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1045 0361-803X/93/1615-1045 ci Am erican Roentgen Ray Society Hippocampal Sclerosis in Children with Intractable Temporal Lobe Epilepsy: Detection with MR Imaging J. 0. Grattan-Smith1 A. S. Harvey2 P . M. D es mo nd 3 C. W. Chow4 Received May 6, 1993; accepted after revision June 28, 1993. 1 D epartm ent of R adiology, R oyal C hildren’s Hospital, Fiemington Rd., P arkville, victoria, 3052, A ustralia. Address correspondence to J. D. Gnat- tan-Smith. 2Depantment of Paediatncs, University of Mel- boume, Melboume, A u st ra li a. 3D epartm ent of R adiology, R oyal M elboum e H osp ital, M elbo um e, A ustra lia. 4Department of Anatom ical Pathology, Royal Children’s Hospital, Parkville, victoria, 3052, Aus- tralia. OBJECTIVE. Hippocampal sclerosis is the most common lesion associated with temporal lobe epilepsy. Temporal lobectomy Is effective for the control of medically refractory seizures In these patients. Before the advent of MR imaging, hippocampal sclerosis was rarely diagnosed preoperatively. The purpose of this study was to determine the frequen y of hippocampal sclerosis In children with Intractable tempo- ra lobe epilepsy and the accur cy and reliability with which hippocampal sclerosis can be diagnosed on the basis of MR findings in children. MATERIALS AND METHODS. We reviewed the MR images of 53 children (mean age, 10 years) with medically refractory temporal lobe epilepsy. The MR images were re vie we d b lin dly and Independently by tw o radiologists on wo occa sio ns, and were classified as showing hippocampal sclerosis, other lesions, or no abnormality. Hippoc- ampal scle osis was diagnosed when evidence of hlppocampal atrophy was present r hippocampal signal intensity was abnormal without evidence of a mass lesion. RESULTS. MR images showed hippocampal sclerosis in 30 chIldren (57%), other lesions in 10 (19%) (tumors in eight, cavernous angloma in one, and ectopic gray matter in one), and no abnormality in 13 (24%) (lntraobserver agreement: kappa = 0.77 and 0.84, Interobserver agreement: kappa = 0.76). MR lateralizatlon was concor- dant with ictal EEG in 36 (92%) of 9 children. Hippocampal sclerosis was bilateral in one child and associated with extrahippocampal lesions In nine. Hippocampal sclero- sis was detected on MR images of 1 (85%) of 13 children with pathologic confirma- tion of hippocampal sclerosis. Beneficial results were seen in 26 (90%) of 29 children who had temporal lobectomy. CONCLUSION. Hippocampal sclerosis is the most common lesion in children with intractable te poral lobe epilepsy, and it can be detected reliably and accurately on MR images. We suspect that hippocampal sclerosis is underdiagnosed in children, possIbly leading to postponement of surgery In children w ith refractory seizures. AJ R 1 99 3;1 61 :1 04 5-1 04 8 Temporal lobe epilepsy is the most common form of intractab e epilepsy i chil- dren [1]. Temporal lobectomy is effective in controlling seizures in approximately 80% of children with intractable temporal lobe epilepsy [2-5]. Although hippocam- pal sclerosis is seen in 60-70% of autopsy and surgical series in adults with refractory temporal lobe epilepsy, it has been variably reported in studies of tem- poral lobectomy in children [2-7]. Recent reports [8-14] indicate that hippocampal sclerosis can be reliably detected with MR imaging in 60-100% of patients; how- ever, a number of issues remain unresolved. There is no universal agreement on the ideal method of MA imaging of the hippocampus or criteria for diagnosing hip- pocampal sclerosis [1 3 , 14]. The application to clinical practice of quantitative MR techniques is unclean [11-14]. We reviewed the MR images of children with well-documented intractable tem- ponal lobe epilepsy to determine the frequency of hippocampal scler sis and the accuracy and reliability with which hippocampal sclerosis could be diagnosed on the basis of MR findings.

