CONGENITAL ANOMALIES

K.CABATANA MD

Disorders  of  Neuralation                  (1-­‐4  w  gestation)

• During  pregnancy,  the  human  brain  and  spine  begin  as  a  flat  plate  of  cells,  which  rolls  into  a  tube,  called  the  neural  tube.    

• If  all  or  part  of  the  neural  tube  fails  to  close,  leaving  an  opening,  this  is  known  as  an  open  neural  tube  defect,  or  ONTD.    

• This  opening  may  be  left  exposed  (80  percent  of  the  time),  or  covered  with  bone  or  skin  (20  percent  of  the  time).

Disorders  of  closure  of  Neural  tubes  

• 1-­‐  Anencephaly  • 2-­‐  Neural  tube  defect    (spinal  defect)  • 3-­‐  encephalocele                                

Open  Neural  Tube  Defects  

ETIOLOGY:

• ONTDs  →95%    • ONTDs  result  from  a  combination  of  genes  inherited  from  both  parents,  coupled  with  environmental  factors.  

•  For  this  reason,  ONTDs  are  considered  multifactorial  traits,  meaning  "many  factors,"  both  genetic  and  environmental,  contribute  to  their  occurrence  

                                       Folic  acid  deficiency:  ➢Drugs  antagonizing  folic  acid:  Valproic  acid,  CBZ,  phenytoin,  phenoba.,  alcohol,  thalidomide,  irradiation,  maternal  diabetes  

➢Syndromal  disorders:  trisomy  18,  13,    

➢Malnutrition  –  zinc  ,  folate  def.

TYPES  OF  ONTDs

PRIMARY        -­‐95%  of  all  NTD          Primary  failure  of  closure/disruption  of  NT  btw  18-­‐28  days.  

Eg.      -­‐Myelomeningocele                        Encephalocele                  Anencephaly

TYPES  OF  NTDSECONDARY  

     -­‐5%    of  all  NTD.          Abnormal  development  of  lower  sacral  segment    during  secondary  neuralization  • Skin  is  usually  intact  • Involves  lumbo-­‐sacral  region  Eg.  Spina  Bifida  Occulta                            Meningocele

ABNORMAL DEVELOPMENT

MALFORMATIONS RESULTING FROM ABNORMALITIES IN GROWTH AND MIGRATION

WITH INCOMPLETE DEVELOPMENT OF THE BRAIN

• Heterotopias

• GENETICALLY LINKED MIGRATION DISORDERS

• ENVIRONMENTALLY INDUCED MIGRATION DISORDER: FETAL ALCOHOL SYNDROME

FETAL ALCOHOL SYNDROME

• one of the more common nongenetic causes of mental retardation

• pregnant women to avoid all alcohol, especially during the first trimester

• pre- and postnatal growth retardation occurs along with cardiovascular, limb, and craniofacial abnormalities

MALFORMATIONS RESULTING FROM CHROMOSOMAL TRISOMY AND

TRANSLOCATION

• translocation syndromes like trisomy 21

• moderately mentally retarded and of short stature

• hypoplastic facies with short noses, small ears with prominent antihelices, and prominent epicanthal folds

MALFORMATIONS RESULTING FROM DEFECTIVE FUSION OF DORSAL

STRUCTURES

• Spinal Bifida

• Cranial Bifida

• Arnold-Chiari Malformation

Spinal Bifida • arches and dorsal spines of the vertebrae are

absent

• spinal cord, however, may be malformed either at one level or at many levels

• meningomyelocele

• meningocele.

Spina  bifida

Spina  Bifida  Occulta

• Very  mild  &  common  form.    • Level  -­‐  L5  &  S1.    

• Asymptomatic   which   can   only  d e t e c t e d   b y   x -­‐ r a y   o r  investigating  a  back  injury.    

• May   be   associated   with  tethered   cord/   recurrent  meningitis  (  dermal  sinus  )

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• Usually  associated  with  skin  visible  signs  on  the  back.    

