Organic Diseases of the Brain PDF

Edema Extracellular ○ Vasogenic: disruption of BBB Increases permeability of the vessel and breaks tight junctions Common to find in white matter (center area) ○ Interstitial: transependymal flow of CSF will give hydrocephalus and accumul...

Edema Extracellular ○ Vasogenic: disruption of BBB Increases permeability of the vessel and breaks tight junctions Common to find in white matter (center area) ○ Interstitial: transependymal flow of CSF will give hydrocephalus and accumulate in the ventricles Intracellular ○ Cytotoxic: increased intracellular fluid secondary to cell injury Increase in osmotic pressure; who controls this? Principal types of brain edema ○ Cytotoxic edema → Infarction, trauma ○ Vasogenic edema → Brain tumor ○ Interstitial edema → Hydrocephalus ○ Osmotic edema → Hemodialysis Etiology ○ Space occupying lesions Malignancies/tumors Hydrocephaly ○ Post-traumatic (cytotoxic edema secondary to trauma) Metabolic disorders (hyperglycemia = common to find abnormal swelling in diabetic patients who are severely uncontrolled - start at 600 level - have delirium and seizures) Herniation Anatomic factors: Rigidness of cranial vault & Dural reflections ○ Types ○ ○ Subfalcine Herniation of Cingulate gyrus under the Falx cerebri Anterior gyrus regulates motivation, attention and behavior Posterior gyrus regulates learning and memory Subdural hematoma ^ ○ Decrease the occupying mass (drain the blood) or if secondary to tumor (resect or not; depending type) ○ Transtentorial (tentorial cerebelli) (uncinate) Temporal lobe is compressed against the free margin tentorium cerebra accompanied by compression of the 3rd cranial nerve Pupil dilatation, impaired ocular movement of the same side of the lesion (ipsilateral) Compression of the posterior cerebral artery resulting in ischemic injury to the visual cortex Main finding: in VF’s (homonymous hemianopsia with macular sparing) Down and out with mydriasis**** SO is the muscle that makes the inferior movement Patient will lose accommodation and have blurry vision Compression in posterior cerebral artery***** contralateral side and will have contralateral homonymous hemianopsia with macular sparing)****** ○ Tonsillar Displacement of cerebellar tonsils through the foramen magnum resulting in compression of the brain stem  Will herniate down to foramen magnum; will have a loss of lower extremities Diagnostic tests ○ CT Scan ○ MRI ○ Surgical (drainage and excision) ○ Diuretics (Mannitol) 1.25 g/kg IV infused over 30-60 minutes; may repeat q 6-8hr Hydrocephalus Increased production or accumulation of cerebrospinal fluid ○ Communicating: obstruction mainly produces CSF and accumulation inside  ○ Non-communicating: obstruction in the passage of CSF ○ Obstruction in the interventricular foramen of Monro can happen ○ Be sure to look at the differences between communicating vs non-communicating Diagnostic tests: ○ CT scan ○ MRI ○ Surgical Drainage Cerebrovascular Disorders Generalized reduction of blood flow lead into hypoxic ischemic injury in water shed areas (dual supply from two arteries) which are junctions between: ○ Anterior and middle cerebral arteries ○ Superior and inferior cerebellar arteries Watershed zones: regions of brain that receive dual blood supply branches of two major arteries MCA, PCA, ACA are the 3 main arteries that supply blood to brain Vascular Disorders Under normal circumstances, the brain receives 15% of the cardiac output and consumes 20% of the total oxygen consumption Parenchymal lesion leading to reduction of blood supply: Infarcts / Hemorrhages HTN Crisis: hemorrhage in basal ganglia *** ○ Infarction: 80% result from local vascular occlusion which may result in hemorrhages within the parenchyma or subarachnoid space More common during or after 70 y/o More common in males More common in areas supplied by MCA Ischemia secondary to occlusion Predisposing factors: Arterial HTN (high BP and males - higher risk) DM (uncontrolled sugar levels can cause hypoxia) Atherosclerosis (occlusion plaques can go to brain and cause occlusions) Smoking (decreases the entrance of oxygen to brain and can have infarct) 50%)** ○ Congenital disorders ○ Trauma ○ Aneurysm Saccular dilations (congenital defect in the media of arteries at points of bifurcation) affecting the vessels composing the Circle of Willis 80% arise at the bifurcation of internal carotid artery branches Affects 1%of population ACA** is the most common place to have aneurysms More common in women Usually before 5th decade Size is important in terms of behavior critical if the size is 4–6 mm Aneurysm is fixed surgically by clips Surgery must be completed within 6 minutes or irreversible brain damage may occur Saccular (out pouch w/ neck) - most common kind of aneurysm & easy to treat & break Arteriovenous malformation (AVM) Most commonly due to congenital vascular abnormalities in the brain (cerebral hemispheres, middle cerebral artery)  ○ Usually congenital; the formation of veins and arteries together is not good ○ Can die 15 years later due to hemorrhage Diagnostic tests: ○ CT scan ○ MRI Treatment: ○ Surgical → drainage ○ Pharmacological → antihypertensives Trauma > 70% of head trauma survivors are permanently disabled Epidural hematoma: ruptured *meningeal artery Subdural hematoma: disruption of bridging veins Traumatic Parenchymal Injuries Concussion ○ Transient loss of consciousness with paralysis and/or seizures followed by complete recovery Contusion ○ hemorrhage of superficial brain parenchyma related to trauma Coup ○ Changes immediately underneath the point of impact Countercoup ○ Changes in most distant point of impact ○ Shaking baby syndrome most affected