Disorders of Neural Tube Formation

8/9/2019 Disorders of Neural Tube Formation

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DISORDERS OF NEURAL TUBE FORMATION

The neural tube usually fuses 18–26 days after ovulation. Failure of closure maylead to anencephaly, encephalocele, spina bifida or spina bifida occulta. Liveborn

anencephalic babies usually die in hours or days.

Epidemiology

Neural tube defects NT!s" are amon# the most common con#enital abnormalitiesbut prevalence varies bet$een countries and races. The prevalence of NT!s in%n#land and &ales fell from the 1'()s on$ards to *ust under ).8+1))) total births by1''. -ome of the decline $as due to antenatal dia#nosis but some is uneplained./n the 0 anencephaly and spina bifida are of approimately eual prevalence andto#ether ma3e up '45 of all NT!s.

Aetiology

ost NT!s result from a comple interaction bet$een several #enes and poorlyunderstood environmental factors.

Genetic factor

NT!s occur in many syndromes and chromosome disorders. 7o$ever, an NT! maybe the only anomaly in a member of a family in $hich case the relatives have anincreased ris3 for all types of NT!.

En!ironmental factor

ericonceptual multiple vitamin supplements containin# folic acid reduce theincidence of neural tube defects. /n %n#land it is recommended that $omen plannin#pre#nancy ta3e )) 9# of folic acid daily before conception and durin# the first 12$ee3s of the pre#nancy. -ome dru#s ta3en durin# the pre#nancy may increase theris3. These include sodium valproate and folic acid anta#onists such as trimethoprim,triamterene, carbama:epine, phenytoin, phenobarbitone, and primidone.

"renatal diagnoi

; Fetoprotein


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Spinal dyrap#im

Spina $ifida cytica

This is a cystic lesion $hich in 8)–')5 is a myelomenin#ocele in $hich the spinalcord is a component of the cyst $all. /t is lumbosacral in about 8)5 of cases. Thereis usually a miture of upper and lo$er motor neurone si#ns dependin# on the leveland there is al$ays disturbance of bladder and bo$el function. -urvivin# infantsreuire comple orthopaedic and urolo#ical support, includin# sur#ery.


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Syringomyelia

This is a tubular cavitation of the spinal cord $hich tends to be in the cervical re#ion

but may involve the $hole cord. /t rarely becomes symptomatic in children. -huntin#of the cavity is sometimes performed and posterior fossa eploration may beunderta3en. /t is often associated $ith the >hiari / malformation in $hich there isdo$n$ard displacement of the lo$er cerebellum, includin# the tonsils fi# 1".

Fig%re &>hiari / malformation. -a#ittal T1 $ei#hted ma#netic resonance ima#e sho$in# anenlar#ed cerebellar tonsil $hich etends belo$ the level of the foramen ma#numarro$". The corpus callosum is normal $ith the cin#ulate #yrus *ust above itcompare to fi#ure 4". This 12 year old boy presented $ith headaches. The >hiari /

malformation can be associated $ith hydrocephalus and syrin#omyelia, $hich he didnot have.

DISORDERS OF REGIONALISATION


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hypotelorism closely set eyes", a sin#le central incisor tooth or the face may benormal.

DISORDERS OF 'ORTI'AL DE(ELO"MENT

Diorder of proliferation and differentiation

Microcep#aly

This is an abnormally small head circumference ? ).th centile on occipito=frontalhead circumference charts", $hich is disproportionately small in relation to the rest of the body. The usual implication of this findin# is that brain #ro$th is not normal.7o$ever, if a small head circumference is detected in the neonatal period it isprudent to perform an ray of the s3ull to loo3 for evidence of early closure of all thecranial sutures total craniosynostosis".

Genetic ca%e

There are familial cases $here the neurolo#ical problems are relatively mild.7o$ever microcephaly is usually associated $ith si#nificant abnormalities such aspyramidal tract si#ns and profound learnin# difficulties. /t is part of more than 4)syndromes listed in the @ford !ysmorpholo#y !atabase.

Non)genetic ca%e

These include ionisin# radiation in the first t$o trimesters of pre#nancy, intrauterine

infections, dru#s and other chemicals, circulatory disturbance, and perinatal hypoic=ischaemic events. &hen there is a si#nificant perinatal insult to the brain the headcircumference may be normal at birth $ith subseuent failure of #ro$th in the firstfe$ months of life. %ually in some types of #enetic microcephaly the head si:e fallsoff as late as A2–A $ee3s of #estation or even after birth, so prenatal dia#nosis byultrasound may be difficult.