Hippo Cam Pal Sclerosis in Children With Intractable Temporal Lobe Epilepsy- Detection With MR Imaging

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1045

0361-803X/93 /1615-1045

ci Am erican Roen tge n Ra y S oc ie ty

H ippocam pa l S c le ro s is in

C h ild ren w ith In trac tab le

Tem po ra l Lobe Ep ilep sy :Detection with MR Imaging

J . 0 . G ra tt an -S mi th 1

A. S. Harvey2

P . M. D es mo nd 3

C . W . Chow4

Rece ived M ay 6 , 19 93 ; ac cep te d a fte r re v is ion

June 28, 1993.

1 D epartm en t o f R ad io log y , R oya l C hild ren ’s

Hosp ita l, F iem in g to n Rd ., P arkv i lle , v ic to ria , 30 52 ,

A us tra lia . A dd res s co rre spondence to J . D . G na t-

tan -Smith .

2D epan tm en t o f P ae d ia tn cs , U n iv e rs ity o f M e l-

b o ume , M e lb o um e , A u st ra li a.

3D epa rtm en t o f R ad io log y , R oya l M elb oum e

H osp ita l, M elbo um e, A us tra lia .

4Depa rtm en t o f A na tom ic a l P a tho lo g y , R o ya l

C h ild re n ’s H o sp ita l, P a rkv ille , v ic to ria , 30 52 , Au s-

tral ia.

OB JECT IVE . H ippocam pal s c le ro s is is th e m os t com m on les ion assoc ia ted w ith

tem po ra l lo b e ep ile p sy . T em po ra l lo b ec tom y Is e ffe c tiv e fo r th e con tro l o f m ed ic a lly

re frac to ry se izu re s In the se pa tien ts . B e fo re the adven t o f M R im ag in g , h ippocam pa l

sc le ro s is w as rare ly d iagnosed p reope ra tive ly . T h e pu rpose o f th is s tudy w as to

de te rm in e th e frequency o f h ippocam pa l s c le ros is In ch ild ren w ith In tra c tab le tem po -

ra l lo b e ep ile p sy and th e accu ra cy and re lia b ility w ith w h ich h ippocam pa l s c le ro s is

c an be d iagnosed on th e bas is o f M R find ings in ch ild ren .

M A TER IALS AND ME THODS . W e rev iew ed the M R im ages o f 5 3 ch ild ren (m ean age ,

10 yea rs ) w ith m ed ic a lly re frac to ry tem po ra l lo b e ep ilep sy . The M R im ages w e re

re vie we d b lin dly and Independen tly b y tw o rad io lo g is ts o n tw o oc ca sio ns , and w e re

c las s ifie d as show ing h ippocam pa l sc le ro s is , o th e r le s ions , o r no abno rm a lity . H ippoc-

am pa l s c le ro s is w as d iagnosed w hen ev id ence o f h lppocam pa l a trophy w as p resen t o r

h ippocam pa l s igna l in tens ity w as abno rm a l w ithou t e v id ence o f a m ass les ion .

R ESU LTS . M R im ages show ed h ippocam pa l sc le ro s is in 3 0 ch Ild ren (57% ), o th er

les ions in 10 (1 9% ) (tum o rs in e igh t, c a ve rnous ang lom a in one , and ec top ic gra y

m atte r in one) , a nd no abnorm ality in 1 3 (24% ) (ln traobse rv e r ag re em en t: kappa =

0.77 and 0 .84 , In te robse rv er agre em ent: k appa = 0 .7 6 ). M R la te ra liza t lo n w as conco r-

d an t w ith ic ta l EEG in 36 (9 2% ) o f 39 ch ild ren . H ippocam pa l s c le ro s is w as b ila te ra l in

one ch ild and assoc ia ted w ith e x trah ippocam pal le s ions In n in e . H ippocam pa l sc le ro -

s is w as dete c ted on MR im ages o f 1 1 (8 5% ) o f 13 ch ild ren w ith patho log ic con firm a -

t io n o f h ippocam pa l sc le ro s is . B ene fic ia l resu lts w ere seen in 2 6 (9 0% ) o f 29 ch ild ren

w ho had tem po ra l lo b ec tom y .

