Showing posts with label Neurology. Show all posts
Showing posts with label Neurology. Show all posts

Wednesday, April 1, 2009

Strokes (aka CVA, aka Brain Attack)

Studying for the neurology section of your NCLEX or USMLE can be overwhelming, but hopefully this review will make it a bit easier. Remember, not all strokes are created equal. But one thing that is, are the deficits from losing a specific section of your brain. One of the more common ways by which you can get these deficits is to lose blood supply to a certain area. Here are some common deficits, depending upon which supply of blood you lose...

· Focal Neurological Deficits: Depend upon area of brain perfused by effected artery
o Internal Carotid Artery/Opthalmic: Amaurosis fugax (transient monocular blindness-retinal ischemia: shade drawn), as well as hemispheric loss mostly from MCA territory
o ACA: Hemiplegia (leg more than arm), Confusion, Incontinence, Primitive reflexes
o MCA: Hemiplegia (arm/face more than leg), Hemianesthesia, Homonymous hemianopia, Drowsiness/Stupor (edema), Aphasia (dominant hemi), Apraxia (nondom hemi)
o PCA: Contralateral Hemisensory deficit, Aphasia, NonMacular Homon Hemianopia
o Vertebral: Ipsilateral face numb, Contralateral limb numb, Diplopia, Dysarthria, Ipsilateral Horners (ptosis, miosis, anhydrosis)
o Basilar: Pinpoint pupils, Quadriplegia, Sensory loss, Cranial nerve/Cerebellar deficit, Locked in state (all paralyzed but eyes)
o Brainstem/Cerebellar: Basilar/Vertebral; Hallmark is crossed deficit-Ipsilateral Cranial nerve deficit and Contralateral Motor deficit, Vertigo, N/V, Nystagmus, Ipsilateral limb ataxia, Rapid deterioration


Specific Stroke Treatment Protocols

Ischemic-ThromboticLarge vesselo Facts:
· Atherosclerosis main cause; Arterial dissection, Hypotension, Homocystinuria, Hyperglycemia (Delayed Calcium recovery in ischemic stroke)
· Common in Carotid bifurcation, MCA
o S/S:
· Progression of deficits over hrs to days with stuttering course
· May have been preceded by TIAs (80%)
· Often has a nocturnal onset (60%)
· Focal deficits depend upon vessel occluded (see above); Usually Carotid, MCA or Basilar
o DX:
· CT w/o contrast to r/o Hemorrhage
o TX:
· HT treated only if severe (more than 220/130) w/Labetalol or Enalapril
· Nimodipine not recommended; HOB elevated; Possible Mannitol and shunt placed



Small Vesselo Facts:
· Lacunar most common thrombotic; Usually caused by Chronic HT or DM
· Most common in small vessels of the Brainstem or Basal Ganglia
o S/S:
· Pure contra-motor hemiparesis/Clumsy hands w/Pons or Internal capsule involvement
· Pure contra-hemianesthesia w/Thalamus involvement
o DX:
· MRI best if small infarct suspected in Cortex/Brainstem
o TX:
· Antiplatelet agents


Hypoperfusion/Watershed: mainly related to low BP, with deficits often seen between the border of the ACA/MCA around the motor strip of the frontal cortex...Volume Resuscitate, Pressors, etc.



Ischemic-Embolic/Cryptogenic
o Facts:
· 50 % of all strokes
· Cardiac source (60%) from AFib/Valve Dz/MI/Cardiomyopathy; Artery source (carotid plaque, DVT w/left to right shunt); Fat/Air embolus; Often in MCA, Vertebral/Basilar
o S/S:
· Rapid onset focal deficit at maximum severity, usually with activity
· May have been preceded by TIA w/breakup of emboli within min-hrs
· May be accompanied by Seizure
· Focal deficits depend upon vessel occluded (see above); Usually MCA or Basilar
o DX:
· CT w/o contrast to r/o Hemorrhage
o TX:
· HT treated only if severe (more than 220/130) w/Labetalol or Enalapril
· TPA if all CI absent; Nimodipine not recommended
· Avoid rhythm conversion; Tx rate only


Hemorrhagic

Epidural (EDH)
o Facts:
· Not always listed as subset of Stroke although presentation often identical
· Usually from a TBI skull fracture that lacerates a meningeal artery. Hematoma puts pressure on brain causing compression, ischemia, and focal neuro deficits.
· Least common intracranial injury; Very uncommon in children/elderly
o S/S:
· Initial LOC, reawakening with clear mentation and then progressive AMS
· Sleepy, NV, Severe HA, dizziness
· Fixed, Dilated pupil on side of lesion w/contra hemiparesis is classic late finding
· Type of Herniation leads to various presentations; Transtentorial (uncal) herniation compresses oculomotor nerve causing ipsilateral fixed, dilated pupil as well as contralateral hemiparesis
o DX:
· Noncontrast CT; Shows lenticular shaped hematoma
o TX:
· Large blood collections are surgically evacuated despite neuro findings
· First step in Pt w/neuro deficit and vomiting is to protect airway by Intubation
· ICP monitor placed post evacuation and artery ligation