Megalencep#aly

e#alencephaly is increased si:e of the brain itself. Lar#e heads can run in normalfamilies but inherited me#alencephaly can be associated $ith si#nificant learnin#

difficulties, neurolo#ical abnormalities, and sei:ures. 7emime#alencephaly isunilateral enlar#ement of one side of the brain, sometimes the hemisphere only.


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Agyria)pac#ygyria *liencep#aly+

There may be complete absence of #yri, in $hich case the terms a#yria orlissencephaly Cree3D Esmooth brain" are used. achy#yria describes a reducednumber of broadened and flat #yri $ith less foldin# of the corte than normal. There

may be varyin# de#rees of a#yria+pachy#yria in the same brain fi# 2".

Fig%re ,Type / lissencephaly. >oronal T1 $ei#hted ma#netic resonance ima#e.


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LIS1 #ene. utations in a second #ene on the H chromosome, doublecortin DCX ",have also been sho$n to cause lissencephaly.

Type II liencep#aly or -al.er)-ar$%rg yndrome

This is also called Ecobblestone lissencephaly and is a different malformation fromtype / lissencephaly. The smooth corte has a #ranular surface and is covered $ithmenin#es that are thic3ened as a result of mesenchymal proliferation. The clinicalfeatures include both nervous system and muscle abnormalities. The infants are veryabnormal at birth. They have abnormal eyes $ith retinal dysplasia, microphthalmia,and anomalies of the anterior se#ment. There may be hydrocephalus or sometimesmicrocephaly. 0sually there is necrosis of fibres in all muscles, similar to that seen insevere muscular dystrophy, and serum creatine 3inase is raised.


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Fig%re 0Jilateral opercular polymicro#yria. >oronal T1 $ei#hted ma#netic resonance ima#e.These bilateral abnormalities arro$s" are relatively subtle and $ere not identified ona computed tomo#raphic eamination. /n the first year of life this boy developed ri#htsided sei:ures and development $as delayed, particularly in lan#ua#e. Later he had

poor ton#ue and pharyn#eal coordination and a ri#ht hemiple#ia. !espite thelateralisation of some of his neurolo#ical si#ns, the scan abnormalities $ere bilateral.

Diorder of cortical organiation

-ome patients have cortical microdys#enesisBmicroscopic abnormalities of corticalarran#ement that have been described in the brains of patients $ith epilepsy, autism,schi:ophrenia, and the fetal alcohol syndrome. The etent to $hich these findin#seplain abnormal brain function is an area of active research. @ther patients haveareas of focal cortical dysplasia $hich are lar#e enou#h to be seen on computedtomo#raphic or ma#netic resonance ima#in# scans fi# ". These dysplasias are acause of early onset sei:ures that may be focal or #eneralised. Iesection of corticaldysplasias may improve sei:ure control.


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Fig%re 1 >on#enital cortical malformation.


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'OMBINED AND O(ERLA""ING 'EREBRAL MALFORMATIONS

There are distinct abnormalities that represent an overlap bet$een different classes

of malformation. This is not surprisin#Bthe terato#enic periods are so closelyspaced that overlaps are li3ely if there is an environmental cause.


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onset" sei:ures. allosal a#enesis is part of the fetal alcohol syndrome and is seen inlactic acidosis and non=3etotic hyper#lycinaemia.

&hen a#enesis of the corpus callosum is the only lesion there may be no symptomsalthou#h tests of perception and lan#ua#e may demonstrate disturbances ofinte#ration of hemispheric function. 7o$ever, some patients have mental retardation,sei:ures or cerebral palsy.

renatal ultrasound allo$s dia#nosis from 2) $ee3s #estation. &hen callosala#enesis is discovered on antenatal scan the pro#nosis is difficult to assess because

the isolated lesion can be associated $ith normal development. < decision toterminate the pre#nancy may depend on the demonstration of associatedabnormalities.

"orencep#aly

The term porencephaly is often used for any cavity in a cerebral hemisphere thatcommnunicates $ith a lateral hemisphere. 7o$ever, it should probably be used onlyfor circumscribed hemispheric necrosis that occurs in utero before the adult featuresof the hemisphere are fully developed. The relatively early development of theselesions is sho$n by their smooth $alls and by associated developmentaldisturbances in the ad*oinin# corte such as polymicro#yria or distortion of the #yralpattern. This is relevant because unilateral or bilateral porencephalic cysts are foundin children dia#nosed as havin# cerebral palsy and there is often debate about thetimin# of the insult. Neuropatholo#ical tets debate $hether or not there is adistinction bet$een porencephaly and schi:encephaly, and some corticalabnormalities do not fit neatly into any #roup fi# ".

