CPR for Carpal Tunnel Syndrome
Original Editor - Cheryl Rentchler
Clinical Prediction Rules of Carpal Tunnel Syndrome:
Clinical prediction rules (CPRs) combine historical and physical examination findings to help clinicians predict the probability of a particular diagnosis. In 2005, Wainner et al published a level IV CPR to aid clinicians in diagnosing carpal tunnel syndrome. These CPRs help to improve the diagnostic accuracy of a clinician. Carpal Tunnel Syndrome is a compressive or entrapment neuropathy of the median nerve at the carpal tunnel at wrist.
Clinical Prediction Rule Components: 
1. Shaking hands to relieve symptoms
2. Wrist ratio >.67
3. Symptom Severity Scale > 1.9
4. Diminished sensation in median sensory field 1 (thumb)
5. Age > 45 years old
Wrist ratio index: as described b.y Johnson et al, is measured by using a pair of sliding calipers to measure the anteroposterior (AP) wrist width and the mediolateral (ML) wrist width at the distal wrist crease. Wrist ratio index is then calculated by dividing the AP wrist width by the ML wrist width in centimeters. Ratios greater than .70 were found to be a predisposing factor for carpal tunnel syndrome. 
Median nerve sensation: was measured on the pad of thumb with the end of a straightened paper clip and compared to sensation at the proximal thenar eminence. Sensory tests were graded as absent, reduced, normal or hyperesthestic
Symptom Severity Scale: The symptom severity scale was published in 1993 by Levine et al . It is an 11 item questionnaire that examines the six critical domains for the evaluation of CTS: pain, paresthesia, numbness, weakness, nocturnal symptoms and overall functional status. Each question is scored from 1 (mildest symptoms) to 5 (most severe symptoms); therefore, a higher score indicates a more severe case of CTS. The SSS has been shown to have good reliability, validity and responsiveness. 
|> 3 positive tests||.98||.54||2.1|
|> 4 positive tests||.77||.83||4.6|
|All 5 tests positive||.18||.99||18.3|
|Sensitivity||Specificity||+ LR||- LR|
|Tinel Part A||.41||.58||
|c/o symptoms waking at night||.73||.31||1.1||.86|
|c/o fumbling or dropping objects with affected hand||.73||.57||1.7||.47|
Interpretation (shifts in probability)
|+ LR||- LR|
large shifts, often conclusive
|> 10||< 0.1|
small shifts, sometimes important
|small and rarely important shifts||
Suggestions for Use in the Clinic:
In 2005, Wainner et al published a level IV CPR to assist in identifying patients presenting with carpal tunnel syndrome.When 4/5 tests are positive the positive Likelihood Ratio is 4.6, and if all of the tests are positive it increases to 18.3. These are significantly higher than positive Likelihood Ratio of other individual tests used to diagnose carpal tunnel syndrome.However, a level IV CPR means the rule has been developed but not validated and further evaluation is required before the rule can be applied clinically, therefore, further research is needed to validate this CPR.
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- Johnson E, Gatens T, Poindexter D, Bowers D. Wrist dimensions: correlation with median sensory latencies. Arch Phys Med Rehabil 1993; 64:556-7.
- Levine D, Simmons B, Koris M, Daltroy L, Hohl G, Fossel A, Katz J. A Self-Administered Questionnaire for the Assessment of Severity of Symptoms and Functional Status in Carpal Tunnel Syndrome. J Bone Joint Surg Am 1993; 75: 1585-92.
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