Dr. M's Classes Rock



CNS DisordersDr. Gary Mumaugh and Dr. Bruce SimatProtection of the BrainScalp - 5 layersSkull - Encloses and protects the brain and special sensesMeningeal Protection Cerebrospinal fluid provides cushion for brain and is a shock absorberProtection of the Spinal Cord - Vertebral Column Protects spinal cordArticulates with the head, rib, pectoral and pelvic girdles Hemopoietic and immune system rolesPoints of attachment for muscles Avenue for vertebral arteries0215582500Edema in the CNSEdemaAn increase in tissue mass due to excess fluidVasogenic EdemaLargely confined to white matter of brain & spinal cordThe blood brain barrier is compromisedDue to infection, toxic agent, abnormally permeable capillariesCytotoxic EdemaThe blood–brain barrier remains intactA disruption in cellular metabolism impairs functioning of the sodium and potassium pump in the glial cell membrane, leading to cellular retention of sodium and waterTypically due to hypoxia or ischemia due to cardiac arrestSwelling largely cellularHydrocephalusExcess fluid within the cranial vault, subarachnoid space, or both3 mechanisms for hydrocephalusOversecretion of CSF: rareImpaired absorption of CSF: many ways, anything that raises venous pressureObstruction of CSF pathways: due to tumor of fibrosisCirculation of CSFThe CSF starts in the bloodstream and returns to the bloodstreamStarts in the ventricles of the brain10% goes into the central canal of the spinal cord and travels down the spine before ending in the subarachnoid space at the bottom of the spine.90% goes through the Foramen of Magendje (Median Aperature) and flows directly into the subarachnoid space 2905125000Reabsorption of CSFReabsorbed through the arachnoid villaReabsorb about 20 ml/hour = rate of productionHydrocephalusHydrocephalus can occur due to?birth defects?or be acquired later in life.?Other causes include?meningitis,?brain tumors,?traumatic brain injury,?intraventricular hemorrhage, and?subarachnoid hemorrhage.5080005969000Increased Intracranial Pressure (ICP)Normal ICP = 5-15 mmHgMonro-Kellie HypothesisExpansion of CNS tissue, cerebrospinal fluid (CSF), or blood must be balanced by proportional constriction of the other two, or there will be an increase in ICPCaused by an increase in intracranial contentTumor growth, edema, excessive CSF, or hemorrhageStage 1 to Stage 4Increased Intracranial Pressure (ICP)What can exacerbate ICP?CNS edema & tumor massesBlocked venous returnHeart failureHemorrhage into tissueSubdural/extradural hematomaIncreased CSF and hydrocephalusWhat can decrease ICP?Expansion of spinal dural sacDecreased CSF & blood volumeBone erosionAtrophy of neural tissueHow can high ICP be treated?Depends on if treatable or reversiblePressure transducer by hole in skull measures ICPDrugs (barbituates)- slow brain metabolismDiuretics- lowers blood volumeEmergency craniotomyHerniation SyndromesA brain herniation is when brain tissue, cerebrospinal fluid, and blood vessels are moved or pressed away from their usual position inside the skull.Brain herniation occurs when something inside the skull produces pressure that moves brain tissues. This is most often the result of brain swelling from a head injury,?stroke, or brain tumor.Brain herniation can occur:Between areas inside the skull, such as those separated by a rigid membrane like the tentorium or falxThrough a natural opening at the base of the skull called the foramen magnumThrough openings created during brain surgeryCompression Syndrome - pressure on adjacent tissue due to an expanding massHerniation Syndrome - compression syndrome with displaced tissueCingulate Herniation - mass in frontal lobe, deep in long fissureUncal Herniation - mass above tentoriumCentral Herniation - massive or generalized swellingTonsillar Herniation - cerebellar tissue compresses brain stemComa - lowest level of consciousnessGlasgow Coma Scale: determine level of consciousness3 = deep coma 15 = normal consciousnessBabinski sign: sharp object pressed firmly to lateral surface of sole of foot – reaction gives depth of comaDevelopmental Anomalies - Neural Tube DefectsNeural tube- becomes primary structure of CNSDefects in which vertebral arch fails to closeSpina bifida MeningoceleMeningomyeloceleSyringomeloceleDefects in which cranium does not close completelyAnencephalyCranial meningocele MeningoencephaloceleCerebrovascular Disorders - Cerebral AneurysmDistention of cerebral arterial wallBerry aneurysm: appear at points of bifurcationFusiform aneurysm: elongated dilations developing along arteryMicroaneurysm: found diffusely in brain parenchymaSigns & symptomsCranial nerve dysfunctionHeadachesLethargyNeck painBruit: noise detectable