Sc#i3encep#aly

This term is used by radiolo#ists to describe clefts $hich traverse the full thic3ness of

the hemisphere, connectin# the ventricle to the subarachnoid space. They aredescribed as type / or Efused=lip $hen the $alls of the cleft are opposed, and type //or Eopen=lip $hen cerebrospinal fluid separates the $alls. -ome of them are #eneticBfamilial cases have been described and some sporadic cases are associated $ithmutations in the homeobo #ene EMX2 . The clefts are freuently bilateral and even$hen unilateral they are often combined $ith cortical dysplasia of the oppositehemisphere.

%pilepsy is common and sometimes the only problem is isolated partial sei:ures.There may be hemiple#ia, uadriple#ia, and learnin# difficulties of variable de#ree. /f there is bilateral involvement of both opercular re#ions there may be facial apraia

and speech difficulties.


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MALFORMATIONS OF "OSTERIOR FOSSA STRU'TURES


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• /t is important to construct a three #eneration family tree, if necessary $ith

eamination and investi#ation of close relatives for subtle epression of adisorder, or evidence of carrier status.

• The aim is to establish a dia#nosis and #ive an accurate ris3. /f it is not

possible to identify the precise aetiolo#y it is usually possible to offer anempiric recurrence ris3 after eamination of the parents.

"renatal diagnoi

• renatal dia#nosis and termination of affected pre#nancies is only one of a

ran#e of reproductive options open to parents, but for many couples it is theoption of choice.

• For the ma*ority of developmental disorders of the nervous system, pre=

implantation #enetic dia#nosis is not yet feasible.

• For a condition follo$in# mendelian inheritance the option of donor #ametes

could be discussed.

• For a condition $ith a stron# environmental component it is imperative that

measures are ta3en to minimise the ris3 of eposure in a future pre#nancy.For neural tube defects, periconceptual supplementation $ith hi#h dose folatehas been sho$n to reduce the ris3 of recurrence in future pre#nancies seeabove".

• &hen a specific dia#nosis has been made and a chromosomal anomaly,

#enetic mutation or biochemical defect has been identified it is usuallypossible to offer prenatal dia#nosis by chorion villus samplin# at 11 $ee3s#estation in a future pre#nancy. /f this is not the case, detailed ultrasoundscannin# may be helpful in some instances.

•rovidin# accurate #enetic advice about developmental anomalies of thenervous system is a challen#in# tas3. Referral for specialist advice is stronglyrecommended .

Learning point

• Neural tube defects NT!s" are some of the most common con#enital

abnormalities of the >N-, althou#h their prevalence in the 0 has fallen.Nevertheless it is still important to counsel $omen of childbearin# a#e aboutthe need to ta3e dietary supplements containin# folate before becomin#pre#nant


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• There is an increased ris3 of NT!s in pre#nant $omen $ho are ta3in# certain

dru#s

• %ven small midline abnormalities over the spinal cord should be ta3en

seriously in case there is underlyin# spinal dysraphism

Learning point

• &hen assessin# children the head circumference should be measured and

plotted on a centile chart. The current measurement should be compared $ithprevious measurements to determine $hether or not there has been apro#ressive chan#e $ith time

• -ome children $ith non=pro#ressive abnormalities of head si:e are normal in

their development, but children $ith micro= or macrocephaly and abnormal

development should probably have ma#netic resonance ima#in# of the brain

Learning point

• The lissencephalies cause ma*or developmental problems and may shorten

life

• /n type // lissencephaly the cerebral malformations may be associated $ith

eye or muscle abnormalities so that a comprehensive assessment isnecessary

• -ome of the less severe mi#rational and or#anisational abnormalities may be

clinically silent. 7o$ever they may be associated $ith learnin# difficulties orsei:ures. any $ill be discovered on ma#netic resonance ima#in# of thebrain. 7o$ever some are microscopic, $hich is relevant in the assessment ofsome patients $ith refractory epilepsy

Learning point

• >ombined malformations may be found in infants $ith severe developmental

and neurolo#ical problems

• 7o$ever, they may be present in patients $ith relatively minor learnin#

difficulties or motor disability. atients $ith a#enesis of the corpus callosummay have no neurolo#ical problems. /t is important to be #uarded about thepro#nosis $hen such abnormalities are found on scannin# in early life

4E5 REFEREN'ES

1. Aicardi J . Diseases of te nervo!s system in cildood" 2nd ed. London#Mac $eit %ress" London" 1&&'.▸ This is a standard work, whichcontains an excellent chapter on malformations of the nervous system.