C ONCLU S IO N . H ippocam pa l s c le ro s is is th e m ost com m on le s ion in ch ild ren w ith

in tra c tab le tem po ra l lo b e ep ile p sy , and it c an be dete c ted re liab ly and accu ra te ly on

MR im ages . W e suspec t th a t h ippocam pa l s c le ro s is is underd iagnosed in ch ild ren ,

poss Ib ly le ad ing to postponem en t o f su rg ery In ch ild ren w ith re frac to ry s e izu re s .

AJ R 1 99 3;1 61 :1 04 5-1 04 8

Tem po ra l lobe ep ilepsy is the m ost comm on fo rm o f in tra c tab le ep ilepsy in ch il-

d ren [1 ]. Tem po ra l lobec tom y is e ffe c tiv e in con tro llin g se izu res in app rox im ate ly

80% o f ch ild ren w ith in tra c tab le tem po ra l lobe ep ilepsy [2 -5 ]. A lthough h ippocam -

pa l s c le ros is is seen in 60-7 0% o f au top sy and su rg ic a l s e ries in a du lts w ith

re fra c to ry tem po ra l lobe ep ilepsy , it has been va riab ly repo rted in s tud ie s o f tem -

po ra l lobec tom y in ch ild ren [2 -7 ]. R ecen t repo rts [8 -14 ] ind ica te tha t h ippocam pa l

sc le ros is can be re liab ly de tec ted w ith M R im ag ing in 60 -100% o f pa tien ts ; how -

eve r, a num be r o f issues rem a in un reso lved . The re is no un ive rsa l ag reem en t on

the idea l m e thod o f M A im ag ing o f the h ippocam pus o r c r ite r ia fo r d iagnos ing h ip -

pocam pa l sc le ros is [1 3 , 1 4 ]. T he app lica tion to c lin ica l p rac tice o f quan tita tiv e MR

techn iques is unc lean [11 -14 ].

W e rev iew ed the M R im ages o f ch ild ren w ith w e ll-docum ented in tra c tab le tem -

pona l lobe ep ilepsy to de te rm ine the frequency o f h ippocam pa l sc le ros is and the

accu racy and re liab ility w ith w h ich h ippocam pa l sc le ros is cou ld be d iagnosed on

the bas is o f M R find ings .

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M ateria ls and M ethods

F ifty -th ree co nse cu tive pa tie n ts o f the Ro ya l C h ild ren ’s H o sp ita l,

M elbou rne , w ith m ed ica lly re fra c to ry s e izu res and c lin ica l a nd ic ta l

EEG ev idence o f tem po ra l lobe ep ilepsy unde rwen t M R im ag ing

be tw een 1987 and 1 992 . The 27 boys and 26 g irls w e re 2 -1 7 yea rs

o ld (m ean , 10 years ) a tth e tim e o f im ag ing . The ch ild re n w ere id e n -

tif ied from a re v iew o f ic ta l EEG re co rd ing s and c lin ica l rec o rd s o f a ll

ch ild ren w ith p a r tia l se izu re s who underw en t v ide o -E EG m on ito ring

in th e depa rtm en t o f n e u ro lo g y . C h ild ren w e re in c lu d ed on ly if se i-

zune onse t w as c lea r ly lo ca lized to the tem po ra l reg ion and c lin ica ls e izu re cha rac te ris tic s we re cons is ten t w ith tem po ra l lobe onse t.

C h ild re n w ere exc lu ded if EEG abno rm a lit ie s w ere poor ly lo ca liz ed

o r e x tra tem pona l o r if c lin ica l s e izu re cha ra c te ris tics w ere inc on s is -

te n t w ith tem po ra l lo be on se t. Ic ta l s in g le -ph o to n em iss ion com -

p ute d to mo grap hy (S PE CT ) w ith 99 mT ch exam eth ylp ro py le ne am in e

ox im e was pe rfo rm ed du ring v ideo-EEG reco rd ing in 24 ch ild ren .

A t the end o f the s tudy pe riod , an te r io r tem po ra l lobec tom y had

been pe rfo rm ed in 28 ch ild ren and a les ion had been resec ted in

one . S e ven o f the se ch ild ren have been repo rted p re v io u s ly [2 ].

