Characteristics of Peripheral and Central Vertigo PERIPHERAL VERTIGO • Onset: Sudden • Intensity: Severe initially, often decreasing over time • Duration: Intermittent episodes lasting seconds to less than a minute for BPPV; continuous and lasting hours to days for vestibular neuritis • Nystagmus: Usually torsional and upbeat (fast phase beating toward forehead) in classic posterior canal BPPV; horizontal in horizontal canal BPPV; horizontal-torsional in vestibular neuritis/labyrinthitis • Head Position: Induces vertigo (BPPV); worsens vertigo (vestibular neuritis) • Neuro Findings: None • Auditory Findings: May be present, including tinnitus (Méniére's disease) and hearing loss (labyrinthitis) CENTRAL VERTIGO • Onset: Gradual or sudden • Intensity: Mild in most but can be severe in stroke and multiple sclerosis • Duration: Usually weeks, months (continuous) but can be seconds or minutes with vascular causes, such as with posterior circulation TIA • Nystagmus: Purely vertical, spontaneous and purely torsional, direction-changing on lateral gaze, downbeating (fast phase beats toward nose) • Head Position: Usually little change but can worsen with head position change • Neuro Findings: Usually present • Auditory Findings: Rarely #Peripheral #Central #Vertigo #diagnosis #findings #signs #symptoms #comparison #neurology

Liver Chemistry Tests - AST, ALT, Alkaline Phosphatase and Bilirubin Metabolism AST and ALT: • AST: liver > skeletal muscle, cardiac muscle > kidney, brain. In liver, 80% of AST is in mitochondria (mAST), Rest cytoplasmic (CAST) • ALT: primarily within liver Alkaline phosphatase: • Synthesis: in hepatocyte canalicular membrane (NOT within bile duct cells) • Other locations: bone, intestine, placenta • Increased levels: due to increased synthesis, not reduced clearance - AP synthesis stimulated by bile acid accumulation in hepatocyte - Elevation usually occurs several days after initial insult Bilirubin metabolism: • Breakdown of heme (80% Hgb, rest myoglobin, cytochromes) • Unconjugated circulates with albumin in serum • Released from albumin upon hepatocyte entry • UGT1A1 responsible for conjugation in hepatocyte • MRP2 transports conjugated bilirubin into bile canaliculi (ATP-dependent process) • MRP3 transports back into plasma where most undergoes reuptake into hepatocyte via OATP1B1 + B3 - Dr. Hersh Shroff @HershShroff #Liver #Chemistry #Tests #Laboratory #Metabolism #ASTALT #AlkPhos #Bilirubin #Hepatology #Pathophysiology #Diagnosis #LFTs