| 1. |
- Amandusson, Åsa, et al.
(author)
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Diagnostic Utility of Repetitive Nerve Stimulation in a Large Cohort of Patients With Myasthenia Gravis
- 2017
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In: Journal of clinical neurophysiology. - : Lippincott Williams & Wilkins. - 0736-0258 .- 1537-1603. ; 34:5, s. 400-407
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Journal article (peer-reviewed)abstract
- PURPOSE: Optimizing the diagnostic utility of repetitive nerve stimulation in myasthenia gravis (MG) may include tailoring the examination to clinical phenotype. Therefore, we analyzed all available repetitive nerve stimulation parameters in a large cohort of patients with confirmed MG diagnosis.METHODS: All repetitive nerve stimulation examinations at the Uppsala University Hospital rendering an MG diagnosis during 1996 to 2014 were analyzed. The deltoid, trapezius, anconeus, nasalis, abductor digiti quinti, and frontalis muscles were examined.RESULTS: Two hundred one patients with MG were diagnosed. Abnormal amplitude decrement was found in 54% of patients with ocular MG, 77% of patients with predominantly bulbar fatigue, and in 83% of patients with predominantly limb fatigue. The deltoid muscle had the highest sensitivity in all MG subtypes, with a mean of 77% sensitivity in all clinical subtypes, and the most pronounced decrement for amplitude (P = 0.0002) and area (P < 0.0001). Technical issues were rare.CONCLUSIONS: These data contribute to further optimization of repetitive nerve stimulation strategies regarding muscle selection and technical performance in the electrodiagnostic workup of MG.
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| 2. |
- Axelson, Hans W.
(author)
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Compound Motor Action Potential Interexaminer Variability in Photoguided Placement of the Recording Electrodes
- 2012
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In: Journal of clinical neurophysiology. - 0736-0258 .- 1537-1603. ; 29:3, s. 256-259
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Journal article (peer-reviewed)abstract
- Interpretation of neurographic data in follow-up studies of patients with neuromuscular disease is sometimes challenging because of the expected variability in repeated tests. In this study, we explored whether the interexaminer variability of the compound motor action potential (CMAP) amplitude is reduced if the examiner is guided by the previously taken photographs of the position of the recording electrodes. The CMAPs were recorded from 20 subjects by unilateral distal stimulation of the median, ulnar, peroneal, and tibial nerve by 4 different technicians. All the subjects were examined on 2 occasions (similar to 1 week apart). On the first occasion, the technicians recorded the CMAP values according to routine protocols. On the second occasion, the technicians had additional guidance from photographs displaying the recording electrode positions from the first study. The CMAP coefficient of variation (CoV) was calculated for each nerve examined by the four technicians. Differences in CoV between the two types of tests (i.e., with or without photographs) were evaluated. When the examiners were guided by the photographs during electrode application, the CMAP CoV for the tibial innervated abductor hallucis (AH) muscle was reduced (P = 0.02) from 18.5% to 13%. There were, however, no significant reductions in CoV for the abductor pollicis brevis (APB, P = 0.23, median nerve), abductor digiti minimi (P = 0.37, ulnar nerve), or extensor digitorum brevis (EDB, P = 0.15, peroneal nerve) muscles. Photographic documentation of the CMAP recording electrodes seems to have a limited overall effect on interexaminer variability in a subsequent study.
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| 3. |
- Molin, Carl Johan, et al.
(author)
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Compound Motor Action Potential : Electrophysiological Marker for Muscle Training
- 2016
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In: Journal of clinical neurophysiology. - 0736-0258 .- 1537-1603. ; 33:4, s. 340-345
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Journal article (peer-reviewed)abstract
- Purpose:The compound motor action potential (CMAP) represents the summated action potentials of all stimulated motor endplates and potentially reflects muscle hypertrophy and increased muscle contractions. Since electrophysiological biomarkers for high-resistance strength training are lacking, the authors evaluated whether the CMAP of distal and proximal muscles differs between healthy men and women who perform and do not perform high-resistance muscle training.Methods:Motor neurography was performed with stimulation of the median nerve (recording of abductor pollicis brevis muscle), peroneal nerve (recording of extensor digitorum brevis muscle), femoral nerve (recording of rectus femoris muscle) and musculocutaneous nerve (recording of biceps brachii muscle), and isometric muscle strength, measured with a hand-held dynamometer, were performed on 83 healthy subjects (52 women).Results:Trained women had 25% higher CMAP amplitude in the rectus femoris muscle than untrained women (P < 0.001), whereas CMAP amplitude in the trained male cohort was 25% higher in the biceps (P = 0.005) compared with untrained men. In the trained group, CMAP amplitude in the biceps correlated with isometric muscle strength (R = 0.30; P = 0.046).Conclusions:The authors' propose the CMAP as an objective neurophysiological parameter for proximal muscle status and training effects in future interventional studies of patients with neuromuscular disorders.
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| 4. |
- Nandedkar, Sanjeev D., et al.