Mean age a t su rge ry w as 1 1 yea rs (range , 5- 1 8 yea rs ), a n d th e

m ean fo llow -up pe riod w as 22 m on ths (range , 1 m on th to 4 yea rs ).

R esu lts o f h is to log ic exam ina tions in 29 ch ild ren w e re rev iew ed by a

ped ia tric n e u ro pa th o log is t w ho d id n o t kn ow the pa tie n t’s id en tity o r

M R find ings . A fte r su rge ry , 21 ch ild ren w e re se izu re free on hav ing

aura s on ly , th ree ra re ly h ad se iz u re s , an d tw o had few er se izu re s

th an be fo re . S e izu re fre quen cy was un changed in o ne ch ild , a nd

one ch ild w ith R asm ussen ’s sy nd rom e d ie d .

M R im ages w e re ob ta ine d w ith a 0 .3 -T iro n co re re s is tive m agne t

(B 3000 , F onan , M e lv ille , N Y ) in 28 ch ild ren , w ith a 1 .5 -T s up er co n-

d u c tin g m agne t (M agne tom , S iem ens AG , En la ngen , G e rm any ) in

18 ch ild re n , a n d w ith b o th u n its in se ven . F iftee n ch ild re n had m u lti-

p ie s tu d ies . W ith th e 0 .3 -T un it, ge ne ra lly co rona l inv e rs io n -reco ve ry

(1500 /30 /500 [TR /T i/T E ]) and ax ia l and co rona l sp in -echo (2000 /

35 ,85 [TR ITE ]) im ages w e re ob ta ined . A 5 .1 -mm slice th ic kness ,

0 .5 -mm in te rs lice g ap , 1 9 2 x 256 m atr ix , and 24 .5 -cm fie ld o f v iew

w ere used . W ith the 1 .5 -T un it, u sua lly m agne tiz a tion -p repa red

ra p id g ra d ie n t-ech o im ages (M P RAG E , 1 0 /4 /1 0# {1 76 }TR/TE/f l ip

ang le ]) w e re ob ta ine d b y us in g a 180 x 256 m atr ix , 25 -cm nec ta ngu-

ar fie ld o f v iew , 2 .8 -m m s lice th ickn es s , an d no in tens lic e g ap . A x ia l

and co rona l sp in -e cho im ages (2 750 /20 ,80 ) w e re ob ta ine d b y us in g

a 7 5# {1 76 }lip ang ie , on e ex c ita tion , 4 -mm s lice th ickn e ss , 1 -mm in te r -

s lic e ga p , 1 92 x 256 m atrix , and 23 -cm fie ld o f v iew . C orona l im ages

we re pu lse ga ted . W ith bo th un its , a x ia l im ages w e re pa ra lle l and

co ro na l im age s w e re pe rp end icu la r to the lo ng a x is o f th e h ipp o c -

am pus , de fined on a sag itta l lo ca liz er.

B ecause o f rap id advances in MR techno logy du ring the cou rse

o f th e s tud y , im ages w ere o b ta ine d w ith tw o d iffe ren t m ach ine s , a n d

consequen tly the qua lity o f the im ages va ried . In add ition , im ag ing

p ro toco ls w e re m od ified as so ftw a re capab ilitie s changed . Tech-

n iq u es fo r q u an tita tive a na lys is w ere no t a va ilab le a t the tim e o f th e

s tu d y . Y oung ch ild re n w ere seda te d w hen neces sa ry , un de r su pen v i-

s io n o f a p ed ia tric an e s the tis t.

M R im age s we re re v iew ed ind ependen tly b y a ped ia tric na d io lo -

g is t and a neu ro rad io log is t. E ach M R study was rev iew ed tw ice by

each rad io log is t. Im ages w ere rev iew ed in random o rde r and w ithou t

know ledge o f the pa tien t’s iden tity , c lin ica l and EEG da ta , the nad io l-ogist’sfirstinterpretation,or the other radiologist’sinterpretation.MR

im age s o f ch ild re n w ho had m u ltip le exam in a tio n s w ere re v iew ed

toge the r. A ll sequences and p lanes o f im ag ing we re rev iew ed , bu t

pa rticu la r a tte n tion was d ire c ted to th e m ed ia l tem po ra l s tru c tu res .