Subdural (SDH)o Facts:
· Not always listed as subset of Stroke although presentation often identical
· Collection of venous blood between Dura and Arachnoid
· Often seen in Pts w/Brain atrophy such as alcoholics and elderly
o S/S:
· Progressive neuro decline over days to weeks often w/no deficit initially, May mimic dementia
o DX:
· Noncontrast CT; Shows crescent shaped hematoma
o TX:
· Large blood collections are surgically evacuated despite neuro findings; Post op care in ICU



Subarachnoid (SAH)o Facts:
· 5 % of all strokes (30,000/yr) ↑ in Women (3:2); Peak 50-60 yo
· Usually from a berry aneurysm associated with HT at bifurcation of Circle of Willis
· Also from trauma, vascular anomaly or blood dyscrasias
· 2 % of population harbor aneurysms
· S/S: · Sudden severe Occipital HA with severity never experienced by Pt although a careful history may show minor S/S (NV, HA) from sentinel bleeding · N/V often follow onset of HA · Impaired consciousness and AMS w/Coma common (50%) · Seizures can occur (10%) as can retinal hemorrhage · Nuchal rigidity and other signs of meningeal irritation i/c neck/back pain · Focal neurologic deficits are frequently absent but if present often show a 3rd nerve Palsy
o DX: · CT w/o contrast immediately (faster and more sensitive for early hemorrhage than MRI); If (-)(10% missed by CT) LP for blood or xanthochromia · Cerebral arteriography to determine exact source of bleed if Pt is stable and surgery is a viable option · Bilateral carotid and vertebral arteriography to r/o other bleed source · EKG may show ST Δ, Prolonged QT, or peaked/inverted T waves
o TX: · Medical: · Sedatives to keep Pt calm · HHN Therapy to ↓ vasospasm which is most frequent cause of death for Pts who survive rupture: Hypervolemic (crystalloid or colloid fluids), Hypertensive (Dopamine), Nimodipine (60 mg q4h) · Attempt to keep BP in Pts normal range w/MAP below 100
· Other: · Obtain early neurosurgical consult; Admit to ICU · Bed rest in dark room · Prevent straining or valsalva · Pneumatic leg compression to prevent DVT · Consult physical, occupational, and speech therapists
Intracerebral (ICH)
o Facts:
· Also known as Intraparenchymal Hemorrhage; Most often in Putamen, Thalamus, Pons or Cerebellum; Often in young Pt, smoker, HT
· 25 % of all strokes; 50 % Mortality (depends on Volume/location)
· HT main cause and causes deep bleed; Also from anticoagulation/thrombolysis, Cocaine/amphetamines, AV malformation, Amyloid angiopathy
o S/S:
· Rapid (5-30m), progressive focal deficits depending on site;
· Vomiting (80 %); Headache (50%)
· Gaze deviation (towards paralyzed side = Cerebellum, Down w/unreactive pupils = Thalamus)
o DX:
· CT w/o contrast
o TX:
· Medical: Strict BP control w/MAP below 100
· Surgical: · Urgent neurosurgery consult if bleeding is in Cerebellum · Surgery for bleed elsewhere of no benefit · Other: · Induced hyperventilation to reduce edema and mass effect · Head of Bed to 30o

Other Facts of Interest
· History & Physicalo DDx includes Hypoglycemia/Hyperglycemia, Epilepsy, Tumor, Fever/Infection
o Thorough neurological exam including CN II-XII, Motor/Sensory function, Visual fields, Ability to speak/comprehend/walk, Reflexes (i/c primitive), Cerebellar function, Patient may lose appreciation of dysfunction (anosagnosia)
o Peripheral/Cervical vascular system i/c bruits/murmurs, DVT and EKG rhythm
o Cervical ROM
o Hx of previous S/S; Hx of Medications/Past surgeries/illnesses
· Diagnosticso Labs: CBC w/plts, CMP (i/c LFTs), ESR, PT/PTT, Syphilis serology, Tox screen, D-dimer, Fibrinogen, Urine Homocysteine; ABG, Cardiac enzymes Coags if hypercoag state suspected
o EKG, CXR
o CT: Door to CT interpretation goal is 45 min
· Non Contrast CT first to r/o hemorrhage (sensitivity for ischemic strokes only 50% in 6hrs)
· Next CT angio (arteriography) to evaluate vessel anatomy/patency/perfusion
o MRI: Only helpful in small infarcts in Cortex and Brainstem lesions and is not helpful in acute hemorrhages; should be avoided if Pt is unstable or will delay therapy
o Others: Carotid Doppler U/S, Transcranial Doppler, Echocardiography or U/S (RL shunt)
· Hypothermia is good for coma following cardiac arrest but no data if helpful for Stroke Pt
· Magnesium does not change morbidity/mortality rates
· Hyperglycemia delays recovery from ischemia w/data suggesting Glucose-Insulin-K helpful
· Supine position best for brain perfusion but increases ICP; Use own judgement
· If BP must be treated other acceptable medications include Clonidine, Labetalol, ACEI; Usually wait 3 wks post stroke
· Syncope occurs from stroke only w/hemorrhage, large MCA, or brainstem involvement