Brain Asymmetry: Diagnostic Approach

Transcription

1 Brin Asymmetry: Dignostic Approch Asimetrí cererl: enfoque dignóstico Alejndro Zulug Sntmrí 1 Sergio Vrgs 2 Sndr Arngo 3 Ricrdo Urie 3 Key words (MeSH) Fcil symmetry Encephlitis Hemimeglencephly Plrs clve (DeCS) Asimetrí fcil Enceflitis Hemimeglencefli Summry Brin symmetries re common finding for rdiologists nd my e cused y multiple etiologies, including congenitl nd cquired cuses. Congenitl cuses re conditions tht pper during the fetl life, while the cquired cuses occur fter irth nd usully efore 2 yers of ge. In cross-sectionl imging, rin symmetries re chrcterized y enlrgement or trophy of ll or prt of cererl hemisphere. This vriility in rin volume my e cused y physiologicl cuses or y nonphysiologicl cuses tht re secondry to congenitl nd cquired processes, cusing n symmetry in the hemispheres. In this rticle we propose prcticl dignostic pproch to rin symmetries sed on the evlution of the cererl hemisphere nd ventriculr system size. Resumen Ls simetrís cererles son entiddes clínics frecuentes encontrds en l práctic diri del rdiólogo. Son cusds por diverss etiologís que pueden ser grupds en congénits y dquirids. Ls congénits son quells que se presentn por condiciones durnte l vid intruterin, mientrs que ls dquirids ocurren después del ncimiento, usulmente ntes de los 2 ños de edd. En los estudios por imágenes, ls simetrís cererles están dds por umento o disminución del volumen de l totlidd o de prte de un hemisferio cererl y est vriilidd en el volumen cererl puede ser por cuss fisiológics, tmién conocids como normles o por cuss no fisiológics secundris procesos congénitos o dquiridos, que dn lugr desproporción de un hemisferio cererl con respecto l otro. En este rtículo se propone un enfoque dignóstico práctico pr ordr este hllzgo, donde, evlundo el hemisferio cererl y el tmño ventriculr, se puede desplegr un serie de posiles dignósticos diferenciles. 1 Rdiologist doctor, CediMed, Ls Vegs Clinic. Rdiology professor CES university nd Universidd Pontifici Bolivrin. Medellín, Colomi. 2 Neurordiologst, CediMed, UPB University professor. Medellín, Colomi. 3 Rdiologist resident, CES University. Medellín, Colomi Introduction When tlking out cererl symmetry, it must e tken into ccount tht this finding my e vrition of the normlity or secondry to some pthologicl process; the ltter my e congenitl due to exposure to nox efore irth, or cquired y exposure, generlly, efore the two yers of life. The ssessment of rin volume nd ventriculr size cn guide the possile cuse of symmetry nd nrrow the rnge of differentil dignoses. The term cererl symmetry lso includes physiologicl symmetry, hemimeglencephly nd hemitrophy cererl. Definitions Physiologicl symmetry or miniml rin symmetry It corresponds to vrint of normlity nd hs een recognized y ntomists, nthropologists, neurologists nd rdiologists. It hs een found through different dignostic methods pneumogrphy, ultrsound, tomogrphy, ngiogrphy nd mgnetic resonnce imging (MRI). This condition is unrelted with ny type of rin dmge nd is lso ssocited with crnil mlformtions (1). Such «norml» symmetry cn