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2. Baraitser M . (1&&)*. +e genetics of ne!rological disorders" ,rd ed. -xfordMonograps on Medical enetics. ,/. -xford# -xford 0niversity %ress" 1&&).▸ Another standard reference book, which remains useful despite theevolution of computerised neurogenetic databases.

A. Bar.o!itc# A6. %ediatric ne!roimaging , 2nd ed. hiladelphiaD Lippincott=Iaven, 1''6.▸T#i compre#eni!e te7t$oo. #a a %ef%l c#apter t#atincl%de can ill%trating t#e normal de!elopment of t#e ner!o%ytem8 T#ere are alo c#apter on congenital a$normalitie of t#e $rainand pine8

. Faer$er EN, ed. CS Magnetic resonance imaging in infants and cildren.Clinics in Developmental Medicine o.1,/. LondonD ac eith ress, 1''4.▸More %ef%l can of c#ildren 9it# de!elopmental pro$lem8

4. Friede RL. Developmental ne!ropatology , 2nd revised and epanded

edition. JerlinD -prin#er=erla#, 1'8'.▸T#i i a ne%ropat#ology te7t$oo.dealing 9it# t#ee complicated de!elopmental a$normalitie8 It%pplement and %nderpin t#e more recent 9or.: 9#ic# i $aed moreon imaging and genetic t%die t#an ne%ropat#ology8

6. leeson J " als C3. e!ronal migration disorders# from genetic diseasesto developmental mecanisms. +rends in e!roscience244452,#,627&.▸ Anexcellent recent review.

M>rossIef Medline M&eb of -cience

(. ovaert ! " de 8ries LS. 3n atlas of neonatal 9rain sonograpy. Clinics inDevelopmental Medicine os. 1/171/2. London# Mac $eit %ress" 1&&).▸"ltrasonography is now the means of performing early and non# invasive examinations of the infant brain so this is an importantreference work for those looking after newborns.

httpD++*nnp.bm*.com+content+(+supplO1+iA.fullPsec=2

http://jnnp.bmj.com/external-ref?access_num=10.1016/S0166-2236(00)01607-6&link_type=DOIhttp://jnnp.bmj.com/external-ref?access_num=10.1016/S0166-2236(00)01607-6&link_type=DOIhttp://jnnp.bmj.com/external-ref?access_num=10906798&link_type=MEDhttp://jnnp.bmj.com/external-ref?access_num=10906798&link_type=MEDhttp://jnnp.bmj.com/external-ref?access_num=000088474900008&link_type=ISIhttp://jnnp.bmj.com/content/74/suppl_1/i3.full#sec-2http://jnnp.bmj.com/external-ref?access_num=10906798&link_type=MEDhttp://jnnp.bmj.com/external-ref?access_num=000088474900008&link_type=ISIhttp://jnnp.bmj.com/content/74/suppl_1/i3.full#sec-2http://jnnp.bmj.com/external-ref?access_num=10.1016/S0166-2236(00)01607-6&link_type=DOI


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Birt# defect ) central ner!o% ytem

-ummary

Neural tube defects NT!s" include spina bifida, anencephaly and encephalocele.

Folate deficiency and some epilepsy medications are ris3 factors for these

conditions. Ta3in# folic acid before and durin# early pre#nancy can si#nificantly

reduce the ris3 of neural tube defects. Tests in pre#nancy such as ultrasound candia#nose these birth defects.

Jirth defects of the central nervous system are called neural tube defects NT!s".

NT!s include conditions called spina bifida, anencephaly and encephalocele. They

are all present at birth and are due to a problem $ith the development of the brain

and+or spinal cord in the developin# baby fetus".

The brain and spinal cord of a #ro$in# fetus develop from a simple structure called

the ne!ral t!9e. The neural tube Q:ips upR alon# its len#th to close and protect thebrain and spinal cord. /f the neural tube doesnRt close at any part alon# its len#th, the


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baby $ill have a neural tube defect. The types of neural tube defects spina bifida,

anencephaly and encephalocele" are due to the place alon# the neural tube that

hasnRt closed, leavin# parts of the brain and+or spinal cord eposed.

< ran#e of #enetic and environmental factors are thou#ht to be responsible forNT!s, includin# the mother havin# not enou#h of the vitamin folate and some

epilepsy medications. Ta3in# folate folic acid" before and durin# early pre#nancy

can si#nificantly reduce the chance that a mother $ill have a baby $ith this 3ind of

birth defect.

