Arq Neuropsiquiat r 2005;63(3-B):855-858
Depart ment of Neuro surgery - Hospit al Nossa Senhora das Graças Curit iba PR, Brazil:1Neurosurgeon ;2Resident in Neurosurgery; 3Neurosurgeon Direct or of t he Residency Program
Received 27 January 2005, received in f inal f orm 18 April 2005. Accept ed 27 M ay 2005.
Dr. Joacir Graciolli Cordeiro - Rua Alcides Munhoz 433 - 80810-040 Curitiba PR - Brasil. FAX: 55413350191.
VENTRAL EXTRADURAL SPINAL MENINGEAL
CYST CAUSING CORD COMPRESSION
Neurosurgical t reat ment
Daniel Monte-Serrat Prevedello
1, Cláudio Esteves Tatsui
1, Andrei Koerbel
1,
César Vinícius Grande
1, Joacir Graciolli Cordeiro
2, João Cândido Araújo
3RESUM O - Cistos meníngeos extradurais espinhais são formados tipicament e por estreita cápsula membrano-sa f ibrót ica, macroscopicament e semelhant e a uma membrana de aracnóide, replet a de líquor e re l a c i o n a-da com uma raiz nervosa ou com a linha média posterior. Eles são extremament e raros em posição ant erior e, quando ocorrem, habit ualment e causam herniação da medula espinhal pela f alha dural vent ral. O caso de um homem de 61 anos de idade que i niciou com t et raparesia, espast icidade e hiperref lexia em mem-b ros inferiores, e f lacidez com hipot rofia nos memmem-bros superiores, sem manif est ação sensit iva, é apre s e n t a-do. A invest igação com ressonância magnét ica demonst rou ext ensa coleção císt ica ext radural vent ral à me-dula de C6 a T11. A lesão f oi abordada diret ament e via laminect omia com int rodução de derivação cist o-perit oneal, reduzindo o cist o e t ornando o pacient e assint omát ico com um seguiment o de 48 meses. Est e é o primeiro caso relat ado de cist o meníngeo ext radural vent ral espont âneo causando compressão medlar. A derivação cist o-perit oneal se most rou ef icaz no t rat ament o do caso e deve ser considerada em sit u-ações em que a ressecção complet a do cist o est eja impossibilit ada, ou dif icult ada pela necessidade de ma-nobras cirúrgicas mais agressivas e arriscadas.
PALAVRAS-CHAVE: cist o meníngeo, cist o aracnóide, lesões ext radurais, derivação cist o-perit oneal.
Cisto meníngeo extradural ventral do canal espinhal causando compressão medular: tratament o neurocirúrgico
ABSTRACT - Spinal ext radural meningeal cyst s are t ypically f ormed by a t hin f ibrot ic membranous capsule, macroscopically similar that of an arachnoid membrane, f illed by cere b ro spinal f luid and relat ed t o a nerv e root or t o the posterior midline. Vent ral locat ion is ext remely rare and w hen it occurs t hey usually cause s p i-nal cord herniat ion through t he vent ral dural gap. A 61 year-old man who began w it h a tw o years long h i s-t o ry of insidious s-t es-t raparesis, spass-ticis-t y and hyperref lexia in low er exs-tremis-t ies, and f laccid as-t rophy of upper lim bs, w it hout sensory manif est at ions, is present ed. Invest igat ion t hrough magnet ic resonance i maging demonst r at ed an ext ensi ve spinal vent r al ext r adural cyst ic collect ion f rom C6 t o T11. The lesion w as ap-p roached through a laminect omy and a cyst -ap-peritoneal shunt w as introduced. The cyst reduced in size sign i-f icant ly and t he pat ient is asympt omat ic over a 48 mont hs i-f ollow -up. This is the i-f irst report ed case oi-f a s p o n-t aneous venn-t ral exn-t radural spinal meningeal cysn-t causing cord compression. Cysn-t -perin-t oneal shunn-t w as eff e c-t ive in c-t he c-t reac-t menc-t of c-t he case and ic-t should be considered in cases in w hich complec-t e resecc-t ion of c-t he cyst is made more dif f icult or risky by t he need of more aggressive surgical maneuvers.
