7. - maternal folic acid deficiency - other potential associated malformations include: 1. Arnold-Chiari Syndrome 2. Hydrocephalus 3. hydromyelia 4. polymicrogyria b) Anencephaly i) congenital absence of part or all brain ii) is second in incidence to spina bifida iii) concurrent with spina bifida www.freelivedoctor.com
12. c) Syringomyelia i) tubular cavitation (syrinx) which extends for variable distances along entire length of spinal cord - may or may not communicate with central canal ii) usually encountered in adults - many cases thought to represent congenital malformation iii) causes relate to trauma, ischemia,tumors iv) motor and sensory deficits anatomical location in spinal cord www.freelivedoctor.com
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14. i) may occur when meningomyelocele anchors lower end of spinal cord - causes downward growth of spinal cord and - creates traction on medulla ii) curvature of medulla iii) breaking of quadringeminal plate iv) intracranial pressure associated with hydrocephalus f) Pathology: i) caudal aspect of cerebellar vermis is herniated through an enlarged foramen magnum www.freelivedoctor.com
21. c) lissencephaly i) cortical surfaces are smooth or imperfectly formed gyri d) heterotopias i) focal defects that lead to modules of ectopic neurons ii) mental retardation iii) may be caused by maternal alcoholism www.freelivedoctor.com
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23. c) Trisomy 13-15 i) Holoprosencephaly - microcephalic brain - absence of corpus collusum - absence of interhemispheric fissure - rarely compatible with life beyond a few weeks ii) arhinencepahaly - absence of olfactory tracts and bulbs (rhinencephalon) - associated with holoprosencephaly or as solitary lesion www.freelivedoctor.com
27. - may be associated with compression of branches of the anterior cerebral artery ii) transtentorial (uncinate) herniation - medial aspects of temporal lobe is compressed against tentorium cerebelli - 3 rd cranial nerve is compressed - pupillary dilation and ocular movement impairment on side of lesion www.freelivedoctor.com
28. - progression of this type of herniation hemorrhages in pons and midbrain (Duret hemorrhages) - may result from the tearing of penetrating veins and arteries supplying upper brainstem iii) tonsilar herniation - displacement of cerebellum (tonsils) through foramen magnum - this type of herniation is life threatening ( compression of brainstem - - CV and resp centers) www.freelivedoctor.com
31. b) middle meningeal arteries occupy space between dura and calvaria i) grooved into inner table of bone ii) branches across temporal-parietal area (mainly as 3 major vessels) c) temporal bone one of thinnest bones of skull i) vulnerable to fractures - minor trauma may cause fracture - and transect branches of middle meningeal artery life threatening epidural hemorrhage www.freelivedoctor.com
34. - venous sinuses are compressed cerebral ischemia (hypoxia) - diffuse cortical impairment confusion and disorientation d) ”Cushing Reflex” is protective response to CBF and oxygenation i) HR (increases filling) ii) myocardial contractility iii) systolic BP e) hematoma can to ~60 ml i) after compensation is exhausted ii) brain shifted laterally away from side of hematoma www.freelivedoctor.com
35. iii) medial temporal lobe compressed against midbrain displaces it through in tentorium fatal event known as “transtentorial herniation” iv) 3rd nerve compression v) pupil fixed and dilated (same side) vi) further compression further hypoxia and impairs neuronal function vii) damage to reticular formation expressed clinically as decline in level of consciousness www.freelivedoctor.com
36. viii) shortly thereafter hemorrhage and necrosis of brainstem irreversible damage death or irreversible coma f) epidural hematomas are progressive and if not treated, are fatal in ~4-48 hrs g) concussion i) transient loss of consciousness due to trauma ii) mainly to brainstems reticular formation - e.g., boxing “knock-out” - deflects head up and posteriorly www.freelivedoctor.com
37. - these motions import quick torque on brainstem and cause functional paralysis of neurons of reticular formation iii) a blow to temporal-parietal area may cause skull fracture but does NOT generally cause a concussion - lateral movement of cerebral hemispheres is prevented by the Falx www.freelivedoctor.com
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39. b) when brain impacts skull i) stationary head struck ii) moving head strikes object c) cause shearing effect in subdural space i) tears veins d) unlike epidural space, subdural space can expand i) since bleeding usually is from veins ii) usually stops spontaneously (i.e., bleeding) - with only ~ 25-50 ml - from local tamponade effect e) can compress veins thrombosis f) usually bilateral www.freelivedoctor.com
43. i) may be reabsorbed only small amounts of residual hemosiderin ii) remain static with potential for calcification iii) hemorrhage may enlarge (rebleeding, usually within 6 months) iv) granulation tissue is vulnerable to re-bleed (shaking of head) c) during genesis of subdural hematoma i) bridging vein severance is precisely located to the subdural space - compartmentalizes blood away from CSF www.freelivedoctor.com
44. - absence of blood in CSF does NOT negate presence of subdural hematoma d) clinical S & S: i) stretching meninges headache ii) pressure on motor cortex contralateral weakness iii) focal cortical irritation seizures iv) bilateral subdural hematoma cognitive dysfunction - misdiagnose as dementia v) rebleeding may cause transtentorial herniation www.freelivedoctor.com
