Dynamic somatosensory evoked potential and magnetic resonance imaging in pudendal neuropathy: A comparative study with respect to the clinical diagnostic criteria

Aim: Pudendal neuropathy (PN) is a common cause of chronic perineal pain and usually diagnosed long after the onset of symptoms. Diagnostic work-up of PN mainly includes radiologic and neurophysiological studies. However, there is no established diagnostic test to confirm the clinical diagnosis. This study aims to evaluate the correlation between the dynamic pudendal somatosensory evoked potential (SEP) and pudendal magnetic resonance imaging (MRI) in patients with PN diagnosed clinically based on Nantes criteria as the gold standard for comparison. Methods: Forty-three patients (25 females, 18 males) were included in the study. Dynamic pudendal SEP as a novel method, which includes both provocative positioning and stimulation of each side separately, and pudendal MRI were performed in each patient. Results: Dynamic pudendal SEPs were found to be abnormal in 42, normal in 12 of the 54 clinically symptomatic nerves and abnormal in 2, normal in 30 of the 32 clinically asymptomatic nerves. Pudendal MRI was abnormal in 19, normal in 35 of the 54 clinically symptomatic nerves and abnormal in 8 and normal in 24 of the 32 clinically asymptomatic nerves. There was 84% agreement between clinical diagnosis and dynamic pudendal SEP (high sensitivity and specificity), 49% agreement between clinical diagnosis and pudendal MRI (low sensitivity and acceptable specificity), 53% agreement between dynamic pudendal SEP and pudendal MRI. Conclusions: The novel dynamic pudendal SEP method seems to be useful in supporting the clinical diagnosis of PN, while pudendal MRI lacks sufficient sensitivity to be used alone in diagnosis of PN.