2 compromise complete hemisphere, one or more loes or girl re. The most frequently ffected re is the retroinsulr cortex, corresponding to the posterior lnguge re (2,3) (Figure 1). Non physiologicl rin symmetry It is clinico-rdiologicl condition resulting from severl congenitl or cquired processes, which give rise to disproportion of the hemisphere with respect to the other. An exmple of this non-physiologicl symmetry is the one tht ppers during cererl infrction in sucute phse (Figure 2). Brin hemitrophy (BHA) It is rre entity (4). The term trophy connotes n irreversile loss of rin tissue (5). Cererl hemitrophy or unilterl cererl trophy is the terminl stge of vrious pthologies tht culminte in the trophy or hypoplsi of single cererl hemisphere. Cognitive disorders, chnges in ehvior, hemiplegi, seizures nd emotionl deficits re possile functionl ssocitions of cererl hemitrophy (6,7). Alper nd Der, in 1939, descried tht cererl hemitrophy cn e given for primry or secondry cuses. Primry BHA is the true cererl hemitrophy or unilterl cererl hypoplsi, s it ctully corresponds to the lck of rin development. In this, dmge occurs in utero, with consequent displcement of the structures of the midline to the side of the pthology nd ssocited with lck of sulcus prominences. These chrcteristics differentite the primry BHA from the secondry, condition in which Identified cuses of cererovsculr type, inflmmtory processes or crnil trum, mong others (4,8,9). Possile cuses of cererl hemitrophy re shown in Tle 1. Tle 1. Possile cuses of BHA Congenitl cuses Idiopthic Intruterine vsculr trum Trum Acquired cuses Perintl intrcrnil hemorrhge Rsmussen encephlitis Post-crnil cererl hemitrophy, prolonged ferile seizures Due to infections: TORCH HIV Vsculr: Dyke Dvidoff Msson syndrome Sturge Weer syndrome Cererl cereellr crossed dischisis Commissurl dischisis Syndrome of hemiplegi, hemitrophy nd hemiconvulsion Ischemi Neoplsms: Bsl gngli germinom Rdition Fcomtosis: Neurofiromtosis Miscellneous: Liner nevus syndrome Síndrome de Fishmn Silver-Russell syndrome Child hemiplegi syndrome Trephine syndrome Congenitl mlformtion Corcttion of the intruterine ort Perintl hypoxi-noxi Mitochondril encephlopthy Lctic cidosis MELES (4,8,10-12) c Figure 1., y c) Physiologicl symmetry. A 34-yer-old womn consulted for hedche, with no history of importnce. Non-contrsted CT imges show slight symmetry etween the cererl grooves of oth hemispheres nd in the frontl horns of the lterl ventricles, with symmetry in the pneumtiztion of the frontl ones nd mstoid cells. Rev. Colom. Rdiol. 2017; 28(1):

3 Neuroimging of CT nd MRI plys n importnt role In the dignosis of this entity. When we re fced with Ptient with cererl prenchym trophy, seizures, hemipresis, hemiplegi nd crniofcil symmetry, MRI is the modlity of choice to evlute the etiology nd extent of the lesion (13). Below is rief description of some of the cuses of BHA: Dyke Dvidoff Msson Syndrome (DDMS) In 1933 Dyke, Dvidoff nd Msson descried, on rdiogrphs of the skull nd pneumoencephlogrphs, chnges in series of nine ptients chrcterized cliniclly y hemipresis / hemiplegi, seizures, fcil symmetry nd mentl retrdtion (8). DDMS or hemispheric infrction is n trophy or hypoplsi of cererl hemisphere secondry to vsculr ltertion s congenitl or cquired ischemic disese, trum or inflmmtion which occurs during childhood, with compenstory hypertrophy of the ipsilterl crnil vult (4,8,14). In the in utero rteril occlusion the compromise of the middle cererl rtery itself, hs een descried s the most frequent cuse. Also, it hs een descried tht DDMS my e secondry to ortic corcttion, condition tht my decrese the flow of the middle cererl rtery in n indirect wy (4,8). In neuroimging there is decrese in the size of the cererl hemisphere, thickening of the ipsilterl crnil vult, incresed development of ipsilterl sinuses nd contrlterl or diffuse cereellr trophy (Figure 3). Chnges in the crnil vult only occur when the rin dmge occurs efore ge three nd re visile pproximtely nine months fter vsculr dmge (8). Due to the delyed growth of the cererl prenchym, compenstory chnges, such s enlrgement of the sinuses of predominnce in the frontl sinus nd increse in the thickness of the diploe with elevtion of the mjor wing of the sphenoid, petrous crest nd sphenoidl plne (14). Tretment of this entity is symptomtic, ut in cse of incpcitting seizures nd hemiplegi, hemispherectomy is indicted with which symptoms re controlled in pproximtely 85 % of the cses (9). c Sturge-Weer Syndrome It is lso known s encephlotrigeminl ngiomtosis. This is congenitl normlity consisting of mlformtion of the corticl veins of the fetus, resulting in progressive venous occlusion with susequent chronic venous ischemi. It hs n incidence of 1 cse per 20,000-50,000 people (15). It is considered fcomtosis, chrcterized y fcil spots in wine from Porto nd fcil ngioms (16). Neuroimging shows sucorticl clcifictions ssocited with loss of cererl prenchyml volume, with growth of the crnil vult nd prnsl sinuses. The ipsilterl choroid plexus cn e enlrged (17,18) (Figure 4). Figure 2. ) Non-physiologicl symmetry. Non-contrsted CT scn. Ptient with 6-hour evolution of left hemipresis. Hypodensity is evident in the right frontotemporl region without significnt chnges in rin volume or in the ventricles; ) three dys fter; c) one week lter. Cytotoxic edem is oserved cusing incresed right hemispheric cererl volume nd compression of the djcent ventricle Brin Asymmetry: Dignostic Approch. Zulug A., Vrgs S., Arngo S., Urie R.

