CNS Congenital Anomalies

CNS Congenital Anomalies - CNS Congenital Anomalies CNS...

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Unformatted text preview: CNS Congenital Anomalies CNS Congenital Anomalies .Jamous M, M.D Dept. of Neurosciences, School of Medicine, JUST Objectives Objectives Review the normal CNS developmentReview the normal CNS development study the common causes of CNS study the common causes of CNS congenital anomalies study the common congenital study the common congenital anomalies, its presentations, diagnosis, and treatment Etiology of Congenital Brain Etiology of Congenital Brain Malformations Chromosomal (6%) Single gene (2%) Environmental (maternal) Nutrition: folic acid deficiency Disease: diabetes Toxins: alcohol, smoking Infections: rubella, toxoplasmosis, CMV, syphilis Radiation Unknown (most cases) CNS development CNS development Primary neurolation 3­4 weeks Secondary neurolation 4 weeks­ after birth Prosencephalic development 2­3 months Neural proliferation 3­4 months Neuronal migration 3­5 months Organization 5 months­ postnatal Myelination birth­ years postnatal Primary neurolation Primary neurolation Occur in 3-4 week gestation It ends by the creation of the neural It tube (NT) internally which will give (NT) rise to the CNS above S2 segment , epidermis externally & neural crest epidermis (NC) at the junction of NT & (NC) Epidermis Epid NC: mesoderm cells which migrate a NC: way from the neural tube and give rise to the PNS,skull, facial and jaw bones, pigment cells, adrenal medulla medulla Neural tube closure Neural tube closure Start at the cervical area (cervico­ medularly junction) Extend cranially and caudally Cephalic neuropore correspond to the commissural plate and lamina terminalis and it close around day 25 Caudal neuropore closes around day 29 and correspond to S2 segment Disorders of primary neurolation Disorders of primary neurolation Split cord syndrome Craniorachischisis Neuroenteric cyst Anencephaly Myeloschisis Arnold chiari malf. Lipomeningocele, myelomeningocele Dermal sinus encephalocele Disorders of primary neurolation Disorders of primary neurolation diplomyelia diplomyelia lipomeningocele Dermal sinus (Split cord syndrome (Diplomyelia Split cord syndrome (Diplomyelia splitting of the notochord around an adhesion between the endoderm and the ectoderm the formation of two neural tubes and subsequently two hemicords notochord also influences the vertebrae formation and thus it is common to have associated segmentation anomalies at the site of diastematomyelia In two­thirds of cases the overlying skin shows nevi, hypertrichosis, lipomas, dimples or hemangiomas. Symptoms are nonspecific and similar to other causes of cord tethering. Myeloschisis & Craniorachischisis Myeloschisis & Craniorachischisis a flattened, plate­like mass of nervous tissue with no overlying skin or membrane the neural folds fail to meet and fuse Most aborted Dermal sinus tract Dermal sinus tract result from incomplete disjunction of result incomplete neuroectoderm from cutaneous ectoderm neuroectoderm The sinus tracts extend deep into the The subcutaneous tissues, reaching the spinal canal in one-half to two-thirds of cases. canal it may be attached to the dura, causing tenting of the thecal sac. tenting When they pass intradurally, they may end in the subarachnoid space, conus medullaris, filum terminale, a nerve root, a fibrous nodule on the surface of the cord, or a dermoid or epidermoid cyst. about 50% of the dermal sinuses end in about dermoid or epidermoid cysts. Conversely, 20% to 30% of dermoid cysts and dermoid tumors have associated dermal sinus tracts. Cause cord tethering in 50 % of cases There may be a history of meningitis from extension of bacteria along the tract or from chemical irritation if the cyst ruptures. :Anencephaly Anencephaly Failure of anterior neuropore to close Brain and calvarium are absent & Replaced by a cerebrovasculorum ­ a tangle of glial and connective tissue Remnants of brainstem and pituitary may be present &so infant is born alive Geographic variability Ireland – high U.S – intermediate Japan – low Most severe case ­ defect from level of lamina terminalis to foramen magnum (holocrania/holoanencephaly); if defect does not extend to foramen magnum ­ meroacrania/meroanencephaly ).Chiari II malformation (Arnold Chiari Malf Chiari II malformation (Arnold Chiari Malf The cerebellar vermis and part of brain stem herniate below foramen magnum One unifying theory suggests that the posterior neuropore remains open too long, thereby decompressing the ventricular system and allowing the bony posterior fossa to close too early forming a small compartment More than 90 percent of these patients develop hydrocephalus within the first six months following closure of the spinal defect Syringomyelia, the common finding Syringomyelia, associated with CM associated Meningocele and Meningocele and myelomeningocele 1. Primary