Assessing motor deficits in compressive neuropathy using quantitative electromyography

Abstract

BackgroundStudying the changes that occur in motor unit potential trains (MUPTs) may provide insight into the extent of motor unit loss and neural re-organization resulting from nerve compression injury. The purpose of this study was to determine the feasibility of using decomposition-based quantitative electromyography (DQEMG) to study the pathophysiological changes associated with compression neuropathy.MethodsThe model used to examine compression neuropathy was carpal tunnel syndrome (CTS) due to its high prevalence and ease of diagnosis. Surface and concentric needle electromyography data were acquired simultaneously from the abductor pollicis brevis muscle in six individuals with severe CTS, eight individuals with mild CTS and nine healthy control subjects. DQEMG was used to detect intramuscular MUPTs during constant-intensity contractions and to estimate parameters associated with the surface- and needle-detected motor unit potentials (SMUPs and MUPs, respectively). MUP morphology and stability, SMUP morphology and motor unit number estimates (MUNEs) were compared among the groups using Kruskal-Wallis tests.ResultsThe severe CTS group had larger amplitude and longer duration MUPs and smaller MUNEs than the mild CTS and control groups, suggesting that the individuals with severe CTS had motor unit loss with subsequent collateral reinnervation, and that DQEMG using a constant-intensity protocol was sensitive to these changes. SMUP morphology and MUP complexity and stability did not significantly differ among the groups.ConclusionsThese results provide evidence that MUP amplitude parameters and MUNEs obtained using DQEMG, may be a valuable tool to investigate pathophysiological changes in muscles affected by compressive motor neuropathy to augment information obtained from nerve conduction studies. Although there were trends in many of these measures, in this study, MUP complexity and stability and SMUP parameters were, of limited value.

Evaluation Of The Compound Muscle Action Potential In Diagnosis Of The Mild Carpal Tunnel Syndrome

“…On contrary this, we found that CMAP Amplitude was not decreased only in patients with severe CTS as a result of the loss of motor units but also in mild CTS. Unlikely our finding, Nashed et al found that there was no difference in peak-to-peak MUAP amplitude between the mild CTS and the control groups [20]. It can be result in due to their very small study group (nine control group and eight mild CTS) In many previous studies, CMAP NP full-duration prolongation assessed by measuring NP is commonly used in CIDP as diagnostic parameter [21][22][23][24][25].…”

Assessment of Motor Units in Neuromuscular Disease

“…MUNE has been applied to compression neuropathies and postpolio syndrome and has shown correlations with disease severity [110,111].…”

The prevalence of carpal tunnel syndrome among long-term manual wheelchair users with spinal cord injury: A cross-sectional study

“…2 In an assessment of motor deficits in nine healthy participants, eight patients with mild, and six individuals with severe CTS, no differences in the median age or sex among the groups were found. 19 However, the small sample size may be an indication that those studies were inadequately powered to detect clinically important effects. Also, our sample had higher mean age and higher mean time since injury.…”

“…2 While some others found associations in terms of duration of symptoms. 1,4,19 Previous studies included different sample sizes from 23 patients 19 to 126 participants 4 and therefore had considerable uncertainty around the prevalence of CTS in long-term wheelchair users, reflected in the wide range of the estimates. Therefore, to estimate the prevalence of CTS and to assess the impact of using wheelchair over the long term in paraplegic patients a large study is still required.…”

“…4 Some studies indicated that there is no association between the prevalence; and age 2,19 or time since injury. 2 While some others found associations in terms of duration of symptoms.…”