A shortened surface electromyography recording is sufficient to facilitate home fasciculation assessment

INTRODUCTION/AIMS

Fasciculations are an early clinical hallmark of amyotrophic lateral sclerosis (ALS), amenable to detection by high-density surface electromyography (HDSEMG). In conjunction with the Surface Potential Quantification Engine (SPiQE), HDSEMG offers improved spatial resolution for the analysis of fasciculations. This study aims to establish an optimal recording duration to enable longitudinal remote monitoring in the home.

METHODS

Twenty patients with ALS and five patients with benign fasciculation syndrome (BFS) underwent serial 30 min HDSEMG recordings from biceps brachii and gastrocnemii. SPiQE was independently applied to abbreviated epochs within each 30-min recording (0-5, 0-10, 0-15, 0-20, and 0-25 min), outputting fasciculation frequency, amplitude median and amplitude interquartile range. Bland-Altman plots and intraclass correlation coefficients (ICC) were used to assess agreement with the validated 30-min recording.

RESULTS

In total, 506 full recordings were included. The 5 min recordings demonstrated diverse and relatively poor agreement with the 30 min baselines across all parameters, muscles and patient groups (ICC = 0.32-0.86). The 15-min recordings provided more acceptable and stable agreement (ICC = 0.78-0.98), which did not substantially improve in longer recordings.

DISCUSSION

For the detection and quantification of fasciculations in patients with ALS and BFS, HDSEMG recordings can be halved from 30 to 15 min without significantly compromising the primary outputs. Reliance on a shorter recording duration should lead to improved tolerability and repeatability among patients, facilitating longitudinal remote monitoring in patients' homes.

[Cramps and fasciculations: is it amyotrophic lateral sclerosis?]

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron disease of the adult age. It is an aggressive condition with a mean disease duration of only 3 to 5 years, characterized by progressive weakness and atrophy of limb, bulbar, and respiratory muscles. In general, death is caused by chronic hypoventilation due to respiratory insufficiency. No causal treatment is known today, but the two therapeutic agents authorized in Switzerland for the treatment of ALS can slow disease progression significantly. Other important therapeutic strategies include invasive/non-invasive ventilation, pain therapy, as well as physio-, ergo- and speech therapy on a regular basis.

Denny-Brown and Pennybacker: 80 years after their pioneering article on electromyography, fibrillation and fasciculation

We present a historical review, highlighting the role of Professor Derek Denny-Brown and doctor Joseph Buford Pennybacker in the development of current electromyography (EMG), of the 80 years since the publication of his original report in 1938 on fasciculation and fibrillation potentials and the subsequent studies describing most of the electrical changes necessary to perform and interpret the EMG.

[The cramp-fasciculation-syndrome (CFS)]

The present review focuses on the cramp-fasciculation syndrome, a benign disorder which is regarded as a hyperexcitability syndrome of the peripheral nervous system. The article presents clinical features, pathophysiology, differential diagnosis, therapy and a case report to illustrate the cramp-fasciculation-syndrome.

Fasciculations demonstrate daytime consistency in amyotrophic lateral sclerosis

INTRODUCTION

Fasciculations represent early neuronal hyperexcitability in amyotrophic lateral sclerosis (ALS). To aid calibration as a disease biomarker, we set out to characterize the daytime variability of fasciculation firing.

METHODS

Fasciculation awareness scores were compiled from 19 ALS patients. In addition, 10 ALS patients prospectively underwent high-density surface electromyographic (HDSEMG) recordings from biceps and gastrocnemius at three time-points during a single day.

RESULTS

Daytime fasciculation awareness scores were low (mean: 0.28 muscle groups), demonstrating significant variability (coefficient of variation: 303%). Biceps HDSEMG recordings were highly consistent for fasciculation potential frequency (intraclass correlation coefficient [ICC] = 95%, n = 19) and the interquartile range of fasciculation potential amplitude (ICC = 95%, n = 19). These parameters exhibited robustness to observed fluctuations in data quality parameters. Gastrocnemius demonstrated more modest levels of consistency overall (44% to 62%, n = 20).

DISCUSSION

There was remarkable daytime consistency of fasciculation firing in the biceps of ALS patients, despite sparse and intermittent awareness among patients' accounts.

Identification of muscle fasciculations from surface EMG: comparison with ultrasound-based detection

The clinical standard for the identification of muscle fasciculations is needle electromyography. However, both surface electromyograms (sEMG) and ultrasound imaging (US) have been recently proposed as alternative and more sensitive approaches. The aims of this study were to: (i) compare the sensitivity to muscle fasciculations of sEMG and US, (ii) assess the rate of agreement (RoA) between the two approaches, and (iii) investigate how much sensitivity and RoA are affected by the selectivity of sEMG detection. Surface EMGs were collected concurrently with US images using an array of 32 electrodes spanning the whole, posterior aspect of the leg. Muscle fasciculations were identified from US videos and from monopolar and single differential sEMGs computed between electrodes spaced by 1, 2, and 3 cm. Results from five healthy subjects showed that US detected as many fasciculations as single differential EMGs, but always less than monopolar sEMGs. However, monopolar sEMGs exhibited a very poor spatial selectivity, likely responsible for the small RoA with US measures. The RoA was maximal for single differential recordings with 3cm inter-electrode distance, however, it was always smaller than 75% (median=30%). Although preliminary, these results suggest that sEMG and US are sensitive to different events in the muscle volume and that their integration may increase the detection sensitivity to muscle fasciculations.

