or iu licen.son

625"

Apr OS OS 05:53p

Shari Damm

519 735 9919

Tile patient has not had further seizures !lince the injury
more than I yeur ago. His symptoms of ru1xicry, diflkulties
concentrating, in·itabllity, nonspecific dizziness and persistent
headaches have not completely resolved. Treatment trials
have included amiuiptylioc 50 mg nightly, topiramate 25 rng
nightly, eseitalopram 10 mg nightly, almotriptan 12.5 mg us
needed nnd ibuprofen 200-400 mg as needed.

Comments
A laser stun gun is n device designed to temporarily immobi-

lize a human target by delivering a direct~urrent type of s hock
through 2 burbc<.l copper dart.~. The shock c<~uses involuntary
muscle contraction. Neuromuscular transmission is thought to
be affected primarily ut the level of the peripheral motor nerve,
alth'ough studies have shown that stimulation of the spinal
cord may occur with dart penetration us far away as

th~

ante-

rior tor:so."-' The mu~cle contraction induced l>y ta.~crs is typically tonic, with reUiined consciousness, no clonic movements
confusion.' T he manu facturer '~ websi te
that n single shot lasts abo ut 5 seconds, delivers
19 pulses per second with a typical charge of I 00 microcoulombs per pulse, generates an average net current of 2 milliamp~res and has un c:;t.itllated peak voltage of 1300 volts.•
111e data ore sparse on how this device may affect the central nervous sysrem. A eliSe has been reponed involving intracranial penetration by .a t11scr delft with loss of consciousness for 5 minutt:s .' The pc.n;on who had been stn1ck
recovered shortly afterward with a mild headache. N o details
were reported on whether a seizure occurred, although only
I o f the 2 dnrt.s struck the p atient.' Another case repo.rt descri bes cranial penetration by a tascr dan ( with the second
dtlrt found in a hair braid) with transient decreased consciousness; no further details were give n.~ Otber reports of secondary loss of c:onsciou~ncss rdatcd to taser shot~ have involved
only cases of severe traumatic head inj uries that resulted fro m
falls d uring neuromusculilf incapacitatio n.'
The description by witnesses of the event involving our
path:rtt is most compatible witlt u generalized tonic-clonic
seizure. The Jo ss of consciousness, clonic movements, foaming at the mouth and postictal conf\1sion experienced by our
patient differcntintc the episode from the usual transient incapacitation induced by tasers. The taser cUJTcnt thut passed to
his brain from the dart in the occiput probably provoked the
seb:vre directly, with a mechanis m akin to that of seizures induced by electl'Ocon vulsive ther apy . In electroconvulsive
tltcrttpy, an in itial charge of 38-00 millicoulombs is used, according to therape utic protocol in the United Sta te~.· It is
plausible that a copper dart penetrating the scalp and discharging 95 pulses of 100 microcoulombs each could trigger
~ generalized convulsion.
Given previous case reports of tnscr-induccd cardiac arrhythmias, one could speculate thut nn initial induced cardiac
and no

po ~ ticta l

e~tim:nes

626

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p.3

arrhythmia and a .secondary hypoxic seizure, or convulsive
syncope, occurred in our case. Convulsive syncope is believed ro result from reticular disinhibition in the bralnstem
resulting from hypoxia-induced cortical dysfunction.' However, this mechanism seems unlikely in tbis case, especially
given Ulal the points of impact of the raser darts were over the
head and upper back and nor the henrt.
Even Jess likely is the po!isibility that the convulsion was
induced by a concussio n resulting from the direct pbysical
impact o.f the darts or impact of the patient's head o n the
ground. Our patient's prolonged period of unresponsiveness
and tlubsequen t postictal confusion is not t)'picul of a concussive convulsion, which is usually characterized by immediate
onset and a rapid recovery thut takes place over a few minutes.•• On the other h arld, we believe that his persistent symptoms after injury may be nnribmable in part to postcoJJcussion
syndro me, presumably secondary to mild traumatic brain injury caused by either the impact of the taser dart or the .~uhse­
quent fall to rhe ground during the provoked seizure.
Until now, most reports of t ascr~rclated adverse events
have understandably coucelltrutcd on cardiac complicatio ns
asso c i~ted wi th shots to the chest.= Our repo1t shows that a
laser shot to the h ead may result in brain-specific compli cations. Jt nlso suggests that seizure should be added to the list
of tascr-rclute<.l adverse events.
'!'his 11r1ict~ h:ts been peer reviewed.

Cornpetl:ng lnlercsls: None <leebred.

Conlrlbutors: All of lh~ author.; were involved in !he prcpunotion of
mauu~crlpt and opprovcd thu lin;•l vcr.<i»n suboniUed fOt" publimlion.

lhi~

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Correspondrmce to: Dr. Richard Wennberg, Torolllo Wes1er11
Hospital. Ste. 5W444, 399 BathurJ'I Sr. , Toromo ON M5T 2S8;
fax 416 603-576.~; r.wertn/)erl(@utoronto.ca

• MARCH 17, 2009 • 1 80(6)