over aneurysm due to turbulanceCerebrovascular DisordersSubarachnoid VasospasmTransitory restriction or narrowing of artery or branchOften experienced with subarachnoid hemorrhageSigns & symptoms - vary due to territory and durationArteriovenous Malformations (AVM)A tangled mass of dilated blood vessels that pass from large or medium sized arteries directly into a vein or venous sinus, bypassing normal capillary bedsSigns & symptoms - ischemia, seizures, headaches, bruit, xanthochromia (yellow color of CSF)Intracranial ThrombophlebitisInflammation & clot formation in the dural venous sinuses and perhaps cerebral veinsOften caused by infections of middle ear, mastoid air cells, paranasal sinuses, scalp, skin around upper lip, nose & eyesSigns & symptoms - dependent on site and history of site infectionGeneral headachePapilledema (swelling of retina at optic nerve)Eye movement abnormalities and painEdema of eyelidsCerebrovascular Accidents – “Stroke”Sudden onset is due directly & indirectly to deficiency in blood supplyOcclusive Cerebrovascular Accidents (CVA)Transient Ischemic Attack (TIA)Thrombotic CVA (most common) Occlusive CVA: Embolic CVAHemorrhagic CVATransient Ischemic Attack (TIA)Short episodes of sudden neurological dysfunction that clear up completelyCauses: hypotension, vasospasms, anemia, polycythemiaSymptoms: depends on arteries involved- aphasia, drop attacks, vertigo, nausea, dysarthria, amaurosis fugax (fleeting blindness) Therapy: anticoagulant drug (ex. Aspirin)Cerebrovascular Accidents – “Stroke”Thrombotic CVA (most common)Permanent damage to part of brain due to ischemiaThrombosis usually due to atherosclerosis“stroke-in-evolution” – may progress over weeksSymptoms: depends on affected areaOcclusive CVA: Embolic CVAEmbolic StrokeEmbolus lodges in brain artery and creates ischemia that leads to an infarctOften associated with atrial fibrillationSymptoms: ischemia, broad function loss, edema, infarctionRapid development of symptoms with no immediate warning signsHemorrhagic CVAInfarction by interrupting blood flow to region downstream from hemorrhageDamage from expanding hematoma (increased ICP)Symptoms: fairly rapid onset, increased blood pressureStrokes3rd most common cause of death in the USAOver 600,000 strokes per year 160,000 deaths per year30% die in acute stage 30% - 40% severely disabledIschemic stroke – 80%Hemorrhagic stroke – 20%Who is at risk?Increases with age, men more than women, oral contraceptive use Cigarette smoking, obesity, genetic predisposition Hypertension, diabetes mellitus, heart diseaseCerebrovascular Accidents – “Stroke”Ischemic Strokes80% of strokesOcclusion of an artery supplying blood to the brain Ischemic CVA will be localized to the area of occlusion Two types of ischemic stroke: Thrombus Athersclerosis with occlusion of the carotid artery, vertebral artery or within the brainEmbolism from outside the brainPossible Sources of EmboliBlood clot from heartPlatelets & fibrous debri from carotid arteryClumps of myoglobin can break from over exerted muscle in extreme sportsFat can break off from a large bone fractureNitrogen bubbles may build up in bloodstream from scuba divers who decompress to fastAmniotic fluid can get into the blood during childbirthHemorrhagic Stroke20% of strokesCaused by a rupture in a cerebral artery Ruptured artery causes inflammation of brain tissue = increased intracranial pressure = damage to both cerebral hemispheres Because of wide spread damage often fatal This type of CVA occurs suddenly Results from arteriosclerosis or severe hypertension Varieties of Hemorrhagic StrokeIntracerebral bleedingSeen in elderly with high blood pressure and fragile vessels, or in patients with bleeding disorders and those on anticoagulantsSubarachnoid bleedingSeen in 30-40 year olds and are mostly due to congenital ateriovenous malformationsSubdural bleedingOften occurs in elderly who fall and strike their headEpidural bleedingUsually from a ruptured temporal artery and is usually caused by major head traumaCerebrovascular Accidents – “Stroke”S & S of StrokesThe actual precise symptoms depend on where the CVA was and how large it isSudden weakness, numbness or paralysis of one side of the bodyLoss of consciousnessSeizure may sometimes occurSudden change in mental status, confusionSlurred speech, dysarthria, aphasiaPrognosis is more guarded if:loss of consciousness if a large part of the left side of the brain is affectedThis is the dominant side for 95% of peopleWhat to do if you suspect a strokeAsk the person to say a complete sentenceAsk the person to raise both hands above their headsAsk the person to walk across the roomWalk behind them to catch of unsteadyIf any