4 Figure 4. Sturge-Weer syndrome. CT without contrst medium, sucorticl clcifictions in the left cererl hemisphere, ssocited to loss of prenchyml volume on this side nd increse in the thickness of the ipsilterl frontl one. In ddition, slight left ventriculr diltion. c Figure 3. Dyke Dvidoff Mnsson syndrome. ) Decrese in the left cererl prenchym nd thickening of the ipsilterl crnil vult. ) Thickening of the left skull with compenstory hypertrophy effect of the ipsilterl sinuses. c) Atrophy of right cereellr hemisphere. Rev. Colom. Rdiol. 2017; 28(1): Figure 5. Rsmussen encephlitis. ) MR sequence DWI Restriction to diffusion in the left cererl hemisphere is evidenced. ) DWI sequence 1000 of the sme ptient two yers lter. There is unilterl corticl trophy with ventriculr dilttion ex vcuo on the sme side. There is no restriction on dissemintion. 4639

5 Figure 6. y ) Hemimeglencephly. Simple skull CT. 3 yers old ptient with ntecedent of convulsions. Increse in the cererl volume of the right hemisphere, ssocited with ipsilterl ventriculr diltion nd giripquigiri complex, configurtion in the form of eight of the Silvin crust nd V shpe. Rsmussen s encephlitis It is focl encephlopthy chrcterized y eing chronic inflmmtion pthology of unknown origin, usully ffecting one cererl hemisphere. Eighty-five per cent of cses re in children under 10 yers. In generl, it is considered n entity of unknown cuse, ut ppers to e relted to infection y the Epstein-Brr nd cytomeglovirus. In MRI, in the T1-weighted sequences, unilterl corticl trophy is oserved ssocited with chronic ventriculr dilttion ex vcuo nd in T2-weighted sequences, high signl is identified tht compromises the pthologicl cererl hemisphere. In the diffusion sequences there exists restriction to the sme (in cute phse). Contrst-enhnced tomogrphy does not show significnt enhncement In the compromised cererl hemisphere (Figure 5). Herpetic encephlitis It is n entity cused y the herpes simplex virus (HSV) type 1. In neontes nd infnts, the trnsmission is trnsplcentl, or during childirth (19,20). Cererl hemitrophy is due to unilterl involvement during initils stges of fetl life, with preference for the limic system (olfctory trct, temporl loes, cingulte gyrus nd insulr cortex). In order from gretest to lest, the condition occurs in the inferior temporl loe, frontl loe nd prietl loes (21). MRI is essentil for the evlution of infnts with infection ecuse oth the cortex nd the white mtter cn e widely compromised (22). CT is useful for ssessing periventriculr clcifictions, mostly from the gry-white mtter union (23). Hemiegloencephli or unilterl megloencephli Descried for the first time y Sim in Its etiology is unknown nd is not ssocited with chromosoml ltertions. It presents with ltertions in neuronl migrtion, lthough it cn lso e considered primry disorder of prolifertion, in which neurons tht re not cple of forming synptic connections, re not eliminted nd re ccumulted. Unlike other rin dysgenesis, it shows n extreme symmetry tht does not correspond to ny of the norml phses of development of the rin. It is chrcterized y hmrtomtous growth of prt or ll of hemisphere where the compromised hemisphere my hve focl or diffuse migrtion defects with res of polymicrogyri, pquigiri nd heterotopis. Three types of hemimeglencephly re descried: Isolted, syndromic nd totl: Isolted form: occurs s spordic disorder without hemicorporl hypertrophy or cutneous or systemic ffection. Syndromic form: is ssocited with other diseses nd cn occur s hemi-hypertrophy of ll or prt of the ipsilterl ody. Totl hemimeglencephly: in which there is lso ipsilterl enlrgement of hlf of the rin stem nd the cereellum. It hs no predilection for rce or gender nd is in 0.1 to 0.3 % of the cses of epilepsy dignosed during childhood. In 90 % of the ptients it is mnifested with generlized focl seizures, delyed development, hemipresis nd heminopsi. Normocephly is common in this entity; however, it my show mcrocephly. It is not ssocited with symptoms of endocrnil hypertension. Neuroimging shows n increse in the size of the lterl ventricle, deep grooves with wide convolutions, contrlterl displcement of the sickle, clcifictions of the white mtter nd nomlous venous development. The cortex of the compromised hemisphere my e norml or with polymicrogyri, lysencephly, giri/pquigiri or heterotopis (24) (Figure 6). Trephine syndrome Descried y Grnt in 1939 (25). It is lso known s sunken flp syndrome (26,27), nd hs n incidence of pproximtely 13 % (26) in ptients who re given decompressive crniectomy. It ws pulished in the study y Yng nd collegues where the syndrome ws dignosed in 14 of 108 crniectomy ptients (27) Brin Asymmetry: Dignostic Approch. Zulug A., Vrgs S., Arngo S., Urie R.

