Neurology Labs

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Neurology Labs

• Brenda Beckett, PA-C
• Clinical Assessment II

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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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Cerebrospinal Fluid

• WBC, RBC
• Protein
• Glucose
• Culture
• Other tests
• (see table p 307-313 Wallach)

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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)

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Multiple Sclerosis

• CSF IgG Index. Compares ratio of CSF IgG albumin
  to serum IgGalbumin ratio.

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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

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Myasthenia Gravis

• Acetylchoine receptor (AChR) antibodies (3
  different Abbinding, blocking, modulating).
• Positive in gt85 of pts with generalized sx, 50
  of pts with occular sx.
• Also check thyroid function. At risk for other
  autoimmune diseases.

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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.

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TDM

• Therapeutic range Concentration where the drug
  has been shown to be efficacious without causing
  toxic effects in most people.

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Drug Category Drugs in that Category Treatment Use
Cardiac drugs          Digoxin, quinidine, procainamide, N-acetyl-procainamide (a metabolite of procainamide) CHF, angina, arrhythmias
Antibiotics Aminoglycosides (gentamicin, tobramycin, amikacin),Vancomycin, Chloramphenicol Infections with bacteria that are resistant to less toxic antibiotics
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Drug Category Drugs in that Category Treatment Use
Antiepileptics Phenobarbital, phenytoin, valproic acid, carbamazepine, ethosuximide, gabapentin, lamotrigine Epilepsy, prevention of seizures
Bronchodilators Theophylline, caffeine Asthma, COPD, neonatal apnea
Immuno-suppressants Cyclosporine, tacrolimus, sirolimus, mycophenolate mofetile Prevent rejection of transplanted organs
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Drug Category Drugs in that Category Treatment Use
Anti-cancer drugs Methotrexate Cancers, rheumatoid arthritis, non-hodgkin's lymphomas, osteosarcoma, psoriasis
Psychiatric drugs Lithium, desipramine, some antidepressants (imipramine, amitriptyline, nortriptyline, doxepin) bipolar disorder, depression
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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

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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.

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Case Study

• Physical exam
• AO, 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 Babinskis
• Remainder of PE unremarkable

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Case Study

• What is your differential diagnosis?
• -
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• What lab testing do you want to perform?
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Case Study

• What additional CSF test(s) would you like to
  order?
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• Results
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Case Study

• What is your diagnosis?
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