Planning of an EMG examination
REPORTING
How do we put all this
together?
„ referral
„ symptom
„ history
„ clinical
findings
„ patient files
Stålberg
History is very important
„
„
„
„
„
„
when did it start ?
how did it start ?
paresthesia
weakness
pain
course of
symptoms
Differential diagnosis
„
what alternatives
need to be
considered
– likelihood of each
alternative
„
don’
don’t forget
consider the
alternative your
colleague has in
his referral
chart
Clinical examination
„
„
„
„
stretch reflexes
muscle strength
sensibility
(unreliable)
inspection
– scars
– tumors
– swelling
Plan
„
“Go where the money is”
is”
– start with the most likely
alternatives
„
when you think you have
arrived at a diagnosis,
rule out those
alternatives that are
differential diagnostic
alternatives
1
Tricks to use when you do
not know what to do
„
When nothing else helps - think!
– logical thinking
– lateral thinking
– consult literature/internet
„
„
„
Check to opposite side and other limbs
Are the electrodes and equipment
working?
Consult a colleague before the patient
leaves
Severe unilateral carpal tunnel syndrome
Ulnar conduction block at the elbow, right side
low sens ampl dig IV and V without motor involvement, left side
Conduction block, radial nerve
Bilateral carpal tunnel syndrome,
left severe, right moderate
Bilateral moderate carpal tunnel syndrome
2
Practical approach
„
Often we start with neurography
– sometimes this is enough
– supplement with inching, centimetering
– autonomic tests
– TMS
– quantitative sensory testing
Strategy
that may change dynamically as
findings evolve
Second step is EMG
„ Successive steps depend on findings
„
– RNS
– SFEMG,Macro EMG
NOTE
Be open to the unexpected
Results must harmonize
„
„
„
„
ampl decay and normal # F
prox ampl higher than dist
jitter/ blocking but no weakness
good strength - low CMAP
-
techn
anomal.inn
techn
bad stim or inexcitabilty
„
„
„
„
good strength - low CMAP
- inexcitable nerve
high F waves - normal MUPs
- central hyperexcitability
biopsy type grouping - normal FD
- cong myopathy
high MUPs in GBS day 3, - no reinnervation (FD normal)
- loss of small MUs
NOTE
Be open for the unexpected
Practical hints - the
examiner
Practical hints - the patient
„
„
„
„
„
„
„
„
inform the patient about reason for EMG
explain expected discomfort
do not display the electrode
term ”pin”
pin” (or similar) better than needle
keep bloody tissues away
do not state number of remaining
muscles
inform about soreness for 11-2 days
inform the patient about next step
„
„
„
„
„
„
„
medical consultation
read referral before you see the patient
check history, phys exam
formulate strategy
inform the patient about the progress
have all supplies ready before exam
use gloves
3
Reporting
Practical hints - the
investigation
„
„
„
„
„
„
Summary of clinical situation
no skin preparation is necessary
support your hand on the area of needle insertion
electrode perpendicular to the skin
small but brisk insertion through the skin
do not go very deep, just beneath the fascia
investigate the muscle at
– rest (denervation),
– slight contraction (MUP) and
– strong contraction (IP)
Results
„
„
„
„
Conclusion
„
„
AANEM 2006
„
„
„
„
„
Demographic data
„ Reason for referral, symptoms,
signs, possible diagnosis
„
AANEM 2006
Neurography report - concise
2. NCS
„
neurophysiological
conclusion
clinical interpretation
1. Pat data and Clinical
problem
Report (AANEM 2006)
1. Clinical problems
2. NCS, specific details
3. EMG, specific details
4. Summary Section: summarize NCS and
EMG - integrate
5. Diagnostic interpretation Section
6. Option: clinical diagnosis, differential
diagnostic alternative
graphic reports
tables
signals
brief summary of essential
findings
Methods,anti/orthoMethods,anti/ortho-dromic,
dromic, ampl methods
SCS
sites, segments, ampl,
ampl, CV,
MCS
sites, segments, data
F-waves nerve, #, latency
H refl
nerve, physiological state, ampl ratio
RNS
nerve, phys state, Hz, ampl,
ampl, decr,
decr,
facilitation
AANEM 2006
4
Graphic reporting of EMG findings
3. EMG
Optimal # muscles
describe spont activity, MUP
shape, IP in tabular for
„ report limitations (pain, ..)
„
„
AANEM 2006
Summary of findings
Conclusion
report only relevant findings on which
you base your conclusion
„ use simple terminology that your
colleagues understand
„ words like “fibrillation potentials”
potentials” or
“polyphasic MUPs”
MUPs” must be avoided
„ sometimes it important to underline
that some findings are normal
„
„
or
„
Neurophysiological conclusion
localization
„ severity
„ pathophysiology
„ time course
„ distribution
„
When in doubt,
doubt, say SO
When in doubt,
doubt, say NO
5. Diagnostic Interpretation
Describe if the study over all is abnormal,
and why
„ provide electrophysiological diagnosis, and
level
„ describe limitations that make the study
incomplete
„ compare to earlier tests
„
AANEM 2006
5
Examples of neurophysiological
conclusion
moderate subacute axonal sensory
and motor polyneuropathy
„ slight conduction block of the ulnar
nerve in the cubital tunnel
„ severe axonal lesion of the
suprascapular nerve in incisura
scapulae
„
Example of a report
summary
EMG: There are slight subacute neurogenic findings in the first
dorsal interosseus and flexor carpi ulnaris muscles.
Nerve conduction studies: The motor conduction velocity of the
ulnar nerve was slightly reduced in the retroepiconylar region at
at
the elbow.
Conclusion. The findings are compatible with a slight axonal and
demyelinating ulnar nerve lesion in the retroepicondylar region at
the elbow.
The symptoms have progressed slowly over a two years and the
patient has clinically arthrosis of the elbow. This ulnar neuropathy
neuropathy
is probably a so called “ tardy ulnar palsy”
palsy” (entrapment due to
arthrosis of the elbow).
Clinical interpretation
“beware of weak ice”
ice”
„ suite the clinical conclusion to you
clinical experience
„ be clear
„ provide differential diagnosis if indicated
„ recommend a control EMG only if there
is a specific reason for it
„
Factors determining the usefulness
of Neurophysiology
„
quality of examination
– (technique,
technique, concept,
concept, interpretation)
– (experience and training of staff)
staff)
clinical material
„ availability
„ waiting list
„ reporting
„ patient acceptance
„ cost / reimbursement
„
Stålberg
6