D I E N O A N YHOC
Chuyen de trong thang
VAI TRO CONG Hl/ONG Tir TRONG CHAN DOAN
•
NHOI MAU NAO DONG MACH THEO CAC GIAI DOAN
Vu Dang Liru*, Pham Minh Thong*
I. GIOI THIEU
Nhdi mau nao la nguyen nhan hay gap xep thii 3 gay tir vong d JVIy, chiem 15-35%. Trong cac nam vira qua, nhimg tien bo ky thuat dac biet tren Cong hudng tir (CHT) khong nhung chi gidi ban tham kham than kinh ve hinh thai, ma cdn cd the tham dd tdi chiic nang va thay ddi sinh ly benh trong qua trinh nhdi mau nao dua tren xung CHT khuech tan (Diffusion) va tudi mau (Perfusion). Tim kiem nguyen nhan, xac dinh vi tri hep tac mach dua xung mach CHT.
II. Liru LUONG MAU NAO VA SINH LY NHOI MAU NAO
Nao khong cd chirc nang dir triJ oxy va Glu- cose, do do phu thudc vao ngudn cung cap nang lugng tir nai khac va luu lugng mau. Luu lugng tudi mau nao binh thudng (DSC) hJng dinh khoang 50ml/phut/100g td chirc nao. Tai cac khu vuc khac nhau, luu lugng tudi mau vung (rDSC) thich hgp theo nhu cau chuyen hda va ap luc tudi mau. Khi cd tac dgng mach, ap lire tudi mau nao giam.
- Vung thiSu mau: cd rDSC tic 20-50ml/phut/100g.
Td chirc nao thieu oxy viing nay dugc bii trir mgt
phan bang each tang cudng su dung oxy. Hd hap te bao van dugc duy tri, nhung bu lai phai ire che tdng hgp Protein. Tao nen su phan each giira luu lugng va chuyen hda oxy, mgt dac tnmg ciia thieu mau.
Neu tdn tai keo dai den lugt tieu thu oxy nao giam, dan tdi nhdi mau giai doan cap.
- Viing nhdi mau: khi rDSC dudi 20ml/phut/100g, nhu md nao se bi nhdi mau. Nhdi mau la qua trinh tien trien dgng hgc, bat dau tir trung tam rdi ra ngoai vi. Viing hoai tu' bat dau d trung tam cua nhdi mau.
+ Vung tranh tdi tranh sang: khi rDSC tir 10-20ml/
phut/1 GOg. The tich tudi mau nao tang do phan xa, luu lugng mau nao chi du dam bao su sdng tam thdi cua te bao, nhung sir dan truyen qua Synap bi gian doan. Tren lam sang bieu hien dau hieu than kinh khu tni. Nhu vay vung nhu md nao nay cd the dugc hdi phuc neu dugc dieu tri thudc tieu sgi huyet.
+ Viing nhiin nao: phan trung tam cua vung tranh tdi tranh sang, luu lugng mau nao giam dudi 10ml/
phut/1 OOg. Su tdng hgp ATP bi gian doan, bom ion Na/K khdng hoat dgn, lam tang lugng Na trong te bao, keo theo nudc vao trong lam phdng te bao (phii nhiem dgc te bao) va te bao se chet neu khdng cd tudi mau trd lai (Hinh 1).
Hinh L Tien trien 6 nhdi mdu
A. Nhdi mau giai doan cap, phdn trung tdm phii nhiem dpc te bao, gidm Ichuech tdn, tirang img vai viing nhiin nao Ichong hoi phuc. 1- Gidm Ichuech tdn, 2- Vung tranh toi tranh sdng. 3- Viing thieu mdu.
B. O nhdi mdu tien trien Ichong duac tdi lap tudn hodn, v&i vung nhan nao lan rpng sang viing tranh toi tranh sdng.. 1- Viing nhiin nao.
