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Neurology Labs. Brenda Beckett, PA-C Clinical Assessment II. Cerebrospinal Fluid (CSF). Clear fluid that occupies subarachnoid space and ventricles Produced in the choroid plexus Obtained by lumbar puncture (L3-L4) Usually: clear, colorless, acellular, sterile Traumatic tap.
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Neurology Labs Brenda Beckett, PA-C Clinical Assessment II
Cerebrospinal Fluid (CSF) • Clear fluid that occupies subarachnoid space and ventricles • Produced in the choroid plexus • Obtained by lumbar puncture (L3-L4) • Usually: clear, colorless, acellular, sterile • Traumatic tap
Cerebrospinal Fluid • WBC, RBC • Protein • Glucose • Culture • Other tests • (see table p 307-313 Wallach)
Multiple Sclerosis • CSF IgG, nonspecific marker (also elevated in: neurosyphilis, Guillan-Barre, head trauma, leukemia, etc) • Measure CSF and serum IgG and albumin. (to determine increased production in CNS vs crossing bb barrier)
Multiple Sclerosis • CSF IgG Index. Compares ratio of CSF IgG: albumin to serum IgG:albumin ratio.
Multiple Sclerosis • Oligoclonal proteins (or bands)- shows discrete bands on electrophoresis. • Perform on CSF and serum • MS will show +CSF, neg serum • myelin basic protein (MBP) may be observed during active demyelinization. • Perform on CSF • Used to monitor therapy
Myasthenia Gravis • Acetylchoine receptor (AChR) antibodies (3 different Ab:binding, blocking, modulating). • Positive in >85% of pts with generalized sx, 50% of pts with occular sx. • Also check thyroid function. At risk for other autoimmune diseases.
Therapeutic Drug Monitoring (TDM) • Measures the level of some drugs as a way to determine the most effective dose or to avoid toxicity. • Most drugs do not need to be monitored this way. • Monitor drugs that have: narrow therapeutic window, toxic side effects.
TDM • Therapeutic range: Concentration where the drug has been shown to be efficacious without causing toxic effects in most people.
TDM • Specimen collection time in relation to dose is important. • Sampling time is most frequent error • Trough vs peak • Most are drawn as trough, except some antibiotics • Steady state • After multiple doses
Case Study History and presentation: • 33yo female, admitted for sudden, bilat loss of vision. 1yr ago, had difficulty walking, improved w/i 2wks. Occ tingling and “electrical” sensation down her back with flexed neck. Occ difficulty expressing herself verbally.
Case Study Physical exam: • A&O, mild distress, speech normal • No light perception bilat, EOMI. No nystagmus, Pupils sluggishly reactive to light. • Paraparesis with spacicity and dissociated sensory loss in LE. • Sensory level at T7. • Brisk patellar DTRs and bilat +Babinski’s • Remainder of PE unremarkable
Case Study • What is your differential diagnosis? - - • What lab testing do you want to perform? -
Case Study • What additional CSF test(s) would you like to order? - Results: -
Case Study • What is your diagnosis? -