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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