of the above are present – CALL 911 Preventing StrokeControlling hypertensionManage and control diabetesLower blood pressureProper diet and exerciseStop smokingAnticholesterol drugs if lipids levels high83mg ASA per dayAny history of TIAMini-stroke lasting 1-3 minutes with involvement of face and speechReferral to vascular surgeon for carotid arteriographyDiagnosis of StrokesHistory is most importantCT scans present with 95% accuracyLumbar puncture if CT normalCT with LP is 100% accurate diagnosticallyMRI are used only if the diagnosis is still uncertainOpen MRI is preferredMany patients have died in and older style MRI scanner which is enclosed and takes a long time for the testCerebrovascular Accidents – “Stroke”Treatment of StrokesIschemic strokesThrombolytic therapy - rtPA – recombinant tissue plasma activator has revolutionized CVA txMust be administered within 3 hoursCerebral edema often follows post-strokeTreated with IV steroidsHeparin used after the initial three hoursHemorrhagic strokesIV sodium nitroprusside to control blood pressureIV Vitamin K and fresh plasma if patient on CoumadinIf ruptured aneurysm, then high risk brain stent is used (50/50 chance of surgical)CNS InfectionWhat are 5 locations of CNS infection?Meningitis: subarachnoid spaceMeningoencephalitis: meninges & adjacent brain tissueEncephalitis: brain tissueMyelitis: spinal cordAbscesses: focalAcute Bacterial Meningitis50-60% fatal if untreatedInfection in subarachnoid spaceTreatment: rapid antibioticsPersistent meningitis can lead to cranial nerve damage, abscess, tissue infarct, and extension into subdural spaceChronic Bacterial MeningoencephalitisSyphilis - plug and inflame tiny vessels of the meningesLyme Disease - variety of symptomsTuberculosis - produces fibrinous exudate in the subarachnoid spaceOther Meningeal InflammationsViral (lymphocytic) meningitisMeningeal signsLight sensitivityAcute: fever, vomiting, drowsiness, stiff neck, muscle aches, back achesRapid developmentBrudzinki’s sign: abrupt flexion of neck leads to involuntary flextion of knees (if supine)Kernig’s sign: attempt to extend knee while thigh flexed results in resistance and pain in hamstringViral Infections of the CNSNo CSF-brain barrierEx. shingles, chicken pox, rubella, cytomegalovirus, measles, herpesReye’s SyndromePotentially fatal post - viral conditionSymptomsRenewed vomiting & lethargy[3/4] clouded consciousness, hyperexcitability recovery[1/4] progressive brain edema deepening coma deathPathophysiology not understoodAspirin is suspected to play a partSubdural EmpyemaCollection of pus between the dura & the arachnoid membraneEstablished then spreads and can expandTreatment: surgical drainage & antibioticsBrain AbscessesAn area of necrosis and pyogenic (pus forming) bacterial infectionInfection introduced at same time as an area of infarct – 2 possible ways:Septic embolismChronic infectionBrain Abscess CausesSeptic embolism may bass into cerebral vasculature29089356921500Embolus gets lodged & infective agent established without interference from immune systemSpread from an established chronic infection contiguous to the brainProbably spread through thrombosed veins or lymphatic drainageOcclusion of veins impairs drainage & leads to infarctionNo distinct symptoms may resemble CVATreatment- antibiotics and surgical excision or drainageCNS Tumors2% of all cancer cases in adults 70% above tentorium (w/in cerebral hemisphere, thalamus, etc.)20% of all cancer cases in children70% subtentorium (brain stem, cerebellum, 4th ventricle)Mitotically active cells are capable of tumorigenesisAstrocytes: contribute to blood-brain barrier, structural supportOligodendrocytes: provide myelin sheathsEpendymal cells: line ventricles & central canal of spinal cordSchwann cells: provide myelination in PNSTreatment - excision or radiationBenign can be just as bad as malignant if inoperableSpinal Cord TumorsMeningioma- tumor of cells of arachnoid membraneSchwannoma- tumor of Schwann cellsPrimary brain tumorsGliomas- 70%; most rise from astrocytomasMeningioma- benign slow-growing tumor, arise from arachnoid membraneAcoustic neuroma- most peripheral nerve tumors in cranial vaultOligodendrogliomas- develop in cortex and subcorticallySecondary brain tumorsTypically metastasize through blood to brainSources- lung, breast, skin, kidney & intestinePituitary gland - ituitary adenoma – 2 types“Secreting type” (less common)- secretes excess hormones“Null cell”- goes undetected until there is damageSymptoms: “tunnel vision,” cranial nerve compression, hypopituitarism (if blood supply compressed)-40165219947300Treatment - surgery or radiation ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download