Outcome from Complicated versus Uncomplicated Mild Traumatic Brain Injury

Hindawi Publishing Co po a ion Rehabili a ion Resea ch and P ac ice Volume 2012, A icle ID 415740, 7pages doi:10.1155/2012/415740 Clinical S udy Ou come om Complica ed e sus Uncomplica ed Mild T auma ic B ain Inju y G an L. I e son,1Rael T. Lange,1, 2 Minna W¨ aljas,3Su i Liima ainen,4P asun Das ida ,5 Kaisa M. Ha ikainen,3Seppo Soimakallio,5and Juha ¨ Ohman3 1Depa men o Psychia y, Uni e si y o B i ish Columbia, 2255 Wesb ook Mall, Vancou e , BC, Canada V6T 2A1 2Depa men o O hopaedics and Rehabili a ion, Wal e Reed Na ional Mili a y Medical Cen e and De ense and Ve e ans B ain Inju y Cen e , 11300 Rock ille Pike, Sui e 1100, No h Be hesda, MD 20852, USA 3Depa men o Neu osciences and Rehabili a ion, Tampe e Uni e si y Hospi al and Uni e si y o Tampe e Medical School, PL 2000, 33521 Tampe e, Finland 4Depa men o Neu osciences and Rehabili a ion and Eme gency Depa men Acu a, Tampe e Uni e si y Hospi al, PL 2000, 33521 Tampe e, Finland 5Medical Imaging Cen e o Pi kanmaa Hospi al Dis ic and Uni e si y o Tampe e Medical School, PL 2000, 33521 Tampe e, Finland Co espondence should be add essed o G an L. I e son, gi e son@in e change.ubc.ca Recei ed 4 No embe 2011; Re ised 3 Feb ua y 2012; Accep ed 27 Feb ua y 2012 Academic Edi o : Anne Felicia Amb ose Copy igh © 2012 G an L. I e son e al. This is an open access a icle dis ibu ed unde he C ea i e Commons A ibu ion License, which pe mi s un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal wo k is p ope ly ci ed. Objec i e. To compa e acu e ou come ollowing complica ed e sus uncomplica ed mild auma ic b ain inju y (MTBI) using neu ocogni i e and sel - epo measu es. Me hod. Pa icipan s we e 47 pa ien s who p esen ed o he eme gency depa men o Tampe e Uni e si y Hospi al, Finland. All comple ed MRI scanning, sel - epo measu es, and neu ocogni i e es ing a 3-4 weeks a e inju y. Pa icipan s we e classi ied in o he complica ed MTBI o uncomplica ed MTBI g oup based on he p esence/absence o in ac anial abno mali y on day-o -inju y CT scan o 3-4 week MRI scan. Resul s. The e was a la ge s a is ically signi ican diffe ence in ime o e u n o wo k be ween g oups. The pa ien s wi h uncomplica ed MTBIs had a median o 6.0 days (IQR =0.75–14.75, ange =0–77) offwo k compa ed o a median o 36 days (IQR =13.5–53, ange =3–315) o he complica ed g oup. The e we e no signi ican diffe ences be ween g oups o any o he neu ocogni i e o sel - epo measu es. The e we e no diffe ences in he p opo ion o pa ien s who (a) me c i e ia o ICD-10 pos concussional diso de o (b) had mul iple low sco es on he neu ocogni i e measu es. Conclusion. Pa ien s wi h complica ed MTBIs ook conside ably longe o e u n o wo k. They did no pe o m mo e poo ly on neu ocogni i e measu es o epo mo e symp oms, a 3-4 weeks a e inju y compa ed o pa ien s wi h uncomplica ed MTBIs. 