The use of short-segment stimulation along the ulnar sensory nerves and across the elbow provided reliable diagnostic confirmation of ulnar neuropathies at the elbow (UNE) in patients presenting with mild and sensory symptoms, according to a study published in Muscle and Nerve. Additionally, researchers found that ulnar sensory short-segment stimulation may localize the site of mild UNE-related nerve compression.
Researchers enrolled asymptomatic control participants (n=20) and patients with clinically suspected mild UNE (n=15). Control participants presented with pain, weakness, sensory symptoms in the upper extremities, or a history of ulnar neuropathy or other peripheral nerve disorders. Conversely, patients with clinically suspected UNE had classic symptoms of the disorder, including elbow pain, positive Tinel sign at the elbow, and/or sensory disturbance in the ulnar nerve distribution. Participants underwent ulnar sensory short-segment stimulation across the elbow. During stimulation, researchers recorded the peak-peak amplitude (μV) and peak latency (msec) shifts of sensory responses between 2 adjacent stimulation sites.
Individuals with UNE were categorized to group A (n=7), composed of patients with completely normal routine ulnar study results, and group B (n=8), composed of patients with normal routine sensory nerve conduction study results (NCS) and abnormal motor NCS study results. The upper limit of normal for peak latency shift was 0.7 msec, whereas the percentage of peak amplitude reduction between sites was 15% at the upper limit of normal. The researchers recorded an abnormal latency shift in the majority of participants (n=12), and almost half of patients had focal sensory conduction block (n=6). Additionally, sensory inching was considered abnormal in 5 of 7 patients who had otherwise normal study results.
Limitations of this study include its very small sample size and the lack of a comparator or placebo stimulation group.
“When patients only demonstrate findings on ulnar sensory inching,” the researchers added, “the underlying pathology is likely very mild [neurapraxic] injury isolated to sensory axons which would suggest a favorable outcome with conservative management.”
Vazquez Do Campo R, Dimberg E, Rubin D. Short segment sensory nerve stimulation in suspected ulnar neuropathy at the elbow: a pilot study [published online August 27, 2018]. Muscle Nerve. doi: 10.1002/mus.26326