KEY WORDS: meningeal cyst s, arachnoid cyst s, ext radural lesions, cyst -perit oneal shunt s.
Spinal meningeal cyst s are rare lesions. Ty p i c a l l y t hey are f ormed by a t hin f ibrot ic membranous c a p-sule, macroscopically similar t o t he arachnoid mem-brane, f illed by cere b rospinal f lu id (CSF). A layer of arachnoid cells coat ing t he cyst is not alw ays d e-monst rat ed, w h ich explain s w hy t he designat ion of meningeal cyst is pref erable t o t hat of arachn o i d c y s t1. Vent ral posit ion is ext remely rare re g a rd l e s s
t he cyst is int ra or ext radurally locat ed2 , 3. Recent ly,
t he 11t h case of an ant erior int radural spinal me-ningeal cyst has been report ed3. All spont aneous
856 Arq Neuropsiquiat r 2005;63(3-B)
A case of a spont aneous giant ant erior menin-geal cyst located ext radurally is presented (t ype I), ext ending f rom C6 dow n t o T11, and det erm i n i n g s e v e remyelopat hy due t o posterior cord compre s-sion w it hout any sign of herniat ion. Treat ment w i-t h cysi-t -perii-t oneal shuni-ting resuli-t ed in complei-t e re-g ression of t he lesion and resolut ion of t he clinic a l pict ure.
This art icle w as an alyzed b y et h ic commission of Nossa Senhora das Graças Hospit al and it s publi-cat ion w as aut horized by t he pat ient .
CASE
A 61-year-old man, w it hout hist ory of t rauma, pre-sented w it h a t w o years long hist ory of insidious t et rapa-resis associat ed t o back and neck pain f or t he same peri-od, w ithout sensory complaint s. Object ively he show ed spast icit y and hyperref lexia in his low er ext remit ies and muscle atrophy in both hands. A magnet ic resonance i m a-ge (M RI) revealed a cyst ic lesion, hypo-intense in T1 and hyper-int ense in T2-w eight ed images, locat ed ant erior t o t he spinal cord exert ing signif icant com pression and extending f rom C6 dow n t o T11 (Fig 1). Furt her w ork-up included a myelogram, which revealed a post erior spinal
c o rd displacement by a ant erior mass f illing def ect (Fig 2A, 2B). CT myelogram, carried out t hree hours af ter c o n-t rasn-t injecn-t ion conf irmed n-t he exn-t radural locan-t ion of n-t he cyst and demonstrat ed it s enhancement, suggesting c o m-m unicat io n w it h t he su barachnoi d space, but w it hout def ining accurat ely it s f ist ulous origin (Fig 2C, 2D).
A C5 - T1 laminect omy w as perf ormed. The cervical canal w as f elt t o be very t ight and surgical maneuvers t o reach its anterior segment w ere considered risky. The-re f o The-re, aft er adequat e explorat ion of dural root sleeves b i l a t e r a l l y, the dura w as opened post ero laterally, to al-lo w t ran sdu ral access t o t he cyst , t h rou gh u lt rasoun d guidance.
Fig 1. Sagital MRI demonstrating an anterior cystic lesion, to t h e spinal cord, hypo-intense in T1 and hyper-intense in T2-weight respectively.
Fig 2. 2A and 2B: Myelogram demonstrating the thecal sac (bla ck point), and the cyst silhouette (filling defect) seen as a negati -ve image localized behind the -vertebral bodies (arrows). 2C: C T-Myelogram done 3 hours after myelogram showing the cyst i n an anterior extradural position (arrows). 2D: Reconstruction b y C T-Myelogram scan showing the cranial limit of the cyst in C6-C7 and the dural limit between cyst and subarachnoid spaces (arrow), but not defining the exact communication point.