1. In oduc ion Mos mild auma ic b ain inju ies (MTBIs) a e no associ- a ed wi h isible abno mali ies on s uc u al neu oimaging. Acomplica ed MTBI, in he o iginal de ini ion [1], was di - e en ia ed om an uncomplica ed mild TBI by he p esence o (a) a dep essed skull ac u e and/o (b) a auma- ela ed in ac anial abno mali y (e.g., hemo hage, con usion, o edema). O he esea che s ha e d opped he dep essed skull ac u e om he c i e ia and simply e ained he c i e ion o an in ac anial abno mali y. The a es o complica ed MTBIs, based on coho s o pa ien s who unde wen acu e compu ed omog aphy ollowing head auma, a e p esen ed in Table 1. The a es o abno mali ies a y conside ably. In gene al, when examining de ails wi hin hese s udies, pa ien s wi h GCS sco es o 13 o 14 a e mo e likely o ha e an abno mali y han pa ien s wi h a GCS sco e o 15. O he possible easons o diffe ences in abno mali y a es could ela e o echnology (e.g., olde scanne s e sus newe scanne s) and e e al pa e ns o neu oimaging (i.e., mo e libe al e susmo econse a i euseo imaging). I is seems logical o assume ha wo se sho -, medium-, and long- e m neu opsychological and unc ional ou come would esul om complica ed e sus uncomplica ed MTBIs. 2Rehabili a ion Resea ch and P ac ice Table 1: Ra es o complica ed mild TBI in adul s. Fi s au ho Yea Coun y To al NNumbe Scanned GCS sco es % Abno mal Li ings on [26] 1991 USA 111 111 14-15 14 S ein [27] 1992 USA 1,538 1,538 13–15 17.2 Je e [28] 1993 USA 712 702 15 9.4 Mo an [29] 1994 USA 200 96 13–15 8.3 Bo czuk [30] 1995 USA 1,448 1,448 13–15 8.2 I e son [31] 2000 USA 912 912 13–15 15.8 Thi uppa hy [32] 2004 India 381 381 13–15 38.9 S iell [33] 2005 Canada 2,707 2,171 13–15 12.1 S iell [33] 2005 Canada 1,822 1,822 15 8.0 Ono [34] 2007 Japan 1,064 1,064 14-15 4.7 Saboo i [35] 2007 I an 682 682 15 6.7 Howe e , he esul s om a se ies o s udies a e mixed. As a g oup, pa ien s wi h complica ed MTBIs pe o m mo e poo ly on neu opsychological es s in he i s wo mon hs ollowing inju y [1–6]. These diffe ences appea o diminish by six mon hs ollowing inju y [7,8]. When diffe ences occu be ween g oups, he effec sizes o hese diffe ences a e lowe han expec ed (i.e., medium o medium-la ge effec sizes o lowe on a small numbe o es s [1–5,7,9]; see Bo ga o and colleagues [5] o an excep ion). Some esea che s ha e epo ed ha pa ien s wi h com- plica ed MTBIs ha e wo se 6–12-mon h unc ional ou come (i.e., Glasgow Ou come Scale) compa ed o pa ien s who sus ained uncomplica ed MTBIs [1,10,11], and hey ha e simila 3–5-yea ou come (i.e., Func ional S a us Exami- na ion) as pa ien s wi h a his o y o mode a e and se e e TBI [12]. The e a e some excep ions, howe e . McCauley and colleagues epo ed ha CT abno mali ies we e no associa ed wi h inc eased isk o pos concussion synd ome a 3 mon hs a e inju y [13]. Simila ly, Lee and colleagues [14] epo ed ha CT and con en ional 3T MRI imaging indings do no p edic neu ocogni i e unc ioning a 1 o 12 mon hs a e inju y, no unc ional ou come a one yea a e inju y. I is becoming inc easingly clea ha complica ed MTBIs ep esen a ai ly b oad spec um o inju y, wi h some people ha ing e y small abno mali ies and excellen unc ional ou come and o he people equi ing inpa ien ehabili a ion and ha ing poo ou come. The pu pose o his s udy is o compa e he ou come o pa ien s wi h complica ed e sus uncomplica ed MTBIs. To da e, ew s udies ha e compa ed bo h neu ocogni i e ou come and sel - epo ed symp oms ollowing uncompli- ca ed and complica ed MTBI. This is a p ospec i e s udy, wi h pa ien s iden i ied om he eme gency depa men unde going MRI and a neu opsychological e alua ion a app oxima ely 3-4 weeks a e inju y. I was hypo hesized ha pa ien s wi h complica ed MTBIs would epo mo e symp oms, pe o m mo e poo ly on neu ocogni i e es ing, and ake longe o e u n o wo k han pa ien s wi h uncom- plica ed MTBIs. We hypo hesized wo se ou come in his g oup because we assume ha complica ed MTBIs end o be mo e se ious b ain inju ies han uncomplica ed MTBIs. 