MarwanAlhalabiMDPhDProfessorinReproductiveMedicineFacultyofMedicineDamascusUniversity&ClinicalMedicalDirectorOrientHospitalAssistedReproductionCenterDamascus,Syria.

Inthe18thcentury,thecorpuscallosumwasconsideredthesiteofthesoul(MauricePtito),andintheearly20thitwasassignedthemereroleofpreventing thecerebralhemispheresfromcollapsingontoeachother

Itwasonlyinthe1950'sthatthecorpuscallosum,inthepioneeringworkofMyersandSperry,wasattributedthefunctionoftransferalofinformation betweenthetwohemispheres

Thiswasfollowedbythedevelopment,intheearly1960's,ofasurgicalinterventionaimedatreducingtheinterhemispherictransmissionofabnormalelectricaldischargesinepileptic patients

Underneaththecerebrumatthecenterofthebrain.

Ø Largestconnectivepathway

Ø 200millionnervefibers

Ø Connectsleft&right

hemisphere

Ø “Communication”

l Transfersthefollowing:

l Motorinformation

l Sensoryinformation

l Cognitiveinformation

l “ALLTHROUGHLEFT&RIGHTHEMISPERES!”

1. Splenium

2. Body

3. Genu

4. Rostrum

5.Isthmus

Motor

Somatosensory Auditory

Visual200,000,000Neuronsconnecteach

hemisphere

• Developmentalabsenceofthecorpuscallosum:Agenesis(ACC)• PartialACC

• CompleteACC

• Eachofthesemaybe:• Isolated:ACCwithnootherabnormalities

• Complex:ACCwithotherabnormalities

• Incidence – difficulttoestimate(asymptomaticindividuals)

• Therearenolargestudies• 1.4per10.000livebirths(CaliforniaBirthDefect

MonitoringProgram)• Prevalenceofassociatedbrainabnormalities- 45,8%(posteriorfossa,interhemispheric cystsandneuronalmigrationdisorders)

• Theoverallrateofchromosomal abnormality - 17,8%(consider- chromosomalanalysis,CGH)

• MeasurementofCCsize– recommendedbysomeauthors

Achiron R, Achiron A..Ultrasound Obstet Gynecol 2001; 18: 343–347.

Corpuscallosum• By18-20weeks’gestation– finalshape

Corpuscallosum:• Approach:mid-sagittalormid-coronalplaneofthebrain• Multiplanar sonographyorTVS– useful• Mid-sagittalview– thinanechoicspace• Mid-sagittalview– pericallosal arteryasamarker(especiallyin

resolution-relateddifficulties)

• 3D/4Dreconstruction

Absenceofthecavumsepti pellucidi (CSP)• NotspecifictoACC(holoprosencephaly,hydrocephalus,septo-opticdysplasia,schizencephaly,encephalocele,porencephaly andhydranencephaly).

• InpartialACC- CSPisusuallypresent

FusedfrontalhornsmimicthepresenceofCSP

Abnormalitiesoftheventricles

• Colpocephaly - dilatationoftheatriaandoccipitalhornsofthelateralventricles• ResultoftheabsenceofCCposteriorportion,whichallows

expansionoftheoccipitalhorns.

• Usuallynotassociatedwithprogressiveventriculomegaly

• LateraldisplacementofLateralVentricleoncoronalviews.

• Upwarddisplacementofthethirdventricle,whichreachesthelevelofthelateralventricles

Abnormalcourseofthepericallosal artery• CompleteACC:thesemicircularloopofthepericallosal arteryislost

• PartialACC:thepericallosal arteryfollowstheanteriorpartoftheCCbutthenlosesitsnormalcoursewheretheCCdisappearsposteriorly;

Wideningoftheinterhemispheric fissure

• Increasedseparationofthehemispheres

• 3parallelechogeniclines(themiddle- falx cerebri)

• Thelateralonesrepresentingthemedialbordersoftheseparatedhemispheres

Signsandsymptoms• Varygreatlyamongindividuals

• Somecharacteristicscommoninindividualswithcallosal disordersinclude

1. Poor motor coordination, 2. Delays in motor milestones such as sitting

and walking, 3. Delayed toilet training, 4. Chewing and swallowing difficulties

5. Vision impairments, 6. Hypotonia7. Low perception of pain, .8. sometimes seizures, spasticity, early

feeding difficulties

• Associatedsyndromes• ACCcanoccurasanisolatedconditionorincombinationwithother

cerebralabnormalities,including• Arnold-chiari malformation,• Dandy-walkersyndrome,• Andermann syndrome(motorandsensoryneuropathy)• Schizencephaly (cleftsordeepdivisionsinbraintissue)• Holoprosencephaly(failureoftheforebraintodivideintolobes.)

• Aicardi Syndrome.• Cephalocele.

Cause• Agenesis of the corpus callosum is caused bydisruption to development of the fetal brainbetween the 3rd and 12th weeks of pregnancy.

• In most cases, it is not possible to know whatcaused an individual to have ACC or anothercallosal disorder.

Cause• However,researchsuggeststhatsomepossiblecausesmayinclude

• chromosomeerrors,

• inheritedgeneticfactors,

• prenatalinfectionsorinjuries,• prenataltoxicexposures,

• structuralblockagebycystsorotherbrainabnormalities

• metabolicdisorders.

Treatment• There are currently no specific medical treatments for

callosal disorders, it usually involves management ofsymptomsand seizures if they occur.

• Patients may benefit from a range of

• developmental therapies,

• educational support, and services.

• Dependsoncoexistenceofotherabnormalities

• Associationwithcorticaldisorders– poorprognosis

• Normalorborderlineintellectualdevelopment– incaseofisolated

• Pediatricdatasuggest– morethan90%mentalretardationorsevereabnormalities

Only& The& Rostrum& (1),& Genu& (2)& And& Body& (3)& Are& Visible;& The& Splenium& Is&Missing.&The&Corpus&Callosum&Is&Short&Posteriorly&And&Does&Not&Seem&To&Overlay&The&Quadrigeminal&Plate

Sunday, July 28, 13

• Agenesis of corpus callosum (ACC)

• Cortical heterotopia,• Infantile spasm, • Chorioretinopathy, • Mental retardation with

or without associated vertebral anomalies.

• X Linked Recessive