Test
|
How
Performed
|
Condition
Tested
|
Positive
Result
|
Interpretation
of Positive Result
|
Phalen test
|
Elbows on
table, forearms vertical, wrists flexed
|
Paresthesia
in response to position
|
Numbness or
tingling on radial digits within 60 s
|
Probable CTS
(sensitivity 0.75, specificity 0.47)
|
Percussion
test (Tinel sign)
|
Lightly tap
along the median nerve from proximal to distal
|
Site of nerve
lesion
|
“Electric”
tingling response in fingers
|
Probable CTS
if positive at the wrist (sensitivity 0.60, specificity 0.67)
|
Carpal tunnel
compression test (Durkan)
|
Direct
compression of the median nerve at the carpal tunnel
|
Paresthesia
in response to compression
|
Paresthesia
within 30s
|
Probable CTS
(sensitivity 0.87, specificity 0.90)
|
Hand diagram
|
Patient marks
site of pain or altered sensation on outlined hand diagram
|
Patient's
perception of symptoms
|
Markings on
palmar side of radial digits, without markings in palm
|
Probable CTS
(sensitivity 0.96, specificity 0.73, negative predictive value 0.91)
|
Hand volume
stress test
|
Hand volume
measured by displacement, repeat after 7-min stress test and 10-min rest
|
Hand volume
|
Hand volume
increased by ≥10 mL
|
Probable
dynamic CTS
|
Direct
measurement of carpal tunnel pressure
|
Wick or
infusion catheter placed in the carpal tunnel
|
Hydrostatic
pressure in resting and provocative positioning
|
Resting
pressure ≥25 mm Hg (variable and technique related)
|
Hydrostatic
compression is believed to be a probable cause of CTS
|
Static
2-point discrimination
|
Determine
minimal separation of two distinct points when applied to palmar fingertip
|
Innervation
density of slow-adapting fibers
|
Failure to
determine separation of at least 5 mm
|
Advanced
nerve dysfunction
|
Moving
2-point discrimination
|
As above,
with movement of the points
|
Innervation
density of fast-adapting fibers
|
Failure to
determine separation at least 4 mm
|
Advanced
nerve dysfunction
|
Vibrometry
|
Vibrometer
placed on the palmar side of digit, amplitude at 120 Hz, increased to threshold
of perception, compare median and ulnar bilaterally
|
Threshold of
fast-adapting fibers
|
Asymmetry
compared with contralateral hand or median to ulnar in ipsilateral hand
|
Probable CTS
(sensitivity 0.87)
|
Semmes-Weinstein
monofilaments
|
Monofilaments
of increasing diameter touched to the palmar side of digit until the patient can
determine which digit is touched
|
Threshold of
slowly adapting fibers
|
Value
>2.83
|
Median nerve
impairment (sensitivity 0.83)
|
Distal
sensory latency and conduction velocity
|
Orthodromic
stimulus and recording across wrist
|
Latency,
conduction of sensory fibers
|
Latency
>3.5 ms or asymmetry of conduction velocity >0.5 m/s versus opposite
hand
|
Probable CTS
|
Distal motor
latency and conduction velocity
|
Orthodromic
stimulus and recording across wrist
|
Latency,
conduction velocity of motor fibers of the median nerve
|
Latency
>4.5 ms or asymmetry of conduction velocity >1 m/s
|
Probable CTS
|
Electromyography
|
Needle
electrodes placed in muscle
|
Denervation
of thenar muscles
|
Fibrillation
potentials, sharp waves, increased insertional activity
|
Advanced
motor median nerve compression
|
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