Determinants and clinical application of muscle fibre conduction velocity.

Contains fulltext : 52347.pdf (publisher's version ) (Open Access)A muscle fibre can be excited by electrical stimulation using a needle electrode. Action potentials elicited this way will be conducted through the muscle fibre and can be recorded at some distance with a second needle electrode. This way, muscle fibre conduction velocity can be estimated. In the present study we have investigated the determinants of conduction velocity in healthy subjects and in patients with various neuromuscular disorders. Our main result was a linear relationship between conduction velocity and fibre diameter that we demonstrated in both groups, using data obtained from muscle biopsies. Furthermore, we evaluated the diagnostic value of the technique to measure muscle fibre conduction velocity with needle electrodes. Our findings showed that the diagnostic value was similar to those of the reference techniques, which were electromyography and muscle biopsy. In some myopathies, such as mitochondrial myopathies, channelopathies, and early motor neuron disease, our technique rendered superior results. In conclusion, this thesis contributes to the knowledge of muscle fibre physiology, and clarifies the use of an invasive technique to measure conduction velocity in electrodiagnosis.RU Radboud Universiteit Nijmegen, 14 december 2007Promotores : Zwarts, M.J., Stegeman, D.F. Co-promotor : Schelhaas, H.J.166 p

Recognising F-response interference as a source of increased jitter in stimulated single fibre EMG.

Contains fulltext : 50499.pdf (publisher's version ) (Closed access

Motor nerve decline does not underlie muscle weakness in type 2 diabetic neuropathy.

Item does not contain fulltextINTRODUCTION: Type 2 diabetes mellitus (DM2) patients may have decreased muscle strength. This decline can have multiple causes, among them diabetic polyneuropathy (DPN). We sought to determine the effect of nerve deterioration on muscle strength in DM2 patients with and without DPN. METHODS: Nineteen DM2 patients with DPN (DPN group), 15 DM2 patients without DPN (DC group), and 18 healthy subjects (HC group) were recruited. We determined motor and sensory nerve function of the lower extremity. Isometric dynamometry was performed to determine maximum torque of the ankle joint. RESULTS: The DPN group had significantly diminished nerve function and muscle strength (P < 0.05) compared with both other groups. Only muscle strength was lower in DC subjects compared with HCs. No significant correlations were found between nerve function and muscle strength. CONCLUSION: These results indicate that reduced ankle joint torque in DM2 patients with and without DPN is independent of the presence of disturbed nerve function.1 augustus 201

Diagnostic yield of muscle fibre conduction velocity in myopathies

Item does not contain fulltextWe prospectively assessed diagnostic yield of muscle fiber conduction velocity (MFCV) studies in patients with signs and symptoms suggestive of a myopathy. Results were analysed with respect to the final diagnosis, and compared to the reference standard, which was qualitative electromyography (EMG), turns-amplitude analysis (TAA), and muscle biopsy. We included 125 patients, in whom a myopathy was diagnosed in 71, and a neuromuscular disorder was excluded in 54. Sensitivity of MFCV for the presence of a myopathy was 84%, and specificity 83%. Diagnostic yield of MFCV was superior to EMG, TAA, and muscle biopsy in patients with metabolic myopathies, non-dystrophic myopathies, and channelopathies. We concluded that measurement of MFCV is a quantitative EMG technique with a high diagnostic yield. In certain myopathies, MFCV may be more informative than conventional EMG examination

The relation between muscle fiber conduction velocity and fiber size in neuromuscular disorders

To determine the relation between muscle fiber conduction velocity (MFCV) and muscle fiber diameter (MFD) in pathological conditions, we correlated invasively measured MFCV values with MFD data obtained from muscle needle biopsies in 96 patients with various neuromuscular disorders. MFCV was significantly correlated with MFD and independent of the underlying disorder. Pathological diameter changes were fiber-type dependent, with corresponding MFCVs. A linear equation expresses the relation well: MFCV (m/s) = 0.043·MFD (μm) + 0.83. We conclude that fiber diameter determines MFCV largely independent of the underlying neuromuscular disorders studied. Copyright © 2006 the American Physiological Society

Successful treatment of respiratory dysfunction in cystinosis by nocturnal non-invasive positive pressure ventilation.