*Kiioa Ciidn doan iiinli dnli - Benli vien Bach Mai
4 I Y HOC LAM SANG s6 53 (Thang 06/2010)
Chuyen d l trong thang
III. CAC XUNG CHT VA MUC DfCH THAM KHAM HJNH ANH TRONG BILAN TAI BIEN NHOI MAU
1. Tham kham pha cap tinh
Cac xung tham kham chinh trong giai doan nay co thg thuc hien dudi 15 phut. Xung Tl EG, T2 EG (T2*), FLAIR, xung mach TOF 3D, xung khuech tan (Diffusion) va tudi mau (Perfusion).
Muc dich cac xung dugc trinh bay trong Bang 1.
Bdng 1. Protocol cdc xung thdm kitdm nhdi mdu nao cap
Xung TIEG T2*
Diffusion FLAIR
TOF 3D ngi sg Perfusion
Hu6ng/Thdi gian Sagital/30 giay Axial/ 2 phiit Axial/ 30 giay Axial/ 3 phiit
Axial/ 3 phut
Axial/ 40 giay
Mvic dfch
Djnh vi, phat hien chay mau cap Mau tu, tim dau hieu giam tin hieu trong mach mau
Phil nhiem dgc te bao, 90% duang tinh giai doan tdi cap
Chan doan phan biet. Tim ton thuang tang tin hieu trong mach mau giai doan sdm
Tac doan gan dgng mach. Ket hgp Diffiision va Perfusion de chgn benh nhan dieu tri tieu sgi huyet
Giam tudi mau. Xac djnh td chirc nguy ca
D$c diem/h^ che
Kem nhay vdi ton thuang nhd than nao
Kem nhay vdi viing hd sau
The tich tham kham han che, khd danh gia mach doan xa Rat kem vdi tdn thuang ho sau va viing thiiy thai duang - Piidt hienpiiu te bdo tren Diffusion:
Ky thuat nay cho phep phat hien sdm rdi loan chuc nang te bao thu' phat sau nhdi mau. Giai doan cap tinh nhdi mau nao, khi gian doan ddng chay mau nao se khdi ddng rat nhanh, tir cac phut dau tien, su suy yeu chuyen hda nang lugng va cac bom van chuyen qua mang te bao. Hau qua keo ddn mgt khdi lugng nudc dang ke tir ngoai te bao vao trong te bao, gay nen phii nhiem dgc te bao hay phii trong te bao.
Hinh anh khuech tan cua nudc va he sd cgng hudng khuech tan ADC (Coefficient apparent de diffusion) bi thay ddi ngay tir gid diu do giam the tich ngoai bao, dan tdi tang tin hieu tren Diffusion va giam tren ADC.
Do nhay hinh anh khuech tan trong chan doan tdn thuong nhdi mau nao cip rlt cao, tren 90%.
- Piidt iiien tliay doi tuai mdu tren Perfusion.
Hinh anh CHT tudi mau mang lai thdng tin ddng hoc mau trong viing nao theo qui md vi mach.
Bang each sir dung chat ai tir, khdng bj khu8ch tan trong nao, lam giam thdi gian thu gian ciia proton.
Khi tiem bolus chat ai tir vao tTnh mach, se tao nen
giam tin hieu tren viing nd di qua trong mao mach nao. Xung T2*, rat nhay vdi chat cd nhay cam tir, dugc cat lap di lap lai tat ca cac giay trong khoang 1 phut de theo ddi sir sut giam tin hieu khi chat ai tii' (Gd) di qua. Qua phan tich dudng cong tien trien theo thdi gian ciia tin hieu, rat nhieu thdng sd cd the thu dugc phan anh ddng hgc mau khu vuc dd:
thdi gian dat dinh (TTP), thdi gian luu thdng thudc trung binh (TTM), the tich tudi mau nao tuong ddi (VSCr), luu lugng tudi mau nao tuong ddi (DSCr).
Trong thuc hanh hay su dung TTP va TTM vi r§t dl nhan ra cac bat thudng tudi mau.
- Piidt hiin viing "tranh toi-tranh sdng " vd lua chon dieu tri tieu sai huyet dua tren xung Diffusion vd Perfusion.