6 Figure 7. y ) Trephine syndrome. A 23-yer-old mle ptient, with history of severe encephlocrnil trum nd crniectomy 1 yer efore. Consulttion due to seizures. Simple tomogrphy: left frontl crniectomy with ventriculo-peritonel shunt tht enters y the right frontl loe. Devition from the midline to the right with slight collpse of the lterl ventricle nd concve deformity of the left frontl nd prietl loe Define ventriculr volume Incresed volume Decresed volume Define ventriculr size Define ventriculr size Smll ventricle Lrge ventricle Smll ventricle Lrge ventricle Physiologicl cererl ssymetry Cererl edem Hemieglencephli Isolted hemieglencephli Syndromic hemieglencephli Totl hemieglencephli Trephine syndrome Unilterl crneosinostosis Dvidoff Dyke Msson syndrome Sturge Weer syndrome Rsmussen s encephlitis Encephlomlci Figure 8. Dignostic pproch lgorithm. Rev. Colom. Rdiol. 2017; 28(1):

7 This compliction occurs in the intermedite nd lte postopertive period (28 to 188 dys, with n verge of 88.9 dys) (26,27). It is the most common postopertive compliction of crniectomy fter the first month of the surgery (27). Ptients with this syndrome often mnifest neurologicl symptoms such s hedche, seizures, dizziness, nd chnges in stte of mind (26,27). The pthophysiology is explined y the exposure of the intrcrnil content to the tmospheric pressure, which leds to ltertion in hydrodynmics of the cererospinl fluid of the cererl perfusion nd, finlly, to the deformity of the cererl prenchym (26,27). In CT nd MRI imges the skin flp is depressed in the site of the crniectomy nd the djcent cererl prenchym tkes shpe (26). It hs een reported tht dynmic tomogrphy with Xenon nd perfusion y tomogrphy re very useful tools for ssessing lood flow in these ptients (28) (Figure 7). Its tretment is crnioplsty (25,27), with which there is improvement of the infusion s cn e demonstrted y perfusion studies y CT (25). Dignostic lgorithm To mke prcticl pproch when we encounter symmetries, the following dignostic lgorithm is proposed. First, one must define wht the pthologicl hemisphere is; second, it is determined whether the hemisphere hs incresed or decresed in size, nd finlly, the ventriculr size of the norml hemisphere is estlished (Figure 8). In this wy we cn define four ctegories: Hemisphere with incresed volume with smll lterl ventricle: The most frequent etiology in this ctegory is pthologies ssocited with cererl edem: trum, sucute ischemi, intrcererl hemorrhge, primry nd metsttic tumors, inflmmtion or rin infection. Hemisphere with incresed volume with lrge lterl ventricle: Hemimeglencephly is the pthology chrcteristic of this ctegory. Hemisphere with decresed volume nd smll ventricle: This finding is frequently found in ptients with unilterl crniosynostosis nd trephine syndrome (sunken flp syndrome). Hemisphere with decresed volume nd lrge ventricle:within this ctegory re ssocited pthologies to encephlomlci, trum nd ischemi, mong others. Also entities such s Dvidoff Dyke Msson syndrome, Sturge-Weer syndrome nd Rsmussen s encephlitis. Conclusiones After reviewing the topic it cn e concluded: It is importnt to know tht rin symmetries re frequent in dily prctice. Brin symmetries re not lwys secondry to pthologicl processes, they my lso e norml finding. The cuses of cererl symmetries re multiple, oth congenitl nd cquired. A Prcticl lgorithm for ddressing rin symmetries cn pe performed y recognizing the volume of the ffected cererl hemisphere nd ventriculr size. Referencis 1. Shpiro R, Gllowy SJ, Shpiro MD. Miniml symmetry of the rin: A norml vrint. 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Act Neurochir (Wien). 2008;150: Skmoto S, Eguchi K, Kiur Y, Arit K, Kurisu K. CT perfusion imging in the syndrome of the sinking skin flp efore nd fter crnioplsty. Clin Neurol Neurosurg. 2006;108: Correspondence Ricrdo Urie González Universidd CES Digonl 29d # 9A Sur-150 Medellín, Colomi ricrdouriegonzlez@gmil.com Received for evlution: My 31, 2016 Accepted for puliction: Septemer 17, Brin Asymmetry: Dignostic Approch. Zulug A., Vrgs S., Arngo S., Urie R.