M. Baris Baslo

Concentric needle electrode for neuromuscular jitter analysis

We used a concentric needle electrode (CNE) with 2 kHZ low‐cut filter and a single fiber electrode (SFE) in the same subjects for neuromuscular jitter measurement in the extensor digitorum communis (EDC) and orbicularis oculi (OOc) muscles. At the same session, 20 jitter values were obtained from each subject with each electrode. For EDC (during voluntary contraction), mean jitter values with SFE and CNE were 23.4 ± 8 μs and 23.3 ± 8 μs in 10 normals; and 56.8 ± 28 μs and 57.4 ± 33 μs in 10 myasthenics. For OOc (during electrical stimulation), mean jitter values with SFE and CNE were 17.9 ± 5 μs and 16.3 ± 4 μs in 11 normal subjects, and 41.2 ± 29 μs and 36.7 ± 27 μs in 10 myasthenics. For both muscles, the numbers of individual abnormal jitter values with SFE and CNE were highly comparable. Both needles labeled the same patients as having “normal” or “abnormal” neuromuscular transmission. CNE may be an alternative to SFE in neuromuscular jitter analysis.

Classification of Juvenile Myoclonic Epilepsy Data Acquired Through Scanning Electromyography with Machine Learning Algorithms

In this paper, classification of Juvenile Myoclonic Epilepsy (JME) patients and healthy volunteers included into Normal Control (NC) groups was established using Feed-Forward Neural Networks (NN), Support Vector Machines (SVM), Decision Trees (DT), and Naïve Bayes (NB) methods by utilizing the data obtained through the scanning EMG method used in a clinical study. An experimental setup was built for this purpose. 105 motor units were measured. 44 of them belonged to JME group consisting of 9 patients and 61 of them belonged to NC group comprising ten healthy volunteers. k-fold cross validation was applied to train and test the models. ROC curves were drawn for k values of 4, 6, 8 and 10. 100% of detection sensitivity was obtained for DT, NN, and NB classification methods. The lowest FP number, which was obtained by NN, was 5.

Compound muscle action potential analysis in different death models: significance for the estimation of early postmortem interval

In this experimental study, we investigated the varieties of excitability of gastrocnemius muscle via sciatic nerve as per different death models (asphyxia, abundant-bleeding and gradual-bleeding) on rats and the significance for the estimation of postmortem interval was evaluated. For this purpose, the rats were applied different stimulus intensities (5, 20, 40 mA) with 0.1 ms duration, before, during and every 5 min after death, using rectangular impulses, and the mean amplitude, onset latency and area values for each compound muscle action potential (CMAP) were elicited. It was detected that amplitude and area increased and onset latencies prolonged in the first postmortem 15 min. From the 15 min, CMAP area and amplitude showed an ever-increasing decrease and the prolongation of onset latencies became apparent. The decrease rate of area and amplitude was found to be statistically significantly different in asphyxia and abundant-bleeding models compared with in gradual-bleeding model, at 30 min measurements. However, there was not any significant difference in onset latency increase rates of three groups. Separately, any significant correlation between the agony and excitability periods among the groups could not be detected. The fact that the increase rate of onset latency did not show a significant difference as per death models indicated that onset latency ratios would be more appropriate criteria in determination of postmortem interval, regardless the reason of death.

Decrement pattern in Lambert–Eaton myasthenic syndrome is different from myasthenia gravis

The decrement pattern at low rates of repetitive nerve stimulation in myasthenia gravis (MG) is characterized by a decrease of compound muscle action potential size within the first 4-5 responses. With subsequent stimuli, compound muscle action potential size either increases or does not change. Following an observation that the pattern of decrement might be different in patients with Lambert-Eaton myasthenic syndrome (LEMS), we retrospectively studied traces from eight LEMS patients and 14 patients with seropositive generalized MG, calculating decrement percent from first to fourth and from first to ninth compound muscle action potential. In the LEMS patients, compound muscle action potential amplitude decreased progressively from first to ninth stimulus at 2, 3 or 5Hz in all traces but one. In contrast, MG patients demonstrated the expected improvement after the initial decrement in all traces except one. In the evaluation of patients suspected of having myasthenia gravis, the finding of progressive decrement pattern at low rates of repetitive nerve stimulation may alert the electromyographer to the possibility of Lambert-Eaton syndrome and prompt the performance of further electrodiagnostic tests.

Abnormal neuromuscular transmission in cluster headache.

Objective.—To identify and investigate any dysfunction of neuromuscular transmission in episodic cluster headache.

Excitability changes at brainstem and cortical levels in blind subjects.