2. Me hods 2.1. Pa icipan s. Pa icipan s we e 47 pa ien s wi h MTBIs who p esen ed o he eme gency depa men o Tampe e Uni e si y Hospi al, Finland (age: M =30.3 yea s, SD =9.4, Range =16–46; educa ion: M =13.0 yea s, SD =2.3). The pa ien s we e selec ed om a la ge coho o head auma pa ien s en olled in a longi udinal s udy, based on mee ing inclusion c i e ia below, ha ing comple e da a on all ou come measu es, and ha ing a known du a ion o ime offwo k. The diagnos ic c i e ia o MTBI used in his s udy we e om he Wo ld Heal h O ganiza ion Collabo a ing Cen e TaskFo ceonMTBI.Inclusionc i e iawe eas ollows:(i) biomechanical o ce applied o he head esul ing in loss o al e a ion o consciousness, con usion, and/o pos auma ic amnesia, (ii) loss o consciousness (LOC), i p esen , o less han 30 minu es, (iii) Glasgow Coma Scale (GCS) sco e 13– 15 a e 30 minu es ollowing inju y, and (i ) pos auma ic amnesia (PTA), i p esen , o less han 24 hou s. Pa ien s unde wen compu ed omog aphy (CT) scan- ning i deemed clinically indica ed, an e alua ion by an ED auma ologis , and o he examina ions as needed. CT scan- ning was pe o med wi hin 24 hou s o admission and is used libe ally o head auma pa ien s. Magne ic esonance imaging (MRI) was conduc ed a app oxima ely h ee weeks a e inju y o esea ch pu poses, al hough he in o ma ion was a ailable o he pa ien ’s heal hca e p o ide s (com- plica ed MTBI g oup M =19.3, SD =15.0, ange =1– 53 days and uncomplica ed MTBI g oup M =25.8, SD = 5.5, ange =16–36 days). The MRI p o ocol included sagi - al T1-weigh ed 3D IR p epa ed g adien echo, axial T2 u bo spin echo, con en ional axial, and high- esolu ion sagi al FLAIR ( luid-a enua ed in e sion eco e y), axial T2∗, and axial SWI (suscep ibili y weigh ed imaging) se ies. Only auma- ela ed indings on CT o MRI we e coun ed as abno mal; mino inciden al indings, such as isola ed whi e Rehabili a ion Resea ch and P ac ice 3 ma e hype in ensi ies, we e no conside ed as abno mal. Pa ien s we e excluded i signi ican non- auma- ela ed ab- no mali ies we e iden i ied. Mos we e excluded due o small essel ischemic disease, bu he e we e also pa ien s wi h mul iple scle osis, unusually la ge en icles, and a his o y o neu osu ge y. This sample included pa ien s (N=13; 27.7%) who had an in ac anial abno mali y on day-o -inju y CT o ollow- up MRI (i.e., a complica ed MTBI). None o he pa ien s equi ed inpa ien ehabili a ion. None o he pa ien s we e in ol ed in li iga ion. All pa ien s p o ided w i en in o med consen acco ding o he Decla a ion o Helsinki. The s udy p o ocol was app o ed by he E hical Commi ee o he Tampe e Uni e si y Hospi al. All pa ien s comple ed sel - epo measu es and neu ocogni i e es ing a 3-4 weeks a e inju y (M =25.8, SD =2.9, Range 21–34 days). 