The central nervous system >N-"

The central nervous system consists of the brain and spinal cord. Joth are $rapped

in a thin linin# called meninges and are surrounded by a fluid called cere9rospinal

fl!id . The brain is attached to the spinal cord by the brain stem, located at the baseof the brain. The spinal cord runs the len#th of the bac3bone and is protected by the

bones vertebrae" of the spine. Nerves branch off from the spinal cord into the parts

of the body.

!evelopment of the fetal >N-

The central nervous system of a #ro$in# fetus starts $ith a simple structure called

the Qneural #rooveR that folds in to form the Qneural tubeR. This then develops into the

spinal cord and brain. Jy day 28 after conception, the neural tube should be closed

and fused. /f it doesnRt close, the result is a neural tube defect./n many cases, these defects can be dia#nosed durin# pre#nancy $ith ultrasound

scans and, rarely, $ith other tests such as amniocentesis analysin# a sample of

amniotic fluid".

Iis3 factors and prevention of >N- birth defects

Neural tube defects are thou#ht to be caused by a ran#e of #enetic and

environmental factors $or3in# in combination. -ome of these factors includeD

• T#e mot#er #a a folate deficiency – if the mother is lac3in# some nutrients,

especially the J=#roup vitamin called folate folic acid", the chance of havin# ababy $ith a NT! is increased. /f folate is ta3en $efore conception and atleast for the first four $ee3s of pre#nancy, around seven out of 1) cases ofNT!s can be prevented. Sou should tal3 to your doctor about ho$ much folateyou should ta3e if you are thin3in# of becomin# pre#nant.

• Genetic – the eact #enetic association is unclear, but a $oman is at

increased ris3 of havin# a baby $ith a neural tube defect if she has a close

relative $ho has had a baby $ith the condition a family history". < $oman


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$ho has already #iven birth to a child $ith a neural tube defect is also atincreased ris3 of havin# subseuent babies $ith a similar condition.

• 7avin# a personal or family history of a NT! can influence the amount of

folate needed to reduce the chance of havin# a baby $ith a neural tube

defect. Sou should tal3 to your doctor about ho$ much folate you should ta3eif you are thin3in# of becomin# pre#nant.

• /n some cases, ho$ever, there is evidence to su##est that some forms of

neural tube defects are caused by specific #enetic chan#es mutations" thatare not related to folate. /n these cases, the neural tube defect is caused bythe baby inheritin# faulty #ene copies from both parents. These faulty #enesprevent the baby from ma3in# use of folate that is necessary to #ro$ anddevelop in pre#nancy even if the folate is present in the ri#ht amount". /nthese cases, ta3in# folate before and durin# pre#nancy $ill not prevent thecondition.

• Medication – particular medications used to treat and control epilepsy are

thou#ht to contribute to the ris3 of neural tube defect.

-pina bifida

/n a baby $ith spina bifida, the bones verte9rae" of the spine fail to fuse. The spinal

cord and nerves protrude or Qpop outR" throu#h the #ap that has been created due to

a failure of closure of the neural tube. This can affect the nerves that spread from this

area into the abdomen and le#s. -pina bifida can occur any$here alon# the len#th of

the spine, but more commonly appears in the lo$er bac3.

Nine out of 1) affected babies also have a build=up of cerebrospinal fluid inside the

brain. This condition is called hydrocephalus and is sometimes referred to as Q$ater

on the brainR. The incidence of spina bifida in ictoria is around one in every 1,2A4

births.

-pina bifida can be mild, moderate or severe and is #raded accordin# to the de#ree

of the defect intoD

• Occ%lta – the bones vertebrae" have not closed completely, but the spinal

cord is unharmed. The characteristic soft lump may be missin#, $hich is $hythis form of spina bifida is sometimes dia#nosed later in life.

• Meningocele – the membrane menin#es" coverin# the spinal cord protrudes

or bul#es out throu#h the #ap in the spine.

• Myelomeningocele – the menin#es, spinal cord and blood vessels protrude

throu#h the #ap.

-pina bifida is incurable. The main form of treatment is sur#ery to seal the #ap. /f the

baby has hydrocephalus, a shunt is inserted into the brain to drain the ecess

cerebrospinal fluid.


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entralOnervousOsystemVopenUWJirth defects = central nervous system = Jetter 7ealth

>hannel?+aW?br+W

Neural tube defects NT!s" include spina bifida, anencephaly and encephalocele.

Folate deficiency and some epilepsy medications are ris3 factors for these

conditions. Ta3in# folic acid before and durin# early pre#nancy can si#nificantly

reduce the ris3 of neural tube defects. Tests in pre#nancy such as ultrasound can

dia#nose these birth defects.

httpD++$$$.betterhealth.vic.#ov.au+bhcv2+bhcarticles.nsf+pa#es+JirthOdefectsOcentral OnervousOsystem

HydrocephalusWater on the brain

Last reviewed: November 12, 2012.