Preprocessing surface EMG data removes voluntary muscle activity and enhances SPiQE fasciculation analysis

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A novel preprocessing step removes the need for manual selection of relaxed surface EMG data.

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SPiQE provides reliable fasciculation analysis from raw thirty-minute recordings in ALS.

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This paves the way for clinical calibration of a potential novel biomarker of disease progression.

Objectives

Fasciculations are a clinical hallmark of amyotrophic lateral sclerosis (ALS). The Surface Potential Quantification Engine (SPiQE) is a novel analytical tool to identify fasciculation potentials from high-density surface electromyography (HDSEMG). This method was accurate on relaxed recordings amidst fluctuating noise levels. To avoid time-consuming manual exclusion of voluntary muscle activity, we developed a method capable of rapidly excluding voluntary potentials and integrating with the established SPiQE pipeline.

Methods

Six ALS patients, one patient with benign fasciculation syndrome and one patient with multifocal motor neuropathy underwent monthly thirty-minute HDSEMG from biceps and gastrocnemius. In MATLAB, we developed and compared the performance of four Active Voluntary IDentification (AVID) strategies, producing a decision aid for optimal selection.

Results

Assessment of 601 one-minute recordings permitted the development of sensitive, specific and screening strategies to exclude voluntary potentials. Exclusion times (0.2–13.1 minutes), processing times (10.7–49.5 seconds) and fasciculation frequencies (27.4–71.1 per minute) for 165 thirty-minute recordings were compared. The overall median fasciculation frequency was 40.5 per minute (10.6–79.4 IQR).

Conclusion

We hereby introduce AVID as a flexible, targeted approach to exclude voluntary muscle activity from HDSEMG recordings.

Significance

Longitudinal quantification of fasciculations in ALS could provide unique insight into motor neuron health.

SPiQE: An automated analytical tool for detecting and characterising fasciculations in amyotrophic lateral sclerosis

OBJECTIVES

Fasciculations are a clinical hallmark of amyotrophic lateral sclerosis (ALS). Compared to concentric needle EMG, high-density surface EMG (HDSEMG) is non-invasive and records fasciculation potentials (FPs) from greater muscle volumes over longer durations. To detect and characterise FPs from vast data sets generated by serial HDSEMG, we developed an automated analytical tool.

METHODS

Six ALS patients and two control patients (one with benign fasciculation syndrome and one with multifocal motor neuropathy) underwent 30-minute HDSEMG from biceps and gastrocnemius monthly. In MATLAB we developed a novel, innovative method to identify FPs amidst fluctuating noise levels. One hundred repeats of 5-fold cross validation estimated the model's predictive ability.

RESULTS

By applying this method, we identified 5,318 FPs from 80 minutes of recordings with a sensitivity of 83.6% (+/- 0.2 SEM), specificity of 91.6% (+/- 0.1 SEM) and classification accuracy of 87.9% (+/- 0.1 SEM). An amplitude exclusion threshold (100 μV) removed excessively noisy data without compromising sensitivity. The resulting automated FP counts were not significantly different to the manual counts (p = 0.394).

CONCLUSION

We have devised and internally validated an automated method to accurately identify FPs from HDSEMG, a technique we have named Surface Potential Quantification Engine (SPiQE).

SIGNIFICANCE

Longitudinal quantification of fasciculations in ALS could provide unique insight into motor neuron health.

Small fiber abnormalities in skin biopsies of patients with benign fasciculations

OBJECTIVE

To determine whether patients with benign fasciculations have evidence for axonal loss in skin biopsies.

METHODS

Epidermal sensory and sweat gland nerve fiber densities were quantified in skin biopsies of 11 patients with benign fasciculations and no other known cause for neuropathy.

RESULTS

Nine of the 11 patients (82%) had significantly reduced epidermal or sweat gland nerve fiber densities at the calf or thigh, in comparison with control values.

CONCLUSIONS

The presence of reduced epidermal and sweat gland nerve fiber density indicates the presence of axonal loss in patients with benign fasciculations.

[Role of fasciculation potentials in the diagnosis of amyotrophic lateral sclerosis]

OBJECTIVE

To explore the role of fasciculation potentials in the diagnosis of amyotrophic lateral sclerosis (ALS).