Im ages w e re c la ss ifie d a s show in g h ip p ocam pa l sc le ro s is , o th e r

les io ns , o r no abno rm a lity . A bno rm a lit ies w e re c las s if ied as le ft

s id ed , rig h t s ide d , on b ila te ra l. H ipp ocam pa l s c le ro s is w a s d ia gnosed

when e v id en ce o f h ip p ocam pa l a trop hy w as p re sen t o r h ipp ocam pa l

s ig na l in ten s ity w a s abno rm a l w ith ou t e v ide nce o f a m ass les io n .

W hen d iffe re n t d iag nose s w e re m ade b y one ra d io log is t, the M R

im ages w e re rev iew ed once m o re and a fina l d iagnos is was m ade .

W hen d iffe ren t d iagnoses w e re m ade by tw o r ad io lo gis ts , th e im a ge s

we re rev iewed in con junc tion and a consensus d iagnos is was m ade .

E th ic a l c on s id e ra tio ns p rec lud ed th e use o f he a lthy ch ild re n as

con tro l su b je c ts , a nd p rac tica l p rob lem s w ith b lin d ing p re c lud ed th e

u se o f ch ild re n w ith e x tra tem pona l le s io ns a s con tro l su b je c ts .

C hance -ad ju s ted in tenobse rve r and in traobse rve r ag reem en t was

m easu red w ith C ohen ’s kappa s ta tis tic .

Resu l ts

The consensus M R d iagnoses fo r the 53 ch ild ren we re

h ippocam pa l sc le ros is in 30 (57% ), o the r le s ions in 10

(19% ), and no abno rm a lity in 13 (24% ). In traobse rve r and

in tenobse rven ag reem en t w as good (in traobse rven kappa ,

0 .77 and 0 .84 ; in te robse rver kappa , 0 .76 ). In tenobse rve r d is -

ag reem en t conce rned e igh t ch ild ren in whom the u ltim a te

d iagnos is was h ippocam pa l sc le ros is o r no abno rm a lity . S ix

o f the e igh t had M R s tud ie s w ith the 0.3 -T un it. U n ila te ra l

abno rm a litie s o f the tem po ra l co rte x w e re d iagnosed on M R

im ages in 39 ch ild ren , conco rdan t w ith the EEG and ic ta l

S PEC T la te ra liza tion in 36 ch ild ren (92% ).

H ippocam pal sc le ros is w as un ila te ra l in 29 ch ild ren and

b ila te ra l in one (F ig s . 1-3 ). Tw en ty -e igh t ch ild ren had h ip -

pocam pal a trophy and increased s igna l on T2 -w e igh ted

im ages; tw o ch ild ren had m a rked h ippocam pa l a trophy w ith -

ou t obse rvab le s igna l abno rm a lity . B ila te ra l h ippocam pa l

sc le ros is was d iagnosed on the bas is o f b ila te ra l h ippocam -

pa l a trophy and inc reased s igna l in tens ity (F ig . 3 ). In n ine

ch ild ren , h ippocam pa l sc le ros is w as assoc ia ted w ith le s ions

ou ts ide the tem po ra l co rte x : anachno id cys t in the m idd le

cran ia l fo ssa in tw o (one ips ila te ra l and one con tra la tena l to

h ippocam pa l sc le ros is ), pen iven tn icu lan h igh s igna l in tens ity

in tw o w ho had ven tn ic u lopen itonea l shun ts , ip s ila tena l fo ca l

o cc ip ita l a trophy in three , ip s ila te ra l pa raven tn icu la r tum o r

pro jec ting in to the tn igo ne in one , a n d gene ra lized ce reb ra l

a trophy in one . M R d iagnoses o f the o the r le s ions in the

tem po ra l co rte x w e re tum o r in e igh t, c ave rnous ang iom a in

one , and hem im acrencepha ly w ith ip s ila tena l e c top ic g ray

m a tte r in one .