(author)
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Cumulative Motor Index : An Index to Study Progression of Amyotrophic Lateral Sclerosis
- 2015
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In: Journal of clinical neurophysiology. - 0736-0258 .- 1537-1603. ; 32:1, s. 79-85
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Journal article (peer-reviewed)abstract
- Purpose:To study disease progression in patients with amyotrophic lateral sclerosis (ALS), we have developed the cumulative motor index (CMI) using the compound muscle action potential amplitude recorded in multiple upper and lower limb muscles.Methods:To study its reproducibility, CMI was measured by 2 operators in 10 healthy subjects on 2 occasions. In 15 patients with ALS, CMI and ALS functional rating score (revised) were measured at 3- to 6-month interval for 12 months or longer.Results:The CMI had good reproducibility in healthy subjects. In one patient with ALS, CMI and ALS functional rating score (revised) remained relatively unchanged. In all remaining 14 patients with disease progression, CMI decreased in a relatively monotonic manner. At 1 year after baseline study, CMI was reduced more than ALS functional rating score (revised) in 10 patients. CMI measurements were possible for longer time period, than analysis from a single distal muscle recording.Conclusions:The CMI can be measured using standard equipment and software available in most electrodiagnostic laboratories. This may be a simple measurement that can be used for clinical studies of ALS progression over longer time periods.
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| 5. |
- Tilki, Hacer Erdem, et al.
(author)
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Effect heating on nerve conduction in carpal tunnel syndrome
- 2004
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In: Journal of clinical neurophysiology. - 0736-0258 .- 1537-1603. ; 21:6, s. 451--456
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Journal article (peer-reviewed)abstract
- The effect of temperature on normal nerves is well known, i.e., an increase in conduction velocity and a decrease in amplitude with an elevation in temperature. There are few reports examining the effect of temperature on abnormal nerves, e.g., in demyelination. To study the effect of increased temperature on demyelinating nerves in entrapment syndromes, the authors investigated 55 median and 48 ulnar nerves of 48 patients with carpal tunnel syndrome, and 48 median and 48 ulnar nerves of 26 healthy subjects. All measurements were obtained at 32[degrees]C and 37[degrees]C. Mean reductions in median sensory amplitude occurring with heating were significantly greater in the patient group than in the control group (P = 0.000). For median sensory response amplitude, the mean decrease was 32.1% in patients with carpal tunnel syndrome and 10.7% in the control subjects. The difference between median and ulnar nerves in the latency was significantly decreased (P = 0.027) after the nerves had heated to 37[degrees]C. It is concluded that the elevation in temperature leads to conduction block in demyelinated sensory nerves, and that temperature provocation may be useful in the diagnosis of nerve disorders. The effect may be different in axonal and demyelinating disorders.
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| 6. |
- Cronberg, Tobias
(author)
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Should Postanoxic Status Epilepticus Be Treated Agressively? Yes!
- 2015
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In: Journal of Clinical Neurophysiology. - 1537-1603. ; 32:6, s. 449-451
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Research review (peer-reviewed)abstract
- Cardiac arrest is common and has a high mortality rate. For resuscitated patients, the development of hypoxic-ischemic brain injury is the major culprit. Withdrawal of life-sustaining therapy is the cause of death for majority of patients with presumed severe brain injury, and assessment of prognosis should be evidence based and multimodal. Postanoxic status epilepticus is not an established criterion of a poor neurologic prognosis, and a good outcome is possible. Patients with postanoxic status epilepticus should therefore be actively treated with prolonged intensive care including antiepileptic and sedative agents to suppress seizure activity, if reliable indicators of a poor prognosis are absent.
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| 10. |
- Quiroz, Matias, et al.
(author)
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The Block-Poisson Estimator for Optimally Tuned Exact Subsampling MCMC
- 2021
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In: Journal of Computational And Graphical Statistics. - : Informa UK Limited. - 1061-8600 .- 1537-2715. ; 30:4, s. 877-888
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Journal article (peer-reviewed)abstract
- Speeding up Markov chain Monte Carlo (MCMC) for datasets with many observations by data subsampling has recently received considerable attention. A pseudo-marginal MCMC method is proposed that estimates the likelihood by data subsampling using a block-Poisson estimator. The estimator is a product of Poisson estimators, allowing us to update a single block of subsample indicators in each MCMC iteration so that a desired correlation is achieved between the logs of successive likelihood estimates. This is important since pseudo-marginal MCMC with positively correlated likelihood estimates can use substantially smaller subsamples without adversely affecting the sampling efficiency. The block-Poisson estimator is unbiased but not necessarily positive, so the algorithm runs the MCMC on the absolute value of the likelihood estimator and uses an importance sampling correction to obtain consistent estimates of the posterior mean of any function of the parameters. Our article derives guidelines to select the optimal tuning parameters for our method and shows that it compares very favorably to regular MCMC without subsampling, and to two other recently proposed exact subsampling approaches in the literature. Supplementary materials for this article are available online.
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