49. a) high velocity i) disrupts tissue by its own mass ii) centrifugal blast - enlarges diameter of cylinder causing disruption iii) can cause immediate death - explosive in ICP, which - herniates cerebellar tonsils into foramen magnum d) seizures are a threat in healed penetrating wounds i) 6-12 months after the trauma www.freelivedoctor.com
53. c) hyperflexion injury i) head or shoulders hit from behind - head driven forward - sharp forward angulation of spinal cord d) consequences of spinal cord injury vary i) concussion - mildest injury - transient and reversible of spinal cord function ii) contusion - more severe trauma ranging from (minor transient bruise hemorrhage) www.freelivedoctor.com
55. - spinal cord necrosis and edema caused by contusion myelomalacia hematoma within cord hematomyelia iii) lacerations and transactions - usually produced by penetrating wounds - are irreversible - cause paralysis of lower limbs (paraplegia) - or quadriplegia (all 4 extemitites www.freelivedoctor.com
63. d) bacterial infections i) leads to mycotic aneurysms e) trauma i) rarely caused dissecting aneurysms 1. Berry aneurysm a) consequence of arterial defects b) arise during embryogenesis i) when arteries bifurcate c) greater than 90% of sacular aneurysms occur at branch points in carotid system d) rupture results in life-threatening SAH i) ~35% mortality during initial hemorrhage www.freelivedoctor.com
65. 2. Atherosclerotic aneurysm a) localized mainly in major cerebral arteries i) vertebral ii) basilar iii) internal carotid b) fibrous replacement of media and c) destruction of internal elastic membrane i) weakens arterial wall aneurysm d) they are fusiform and elongate e) rarely rupture i) major complication is thrombosis www.freelivedoctor.com
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67. i) occurs in preferential sites (order of frequency) - basal ganglia-thalamus (65%) - pons (15%) - cerebellum (8%) - Other causes of cerebral hemorrhage, independent of hypertension: AVM leakage, erosion of blood vessel by neoplasm, bleeding diathesis – (e.g., thrombocytopenic purpura), endothelial injury via microorganisms (e.g., ricketisiae), embolic infarction (hemorrhage into area of necrosis) www.freelivedoctor.com
68. d) compromises integrity of arterial wall by depositing i) lipid ii) hyaline material (i.e., protein) iii) i and ii known as “lipohyalinosis ” iv) weakening wall leads to Charcot- Bouchard aneurysm - located mainly along trunk of a blood vessel rather than at its bifurcation e) onset of symptoms is abrupt i) weakness usually dominates www.freelivedoctor.com
70. ii) when hemorrhage is progressive - death within hours to days - as hematoma enlarges, may cause death via transtentorial herniation - may rupture into ventricle with massive hemorrhage distension of 4th ventricle and compression of vital centers - Routine hemorrhage catastrophic loss of consciousness damage to reticular formation – death prior to arriving at hospital www.freelivedoctor.com
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72. 1. Global Ischemia a) pattern of injury reflects anatomy of cerebral vasculature i) Watershed infarcts: anterior, middle and posterior cerebral arteries perfuse overlapping territories - no anastamoses between their terminal branches - areas of overlap are therefore not perfused as well and infarcts (via global ischemia) occur in these “watershed areas” www.freelivedoctor.com
73. ii) Laminar necrosis : also reflects topography of cerebral vasculature - intraparenchymal pial vessels - penetrate at right angles and are deep penetrators into grey matter - more focal areas of ischemia iii) Selective neuronal sensitivity - Purkinje cells of cerebellum - pyramidal neurons of Sommer sector I hippocampus www.freelivedoctor.com
77. e) clinical outcome dependent on structures involved i) proximal and MCA occluded by atherosclerosis and thrombosis - resultant infarct transects internal capsule hemiparesis or hemiplegia f) localized ischemia associated with 3 distinct clinical syndromes i) TIA (transient ischemic attack) - focal cerebral dysfunction last less than 24 hrs (usually only a few minutes in duration) - signifies risk for infarct www.freelivedoctor.com
78. ii) stroke in evolution - progression of neurological symptoms while patient is under observation - uncommon and usually reflects propagation of a thrombus in carotid or basilar artery iii) complete stroke - stable neurologic defects resulting from cerebral infarct www.freelivedoctor.com
81. - occlusion of carotid artery produce infarcts (most often) to portions of distribution of the MCA b) Circle of Willis i) deficits depend on collateral circulation ii) MCA often occluded by thrombosis complicating atherosclerosis in circle of Willis www.freelivedoctor.com
82. c) Parenchymal arteries and arterioles i) rarely become atherosclerotic ii) damaged by hypertension iii) small lacunar infarcts iv) when occur in numbers - multiple infarct dementia v) fibronoid necrosis (hypertensive encephalopathy) via malignant hypertension - minute hemorrhages (petechiae) www.freelivedoctor.com
83. d) capillary bed i) small emboli (fat or air) occlude capillary bed - petechiae most common in white matter e) cerebral veins i) venous sinus thrombosis is potentially lethal for the following: - systemic dehydration (e.g., infants with g.i. fluid loss) - phlebitis (mastoiditis or bacteremia) - obstruction by neoplasm - sickle cell disease www.freelivedoctor.com