Arq Neuropsiquiat r 2005;63(3-B) 857
The cyst w as pu nct ur ed t ransdu ral ly an d part i a l l y emp t i ed , w it h t he t ot al rem oval o f ap pro xim at el y 20 ml of cryst al clear liquid resembling CSF. Aft er 20 minut e s of observation the cyst refilled. The insertion of a cyst p e r t oneal drain w as t hen considered t hen t he best surg i-cal opt ion, w hich proved t o be ef f ect ive in decompre s s-ing t he spinal cord (Fig 3) and provids-ing tot al subsidence of signs and sympt oms in a 4-year f ollow -up, as opposed t o a more radical and extensive pro c e d u re in search f or a f ist ulous communicat ion.
DISCUSSION
Ext radural meningeal cysts are t ypically located post eriorly t o t he spinal cord and usually originate f rom a point close t o a dural root exit or in t he p o s-t erior midline1 0. Pat hophysiological mechanism of
t he lesion is not very w ell understood. It could re p-resent t he exp ansion an d p rolif erat ion o f arach-noid granulat ions t hrough a low resist ance dural re g i o n1 , 1 0, or t he occurrence of a congenit al or t r a
u-mat ic arachnoid diverticulum, w hich w ould expand due t o pro g ressive CSF ent rance t hrough an osmot-i c1 0 - 1 3or an unidirect ional valve mechanism1 1 - 1 3.
Ap-p roAp-priat e characterization of such entit y is confus-in g an d r edundant confus-in t he lit erat ure. Nabors an d c o l s .1subdivided the meningeal cysts in three g ro u p s :
I - ext radural cyst s w it hout associat ed nervous f bers, II - ext radural cysts w it h associated nervous f i-bers, and III - intradural cysts. Commonly t hese lesi-ons are locat ed post ero-laterally t o t he spinal cord , and t hey can ext end along several spinal levels1.
Analyzing t he various cases of spinal cord vent ral h e rniat ion, Kumar and cols.9suggest ed a modif
ica-t ion in ica-t he classif icaica-t ion by Nabors and cols.1, of s p
i-nal meningeal cyst s t o include t his mechanism of spinal cord herniat ion in group II-B9.
The seldom ment ioned ant erior locat ion of a spi-nal meningeal ext radural cyst may re i n f o rce the con-genit al or t raumat ic hypot hesis, considering t hat t he ant erior dural aspect re p resent s an area of ma-jor t issue re s i s t a n c e1 , 1 0. Besides, all cases of
sponta-neous ventral ext radural spinal meningeal cyst are relat ed t o spinal cord hern i a t i o n4 - 9, due t o negative
p re s s u re exert ed by t he CSF dynamics inside t he cyst over t he spinal cord t hrough the ventral dural flaw4 , 8.
This is t he f irst re p o rt ed case of a spont aneous vent ral ext radural spinal meningeal cyst exert ing a compressive mass ef f ect on t he spinal cord, pro b-ably r e p resen t in g a unid ir ect io nal valve mecha-nism t hrough a smaller dural def ect . Recent ly, cyst vo lu me en largement h as b een demonst rat ed b y cinemat ic magnet ic resonance st udies, associat ed t o higher pressures in t he subarachnoid space by Valsalva maneuver13.
Among ext radural post erior cyst s, t horacic loca-t ion is loca-t he mosloca-t common (67% ), f ollow ed by lum-bosacral (20% ), t h oracolumbar (9% ) and cerv i c a l regions (4% ). Sympt om s are r elat ed t o cyst com-p ressive eff ect , f laccid or scom-past ic com-paracom-paresis being t he most common presentat ion (70% ), w hich may be accompanied by lumbar or dorsal pain, hypere s-t hesia, and r adiculopas-t hy, u sually w is-t h a sensory l e v e l1 2. The pat ient in t he present case had no
sensory sympt oms, dif f erent f rom most cases report -ed in t he lit erat ure, probably because t he unusu-al ant erior locat ion of t he cyst w as mainly re l a t e d t o t he mot or f unct ion port ion of t he spinal cord.