Hydrocephalus is a buildup of fluid inside the skull that leads to brain swellin.

Hydrocephalus means !water on the brain.!

Causes, incidence, and risk factors

Hydrocephalus is due to a problem with the flow of the fluid that surrounds the brain. "his

fluid is called the cerebrospinal fluid, or #$%. &t surrounds the brain and spinal cord, and

helps cushion the brain.

#$% normally moves throuh the brain and the spinal cord, and is soaked into the

bloodstream. #$% levels in the brain can rise if:

• The ow of CSF is blocked

• It does not get absorbed into the blood properly

• Your brain makes too much of it

"oo much #$% puts pressure on the brain. "his pushes the brain up aainst the skull and

damae brain tissue.

http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Birth_defects_central_nervous_systemhttp://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Birth_defects_central_nervous_systemhttp://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Birth_defects_central_nervous_systemhttp://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Birth_defects_central_nervous_system


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Hydrocephalus may bein while the baby is rowin in the womb. &t is common in babies

who have a myelomeninocele, a birth defect in which the spinal column does not close

properly.

Hydrocephalus may also be due to:

• enetic defects

• Certain infections during pregnancy

&n youn children, hydrocephalus may be due to:

• Infections that a!ect the central ner"ous system #such as meningitis orencephalitis$, especially in infants

•

%leeding in the brain during or soon after deli"ery #especially in prematurebabies$

• In&ury before, during, or after childbirth, including subarachnoidhemorrhage

• Tumors of the central ner"ous system, including the brain or spinal cord

• In&ury or trauma

Hydrocephalus most often occurs in children. 'nother type, called normal pressure

hydrocephalus, may occur in adults and the elderly.

Symptoms

$ymptoms of hydrocephalus depend on:

• 'ge

• 'mount of brain damage

• What is causing the buildup of CSF uid

&n infants with hydrocephalus, it causes the fontanelle (soft spot) to bule and the head to be

larer than e*pected. +arly symptoms may also include:

• (yes that appear to ga)e downward

• Irritability

• Sei)ures

•

Separated sutures

http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001558/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A000752/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A000752/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A000752/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001558/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A000752/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A000752/


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• Sleepiness

• *omiting

$ymptoms that may occur in older children can include:

• %rief, shrill, high+pitched cry

• Changes in personality, memory, or the ability to reason or think

• Changes in facial appearance and eye spacing

• Crossed eyes or uncontrolled eye mo"ements

• i-culty feeding

• (.cessi"e sleepiness

• /eadache

• Irritability, poor temper control

• 0oss of bladder control #urinary incontinence$

• 0oss of coordination and trouble walking

• 1uscle spasticity #spasm$

• Slow growth #child 2 + 3 years$

• Slow or restricted mo"ement

• *omiting

Signs and tests

"he doctor or nurse will e*amine the baby. "his may show:

• Stretched or swollen "eins on the baby4s scalp

• 'bnormal sounds when the health care pro"ider taps lightly on the skull,suggesting a problem with the skull bones

• 'll or part of the head may be larger than normal, usually in the front part

• (yes that look 5sunken in5

• White part of the eye appears o"er the colored area, making it look like a5setting sun5

• 6ee.es may be normal


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ithout treatment, up to in 10 people with hydrocephalus will die. "hose who survive have

different amounts of intellectual, physical, and neuroloical disabilities.

"he outlook depends on the cause. Hydrocephalus that is not due to an infection has the best

outlook. ersons with hydrocephalus caused by tumors usually do very poorly.

3ost children with hydrocephalus that survive for 1 year will have a fairly normal life span.

Complications

"he shunt may become blocked. $ymptoms of such a blockae include headache and

vomitin. $ureons may be able to help the shunt open without havin to replace it.

"here may be other problems with the shunt, such as kinkin, tube separation, or infection in

the area of the shunt.

ther complications may include:

• Complications of surgery

• Infections such as meningitis or encephalitis

• Intellectual impairment

• 9er"e damage #decrease in mo"ement, sensation, function$

• :hysical disabilities

Calling your health care pro"ider

$eek immediate medical care if your child has any symptoms of this disorder. 4o to the

emerency room or call 511 if emerency symptoms occur, which include:

• %reathing problems

• (.treme drowsiness or sleepiness

• Feeding di-culties

• Fe"er

• /igh+pitched cry

• 9o pulse #heart beat$

• Sei)ures

• Se"ere headache


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• Sti! neck

• *omiting

6ou should also call your health care provider if the child has been dianosed with

hydrocephalus and the condition ets worse and you are unable to care for him or her athome.

