Abstract Details

Title The Sensitivites of Median Mixed Palmar Distal Latencies in the Diagnosis of Carpal Tunnel Syndrome (Onset, Peak, Either Onset or Peak, or Onset and Peak)

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) P4 - Poster Session 4 (5:30 PM-6:30 PM)

Poster/Presentation
Number 12-040

Objective To determine whether using mixed palmar distal onset latency (OL) or peak latency (PL) provides higher sensitivity for detecting median neuropathy at the wrist (MNW) during electrodiagnostic studies.

Background Carpal Tunnel Syndrome (CTS) is the most common entrapment neuropathy of the upper extremity, and nerve conduction studies play a crucial role in its diagnosis. At present, there is no consensus on whether measuring palmar distal OL or PL is more sensitive for the diagnosis of CTS, and current practice is largely institution-dependent rather than evidence-based. Since early detection improves management, this question is of clinical importance.

Design/Methods In this retrospective study, we used Boston Medical Center's EMG lab database to analyze more than 500 hands that met electrodiagnostic criteria for MNW (prolonged mixed palmar OL or PL), to compare the sensitivities of mixed palmar OL versus PL for diagnosing CTS. For both latencies, we used a cut-off of 0.4 ms between the median and ulnar studies. CTS patients were sub-categorized as either clinically-confirmed, possible with confounds (cervical radiculopathy, polyneuropathy), or subclinical (met electrodiagnostic criteria but were asymptomatic).

Results For hands fulfilling criteria for clinical CTS (N = 229), OL was 85.8% sensitive compared to 78.7% for PL, and 71.5% if both criteria were required. Therefore, using OL alone missed 14.2% of cases, and using PL alone missed 21.3% of cases. For hands with possible clinical CTS (N = 90), OL and PL were 78.9% and 72.2% sensitive respectively, decreasing to 61.1% if both were required.

Conclusions Our results show that OL is more sensitive than PL in detecting CTS, and that the best way to maximize sensitivity is to use criteria such that either OL or PL are abnormal. This approach will avoid missing 15-20% of clinical CTS cases, a novel finding that has not been demonstrated in the literature thus far.

Authors/Disclosures
Elie Sader, MD PRESENTER	No disclosure on file
Alexandre Mason Sharma, MD	Dr. Mason Sharma has nothing to disclose.
Michelle Kaku, MD (Icahn School of Medicine at Mount Sinai, Neurology Dept.)	Dr. Kaku has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Fatcliffe Harten Galamaga LLP.
Peter Siao Tick Chong, MD (Boston Medical Center)	No disclosure on file

��ɫ��

��ɫ��