1.Hydrocephalus(literally, "water brain")

2. Congenital/infantilehydrocephalus The cranial bones fuse by the end ofthe third year; for the head to enlarge,hydrocephalus must develop beforethis time. It may begin in utero but usuallyhappens in the first few months of life 3. even of mild degree, it molds theshape of the skull in early life in radiographs the inner table isunevenly thinned, an appearancereferred to as "beaten silver" or asconvolutional or digital markings. The frontal regions are unusuallyprominent [bossing] 4. Face relatively small and pinched Skin over the cranial bones tight andthin Prominent distended veins. 5. Usual causes Intraventricular matrix hemorrhages inpremature infants fetal and neonatal infections Arnold -Chiari malformation Aqueductal atresia and stenosis Dandy-Walker syndrome. 6. Clinical features Rapid head enlargement Tense anterior and posteriorfontanelles Infant is fretful, feeds poorly, and mayvomit frequently. With continued enlargement of thebrain, inactivity sets in and the infantappears languid, uninterested in hissurroundings, and unable to sustainactivity. 7. Later, the upper eyelids are retractedand the eyes tend to turn downparalysis of upward gaze sclerae above the irises are visible;"setting-sun sign" caused by hydrocephalic pressure onthe mesencephalic tegmentum. 8. Gradually the infant adopts a postureof flexed arms and flexed or extendedlegs. Signs of corticospinal tract damageare usually elicitable. Movements are feeble and sometimesthe arms show tremors 9. later the optic discs become pale andvision is reduced. If the hydrocephalus becomesarrested, the infant or child is retardedbut often surprisingly verbal. The head may be so large that thechild cannot hold it up and mustremain in bed 10. If the head is only moderatelyenlarged, the child may be able to sitbut not stand or stand but not walk. If ambulatory, the child is clumsy. Acute exacerbations of hydrocephalusor a febrile illness may causevomiting, stupor, or coma. 11. Non-communicatinghydrocephalus 12. beaten-silver appearance 13. Intracranial pressure The intact cranium and vertebralcanal, together with the relativelyinelastic dura, form a rigid container,such that an increase of any of itscontentsbrain, blood, or CSFwillelevate the ICP. 14. an increase in volume of any one ofthese three components must be atthe expense of the other two [Monro-Kellie doctrine]Compensatory measures Small increments in brain volume donot immediately raise the ICP due todisplacement of CSF from the cranialcavity into the spinal canal 15. deformation of the brain and limitedstretching of dural folds, specifically,the falx cerebri and the tentoriumcerebelli Failure of compensating measures -mass within one dural compartmentleads to displacement, or "herniation"from that compartment into anadjacent one 16. Further increment in brain volume willreduce the volume of intracranialblood contained in the veins and duralsinuses. CSF is formed more slowly As the brain, blood, or CSF volumescontinue to increase, theaccommodative mechanisms fail andICP rises exponentially 17. Cerebral perfusion pressure(CPP). numerical difference between ICP andmean blood pressure within thecerebral vessels elevation in ICP that approaches thelevel of mean systemic bloodpressure widespread reduction incerebral blood flow/perfusion. 18. In its most severe form, this globalischemia produces brain death. Lesser degrees of raised ICP andreduced cerebral circulation causecorrespondingly less severe, but stillwidespread, cerebral infarction that issimilar to what arises after cardiacarrest. 19. Determinants of the degree of cerebraldamage are the severity and theduration of reduction of CPP 20. CAUSES OF RAISED ICP A cerebral or extracerebral masssuch as brain tumor; massiveinfarction with edema; extensivetraumatic contusion; parenchymal,subdural, or extradural hematoma; orabscess Generalized brain swelling, asoccurs in ischemicanoxic states,acute hepatic failure, hypertensiveencephalopathy, hypercarbia, and theReye hepatocerebral syndrome 21. An increase in venous pressure-cerebral venous sinus thrombosis,heart failure, or obstruction of thesuperior mediastinal or jugular veins. Obstruction to the flow andabsorption of CSF - within theventricles or in the subarachnoidspace at the base of the brain,extensive meningeal disease 22. Any process that expands thevolume of CSF (meningitis,subarachnoid hemorrhage) orincreases CSF production (choroidplexus tumor). 23. CLINICAL FEATURES OFRAISED ICP Headache Nausea and vomiting Drowsiness Ocular palsies Papilledema periodic visualobscurations. Protracted papilledema opticatrophy and blindness 24. The consequences of increasedintracranial pressure differ ininfants and small children, whosecranial sutures have not closed. 25. TRANSTENTORIAL ANDOTHER HERNIATIONS An expanding lesion in thesupratentorial compartment, such as asubdural hematoma or a tumor in acerebral hemisphere, may push themedial part of the temporal lobe (theuncus) down into the tentorial notch 26. UNCAL herniation presses on the ipsilateral oculomotornerve. The first clinical sign of this event isimpairment of the pupillary light reflexbecause the preganglionicparasympathetic fibers for constrictionof the pupil are superficially located inthe nerve. 27. Further herniation damage to descending motor fibers inone or both cerebral peduncles weakness, spasticity, and exaggeratedtendon reflexes on either side orbilaterally. midbrain displacement toward theopposite sidethe pressure of the rigidedge of the tentorium on the basispedunculi upper motor neuronparesis on the same side of the body asthe cerebral lesion. 28. Sometimes the downwarddisplacement of the brain occlusionof one or both posterior cerebralarteries by stretching these vesselsover the free edge of the tentorium, 29. Later stages Contralateral oculomotor nerve maybe affected. The pupil that dilates first is the mostreliable lateralizing sign for thecausative lesion. 30. Subfalcial herniation A space-occupying lesion pushes thecingulate gyrus of one hemisphereacross the midline beneath theanterior part of the free edge of thefalx cerebri. 31. Upward transtentorial herniation brain stem and cerebellum aredisplaced into the supratentorialcompartment by a mass in theposterior fossa. may also cause medullary coning,when the brain stem and part of thecerebellum descend through theforamen magnum into the spinalcanal. 32. Cerbellar tonsils compress themedulla, and the condition can bequickly fatal. Medullary coning can occur afterwithdrawal of CSF from the lumbarsubarachnoid space in a patient withraised intracranial pressure 33. (1) cingulate herniation under the falx, (2) downwardtranstentorial (central) herniation, (3) uncal herniation over theedge of the tentorium, or (4) cerebellar tonsillar herniation intothe foramen magnum. Coma and ultimately death result when(2), (3), or (4) produces brainstem compression.