:re"ention

rotect the head of an infant or child from in7ury. rompt treatment of infections and other

disorders associated with hydrocephalus may reduce the risk of developin the disorder.

6eferences

;7 Saunders (lse"ier@ A2;;>chap 3B37;;7

A7 6osenberg '7 %rain edema and disorders of cerebrospinal uidcirculation7 In> %radley W, aro! 6%, Fenichel 1, =anko"ic =, eds7Neurology in Clinical Practice7 3th ed7 :hiladelphia, :a> %utterworth+/einemann@ A22B>chap D7

8eview 9ate: 11122012.

8eviewed by: Neil ;. ;aneshiro, 39, 3H', #linical 'ssistant rofessor ofediatrics, , $tephanie $lon, and Nissi an.

'77'717, isclaimer

'.9.'.3., &nc. is accredited by


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constitute endorsementscof those other sites. A 155BC2011 '.9.'.3., &nc. 'ny duplication or

distribution of the information contained herein is strictly prohibited.

Copyright E A2;D, '77'717, Inc7

MicrocephalyLast reviewed: November 1D, 2011.

3icrocephaly is a condition in which a persons head is sinificantly smaller than normal for

their ae and se*, based on standardi>ed charts. Head si>e is measured as the distance around

the top of the head.

Common Causes

3icrocephaly most often occurs because the brain fails to row at a normal rate. $kull rowth

is determined by brain rowth. Erain rowth takes place while in the womb and durin

infancy.

#onditions that affect brain rowth can cause microcephaly. "hese include infections, enetic

disorders, and severe malnutrition.

4enetic conditions that cause microcephaly include:

• Cornelia de 0ange syndrome

• Cri du chat syndrome

• own syndrome

• 6ubinstein+Taybi syndrome

• Seckel syndrome

• Smith+0emli+pit) syndrome

• Trisomy ;B

• Trisomy A;

"hese additional conditions may indirectly cause microcephaly:

• Gncontrolled phenylketonuria #:


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• Congenital to.oplasmosis

• Congenital cytomegalo"irus #C1*$

• Gse of certain drugs during pregnancy, especially alcohol and phenytoin

Call your health care pro"ider if

3icrocephaly is often dianosed at birth or durin routine well-baby e*aminations when the

infants heiht, weiht, and head circumference is measured. &f you suspect your infants head

si>e is too small or not rowin normally, consult your health care provider.

What to e.pect at your health care pro"ider4s o-ce

3icrocephaly is usually discovered by the health care provider durin routine e*amination.

Head measurements are part of all well-baby e*aminations up to 1F months (loner in certain

circumstances). "hey are painless and take only a few seconds while the measurin tape is

placed around the infants head.

9ocumentin microcephaly in detail may include:

• What is the head circumferenceH

• Is the head growing at a slower rate than the bodyH

• What other symptoms are thereH

Note: ' record of the head circumference should be maintained over time.

'lthouh the health care provider maintains records on your baby, it may be helpful to

maintain your own records, and brin them to the health care providers attention if you

notice that the infants head rowth pattern seems to be decreasin.

&f your health care provider dianoses your child with microcephaly, you should note that in

your childs personal medical records.

6eferences

;7

A7 chap 3B37;27

8eview 9ate: 111D2011.

http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001360/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001343/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0001418http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001928/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001928/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001360/http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001343/http://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0001418http://www.ncbi.nlm.nih.gov/pubmedhealth/n/pmh_adam/A001928/


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8eviewed by: 9avid #. 9udale, &&&, 39, rofessor of 3edicine, 9ivision of 4eneral

3edicine, 9epartment of 3edicine,


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&t is most often caused by enetic abnormalities that interfere with the rowth of the cerebral

corte* durin the early months of fetal development. &t is associated with 9owns syndrome,

chromosomal syndromes, and neurometabolic syndromes. Eabies may also be born with

microcephaly if, durin prenancy, their mother:

• abused drus or alcohol,

• became infected with a cytomealovirus,

• rubella (4erman measles), or varicella (chickenpo*) virus,

• was e*posed to certain to*ic chemicals, or

• had untreated phenylketonuria (;ures,

• difficulties with coordination and balance, and

• other brain or neuroloical abnormalities.

$ome children with microcephaly will have normal intellience and a head that will row

bier, but they will track below the normal rowth curves for head circumference.