OBJECTIVES This study was designed to search potential changes in trigemino-facial system in blind subjects by the use of relatively well-established electrophysiological methods. Excitability changes in the motor cortex were also investigated by transcranial magnetic stimulation studies (TMS) with the expectation of finding some abnormal interactions between the cortex and brainstem. METHODS Twenty blind (BS) and 13 control subjects (CoS) were included in the study. Blink reflex and its recovery with paired electrical stimulation were studied at 150, 200, 300, 400 and 500 ms interstimulus intervals (ISI). Facial F waves elicited by buccal branch stimulation were recorded from nasalis muscles. Motor cortex excitability with recordings from left first dorsal interosseus muscle was studied by using magnetically elicited silent periods and paired magnetic stimuli, subthreshold conditioning and suprathreshold test, given at ISIs of 2, 3, 4, 10, 12, 15 and 20 ms. RESULTS Blink reflex recovery was significantly reduced in BS group comparing to CoS at 400 and 500 ms ISIs. This difference between the groups was more prominent for the responses evoked by the initial stimulation side and faded away with stimulations on the contralateral side. Facial F wave amplitudes and F/M amplitude ratios were higher in BS group. In TMS studies, the early inhibitions at 2 and 4 ms were found to be significantly less in BS as compared to that of CoS. CONCLUSIONS The reduced blink reflex recovery and its fast restoration with continuing stimulation might be explained by conditioning and extinction processes which have been shown to be mainly carried out by cerebellar-brainstem pathways. Our TMS studies showed reduced intracortical inhibition in the motor cortices of BS cases and facial F wave studies revealed the possible effect of this altered excitability on the facial motor nuclei. SIGNIFICANCE Firing probabilities of facial motor neurons in BS are probably determined by the equilibrium between the low-set excitability of blink reflex interneurons and the enhanced excitability brought on by the descending motor pathways.

Effect of triggering potential on calculations of jitter in single-fiber EMG.

Jitter values are calculated in reference to a triggering potential during single‐fiber electromyography (SFEMG) performed during voluntary contraction. When there are more than two single‐fiber action potentials (SFAP) and the selected triggering potential is from an abnormal end‐plate, all the jitters calculated from the same trace will be affected. In this study, the effect of triggering potential on calculated jitter was investigated in myasthenic and healthy volunteers by switching the triggering potential and recalculating the jitter off‐line. Selecting a triggering potential from an abnormal end‐plate increased the number of abnormal individual jitters as well as the mean jitter. Therefore, if the equipment software has the capacity to change the trigger potential, the triggering potential should not be from an abnormal end‐plate if all possible jitter values are to be calculated for traces having three or more single‐fiber potentials. Otherwise, only one jitter value should be included from any one trace to prevent false‐positive results.

Feature extraction and classification of neuromuscular diseases using scanning EMG

In this study a new dataset are prepared for neuromuscular diseases using scanning EMG method and four new features are extracted. These features are maximum amplitude, phase duration at the maximum amplitude, maximum amplitude times phase duration, and number of peaks. By using statistical values such as mean and variance, number of features has increased up to eight. This dataset was classified by using multi layer perceptron (MLP), support vector machines (SVM), k-nearest neighbours algorithm (k-NN), and radial basis function networks (RBF). The best accuracy is obtained as 97.78% with SVM algorithm and 3-NN algorithm.

Interface design for automation of the scanning EMG method

Scanning EMG is a method developed for examining the electro-physiological cross section and the size of the motor unit of a human muscle. Electrical specifications of the motor unit can be obtained as well as anatomical distribution of muscle fibers and pathological changes between different muscles can be examined by the help of this method. In this paper; an automation system which is designed for the execution of scanning EMG method, whether manually or automatically, and a user-interface are described. Parameters like step count and step size which are about the movement of an electrode, moved by a linear actuator, through muscle fibers can be defined as reference by user via designed interface. As a result, acquired signals are digitalized by data-acquisition card (DAQ) and saved as text file for the future signal process tasks.

Surface stimulation single-fiber electromyography in myasthenia gravis.

Summary Surface stimulation for single-fiber electromyography has been proposed previously as a novel technique based on a study performed on healthy subjects. The current study was designed to determine the diagnostic value of surface stimulation single-fiber electromyography in patients with myasthenia gravis. Ten patients with myasthenia gravis were recruited for the study. Surface stimulation of the facial nerve trunk, as well as extramuscular needle stimulation of its zygomatic branch was performed. Twenty single-fiber potentials were recorded from the orbicularis oculi muscle for each stimulation type in each patient. For both stimulation techniques, mean jitter values and the total number of abnormal individual junctions were found to be abnormally high. Jitter values obtained by surface stimulation were comparable with those obtained by needle stimulation.