Standards for quantification of EMG and neurography.

This document is an update and extension of ICCN Standards published in 1999. It is the consensus of experts on the current status of EMG and Neurography methods. A panel of authors from different countries with different approach to routines in neurophysiological methods was chosen based on their particular interest and previous publications. Each member of the panel submitted a section on their particular area of interest and these submissions were circulated among the panel members for edits and comments. This process continued until a consensus was reached. The document covers EMG topics such as conventional EMG, Macro EMG, applications of surface EMG and electrical impedance myography. Single Fiber EMG is not included, since it is the topic in a separate IFCN document. A neurography section covers topics such as motor and sensory neurography, F wave recordings, H-reflex, short segment recordings, CMAP scan and motor unit number methods. Other sections cover repetitive nerve stimulation and Pediatric electrodiagnostic testing. Each method includes a description of methodologies, pitfalls, and the use of reference values. Clinical applications accompany some of these sections.

Nerve conduction study of the three supraclavicular nerve branches.

INTRODUCTION: We describe a new nerve conduction study technique with reference values for the 3 branches of the supraclavicular nerve (SCN) in young healthy subjects and application of it in 2 patients. METHODS: The recording electrode was placed on the posterior border of the sternocleidomastoid muscle, 6-7 cm from the sternoclavicular joint. SCN branches were stimulated below the clavicle, 2.5, 7, and 10.5 cm lateral to the sternoclavicular joint. RESULTS: Twenty healthy volunteers (10 men), 19-38 years, mean 25.9 years (SD 6.3), and 2 patients with SCN lesions were studied. The mean conduction velocities of the SCN branches were 70-78 m/s (SD 8-10 m/s), and amplitudes 3-4 µV (SD 0.9-2.0 µV). There were no side-to-side or gender differences. DISCUSSION: The 3 SCN branches could be studied in all subjects. We provide reference values for young subjects. This new method was useful in verifying SCN lesions in 2 patients. Muscle Nerve 58: 300-303, 2018.

The effect of surgery in encephalopathy with electrical status epilepticus during sleep.

PURPOSE: We analyzed clinical and electroencephalography (EEG) outcomes of 13 patients with pharmacoresistant encephalopathy with electrical status epilepticus during sleep (ESES) following epilepsy surgery. METHODS: All patients had symptomatic etiology of ESES and preoperative neuropsychological deterioration. Ten patients had daily atypical absences. Clinical outcome was assessed at 6 months and at 2 years after surgery. Clinical and EEG data were reviewed retrospectively. The spike propagation pattern and area and source strength in source montage were analyzed from preoperative and postoperative EEG studies. KEY FINDINGS: Preoperative sleep EEG showed electrical status epilepticus during sleep (SES) with one-way interhemispheric propagation in nine patients and with two-way interhemispheric propagation in four. The age of the patients at the time of surgery ranged from 3.6-9.9 years. Focal resection (two patients) or hemispherotomy (one patient with postoperative EEG) either terminated SES or restricted the discharge to one region. Either reduced SES propagation area or source strength was found in four of eight callosotomy patients with postoperative EEG. Of patients who had seizures preoperatively, Engel class I-II seizure outcome was observed in two of three children after focal resection or hemispherotomy and in two of eight children after callosotomy. None of these patients with Engel class I-II outcome had SES with two-way interhemispheric propagation on preoperative EEG. Cognitive deterioration was halted postoperatively in all except one patient. Cognitive catch-up of more than 10 IQ points was seen in three patients, all of whom had shown a first measured IQ of >75. SIGNIFICANCE: Patients with pharmacoresistant ESES based on symptomatic etiology may benefit from resective surgery or corpus callosotomy regarding both seizure outcome and cognitive prognosis.

Neuropathic symptoms and findings in women with Fabry disease.