2.2. Measu es. Pos concussion symp oms we e assessed using he Ri e mead Pos -Concussion Ques ionnai e (RPSQ) [15]. The RPSQ is a 16-i em sel - epo ques ionn- ai e ha measu es he se e i y o common pos oncussion symp oms on a 5-poin Like scale. The pa ien s a ed he p esence o he symp oms o e he pas 24 hou s on a scale om0 o4(0=no expe ienced a all a e he inju y, 1 = expe ienced bu no mo e o a p oblem compa ed wi h be o e he inju y, 2 =amildp oblem,3=a mode a e p oblem, and 4=a se e e p oblem). A o al sco e was calcula ed by adding all i ems wi h a sco e g ea e han 1 (no p esen anymo e). Possible dep essi e symp oms we e assessed using he Beck Dep ession In en o y-Second Edi ion (BDI-II) [16], a 21-i em sel - epo ques ionnai e. Subjec s we e asked o a e each i em on a ou -poin scale anging om ze o o h ee. In his s udy, we used he o al sco e which is he sum o all 21 i ems, gi ing a ange om ze o o 63. I should be no ed ha many symp oms on his ques ionnai e o e lap wi h pos concussion symp om measu ed by he RPSQ. Sel - epo ed a igue was examined using he Ba ow Neu ological Ins i u e Fa igue Scale (BNI-FS), an 11-i em sel - epo ques ionnai e designed o assess a igue du ing he ea ly s ages o eco e y a e b ain inju y [17]. Subjec s we e asked o a e he ex en o which each o he 10 p ima y i ems has been a p oblem o hem since he inju y on a 7- poin scale. Response op ions a e as ollows: 0-1 = a ely a p oblem; 2-3 =occasional p oblem, bu no equen ; 4-5 = equen p oblem; 6-7 =a p oblem mos o he ime. The inal i em (i em 11) asks subjec s o p o ide an o e all a ing o hei le el o a igue on a scale om 0 (no p oblem) o 10 (se e e p oblem). In his s udy he o al BNI-FS sco e is used which is he sum o all 10 sco es (min =0, max =70). Gene al e bal in elligence was assessed wi h he Wech- sle Adul In elligence Scale-Thi d Edi ion (WAIS III) in o - ma ion sub es [18]. Lea ning and memo y was assessed wi h he Rey Audi o y Ve bal Lea ning Tes (RAVLT) o al sco e ( o al numbe o wo ds ecalled in ials 1 h ough 5) and delayed ecall (numbe o wo ds ecalled a e 30 mi- nu es delay) [19]. A en ion and execu i e unc ioning we e assessed wi h S oop Colo Wo d Tes (colo -wo d in e - e ence sco e, Golden e sion) [19], T ail Making Tes (TMT) A and B ( ime needed o inish he ask) [20], and wo e bal luency asks: animal naming (ca ego y luency, o al numbe o wo ds in one minu e) and single-le e -based wo d gene a- ion (phonemic luency, o al numbe o wo ds p oduced ac oss he 3 ials) [21]. Raw sco es o he neu ocogni i e es s we e analyzed unless o he wise s a ed. 3. Resul s The e we e no signi ican diffe ences be ween MTBI g oups o age, educa ion, gende , GCS sco e, mechanism o inju y, days es ed a e inju y, o du a ion o LOC, PTA, o e o- g ade amnesia (see Table 2). The e was a la ge s a is ically signi ican diffe ence in ime o e u n o wo k be ween g oups. The pa ien s wi h uncomplica ed MTBIs had a median o 6.0 days (mean =12.9, SD =18.8, IQR =.75– 14.75, ange =0–77) o wo k compa ed o a median o 36 days (mean =58.0, SD =83.8, IQR =13.5–53, ange =3–315) o he complica ed MTBI g oup. The e we e no signi ican diffe ences be ween MTBI g oups o sel - epo ed dep ession (BDI-II) o pos concus- sion symp oms (RPSQ) (all P>.05). The e we e, howe e , medium effec sizes o he BDI-II o al sco e (Cohen’s d=.52) and RPSQ o al sco e (d=.43) be ween g oups. These effec s sizes sugges ha he complica ed MTBI g oup epo ed ewe dep ession symp oms and pos concussion symp oms compa ed o he uncomplica ed MTBI g oup. The e was no a s a is ically signi ican diffe ence in he pe cen ages o pa ien s in he uncomplica ed (44.1%) e sus complica ed (38.5%) MTBI g oups who me ICD-10 c i e ia o pos concussional synd ome based on he epo - ing o symp oms on he RPSQ as “mild” o g ea e (i.e., sco e o 2 o highe