O f the 17 ch ild re n w ho had su rge ry and in whom h ippo -cam pa l s c le ros is was d iagnosed on the bas is o f M R find ings ,

h is to log ic exam ina tion show ed h ippocam pa l s c le ros is in 11

and no abno rm a lity in s ix in w hom app rop ria te h ippocam pa l

tissue was no t p resen t in the su rg ica l spec im en . O f the s ix

ch ild ren w ho had su rge ry and in w hom a tum o r w as d iag -

nosed on the bas is o f MR find ings , h is to log ic exam ina tion o f

the ava ilab le spec im en show ed dysem b ryop las tic neu roep i-

the lia l tum o r in tw o , gang liog liom a in one , as tro cy tom a in

one , ch ron ic encepha litis in one , and no abno rm a lity in one .

T he cave rnous ang iom a and g ray m a tte r he teno top ia w e re

h is to log ica lly con firm ed . O f the fou r ch ild ren who had su rge ry

and in whom no abno rm a lity was d iagnosed on the bas is o f

M R find ings (a ll fou r im aged w ith the low -fie ld -s treng th un it) ,

h is to log ic exam ina tion showed h ippocam pa l s c le ros is in tw oand no abno rm a lity in tw o in whom app rop ria te h ippocam pa l

tissue w as no t p resen t in the su rg ica l spec im en . M R im ages

show ed ev idence o f h ippocam pa l s c le ros is in 11 (85% ) of 13

ch ild ren w ith h is to log ica lly p roved h ippocam pa l sc le ros is .

Discuss ion

Th is s tudy repo rts the M R find ings in a g roup o f ch ild ren

w ith we ll-docum en ted and in tra c tab le tem po ra l lobe ep i-

lepsy . T he d iagnos is o f tem po ra l lobe ep ilepsy w as based on

typ ica l c lin ica l se izu re cha rac te ris tic s and ic ta l EEG loca liz a-

tion to the tem po ra l lobe . A lthough in tra c ran ia l e le c trodes

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A JR :161 , N ovem be r 1993 H IPPOCAM PAL SC LEROS IS IN CH ILDREN 1047

F ig . 1 . -1 2 -y e a r- ol d bo y w ith r igh t-s ided h ip po cam pal s c le ro s is .

A , Ang le d co ro na l M P RAG E (1 0 I4 l1 0 M R Im age show s m a rked h ip pocam pal a trop hy ( a r row ) on r igh t s id e . C om pa re w ith n orm a l h ipp ocam pu s on

le f t bo unded sup er io r ly by a lv eu s .

B an d C , C or on al p ro to n d en sity -w eig hte d (B ) an d T2 -w e lgh ted (C ) (2 50 0 /3 0 ,8 0 ) M R Im ages sh ow the a re a o f Inc re as ed s ign a l In te ns ity ( a r rows) is

local ized to h ipp ocam pu s on r igh t s ide .

F ig . 2 .-9 -ye ar-o ld g ir l w ith le ft-s id ed h ip -

po c ampa l sc le ros is .A an d B, A ng led ax ia l (A ) a nd c or on al (B ) T2 -

we igh ted ( 2500 /80 ) MR Im ages show poorly d e -fin ed are a o f in cre as ed s ign a l In ten s ity

( a r rows) e x ten d in g a lo n g h lpp ocam pus . H ip -

po c ampa l a tro ph y w as be tte r v isua liz ed on M P

R AG E c oro na l s eq ue nce (n ot s ho wn ).

F ig . 3 .-7 -ye ar-o ld g irl w ith b ila te ra l h ip po cam pal sc le ros is .

A, A ng led co ron a l M P RAG E (1 0 I4 I1 0 M R Im ag e show s b ila te ra l h ip po cam pal a tro ph y ( a r rows) , more ma rk ed on le f t s ide than on righ t s ide .

