Voháňka S., Vytopil M., *Lukáš Z., **Dušek L. Toman J***

Transcription

1 Quantitative analysis of motor unit action potentials as a non-invasive technique assessing subclinical skeletal muscle involvement in patients with dilated cardiomyopathy and conduction system disease. Voháňka S., Vytopil M., *Lukáš Z., **Dušek L. Toman J*** Department of Neurology and *Pathology, University Hospital Brno, Jihlavska 20, Brno, **Centre of Biostatistics and Analyses, Masaryk University, Kamenice 126/3, Brno, ***Department of Cardiology, Saint Anne University Hospital, Pekařská 53, Brno Czech Republic Grant IGA MH CR 5919/3

2 Dilated cardiomyopathy and/or cardiac conduction disturbances are often present in patients suffering from progressive muscular dystrophies. Cardiac disturbances may in some cases dominate the clinical picture and threaten the patient by the risk of sudd Skeletal muscle involvement in dilated cardiomyopathy and conduction disturbances may be assessed by evaluation of muscle biopsy. Use of muscle biopsy as an invasive procedure in patients with no clinical skeletal muscle symptoms is, however, questionabl Objective Evaluation of the diagnostic value of quantitative analysis of motor unit potentials (QAMUP) in assessing subclinical muscle involvement in patients with dilated cardiomyopathy or conduction disturbances.

3 Patients 22 patients suffering from dilated cardiomyopathy 15 patients with severe heart rhythm disturbances Inclusion criteria Dilated cardiomyopathy and/or severe heart rhythm disturbance (PM implanted) Age of the onset under 40 years Exclusion criteria No signs of atherosclerotic heart disease

4 Methods: quantitative EMG QAMUP in 3 of 4 muscles (deltoid, biceps brachii, lateral vastus, and anterior tibial) was performed and analysed according to standard protocol introduced by Stalberg and Bischoff. Four MUPs parameters in each examined muscle were followed: 1 Mean amplitude 2 Mean duration 3 More than 2 outliers in MUPs amplitude 4 More than 2 outliers in MUPs duration Cumulative QAMUP scale ranging from 0 to 5* (normal to strongly myopathic) was introduced and reflected the number of abnormalities in the 3 examined muscles in each patient. 0 1 parameter borderline 1 1 abnormal or 2 borderline 2 2 abnormal 3 3 abnormal 4 4 abnormal 5 5 or more abnormal

5 Methods: muscle biopsy Muscle biopsy was performed in all subjects. Following signs were evaluated: 1. Fibre type disproportion 2. Fibre size abnormalities (atrophy/hypertrophy) 3. Internal nuclei 4. Fiber splitting 5. Degeneration/regeneration 6. Increased endomysial connective tissue Myopathic muscle biopsy* Normal muscle biopsy* * hematoxylin and eosin staining

6 Correlation between histology and EMG All patients (n = 37) 38% Correlation EM G vs. histology 62% 19% Histology abnormal Histology normal 43% Abnorm al (n = 23) Norm al (n = 14) 27% 18 EM G exam ination n = EMG exam ination 11% n = 10 Both abnormal 9 n = 7 9 Both norm al False positive EMG n = 4 False negative EMG 0 Abnormal Normal 0 Abnormal Normal EMG vs. histology: p = 0.802

7 Correlation between EMG grading and muscle biopsy (p= 0.442) 45 % Abnormal histology Norm al histology EM G gr ading

8 Results Association between QAMUP score and muscle biopsy outcome was statistically evaluated using contingency tables and the significance of cut-off level for individual quantitative parameters was defined on the basis of comparative evaluation of distribution 1 Significant correlation of quantitative EMG data and myopathic muscle biopsy was found between: Muscle Parameter significance cut-off level Lateral vastus Mean duration of MUPs Mean amplitude of MUPs p= p= cut-off level<700 uv Deltoid Mean duration of MUPs p= cut-off level<8.3 ms 2 3 No correlation was found between cumulative 3-muscle score and myopathic biopsy (p= 0.442). The results of anterior tibial and biceps examination showed no diagnostic value.

9 Results Vastus lateralis muscle: Mean amplitude Cut-off< 700 µv Deltoid muscle: Mean duration p= Pathol Patol Norm Cut-off:< 8.3 ms p = Pathol Patol Norm

10 Conclusion Analysis of selected quantitative MUPs parameters in deltoid and lateral vastus is a useful tool in diagnosing subclinical skeletal muscle involvement in patients with dilated cardiomyopathy or conduction system disease. References Stalberg, E., Bischoff, Ch., Falck, B.: Outliers, a way to detect abnormality in quantitative EMG. Muscle& Nerve 17,1994, p Bischoff, C., Stalberg, E., Falck, B., Edebol EEG-Olofson, K.: Reference values of motor unit action potentials obtainer with multi- MUAP analysis. Muscle&Nerve 17, 1994, p