on indi idual i ems). In con as , 17.6% o he pa ien s in he uncomplica ed MTBI g oup me ICD- 10 c i e ia o pos concussional synd ome based on he e- po ing o symp oms on he RPSQ as “mode a e” o g ea e (i.e., sco e o 3 o highe on indi idual i ems); no pa ien s in he complica ed MTBI g oup me his c i e ion o he synd ome. As seen in Table 3, he e we e no signi ican diffe ences be ween MTBI g oups on he neu opsychological es s (all P>.05). Al hough no signi ican ly diffe en , medium effec sizes we e ound o he RAVLT o al sco e (d=.39), RAVLT delayed ecall sco e (d=.47), Animal Naming es (d= .43), and S oop Colo -Wo d (d=.47). Pa adoxically, he complica ed MTBI g oup pe o med be e on e bal lea ning and memo y (RAVLT) and execu i e unc ioning (S oop), bu wo se on a es o e bal luency (Animal Nam- ing). The p e alence o low sco es ac oss he ba e y o cog- ni i e es s was de e mined o each g oup (i.e., eigh sco es (no including he Rey Copy) de i ed om he six es s we e conside ed simul aneously). A low sco e on he neu ocog- ni i e es s was de ined as alling below he 10 h pe cen ile compa ed o published no ma i e da a. The e was no a signi ican diffe ence in he pe cen age o pa ien s wi h un- complica ed (26.5%) e sus complica ed (23.1%) MTBIs who had wo o mo e low sco es, when eigh es sco es we e conside ed simul aneously. 4Rehabili a ion Resea ch and P ac ice Table 2: Demog aphic and inju y se e i y cha ac e is ics. Uncomplica ed MTBI Complica ed MTBI MSDMSDpd Age (in yea s) 30.8 9.0 29.2 10.9 0.601 .17 Educa ion (in yea s) 13.1 2.3 12.9 2.3 0.859 .06 WAIS-III in o ma ion (SS) 10.9 2.4 10.4 1.4 0.492 .23 GCS sco e in ED 14.9 0.3 14.9 0.3 0.693 .13 Days es ed a e Inju y 26.0 2.9 25.4 3.0 0.523 .21 Du a ion o loss o consciousness (minu es) 0.6 1.5 1.0 1.5 0.514 .25 Du a ion o pos auma ic amnesia (minu es) 333.0 448.2 366.7 420.8 0.822 .08 Du a ion o e og ade amnesia (minu es) 9.2 23.6 21.5 66.6 0.354 .34 Numbe o days o e u n o wo k 12.9 18.8 58.0 83.8 0.002 1.2 % %χ2 Gende Male 17 50.0 7 53.8 0.813 — Mechanism o inju y MVA 15 44.1 5 38.5 0.726 — O he bodily inju ies 9 26.5 4 30.8 0.768 — CT: day o inju y Abno mal 0 0 8 61.5 — — MRI: 3 weeks a e Abno mal 0 0 12 92.3 — — No a ailable 0017.7 No e: N=47 (uncomplica ed MTBI, n=34; complica ed MTBI, n=13). Cohen’s effec size (d): small (.20), medium (.50), la ge (.80). CT=compu ed omog aphy; MRI: magne ic esonance imaging; GCS: Glasgow Coma Scale; MTBI: mild auma ic b ain inju y; MVA: mo o ehicle acciden . A Mann- Whi ney U es was used o he numbe o days o e u n o wo k compa ison. Table 3: Desc ip i e s a is ics ( aw sco es) and effec sizes: sel - epo and neu ocogni i e es s. Uncomplica ed MTBI Complica ed MTBI MSDMSD pd Sel - epo Measu es BDI-II o al 7.6 6.7 4.5 4.0 .130 .52 RPSQ o al 11.6 11.8 7.2 6.2 .358 .43 Ba ow Fa igue Scale 16.4 15.3 13.0 9.7 .464 .25 Neu ocogni i e Tes s RAVLT o al 56.9 7.8 60.2 10.1 .237 .39 RAVLT delay 11.1 2.8 12.4 2.6 .159 .47 RCFT copy 35.7 0.7 35.6 0.8 .792 .09 RCFT Immedia e 25.4 5.9 23.8 5.2 .402 .28 Phonemic Fluency o al 38.7 9.4 39.8 13.4 .766 .10 Animal Naming o al 25.1 6.4 22.5 5.0 .194 .43 T ails A (in seconds) 27.3 9.5 28.5 8.7 .685 .13 T ails B (in seconds) 62.5 24.8 57.5 13.3 .495 .23 S oop Colo -Wo d 42.1 8.2 45.9 7.2 .157 .47 No e: N=47 (uncomplica ed MTBI, n=34; complica ed MTBI, n=13); Cohen’s effec size (d): small (.20), medium (.50), la ge (.80). BDI-II: Beck Dep ession In en o y-Second Edi ion; RPSQ: Ri e mead Pos concussion Scale; RCFT: Rey Complex Figu e Tes ; RAVLT:Rey Audi o y Ve bal Lea ning Tes ; MTBI:mild auma ic b ain inju y. Rehabili a ion Resea ch and P ac ice 5 4. Discussion A subs an ial mino i y o pa ien s who sus ain an MTBI anda ee alua edinaneme gencydepa men willha ea isible abno mali y on ea ly CT scanning (Table 1). These pa ien s a e concep ualized as ha ing a complica ed MTBI. Resea che s ha e epo ed ha hose wi h complica ed MTBIs, as a g oup, a e mo e likely o ha e ea ly cogni i e de ici s [1–6]andwo semedium[1,10,11] and long- e m [12] unc ional ou come. In con as , howe e , some e- sea che sha eno oundimpo an diffe ences be ween hose wi h complica ed e sus uncomplica ed MTBIs. Fo example, in one s udy, pa ien s wi h complica ed MTBIs we e no mo e likely o ha e a pos concussion synd ome a h ee mon hs a e inju y [13], and ano he esea ch g oup epo ed ha neu oimaging indings did no p edic cog- ni i e unc ioning a one o 12 mon hs a e inju y, o unc- ional ou come a one yea a e inju y [14]. In he p esen s udy, as hypo hesized, pa ien s wi h com- plica ed MTBIs ook longe o e u n o wo k. I has been no ed ha mos pa ien s e u n o wo k a e inju y despi e ha ing some symp oms [22]. In his s udy, we did no expli- ci ly examine i he pa ien s had symp oms p io o e u ning o wo k. Ye , he majo i y o he s udy popula ion had e- u ned o wo k by he ime o he neu opsychological as- sessmen . The e o e, hei sel - epo ed symp oms a he ime o e alua ion likely e lec hei si ua ion a e e u ning o wo k, suppo ing he idea ha i is common o e u n o wo k while s ill ha ing some symp oms. One possible eason o why in ac anial lesions we e co ela ed wi h longe ime offwo k may be ha doc o s a e likely o g an longe sick lea es when he e is objec i e e idence o b ain inju y; in ha case he du a ion o he pos inju y sick lea e migh e lec , in pa , he beha io o doc o s in he Finnish sys em. We ha e no way o de e mining whe he , o no , doc o s in he communi y a e likely o g an longe sick lea es o pa ien s wi h complica ed MTBIs, bu we ha e anecdo al e idence om eme gency depa men physicians ha hey end o p esc ibe longe ini ial pe iods o lea e o pa ien s wi h mo e se ious inju ies such as hose wi h in ac anial ab- no mali ies. In he p esen s udy, he pa ien s wi h complica ed e sus uncomplica ed MTBIs we e compa ed on neu ocogni i e es ing and symp oms a ings a app oxima ely 3-4 weeks a e inju y. I was hypo hesized ha hose wi h complica ed MTBIs would pe o m mo e poo ly on cogni i e es ing and epo mo e symp oms han hose who did no ha e imaging abno mali ies. Con a y o hese hypo heses, he e we e no diffe ences be ween he wo g oups on neu ocogni i e es - ing o symp om epo ing. Su p isingly, he e we e ends owa d hose wi h complica ed MTBIs epo ing ewe sym- p oms and pe o ming somewha be e on cogni i e es ing. The e a e me hodological diffe ences and limi a ions wi h he p esen s udy, in compa ison o p e ious s udies, ha migh ha e in luenced he esul s. Fi s , he e we e a small numbe o subjec s in his s udy ha we e iden i ied as ha ing imaging abno mali ies; hus, he s a is ical analyses we e unde powe ed. Howe e , when examining he means and SDs, he e was no a end owa d g ea e symp oms o Figu e 1: Hemoside in de ec ed wi h mul iecho suscep ibili y