6 giai doan tdi cap ciia nhdi mau nao, phan tich k6t hgp tudi mau va khu6ch tan cho phep xac dinh phan biet:
+ Viing tdn thuong giam tudi mau tren Perfusion rdng hon viing bit thudng tren Diffusion (vung khdng tuong xung giira Per/Dif "viing tranh tdi tranh sang"). Viing nay vin cd thg thiy trong gin
DIEN DAN Y HOC
Chuyen d i trong thang
80% cac trudng hgp sau 6 gid va khoang 40% cac trudng hgp sau 24 gid (Hinh 2).
+ Viing giam tudi mau triing khit vdi viing giam ADC, ggi y tdn thuang hoai tir lan rdng va tuan hoan bang he rat kem (Hinh 3).
+ Viing giam ADC lan rdng hon viing giam tudi mau bit thudng tren Perfusion tuong img vdi viing tudi mau lai sdm.
Kha nang nhan dinh phan biet vimg tdn thuong sinh ly benh tren CHT cho phep quyet dinh dieu tri tieu sgi huylt, dua tren dac diem timg trudng hgp
cu the. Theo each danh gia khai niem ciing nhac la cira sd dieu trj dudi 3 tieng, vdi khai niem "thdi gian td chirc cu the" 'horloge tissulaire individu- elle', thi cira sd dieu tri cd the keo dai tdi 6 tiing.
Neu khdng biet chinh xac gid cu the, dua vao cac dac diem tren CHT cd the phan biet vimg thieu mau khdng hdi phuc vdi vimg tranh tdi tranh sang (td chirc giam tudi mau, cdn sdng, nhung nguy ca tien trien thanh hoai tir neu giam tudi mau keo dai), viing nay chinh la dich ma dieu tri tieu sgi huylt nham tdi.
/I i^' ••/ \
FLAIR
•** .-1
'•^miil^
Diffusion Carte d'ADC
^^^B ^^
Perfusion (temps de transit)
Hinh 2. Nhdi mdu giai doan toi cap, thay vung "tranh toi tranh sdng", hinh sdng tdng tin hieu Wen Diffusion, gidm tren ADC thuoc ranh gidi nhanh sdu dong mach nao giUa trdi, tren Per thay gidm lan rong todn bo vimg cap mdu dong mach nao giira tren Cartography TTM.
Hinh 3. Nhdi mdu giai doan toi cap, chong ichit Dijf/Per, sau 2 gia tit Ichi CO bieu Men dot ngot mat ngon ngit. Xung FLAIR Ichong thdy bdt thuang. Tren xung Diffvd Per thdy vung tin hieu bat thuang thuoc ranh giai dong mach nao giO-a co su chong Ichit giira Diffvd Per chimg to vimg nhdi mdu se Ichong lan rong va co tdi thong bdn phdn dong mach tren CHT mach (miii ten)
6 I Y HOC LAM SANG s6 53 (Thang 06/2010)
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2. Tham kham pha ban cap
Muc dich xac dinh hau qua, bien chiing chay mau va nhan dinh thdi gian nhdi mau, ciing nhu tham kham mach mau tim nguyen nhan. Cac xung ca ban gidng nhu tren, n l u nghi ngd phinh tach dgng mach canh thi cin them xung Tl SE xda md cat ngang tham kham mach canh trong va ngoai sg.
IV. HINH ANH TREN CAC XUNG CHT THEO TIEN TRIEN 6 TON THU^ONG NHOI MAU
Tdn thuong nhdi mau cd the chia theo 4 giai doan: giai doan tdi cap (<6h), giai doan cap (6 - 48h), giai doan ban cap (48h - 3 tuan) va giai doan man tinh (> 3 tuin).