– Dimple    –  Dermal  Sinus    – lipoma   /   Pad   of   subcutaneous  fat  

– small  hair  growth    – Nevus   flaminous   (red   spot)   or  port  wine

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Dimple                         18

Tuft  of  hair 19

Dimple  with  nauves  port  wine 20

Meningocele• Least  common  form    

• Sac   contains   meninges   and  cerebro-­‐spinal   fluid.   And  covered  with  skin  

• Cerebro-­‐spinal   fluid   protects  the  brain  and  spinal  cord.    

• The   nerves   are   not   badly  damaged   and   ab l e   to  function  normally.    

• Small   sac  which   increases  on  crying    

• Limited  disability  is  present.   21

MeningoceleInvestigation:-­‐  • MRI  HEAD  –  exclude    hydrocephalus/  dysgenesis  

• MRI  SPINE  –  exclude                (i)Diastematomyelia  –  division  of  spinal  cord  into  two  halves  by  projection  of    fibrocartilagenous  or  bony  septum  from  post  vertebral  body  

         (ii)  Tethered  cord  –  slender  threadlike  filum  terminale  attached  to  coccyx  conus  here  is  below  L2  instead  L  1  

Treatment  –    • Skin  intact  –  surgery  in  infancy  • Skin  lacerated  –  urgent  treatment  • Look  for  recto  vaginal  fistula

Tethered  cord  • The   spinal   cord   could   be  caught  against  the  vertebrae    

• Normal  cord  ends  at  lower  end  of  L  1  

• Motor   weakness   of   lower  limbs  

• Sphincteric   problems   such   as  inefficient  bladder  control.  

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Autopsy  of  Infant  with  tethered  cord 24

Myelomeningocele• Most  serious  and  common    

• The  cyst  not  only  contains  meninges  and  CSF  but  also  the  nerves  and  spinal  cord.    

• The  spinal  cord  is  damaged  or  not  properly  developed  resulting  in  motor  and  sensory  deficit.    

• Majority  have  bowel  and  bladder  problems.   25

• Myelomeningocele,  is  the  most  severe  and  occurs  when  the  spinal  cord  is  exposed  through  the  opening  in  the  spine,  resulting  in  partial  or  complete  paralysis.  and  may  have  urinary  and  bowel  dysfunction.  

Meningomyelocele  Sac + CSF + neural

element + discontinuous skin +

hydrocephalus(80%). TYPE – 94% of all NTD -

Lumbo sacral - Area of well developed

skin at periphery With thin apex covered by glistening

arachnoid membrane - Usually CSF oozing +

Myelomeningocele

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Intact  Mylomeningocele

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Thin transparent membrane

Intact  Mylomeningocele covered  by  thin  membrane

surrounded  by  hyper  pigmentation

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ARNOLD  CHIARI  SY  ARNOLD  CHIARI  SYNDROME  NDROAME

           ARNOLD  CHIARI                          SYNDROME

Cephalocele

• Skull-base or calvarial defect that is associated with herniation of intracranial contents

• Meningo-encephalocele- herniated contents contain both meninges and brain tissue

• Meningocele- herniated contents contain meninges only

Pathologenesis• Skull-base cephaloceles-represent defects of

endochondral bone; caused either by failure of induction of bone due to faulty neural tube closure or disunion of basilar ossification centers

• Calvarial cephaloceles-represent defects of membranous bone;caused either by a defect of bone induction, mass effect and pressure erosion of bone by an expanding intracranial lesion, or failure of neural tube closure

CLASSIFICATION BASED ON LOCATION

• Occipital

• Frontoethmoidal

• Parietal

• Nasopharyngeal.

Occipital Cephaloceles• Most common location for the development of a

cephalocele

• Associated with a less favorable prognosis

• Supratentorial and infratentorial structures herniates with equal frequency

• Poor prognostic indicators include hydrocephalus, microcephaly, and the presence of brain tissue in the herniated sac

Frontoethmoidal Cephaloceles

• Failure in the normal regression of a projection of dura that extends from the cranial cavity to the skin through a persistent foramen cecum or fonticulus frontalis.