weigh ed imaging using a 3 Tesla scanne . Mul iecho SWI image (Philips Achie a 3T; 5 echoes; oxel size =0.32 ×0.32 × 0.75 mm3). Cou esy o Alexande Rausche , Ph.D., UBC MRI Resea ch Cen e, Depa men o Radiology, Uni e si y o B i ish Columbia, Vancou e , Canada. wo se cogni i e es pe o mance in he complica ed MTBI g oup. In ac , he e we e ends owa d ewe symp oms and be e pe o mance in his g oup. This educes he likelihood ha he p esen indings ep esen a Type 2 s a is ical e o . Second, mos p e ious s udies classi ied pa ien s as ha ing complica ed MTBIs based on day-o -inju y CT scanning only, and some o hese s udies a e olde and he CT echnol- ogy migh ha e been less e ined. The p esen s udy iden i ied subjec s based on CT and MRI, wi h some o ou sample no showing day-o -inju y CT abno mali ies—only abno - mali ies on MRI. Thi d, some p e ious s udies ha e included subjec s wi h complica ed MTBIs who equi ed inpa ien ehabili a ion. None o he p esen pa ien s we e inju ed ha badly. Finally, some p e ious s udies ha e included pa ien s in li iga ion, whe eas no pa ien s in his s udy we e in ol ed in li iga ion. The e o e, i is possible ha he p esen g oup o pa ien s wi h complica ed MTBIs we e less se e ely inju ed han some o he samples om p e ious s udies. As echnology e ol es, some esea che s will be emp ed o b oaden he c i e ia o complica ed MTBI. In he pas , in ac anial abno mali ies we e iden i ied using CT o con en ional MRI. Wi h ad ancemen s in echnology, smalle and smalle abno mali ies can be de ec ed using s uc u al imaging. Fo example, he a ea o hemoside in (i on- ich s aining o issue om an a ea wi h pas blood) shown in Figu e 1 using mul iecho suscep ibili y weigh ed imaging (SWI) wi h 5 echoes [23,24]ona3TeslaMRI scanne would be unde ec able wi h a mode n CT scan and would likely be missed using 1.5 o 3.0 Tesla MRI con en ional sequences [25]. The e o e, in pas s udies his subjec would be classi ied as ha ing an uncomplica ed MTBI, bu in u u e s udies his abno mali y migh quali y o classi ica ion as a complica ed MTBI. Howe e , his subjec was ac ually a heal hy con ol subjec in one o ou s udies. He had no known his o y o an inju y o his b ain. 6Rehabili a ion Resea ch and P ac ice Thus, no only migh he c i e ia o a complica ed MTBI e ol e o include smalle and smalle abno mali ies—bu some o hese abno mali ies migh no be ela ed o he MTBI— hus esul ing in misdiagnosis. In conclusion, pa ien s wi h complica ed MTBIs ook longe o e u n o wo k. They did no , howe e , pe o m mo e poo ly on neu ocogni i e measu es o epo mo e symp oms, a 3-4 weeks a e inju y compa ed o hose wi h uncomplica ed MTBIs. As he li e a u e e ol es, i is be- coming clea ha complica ed MTBIs ep esen a b oad spec um o inju y, wi h some people ha ing e y small ab- no mali ies and excellen unc ional ou come, o he people equi ing inpa ien ehabili a ion and ha ing poo ou come, and a di e se se o ou comes in be ween. Acknowledgmen s This esea ch was unded by Compe i i e Resea ch Funding o he Pi kanmaa Hospi al Dis ic , Tampe e Uni e si y Hos- pi al. The au ho s hank Pasi Jolma (M.D., Ph.D.) o help wi h ec ui ing he pa ien s and conduc ing neu ological ex- amina ions. This s udy was p esen ed a he annual mee ing o he Na ional Academy o Neu opsychology, Oc obe 2010, Vancou e , BC, Canada. 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