failure of neural tube closure –Myelomeningocele­ ­Meningocele­ mesenchyme destined to form the posterior elements remains trapped laterally, causing a wide spina bifida. Most frequently located in the thoracolumbar area. Rule of 80's (80% have hydrocephalus, 80% require shunt, and 80% will have IQ >80 ) Lipomeningocele Lipomeningocele caused by premature separation of the neural ectoderm from the cutaneous ectoderm.which allows the mesench to enter the ependyma­lined canal of the neural tube inducing fat formation Three types: ­intradural lipomas (4%) ­lipomyelomeningoceles (84%), ­fibrolipomas of the filum terminale (12%). (12%). May have symptoms related to associated abnormalities such as tethering of cord or neural element compression. Include motor and sensory deficits, reflex changes, gait abnormalities, bowel/bladder problems, musculoskeletal problems. Encephalocele Encephalocele Bony defects in midline Brain tissue can protrude through hole Most common in occipital region Prognosis depends on quantity of cerebral tissue that herniates into the defect CNS development CNS development At the time of closure of the anterior neuropore, At three dilatations or vesicles develop in the rostral aspect of the neural tube: prosencephalon aspect prosencephalon (forebrain), mesencephalon (midbrain), and mesencephalon rhombencephalon (hindbrain). rhombencephalon These are separated by the cephalic, pontine These flexure respectively flexure Cervical flexure separate rhombencephalon from the cervical cord the Pontine flexure is the last to develop Prosencephalic development Prosencephalic development Peak time 2­3 months Notochord & Prechordal mesoderm will cause ventral induction of the forebrain to develop the prosencephalon Prosencephalon cleavage will give: 1­paired optic and olfactory structure 2­telencephalon cerebral hemisphere, Caudate & putamen 3­diencephalons thalamus, hypothalamus & Basal Ganglia Midline prosencephalic development Midline prosencephalic development will give rise to corpus callosum, septum pellucidum, optic nerve­chiasm and hypothalamus Disorder of prosencephalic development Disorder of prosencephalic development Prosencephalic formation ­Aprosencephaly/ atelencephaly Prosencephalic cleavage ­Holoprosencephaly/ holotelencephaly Midline prosencephalic development ­Agenesis of corpus callosum ­Agenesis of septum pellucidum Neuronal proliferation Neuronal proliferation Peak time 3­4 months Neuroblast proliferate in ventricular and subventricular zones which will produce proliferative units by symmetrical divisions The proliferative units enlarge by asymmetrical divisions Neuronal proliferation & migration Neuronal proliferation & migration Disorders of neuronal proliferation Disorders of neuronal proliferation Micrencephaly Macrencephaly ­Isolated ­Associated with growth disturbance ­Neurocutaneous syndrome ­Chromosomal disorders ­Unilateral (hemimegalencephaly) Disorders of neuronal migration Disorders of neuronal migration Lissencephaly­ pachygyria (smooth brain) Schizencephaly Polymicrogyria Hetertopia Presentation: Mental Retardation, Intractable epilepsy Hydrocephalus Hydrocephalus Hydrocephalus Hydrocephalus -Hydrocephalus is -Hydrocephalus enlargement of the ventricles often due to obstruction or overproduction or poor absorption of cerebrospinal fluid. -It can be communicating or non-communicating -Incidence of 1 in 1,000 births -Incidence Hydrocephalus Hydrocephalus Infants 1. Increasing head circumference. 2. Irritability, lethargy, poor feeding, and vomiting. 3. Bulging anterior fontanelle. 4. Widened cranial sutures. 5. McEwen's cracked pot sign with cranial percussion. 5. cracked 6. Scalp vein dilation (increased collateral venous 6. drainage). drainage). 7. Sunset sign (forced downward deviation of the eyes, a 7. neurologic sign almost unique with hydrocephalus). neurologic 8. Epidsodic bradycardia and apnea. Hydrocephalus Hydrocephalus Older Children 1. Headaches. 2. Vomiting. 3. Seizures. 4. Decreased level of consciousness. 5. Focal neurological deficit. Hydrocephalus Hydrocephalus Congenital Causes -Aqueductal anomalies -Dandy Walker malformation -Chiari II malformation -Myleomeningocele -Intrauterine viral infection (CMV, mumps, rubella) -Toxoplasmosis -Congenital tumors -Vein of Galen aneurysms -Chromosomal anomalies (trisomy 13 and 18) Treatment of hydrocephalus Treatment of hydrocephalus Observation in border­line cases Shunting (ventriculoperitoneal) Endoscopic Third ventriculostomy Types of CSF shunting Complications of shunting Craniosynostosis Craniosynostosis Premature closure of the cranial sutures, 1/2000 birth M>F Usually sporadic Abnormal skull shape Raised ICP Vs. Lazy suture Presentation Presentation Surgical indications Timing of surgery ...
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This note was uploaded on 12/24/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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