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Abstract Details

New Measurement in the Diagnosis of Critical Illness Myopathy: Stimulus Intensity and Compound Muscle Action Potential Duration Relationship
Neuromuscular and Clinical Neurophysiology (EMG)
P1 - Poster Session 1 (8:00 AM-9:00 AM)
11-013
CIM is most common cause of ICU-acquired muscle weakness. In electrophysiological diagnosis, synchronous dispersion observed in distal and proximal stimulation in CMAP negative-peak-time(NP_Duration), which has a high diagnostic value, cannot be observed in some patients or is at borderline. Based on our observation that "prolongation of NP_Duration is more evident at low stimulation-intensities", NP_Duration at submaximal stimulation-intensities and contribution to diagnosis of CIM were examined.
Development of new parameters for earlier prediction and more specific presentation of development of critical illness myopathy(CIM).
Study was conducted with ulnar nerve stimulation and recording from ADM muscle in 11 patients diagnosed with CIM after EMG and 12 healthy individuals.  Maximal-stimulation-intensity(SMax), and minimal(SMin) at which first muscle action potential was detected, were determined.By dividing SMax–SMin range into 4 equal parts, 6 percentage stimulation-intensities(SMin,S%20,S%40,S%60,S%80,SMax) were determined. Amplitude of CMAPs(Amp_Sx) and NP_Duration(Duration_Sx) and ratio of NP_Duration at each stimulation-intensity to Duration_SMax(MaxRatio_Duration_SX) were calculated. 2-level[STIMULATION-VIOLENCEXGROUP]repeated-measures ANOVA was applied in analysis.
In patient group, Amp_S60%, Amp_S80% and Amp_SMax values were significantly lower(p=0.002,p=0.000,p=0.032). NP_Duration was significantly longer in patient group than in control group at all stimulation-intensities(p=0.000). However, in 2 patients(18%), NP_Duration was longer than normal only in Smin and S%20. Moreover, in patient group, NP_Duration was maximum at SMin intensity and gradually shortened as stimulation-intensity increased, while in healthy individuals it was vice versa. Consistent with this finding, MaxRatio_Duration_SMin and MaxRatio_Duration_S%20 in patient group were significantly higher than in control group(p=0.000, p=0.000).
Prolongation of NP_Duration, which has electrophysiological-diagnostic value for CIM, was detected with higher sensitivity at SMin and S%20 stimulation-intensities which can be performed in a short time, compared to supramaximal stimulation-intensity used in routine examinations. It was thought that this new finding was due to difference in muscle fibers stimulated at different stimulation intensities and phase-cancellation and would increase true-positivity in the early stages of CIM.
Authors/Disclosures
Özge Berna Gültekin-Zaim, MD (Hacettepe University Faculty of Medicine Neurology Department)
PRESENTER
Dr. Gültekin-Zaim has nothing to disclose.
No disclosure on file
Cagri Mesut Temucin (Hacettepe University Medical School Neurology Dep) Cagri Mesut Temucin has nothing to disclose.