B an d C , P r ot on d e ns it y- we ig h te d (B ) an d T2-we igh ted (C ) ( 2500 /30 ,80 ) MR images show a rea s o f Inc rea sed s ign a l In ten s ity ( a r rows) loc a lize d to

h lp po cam pu s b ila te ra l ly . In de penden t b ila te ra l tem po ra l lob e hype rp erfus ion w as seen on Ic ta l S P EC T Im ages (n ot s ho wn ).

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we re no t used , EEG loca liza tion w ith sca lp e le c trodes w as

suppo rted by the resu lts o f ic ta l SPEC T in 21 ch ild ren and

the bene fic ia l re su lts o f tem po ra l lobec tom y in 26 ch ild ren .

A bno rm a litie s on M R im ages w e re de tec ted in 75% o f ch il-

d ren , h ippocam pa l sc le ros is be ing the m ost comm on les ion .

EEG con firm a tion o f la tena liza tion w as p re sen t in 92% .

O ve ra ll ag reem en t be tween the two obse rve rs w as good ,

ind ica ting tha t h ippocam pa l s c le ros is and o the r le s ions can

be de tec ted re liab ly on M R im ages o f ch ild ren .

H ippocam pa l sc le ros is was d iagnosed on the bas is o f M Rfind ings in 57% o f ch ild ren in ou r s tudy and was con firm ed

pa tho lo g ica lly in a ll ch ild re n w ho had su rge ry in w hom

app rop r ia te h ippocam pa l tissue w as ava ilab le fo r exam ina -

tion . T he m e thod o f m es ia l tem po ra l re sec tion a t ou r in s titu -

tion (subp ia l a sp ira tion as opposed to en b loc resection )

m ean t tha t adequa te h ippocam pa l tis sue fo r pa tho log ic

exam ina tion was ava ilab le in on ly 11 o f 17 ch ild ren w ho had

M R evid ence o f h ippocam pa l sc le ros is . H ippo cam pa l sc le ro -

s is is de tec ted on M R im ages on at su rge ry in 60 -70% o f

adu lts w ith in tra c tab le tem po ra l lobe ep ilepsy [10 , 13 ]. T he

p reva lence o f h ippocam pa l sc le ros is in ch ild ren w ith in tra c-

tab le tem po ra l lobe ep ilepsy can be de te rm ined on ly from

su rg ica l se r ie s , w he re it has been va riab ly repo rted in 9 -

60% [2 -6 ]. The s tud ie s show ing few e r ch ild ren w ith h ippo -cam pa l sc le ros is m ay re fle c t the absence o f h ippocam pa l

tissue in th e ir su rg ica l spec im ens, a se lec tion b ias tow ard

ea rly su rge ry w hen im ag ing show s a m ass le s ion , on a d iffe r-

en t spec trum o f tem po ra l lobe abno rm a litie s in ch ild ren w ho

have in tra c tab le tem po ra l lobe ep ilepsy in ear ly ch ildhood .

The repo rted M R fea tu res o f h ippocam pa l sc le ro s is

in c lude h ippocam pa l a trophy , in c reased s igna l in tens ity on

T2-w e igh ted im ages, loss o f in te rna l a rch itec tu re o f the h ip -

pocam pus, and loss o f s igna l in tens ity on T i -w e igh ted

im ages [13 , 14 ]. In ou r s tudy , on ly the firs t tw o we re used as

c rite ria fo r a d iag nos is o f h ip p ocam pa l sc le ros is . In te re s t-

in g ly , in c reased s igna l in tens ity on T2 -we ighted im ages w as

seen in 28 o f 30 ch ild ren w ith h ippocam pa l sc le ros is ; th e firs t

echo o f the doub le -echo co rona l sequence was pa rticu la r ly

use fu l in m a rg ina l cases . Th is is in con tra s t to som e stud ie s

in adu lts , in w hom dem ons trab le s igna l abno rm a litie s w e re

ra re [1 5 ]. A recen t s tud y w ith T2 quan tita tive m easu rem en t

has show n in crea sed s igna l in tens ity in pa tien ts w ith in trac-

ta b le tem pora l lo be ep ile psy when no s igna l abnorm a lity

w as v is ib le (Jackson GD et a l., p re sen ted a t the Am erican

Ep ile psy Soc ie ty m ee ting , Decem be r 1 992). It is p oss ib le

tha t s igna l abno rm a litie s assoc ia ted w ith h ippocam pa l s c le -

ros is a re m o re p ronounced in ch ild re n o r tha t lo ss o f s ig na l

in tens ity occu rs w ith in c reas ing age .