OBJECTIVE: To examine the neurologic and neurophysiologic findings and neurologic symptoms in 12 women with Fabry disease and to study the relationship between the subjective symptoms and the findings on the various tests done. METHODS: Neurography, vibratory and thermal quantitative sensory testing (QST), skin biopsy for measuring intraepidermal nerve fiber density (IENFD). Heart rate variability (HRV) and sympathetic skin response (SSR) tests for detecting autonomic dysfunction, pain-, depression- and somatic symptom questionnaires and clinical examination. RESULTS: Only two women had no persistent symptoms or signs of polyneuropathy, 10 had symptoms of small fiber neuropathy. Neurological examination was normal in most patients. Five patients had decreased IENFD or thermal hypoesthesia in QST. In QST, Adelta-fiber function for innocuous cold was more often impaired than C-fiber function. Conventional nerve conduction studies were mostly normal. Carpal tunnel syndrome (CTS) incidence was increased, 25% had symptomatic CTS. CONCLUSIONS: Heterozygous women carrying the gene for Fabry disease have symptoms and findings of small-fiber polyneuropathy more often than has previously been considered. The prevalence of CTS is also increased. SIGNIFICANCE: While the clinical diagnosis of small-fiber neuropathy is difficult, the diagnostic yield can be increased using a combination of thermal QST and IENFD measurements.

Well-tolerated chemoprophylaxis uniformly prevented Swedish soldiers from Plasmodium falciparum malaria in Liberia, 2004-2006.

BACKGROUND: Between 2004 and 2006, 1,170 Swedish soldiers were deployed to Liberia. They were prescribed mefloquine or atovaquone/proguanil as malaria chemoprophylaxis. Our study aims were to estimate the chemoprophylaxis effectiveness and adverse events. METHODS: Cases of malaria were routinely reported during and after the mission. After return to Sweden, the soldiers filled in a questionnaire concerning type of accommodation, use of prophylaxis, and adverse events. RESULTS: No cases of Plasmodium falciparum malaria were recorded during a total of approximately 7,000 person-months. Adverse events (AE) were reported by 57% in the mefloquine group and 34% in the atovaquone/proguanil group. In the mefloquine group, the soldiers reported more neuropsychological AE. CONCLUSIONS: Both drugs were safe and 100% effective as long-term prophylaxis for prevention of P. falciparum malaria. Atovaquone/ proguanil was better tolerated with respect to self-reported AE.

Occurrence of A-waves in F-wave studies of healthy nerves.

A-waves are compound muscle action potentials that follow the M-wave with a constant shape and latency; usually they are detected during F-wave studies. A large reference value database for F-wave parameters from the median, ulnar, peroneal, and tibial nerves was collected from 121-196 subjects aged 14 to 95 years without known pathology involving the studied nerves. From this material, we studied retrospectively the occurrence of A-waves. To be included, an A-wave had to be clearly discriminated from the baseline in at least 8 of 20 traces with a jitter of less than 0.5 ms. A-waves occurred in 25% of the tibial nerves studied and 14% of the peroneal nerves but in only 2% of median and ulnar nerves. In the peroneal and tibial nerves, the frequency of A-waves increased with age, suggesting that A-waves may be related to normal age-related mild neuropathic changes of alpha motor neurons. Thus, A-waves are frequently found in lower-extremity nerves in healthy subjects and less commonly in upper-extremity nerves. Their presence must therefore be interpreted with caution and cannot be taken as necessarily indicative of abnormality.

Reference values of F wave parameters in healthy subjects.

OBJECTIVE AND METHODS: A large reference value database for F wave parameters was constructed with data from 121 to 196 healthy subjects; the age range of the subjects was 14-95 years. We studied the following parameters: minimum F wave latency (FMINLAT), mean F wave latency (FMEANLAT), maximum F wave latency (FMAXLAT), number of F waves/20 stimuli (FNUMBER) and F wave dispersion (FDISP=FMAXLAT-FMINLAT). The median, ulnar, peroneal and tibial nerves were studied. RESULTS: Height explains almost half of the FMINLAT variability. The F wave latency increases with height in the arms by 0.2 ms/cm and in legs 0.4 ms/cm. The effect of age on F wave latency in the arms is relatively small, only 0.03 ms/year; and in the legs age increases the FMINLAT by 0.1 ms/year. Gender does not affect FMINLAT in a systematic way. The peroneal nerve has slightly longer FMINLAT than the tibial nerve, while the FNUMBER is higher in the tibial nerve than the peroneal nerve. The differences between the ulnar and median nerve are slight. There is a very high correlation between all 3 latency parameters (FMINLAT, FMAXLAT and FMEANLAT), but no correlation between FDISP and FNUMBER and the other parameters. Side to side comparisons reveals no significant differences in any of the parameters except for the median nerve FMINLAT and FMEANLAT, which is 0.2 ms longer on the right than left. If side difference of more than 2 standard deviation is taken as the upper limit for normal, the side difference in arms is 1.4 ms and in legs 3 ms. In repeated studies the interexaminer variability is small; the correlation coefficient between the different F parameters is high (P>0.6 in arms and P>0.7 in legs). In the arms the upper limit for a significant difference of FMINLAT on repeated studies in the median nerve is 1.0 and 1.7 ms for the ulnar nerve. In the legs, FMINLAT for the peroneal nerve is 2.6 ms and for the tibial nerve is 2.1 ms. CONCLUSIONS: This large reference value database can be used not only to evaluate single measurements in relation with height and age, but also to compare right and left side and changes over time at repeated studies.