M yelogram demonst rat es f indings compat ible w it h an expanding ext radural process, w hich a f ill-i ng d ef ect1 4.In such cases, a l at e CT- m y e l o g r a m
scan can demonstrate cont rast inside the lesion, c o n-f i rming it s communicat ion w it h t he subarachnoid s p a c e1 4 , 1 5. M RI is t he st andard met hod o f choice
f or diagnosis, defining t he locat ion and ext ension of t he cyst ic lesion, in addit ion t o supply pro g n o s-t ic inf ormas-t ion abous-t s-t he condis-t ion of s-t he spinal c o rd b y t he event ual presence o f at rophy or sig -nal changes caused by t he mass ef f e c t1 5 , 1 6. CT- m y
e-logram can aid in det ermining t he communicat ion betw een t he ext radural cyst and t he subarachnoid s p a c e1 5. Neit her imaging studies nor surgical
explo-r at io n in t he p explo-resent case w eexplo-re able t o d em o st rat e t he origin of t he communicat ion, inf erred o n-ly by ref illing of t he cyst af t er it s part ial empt ying and by cont rast enhancement .
The proposed ideal surgical t reatment t o spinal meningeal cyst s is cyst resect ion and closing of dur-al f law , in order t o avoid t he re c u rrence of f íst u-l a1 , 3 , 1 0 , 1 7 , 1 8. Because t he commonest locat ion of t
he-se lesio ns is d orsolat eral , a lam in ect omy u sually f acil it at es cyst d issect i on in relat io n t o t he dura m a t e r. Wide f enest ration and shunting of t he cyst t o t he perit oneum, pleu ral cavit y or right at rium are also t reat ment alt ernat ives17,19,20.
Ext ension and anterior locat ion of t he cyst pro-t ruding pro-t he cord pospro-t eriorly, in pro-t h e presenpro-t case, p revented a f ull explorat ion, due t o risks of dam-age t o spinal cord secondary t o excessive manipula-t ion and remanipula-t racmanipula-tion. Imanipula-t w as also f elmanipula-t manipula-t hamanipula-t shunmanipula-t ing manipula-t h e cyst t o t he sub arachno id sp ace w ould n ot so lve t he problem, considering t hat communication bet-w een bot h spaces bet-w ould persist .
858 Arq Neuropsiquiat r 2005;63(3-B)
t h rough an int radural approach due t o dif f i c u l t i e s of mobilizin g t h e t h ecal sac at t he cervical level. A f t er i t s im plant at io n, t he syst em appro p r i a t e l y drained t he cyst t o t he perit oneal cavit y w it h signi-f i cant r ed uct i on o signi-f it s m ass esigni-f signi-f ect o n t he spi nal cord (Fig 3). Tot al remission of t he clinical pict ure could be demonst rat ed at a 4 year f ollow up.
Because all spont aneous vent ral ext radural spi-nal meningeal cyst s report ed in t he lit erat ure are relat ed t o spinal cord herniat ion t hrough t he ven-t ral dural sleeve, surgical ven-t reaven-t menven-t usually consis-t ed of excision of consis-t he arachnoid cysconsis-t w henever iconsis-t is possible, section of t he dent ate ligament , re l e a s e of t h e ad hesio ns, d et achm ent of t he spinal cord f rom t he hernial orif ice, and f inally sut ure of t he dural t ear or placement of a dural pat ch4-9.
The only case re p o rted in lit erature relat ed t o a vent ral spinal cyst treat ed by a cystoperit oneal shunt is in a 52-year-old man w it h a previous severe bra-chial plexus injury. Alt hough a complet e re s o l u t i o n of t he cyst could be d emonst rat ed, t here w as no change f rom his preoperat ive clinical condit ion2 0.
This is t he only re p o rt of a spont aneous vent ral m eningeal spinal cyst causin g cord com pre s s i o n , adequat ely t reat ed by shunt ing t o t he perit oneal cavit y, w it h an excellent result .
Sh unt in g ext radural sp inal cyst s t o perit oneal cavit y is an eff ect ive t reat ment. It should be consi-dered as t he f irst choice in sit uat ions w here loca-t ion or exloca-t ension of loca-t he lesion prevenloca-ts iloca-t s comple-t e reseccomple-t ion.
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