Tin hieu tren cac xung theo tien trien d nhdi mau dugc trinh bay tren bang 2:
Bdng 2. Tien triin theo thdi gian tin hieu cua nhdi mdu dong mach Thdi gian
<6h 6-48h 48h-10d
>10d
Tl Ddng Ddng/giam Giam Giam
FLAIR/T2SE Ddng
Tang Tang Tang
Diff(B=0) Ddng Tang Tang Tang
Diff (B=1000) Tang Tang ++
Tang/ddng Tang/ddng
ADC Giam Giam Thay ddi Tang 1. Giai doan toi c^p (<6h)
Xung Diffusion rat nhay phat hien viing thilu mau tdi cap thay giam khuech tan tuong iing cd hinh tang tin hieu, va giam tren ADC (Hinh 4). Cac xung CHT thdng thudng da sd binh thudng hoac thay bat thudng kin dao nhu tang tin hieu ldng
mach tren xung FLAIR va T2 do ddng chay cham bi li tre hoac ddng chay dao ddng. Tren T2* thay hinh giam tin hieu mach mau vdi kich thudc ldn do
"dau hieu nhay cam tir" tuong img vdi cue huylt khdi cap tinh. Xung mach TOF 3D danh gia va xac dinh vi tri hep hay tac.
Hinh 4. Nhdi mdu giai doan tdi cap (phii nhiim ddc). CHT thuc hien sau 4h tir khi co trieu chimg. Tren Diffusion thay hinh tdng tin hieu nhdn beo va ddu nhdn dudi trdi, tren ADC gidm tin hieu do phu nhiim doc te bdo. Tren FLAIR hinh tdng tin hieu rdt idn dao, cdc mach mdu trong ranh cudn nao tdng tin hieu
tuang img vdi ddng chdy cham vd do tudn hodn tir nhanh ben.
DIENDAN Y HOC Chuyen de trong thang
2. Giai doan cap (6-48h)
Viing nhGn nao se tang tin hieu manh tren Diffusion va ADC giam. 0 giai doan nay, dau hieu nhiin nao cd the thay tren xung CHT thdng thudng dudi dang tang tin hieu tren T2 va FLAIR, cho phep danh gia chinh xac giai phau vimg nhdi mau.
(Hinh 5).
Cac te bao Neuron rat nhay cam vdi thieu mau, su thay ddi tin hieu dau tien la viing chat xam, trong khi do viing chat trang cd the cd tin hieu binh thudng trong 24h dau. Cd the thay dau hieu de day
cac cau triic lan can (ranh cudn nao va nao that) do phii nao. Thuc hien tiem thudc ddi quang tir khdng mang tinh he thdng, nlu cd tiem thi cd the thay cac dau hieu ngam thudc mach mau cd dang ddng chay cham gap 70% cac nhdi mau viing vd, ngam thudc mang nao gap trong 1 /3 cac trudng hgp, ngam thudc trong ldng mach va mang nao xuat hien trudc khi ngam thudc trong nhu md va mat di sau 1 tuan.
Phat hien nhdi mau trong 24h dau, vdi CHT duong tinh 80%) cac trudng hgp, cdn vdi CLVT khoang 60%.
1 / ~ \
^
\ J2 / J!0
^ _ -
J60
Temps
' Signal
il'U&
Diffusion ADC
(••^''^\
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FLAIR
Hinh 5. Nhdi mdu giai doan cap (phii trong te bdo). CHT time hien 48h sau ichi cd trieu chung.
Nhdi mdu vung vd nao thdi duang phdi. Tdng tin hieu manh tren Diffusion, gidm tren ADC, thdy ro tren xung FLAIR.
3. Giai doan ban cip (48h - 3 tuan)
Giai doan nay dac trung tren lenh ly than kinh la hien dien phii van mach bat dau dien ra, va tien trien thanh viing hoai tii' tai giira d nhdi mau. Phii van mach tdi da dien ra trong khoang thdi gian nay.
Tren anh Diffusion thay tang tin hieu gidng giai doan cap, nhung ngugc lai gia trj ADC thay
ddi tang din va qua nguong gia tri gia binh thudng (khoang tuin thii 2 sau khi bi), de cudi ciing tang cao hon nhu md td chiic lanh (phii van mach, pha vd hang rao mau nao, va ly giai te bao cua nhdi mau ban cip) (Hinh 6,7). Hinh tang tin hieu khulch tan cua nhoi mau tdn tai trung binh khoang 2 thang sau khi cd trieu chiing lam sang khdi dau.
