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, GuillanBarre, 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.
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
Drug Category
Drugs in that Category Treatment Use
Antiepileptics
Phenobarbital,
Epilepsy,
phenytoin, valproic acid, prevention of
carbamazepine,
seizures
ethosuximide,
gabapentin, lamotrigine
Bronchodilators
Theophylline, caffeine
Immunosuppressants
Cyclosporine,
Prevent
tacrolimus, sirolimus,
rejection of
mycophenolate mofetile transplanted
organs
Asthma, COPD,
neonatal apnea
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
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?