Reduced variance of latencies in pudendal evoked potentials after normalization for body height

Abstract

The value of the Somatosensory Evoked Potentials (SEP) in the assessment and detection of neurological disorders could be considerably enhanced if the normative standards of (SEP) characteristic parameters were normalized taking into account all other systematic sources of variance. The present study examines the influence of body height on the peak and interpeak latencies of the pudendal somatosensory evoked potentials. We examined the peak latency (L1) of the evoked potential recorded at the L1 vertebra and the onset latency (ONc) of the cortical evoked potentials, after stimulation of the pudendal nerve, as a function of body height in 40 normal male subjects (age 20-40 years). Significant positive correlation was found between both (ONc) latency and ONc-L1 interpeak latency and body height (H). Assuming that the latter is proportional to the length of the neural pathways, the experimental data were fitted using a theoretical model representing the conduction in the sensory neuraxis as a function of body height. Using the estimated fitting functions, we normalized our data with regard to a typical value of body height. The normalized values of the aforementioned latencies reveal a significantly reduced variance, as compared to the original ones, and consequently their diagnostic importance is significantly increased. Similar procedures applied to the L1 (spinal) latencies and the latencies of the bulbocavernosus reflex (BCR) reveal no correlation with body height and this is discussed on the basis of neuroanatomical considerations.

Sensory evoked cortical potentials of the lower urinary tract in healthy men

“…However, there is still controversy about the exact topographical distribution and density of the urethral sensory innervation in humans and minimal P1 latencies were clearly longer than normal pudendal SEP latencies for clitoral, penile, or perineal stimulation sites. 21 Tallying with this some subjects demonstrated early potentials for mUR and dUR that could be attributed to afferent pudendal activation. Interestingly, SEPs from mUR were more difficult to assess and demonstrated a higher N1 latency variability compared to the other LUT locations.…”

“…Faster conducting fibers belonging to the pudendal nerve that contribute to the afferent innervation of the distal parts of the urethra may contribute to this finding. However, there is still controversy about the exact topographical distribution and density of the urethral sensory innervation in humans and minimal P1 latencies were clearly longer than normal pudendal SEP latencies for clitoral, penile, or perineal stimulation sites . Tallying with this some subjects demonstrated early potentials for mUR and dUR that could be attributed to afferent pudendal activation.…”

Neurophysiologic studies of the penilo‐cavernosus reflex: Normative data

“…The present study also confirmed the previously reported absence of correlation between the subject's height and latency of the sacral reflex on single electrical stimulation. 27 The absence of correlation between anatomic length of the sacral reflex arc and reflex latency underlines the relatively more important central conduction delay within the conus medullaris in comparison to conduction along afferent and efferent nerve pathways. No correlation of age with latency or any other measured parameter was also found.…”

Effects of Pudendal and Cortical Paired Associative Stimulation on Plasticity of Sphincter Responses after Incomplete Spinal Cord Injury: A Feasibility Study

“…Latencies of the peak of the first positive deflection (so-called P1 wave) are given in Table 3. Latencies for three of those subjects (starred) were longer (> mean +3 SD) than expected from a control, neurologically normal population allowing for the height of subjects [18]. Table 3 changes were also observed in 5 subjects who lacked a pSSEP.…”