Abstract Details

Title Using the Combined Sensory Index for Higher Diagnostic Yield in Mild Carpal Tunnel Syndrome

Topic Clinical Neurophysiology

Presentation(s) P02 - (-)

Poster/Presentation
Number 226

Objective

Background BACKGROUND: Mild CTS is electrodiagnostically defined as a median sensory abnormality alone. Often, the D2 sensory study does not detect mild CTS. The CSI is the sum of three median comparison studies, the median-radial (thumbdiff), median-ulnar digit IV (ringdiff), and median-ulnar palmar (palmdiff), with 1.0 or greater being positive, and was demonstrated as sensitive in detecting mild CTS. We use the following algorithm, modified from Robinson et al: first we attempt the D2 sensory, but if that is normal and clinical suspicion is high, we perform the thumbdiff; if the thumbdiff is < 0.2 ms, evaluation is stopped; if the thumbdiff is 0.2-0.6 ms, we perform a full CSI; and if the thumbdiff is > 0.6 ms, evaluation is stopped and called positive.

Design/Methods DESIGN/METHODS: We retrospectively identified patients who presented with CTS symptoms between 11/2010-6/2012. Patients diagnosed as normal, those having mild CTS by D2 sensory, and those with mild CTS by CSI/thumbdiff were separated into groups for analysis.

Results RESULTS: Among patients with mild CTS, 31/51 (60.8%) were diagnosed by either CSI or thumbdiff (p < 0.001). Of the mild CTS patients diagnosed by thumbdiff or CSI, 17/31 (54.8%) were diagnosed by thumbdiff alone (p < 0.001). Of all patients with CTS symptoms, 51/74 (68.9%) had mild CTS by D2 sensory (51% sensitive), or CSI/thumbdiff (60.8% sensitive).

Conclusions CONCLUSIONS: Our data suggests that the CSI/thumbdiff algorithm, although more labor-intensive, is more sensitive to diagnose mild CTS than the D2 sensory study. If mild CTS is diagnosed earlier, treatment can be initiated sooner. Also, our data suggests that the thumbdiff alone can be used in many cases, and may reduce patient discomfort compared with the full CSI.

Authors/Disclosures
Lawrence A. Zeidman, MD, FAAN (Endeavor Health Northshore Department of Neurology) PRESENTER	Dr. Zeidman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Johnson & Johnson. Dr. Zeidman has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Zeidman has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Pfizer. Dr. Zeidman has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Smith Blake Hill LLC. The institution of Dr. Zeidman has received research support from Octapharma. Dr. Zeidman has received publishing royalties from a publication relating to health care.
Simran Singh, DO	No disclosure on file
	No disclosure on file
Joseph J. Higgins, MD, FAAN (AEGRIS LLC)	No disclosure on file

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