• Persistence of this projection of dura -give rise to a dermal sinus tract- give origin to a dermoid or epidermoid tumor

• Examination reveals a superficial skin-covered mass or nasal dimple and frequently hypertelorism

SUBTYPES

• Frontal and nasal bones (frontonasal cephalocele)

• Frontal, nasal, and ethmoidal bones (frontoethmoidal cephalocele)

• frontal, lacrimal, and ethmoidal bones extending into the anteromedial portion of the orbit (naso-orbital cephalocele)

Parietal cephaloceles

• Uncommon

• Prognosis is generally poor -common association with major brain anomalies

• Common location for Atretic cephaloceles

Nasopharyngeal Cephaloceles

• Uncommon

• Occult

• Lesions usually do not present until the end of the first decade of life

• Diagnosed during an evaluation for persistent nasal stuffness or excessive “mouth breathing.”

• Result in both endocrine and visual dysfunction

Arnold-Chiari Malformation

• elongation and displacement of the brain stem and a portion of the cerebellum through the foramen magnum

• Hydrocephalus, spina bifida with meningocele, or meningomyelocele associated conditions

MALFORMATIONS CHARACTERIZED BY EXCESSIVE GROWTH OF ECTODERMAL AND MESODERMAL TISSUE

AFFECTING SKIN, NERVOUS SYSTEM, AND OTHER TISSUES

• Intracranial Lipomas

• Dermal Sinuses

• Arachnoid cysts

Intracranial Lipomas• Normal development, an undifferentiated

mesenchyme that surrounds the developing brain gives - leptomeninges and the subarachnoid space

• Abnormal differentiation - undifferentiated mesenchyme may lead to the formation and deposition of fat in the subarachnoid space

• Lipomas typically contain blood vessels and cranial nerves, creating an obstacle to their surgical removal

COMMON LOCATIONS• Deep interhemispheric fissure

• Quadrigeminal plate cistern

• Interpeduncular cistern

• Cerebellopontine angle cistern

• Sylvian cistern

Dermal sinuses • 3rd-5th weeks of intrauterine life -defect occurs in the

separation of neuroectoderm (the embryological precursor of nervous tissue) from surface ectoderm (the embryological precursor of skin

• Abnormal communication between the dermis and the intracranial cavity

• Composed of stratified squamous epithelium (epidermal component) as well as hair follicles, sebaceous glands, and sweat glands (dermal component).

Clinical presentation

• Benign cutaneous cosmetic blemish

• Serious intracranial infection

• Tumorlike process due to mass effect from a dermoid or epidermoid cyst.

Arachnoid Cysts• CSF-containing lesions covered by membranes

that consist of arachnoid cells and collagen fibers

• Result from an anomalous splitting and duplication of the endomeninx

• 2/3RDS - located in the supratentorial space, most commonly the sylvian cistern; 1/3RD - located in the infratentorial space

Clinical manifestations • Intracranial hypertension

• Obstructive hydrocephalus

• Headache

• Seizure

• Neurologic deficit

MALFORMATIONS RESULTING FROM ABNORMALITIES IN THE VENTRICULAR

SYSTEM

• Syringomyelia

• Syringobulbia

• Hydrocephalus

Factors  Associated  With  Increased  Risk  of  NTDs.  .  .

• Family  history  of  NTD  

• A  previous  pregnancy  affected  with  NTD  

• Maternal  insulin-­‐dependent  diabetes  

• Maternal  obesity  

• Anti-­‐epileptic  drugs  (Valporic  Acid,  Carbamazapine)  

• Lower  socioeconomic/educational  level,  dietry  deficiency  specially  folic  acid  

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   The  only  most  significant  risk  factor  associated  with  NTDs  is  folic  acid  deficiency

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Folic  Acid  For  Women• As  NTD  occur  before  diagnosis  of  pregnancy.  

• All  women  of  childbearing  age  should  receive  400  micrograms  (0.4  mg)  of  folic  acid  daily.    

• Women  who  have  had  a  previous  child  with  NTD  should  receive  4000  micrograms  (4  mg)  of  folic  acid  daily.  2  months  before  pregnancy

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Neural  tube  defects  –  prevention  

➢Folic  acid  deficiency:  If  previous  history  of  NTD  in  family  :  4mg  –  1  –  2  month  before  pregnancy  To  3  months  thereafter  

Else  for  every  other  women  of  child  bearing  age  :  0.4mg  –  1  month  before  conception  till  12  weeks  gestation.  

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