Is there any treatment for microcephalyH

Comment on this Share Your Story

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"here is no treatment for microcephaly that can return a childs head to a normal si>e or

shape. "reatment focuses on ways to decrease the impact of the associated deformities and

neuroloical disabilities. #hildren with microcephaly and developmental delays are usually

evaluated by a pediatric neuroloist and followed by a medical manaement team. +arly

childhood intervention prorams that involve physical, speech, and occupational therapistshelp to ma*imi>e abilities and minimi>e dysfunction. 3edications are often used to control

sei>ures, hyperactivity, and neuromuscular symptoms. 4enetic counselin may help families

understand the risk for microcephaly in subse?uent prenancies.

What is the prognosis for microcephalyH

$ome children will only have mild disability. thers, especially if they are otherwise rowin

and developin normally, will have normal intellience and continue to develop and meet

reular ae-appropriate milestones.

What research is being done on microcephalyH

"he National &nstitute of Neuroloical 9isorders and $troke (N&N9$) conducts research

relatin to microcephaly in its laboratories at the National &nstitutes of Health (N&H) and

supports additional research throuh rants to ma7or medical institutions across the country. '

small roup of researchers studyin a rare neurometabolic syndrome (D-49H), which

causes microcephaly, have successfully used amino acid replacement therapy to reduce and

prevent sei>ures.

Defnition%y 1ayo Clinic sta!

3icrocephaly (my-kroh-$+%-uh-lee) is a rare neuroloical condition in which an infants

head is sinificantly smaller than the heads of other children of the same ae and se*.

$ometimes detected at birth, microcephaly usually is the result of the brain developin

abnormally in the womb or not rowin as it should after birth.

3icrocephaly can be caused by a variety of enetic and environmental factors. #hildren with

microcephaly often have developmental issues. 4enerally theres no treatment for

microcephaly, but early intervention may help enhance your childs development and improve

?uality of life.

Coping and support%y 1ayo Clinic sta!

hen you learn your child has microcephaly, you may e*perience a rane of emotions,

includin aner, fear, worry, sorrow and uilt. 6ou may not know what to e*pect, and you

may worry about your childs future. "he best antidote for fear and worry is information and

support. repare yourself:

http://www.medicinenet.com/script/main/art.asp?articlekey=4812http://www.medicinenet.com/script/main/art.asp?articlekey=4812http://www.medicinenet.com/script/main/art.asp?articlekey=4553http://www.medicinenet.com/script/main/art.asp?articlekey=4553http://www.medicinenet.com/script/main/art.asp?articlekey=34038http://www.medicinenet.com/script/main/art.asp?articlekey=34038http://www.medicinenet.com/script/main/art.asp?articlekey=2222http://www.mayoclinic.com/health/AboutThisSite/AM00057http://www.mayoclinic.com/health/AboutThisSite/AM00057http://www.medicinenet.com/script/main/art.asp?articlekey=4812http://www.medicinenet.com/script/main/art.asp?articlekey=4553http://www.medicinenet.com/script/main/art.asp?articlekey=34038http://www.medicinenet.com/script/main/art.asp?articlekey=2222http://www.mayoclinic.com/health/AboutThisSite/AM00057http://www.mayoclinic.com/health/AboutThisSite/AM00057


30/32


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• &n anencephaly, the bones of the skull and brain do not develop properly. Eabies with

anencephaly are missin lare areas of the brain and have an incomplete skull.

• 'nencephaly affects about 1 out of every 1,000 prenancies, but most cases end up as

miscarriaes. 'bout 1 out of every 10,000 babies in the


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'nencephaly is a comple* condition that is likely caused by the interaction of multiple

enetic and environmental factors. $ome of these factors have been identified, but many

remain unknown.

#hanes in do>ens of enes may influence the risk of anencephaly. "he best-studied of these

enes is 3"H%8, which provides instructions for makin a protein that is involved in

processin the E-vitamin folate (also called folic acid or vitamin E5). #hanes in other enes

related to folate processin and enes involved in the development of the neural tube have

also been studied as potential risk factors for anencephaly. However, none of these enes

appear to play a ma7or role in causin the condition.

8esearchers have also e*amined environmental factors that could contribute to the risk of

anencephaly. ' shortae (deficiency) of folate appears to play a sinificant role. $tudies have

shown that women who take supplements containin this vitamin before they et prenant

and very early in their prenancy are sinificantly less likely to have a baby with anencephalyor a related neural tube defect. ther possible risk factors for anencephaly include diabetes

mellitus, obesity, e*posure to hih heat (such as a fever or use of a hot tub or sauna) in early

prenancy, and the use of certain anti-sei>ure medications durin prenancy. However, it is

unclear how these factors may influence the risk of anencephaly.

Reviewed on 10/23/2012
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