Anomalous superficial radial nerve: a patient with probable autosomal dominant inheritance of the anomaly.

The sensory symptoms due to lesions of the superficial branch of the radial nerve are usually limited to the dorsolateral area of the hand. We describe a 40-year-old woman who presented with numbness of the dorsomedial aspect of the right hand following arthroplasty of the wrist. Clinically, the sensory loss suggested a lesion of the dorsal branch of the ulnar nerve. However, nerve conduction studies showed that the sensory loss was due to a lesion of a branch of the superficial branch of the radial nerve. The patient had bilateral, anomalous innervation of the dorsum of the hand-the dorsal branch of the ulnar nerve could not be demonstrated with nerve conduction techniques and the superficial branch of the radial nerve innervated most of the dorsum of the hand. Antidromic stimulation of the dorsal branch of the ulnar nerve and superficial branch of the radial nerve with paired surface recording of sensory nerve action potentials from the dorsolateral (radial side) and dorsomedial (ulnar side) hand is useful for evaluating this anomaly. Our patient had two children, one of them with a similar anomaly. This suggests an autosomal dominant inheritance of the anomaly.

Neurophysiologic parameters and symptoms in chronic renal failure.

We studied: (1) the sensitivity of various neurophysiologic parameters in the diagnosis of uremic polyneuropathy, (2) the relationship between subjective symptoms and neurophysiologic parameters, and (3) the effect of a single hemodialysis on the neurophysiologic parameters in 21 patients undergoing hemodialysis. The following parameters were studied: sensory and motor nerve conduction, including F-wave parameters; vibration detection thresholds; and thermal thresholds. The clinical findings and subjective symptoms were studied using a standardized questionnaire. The most sensitive parameters in the diagnosis of uremic neuropathy were F-wave parameters from lower limbs, vibration detection thresholds from the feet, and the sural nerve sensory action potential amplitude. The nerves from the upper extremities on the side of the fistula should not be used in the diagnosis of uremic polyneuropathy due to numerous mild local nerve lesions. The positive neuropathic symptoms correlated with quantitative vibratory detection thresholds and sensory nerve conduction studies, especially the amplitude of the sensory nerve action potential in the sural nerve. We found no significant change in any of the neurophysiologic parameters following a single hemodialysis session.

Electrophysiological findings in X-linked myopathy with excessive autophagy.

We report electrophysiological features and magnetic resonance imaging muscle findings in 4 patients and 1 female carrier of X-linked myopathy with excessive autophagy. Motor units were polyphasic with high mean amplitude and normal duration. The thigh muscles were most severely involved, but myotonic discharges were abundant in both clinically affected and unaffected muscles. Along with the clinicopathological features, these electrophysiological findings distinguish X-linked myopathy with excessive autophagy from other limb-girdle myopathies.

Multi-MUP analysis of laryngeal muscles.

We performed quantitative motor unit potential (MUP) analysis of the thyroarytenoid (TA) and cricothyroid (CT) muscles, using multi-MUP-analysis in 40 healthy volunteers. The method is well tolerated, easy to perform, and examination of one muscle takes 5-10min. The mean MUP amplitude of both muscles was significantly larger in men than in women. The method can safely be used in clinical routine.