Cystinosis is a rare metabolic disorder characterized by lysosomal cystine accumulation leading to multi-organ damage, with kidneys being clinically first affected. Longer survival of cystinosis patients due to successful renal replacement therapy, revealed previously unknown extra-renal symptoms of cystinosis, generally appearing after the first decade. Respiratory insufficiency caused by overall respiratory muscle myopathy is a severely invalidating and sometimes a life-threatening complication of cystinosis. We report a successful treatment of hypoventilation, due to diaphragm myopathy in a cystinosis patient, by nocturnal non-invasive positive pressure ventilation (NIPPV). After initiation of NIPPV the clinical condition of the patient improved and blood-gasses normalized, indicating that this treatment modality should be considered in cystinosis patients with severe respiratory insufficiency

Successful treatment of respiratory dysfunction in cystinosis by nocturnal non-invasive positive pressure ventilation.

Item does not contain fulltextCystinosis is a rare metabolic disorder characterized by lysosomal cystine accumulation leading to multi-organ damage, with kidneys being clinically first affected. Longer survival of cystinosis patients due to successful renal replacement therapy, revealed previously unknown extra-renal symptoms of cystinosis, generally appearing after the first decade. Respiratory insufficiency caused by overall respiratory muscle myopathy is a severely invalidating and sometimes a life-threatening complication of cystinosis. We report a successful treatment of hypoventilation, due to diaphragm myopathy in a cystinosis patient, by nocturnal non-invasive positive pressure ventilation (NIPPV). After initiation of NIPPV the clinical condition of the patient improved and blood-gasses normalized, indicating that this treatment modality should be considered in cystinosis patients with severe respiratory insufficiency

Head orientation and electrode placement potentially influence fetal scalp ECG waveform

Contains fulltext : 215804.pdf (publisher's version ) (Open Access)BACKGROUND: Fetal monitoring based on electrocardiographic (ECG) morphology is obtained from a single unipolar fetal scalp electrode. Ideally, it should be obtained from multiple leads, as ECG waveform depends on alignment between electrode and electrical heart axis. This alignment is unknown in fetuses. Besides, fetuses are surrounded by conductive media, which may influence ECG waveform. We explored the influence of electrode position and head orientation on ECG waveforms of unipolar and bipolar scalp ECGs recorded in air and in conductive medium. METHODS: We recorded ECGs in one adult subject at five different scalp positions in five different head orientations both in dry and immersed conditions. The ratio between T-amplitude and QRS-amplitude (T/QRS ratio) of unipolar and bipolar scalp ECGs was determined and compared between all conditions. RESULTS: In the dry condition, we observed in the unipolar leads little to no difference between different electrode positions (maximal T/QRS difference 0.00-0.01) and minor differences between head orientations (0.02-0.03), whereas bipolar leads showed no recognizable ECG signal at all. During the immersed condition, we found variation in the unipolar leads, both between electrode positions (maximal T/QRS difference 0.02-0.05) and between head orientations (0.03-0.06). Bipolar leads showed different ECG signals in contrasting head orientations. CONCLUSIONS: Both unipolar and bipolar scalp lead-derived ECG waveforms are influenced by electrode position and head orientation when the subject is submerged in a conductive medium. Fetal monitoring based on single scalp lead ECG waveform might be suboptimal, as it lacks correction for fetal head orientation and electrode position

Symptomatic distal myopathy with cardiomyopathy due to a MYH7 mutation.

Contains fulltext : 52264timmermans.pdf (publisher's version ) (Closed access)Mutations in the myosin heavy chain gene (MYH7) can cause several distinct phenotypes depending on the location of the mutation: hypertrophic cardiomyopathy (several exons), myosin storage myopathy (exon 37/39) or Laing distal myopathy (exons 32-36). Here, we describe a unique combination of hypertrophic cardiomyopathy and hypertrophic distal myopathy in a family with a MYH7 Val606Met mutation (exon 16)