In ou r s tudy , n ine ch ild ren w ith h ippocam pa l sc le ros is had

add itiona l le s ions ou ts ide the co rte x o f the tem pora l lobe ,

ra is ing doub t abou t lo ca liza tion o f the ep ilep togen ic fo cus .

A rachno id cys ts and pen iven tn icu la r w h ite m a tte r g lio s is a re

un lik e ly to cause se izu res by them se lves . H ow eve r, co rtica l

a trophy o r tum o r in the pos te r io r co rte x can m an ife s t e le c tn i-

ca lly and c lin ic a lly as tem po ra l lobe ep ilepsy . The ch ild ren

w ith d isco rdan t M R and EEG abnorm a lities and th e ch ild ren

w ith b ila te ra l se izu re on se t ha ve no t undergone su rge ry .

No les ion w as de tec tab le on MR im ages o f 13 ch ild ren ,

seven o f w hom we re exam ined w ith the h ighe r-fie ld -s treng th

un it. In fo u r c h ild ren w ith n o rm a l M R find ings , tem pora l

lo bec tom y w as pe rfo rm ed because o f re su lts o f e le c trophys -

io log ic s tud ie s . These fou r ch ild ren w e re exam ined on the

low -fie ld -s treng th m agne t ea rly in the s tudy period . T he qua l-

ity o f these im ages wou ld no t be accep tab le now . H ippocam -

pa l s c le ros is was found a t pa tho log ic exam ina tion in tw o

ch ild ren , and no abno rm a lity w as found in tw o ch ild ren in

w hom app rop ria te h ippocam pa l tissue w as no t ava ilab le fo r

exam ina tion . S om e ch ild ren w ith no rm a l MR find ings had

m ino r deg rees o f h ippocam pa l asymm e try , bu t in the

absence o f an app rec iab le in crease in h ippocam pa l s igna l

on T2 -we igh ted im ages , h ippocam pa l sc le ros is w as no t

d iagnosed . Q uan tita tive te chn iques m ay have led to a d iag -

nos is o f h ippo cam pa l sc le ros is in som e o f the se ch ild ren . Itis a lso poss ib le tha t som e o f the ch ild ren w ith no rm a l M R

fin d ings who have no t unde rgone su rge ry have sub tle m ig ra -

tiona l abno rm a litie s on m icrodysgenes is o f the tem po ra l con -

tex , w h ich is no t de te cta b le w ith MR .

A ll d iagnoses o f h ippocam pa l s c le ros is based on M R

im ages we re con firm ed pa tho log ica lly if app rop r ia te tis sue

was ava ilab le fo r exam ina tion . O u r resu lts sugges t tha t h ip -

pocam pa l sc le ros is is as p reva len t in ch ild ren , and as read ily

d iagnosed on the bas is o f M R find ings , as in adu lts . W e sus-

pect tha t h ippo cam pa l sc le ros is is underd iagnosed in ch il-

d ren , poss ib ly lead ing to pos tponem en t o f su rge ry in

ch ild ren w ith in tra c tab le se izu res .

A C KNOWLEDGMENTS

W e thank Pe te r B uchanan fo r adm in is tra tive ass is tance ; E ric G il-

fo rd , M ichae l K ean , and the M RI s ta ff a t S t. V in cen ts H osp ita l, M el-

bounne , fo r im ag ing ou r pa tien ts ; Ian J . H opk in s , L lo yd K . S h ie ld ,

K ev in J . C o llin s , and G eo ffe ry L . K Iug fo r con tribu tions to pa tien ts ’

tre a tm en t; an d B ria n M . T re ss , Ian J . H op k in s , a nd Sam F . B e rko v ic

fo r rev iew in g th e m anu sc rip t a n d p ro v id in g he lp fu l su gge s tio ns .

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