8 I Y HOC LAM SANG s6 53 (Thang 06/2010)
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Hinh 6. Nhdi mdu giai doan bdn cap (gid binh thudng tren ADC). CHT duac thuc hien sau 1 tudn khi cd bieu Men ldm sdng. Cdc xung thudng qui tren CHT thdy rd vimg nhdi mdu bdn cap tdng tin hieu tren FLAIR. Tren Diffusion thdy tdng tin hieu viing ranh gidi ndng nao giira trdi vd vdi ADC tin hieu ngang nhu md lanh, chi mot phdn nhd phia sau tdng tren ADC ggi y phix van mach.
Hinh 7. Nhdi mdu bdn cap (piiii van mgcli). CHT thirc hien 3 tudn sau trieu cin'mg ldm sdng. Hinh tdng tin hieu Diffusion vdi cdc d gidm tin hieu (viing chdy mdu), thay rd tren T2*. ADC tdng do pint van mach
Tren CHT cac xung thudng qui, nhdi mau cd hinh anh tang tin hieu tren T2, FLAIR va giam tin hieu tren T l . Khi tiem thudc Gd thay cd ngim thud nhu md do vd hang rao mau nao. Mac dii va
hang rao mau nao cd the xuat hien tir ngay dau tien ciia nhdi mau tren md benh hgc, ngam thudc nhu md thi hiem khi thay trong cac ngay dau sau nhdi mau, thudng vao khoang giiia ngay thir 10 va 20,
DIEN DAN Y HOC Chuyen d§ trong thang
va mit din di. Hinh anh ngam thudc hdi nao kha thudng gap va kha dien hinh quan sat thay trong nhdi mau vd. Khi nhdi mau vung sau, hinh anh ddi khi khdng diln hinh vdi viing ngam thudc dang mang hoac hinh vdng cd the can chan doan phan biet vdi benh ly khac. Khi cd nghi ngd chan doan, cd the kilm tra thuc hien chup sau vai ngay hoac vai tuin, nlu nguon gdc tdn thuang do nhdi mau se thay ddi nhanh ca ve hinh anh ngam thudc.
4. Giai doan man tinh
Hinh anh hau qua sau nhdi mau rat khac nhau, theo ban chat nhu md cdn lai. Su thay ddi lien quan Gliose se tao ra hinh anh tin hieu khac nhau tren Diffusion va tang tren ADC, tang tin hieu tren T2/
FLAIR, va ddng hoac giam tin hieu tren T l . Khi nd tao ra hinh khuyet nao, thi tin hieu gidng nhu dich nao tuy (Hinh 8). Khi cd xuat hien chuyen dang chay mau, thi tin hieu gan vdi san pham giang hda Hemoglobin cd dang giam tin hieu manh tren T2*.
Hinh 8. Nhdi mdu nao man tinh viing cap mdu thuoc nhanh nong dong mach nao giiia phdi giai doan di chimg. Vimg khuyet nao gidm tin hieu tren FLAIR vd Diffusion, vd tdng tren ADC giong dich nao tuy, vimg tieu thdn kinh dim (gliose) xung quanh tdng tin hiiu trin FLAIR.
V. CAC NGUYEN NHAN NHOI MAU
Tai bien huyet khdi di chuyen gay tac mach kha thudng gap nhu mang xa vira mach canh doan trong va ngoai sg hay gap tren ngudi cao tudi, huyet khdi tir tim. Tach ddng mach canh chiem 5% hay gap d ngudi tre. Khoang 10%) tai bien nhdi mau khdng tim dugc nguyen nhan.
VI. KET LUAN
CHT cd do nhay rat cao chan doan xac dinh nhdi mau, dac biet trong nhihig gid dau qua xung Diffusion. CHT khdng nhirng giiip chan doan cac giai doan, tien lugng va chi djnh dieu tri tieu sgi huyet, nd cdn giiip tim nguyen nhan gay nhdi mau qua xung mach CHT.
TAI LIEU THAM K HAO CHINH
1. Imagerie Neurologique. JF Meder et JP Pruvo. 2007.
2. Accidents vasculaires cerebraux ischDmiques. B Daumas-Duport et al. EMC. 2008.
3. Neuroradiology. RI Grossman and DV Yousem. 2004.
4. Neuroradiology. Mauricio Castillo. 2004.
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