METHODS

A total of 60 ALS patients were recruited from August 2009 to August 2010 at our hospital. Standard examinations of electromyography and nerve conduction were performed. And fasciculation potentials were measured in the resting muscles with a band pass of 20 Hz-10 kHz, a sensitivity of 0.05 - 0.5 mV/D and a sweep speed of 5 ms/D. Each muscle was observed for 1 - 5 minutes. The amplitude, duration and phase of fasciculation potentials were recorded.

RESULTS

The occurrence rate of fasciculation potential in sternocleidomastoid was more than that of fibrillation and positive sharp wave in ALS patients (36.7% vs 13.3%, χ² = 8.71, P < 0.05). The amplitude and duration of fasciculation potentials in ALS patients with a duration of over 18 months were higher than that of those with a duration of under 8 months [(1.8 ± 0.9) mV, (1.0 ± 0.6) mV; (15.2 ± 4.1) ms, (11.2 ± 3.0) ms; q = 3.43, 3.51, P < 0.05)]. The patients with definite ALS might increase if fasciculation potentials were considered as spontaneous potential (80% vs 60%; χ² = 5.71, P = 0.02).

CONCLUSION

With different morphologies at different disease stages, fasciculation potentials may be useful in the earlier diagnosis of amyotrophic lateral sclerosis.

ANCA-related vasculitic neuropathy mimicking motor neuron disease

Several conditions have been reported to mimic motor neuron disease (MND) and misdiagnosis remains a common clinical problem. Peripheral neuropathy is a classic feature of many vasculitic syndromes and in some patients it may be the only manifestation of vasculitis. We report a case of ANCA-related vasculitic neuropathy where the clinical presentation was suggestive of MND. A 42-year-old woman was admitted to our centre to confirm a diagnosis of MND made elsewhere. Clinical examination revealed postural tremor at the right hand, mild tongue atrophy with diffuse fasciculations and brisk tendon reflexes without other muscular weakness or atrophies. Electromyography demonstrated denervation in tongue and in the first dorsal interosseous of right hand ; motor evoked potentials disclosed normal central motor conduction time. Laboratory studies revealed only a mild increase of p-ANCA. A muscle biopsy showed a small inflammatory infiltrate around a vessel. The patient started high dosage of oral steroids. After one year of follow-up the patient suspended oral steroids, postural tremor of the right hand disappeared and tongue fasciculations were reduced. Vasculitis may mimic a MND, particularly in the absence of sensory involvement. Caution should be exercised in the clinical diagnosis of MND. Muscle biopsy is indicated in patient with atypical MND especially in those with an exclusive involvement of lower motor neuron.

Reliability of a novel neurostimulation method to study involuntary muscle phenomena

Experimental methods involving painful electrical stimulation of a peripheral nerve showed the existence of a minimum stimulation frequency capable of inducing cramp, termed "threshold frequency" (TF). Our aim was to test an alternative method to induce fasciculations and cramps electrically. Two daily sessions of electrical stimulation of the abductor hallucis muscle were performed in 19 volunteers on 3 days: stimulation trains of 150 monophasic square pulses (duration 152 micros) of increasing frequency (current intensity 30% higher than maximal; frequency of the first trial, 4 pps; recovery between trials, 1 min) were delivered to the main muscle motor point until a cramp developed. Once a cramp was induced the protocol was repeated after 30 min. To verify by electromyography that cramp occurred, a surface electrode array was placed between the motor point and the distal tendon. Ambient and skin temperature were kept constant in all sessions. Fasciculations and cramps were elicited in all subjects. We observed the following median (interquartile range) values of TF: day 1 (session 1), 13 (6) pps; day 1 (session 2), 16 (4) pps; day 2 (session 1), 16 (6) pps; day 2 (session 2), 18 (6) pps; day 3 (session 1), 17 (4) pps; day 3 (session 2), 18 (8) pps. TF intersession intraclass correlation coefficients were 0.82, 0.92, and 0.90 for days 1, 2, and 3, respectively. TF interday intraclass correlation coefficient was 0.85. The absence of pain due to the stimulation and the demonstration of TF reliability support the use of our method for the study of involuntary muscle phenomena.

Predictors of delay in the diagnosis and clinical trial entry of amyotrophic lateral sclerosis patients: A population-based study

BACKGROUND

The El Escorial and the revised Airlie House diagnostic criteria for amyotrophic lateral sclerosis (ALS) were introduced to select patients for clinical trials. Heterogeneity of clinical presentation at onset and delay in diagnosis may decrease the likelihood for trial entry.

OBJECTIVE

Identify risk factors for delay in the diagnosis and trial exclusion.

METHODS

ALS incident cases were identified with El Escorial (EEC) and Airlie House criteria (AHC) through a population-based registry established in Puglia, Southern Italy, in the years 1998-99.

RESULTS

130 ALS incident cases were diagnosed with a median interval between onset of symptoms and diagnosis of 9.3 months and not different across both EEC and AHC categories. Twenty percent of cases were not eligible for clinical trials according to the AHC. About 5% of subjects in this series died with only lower motor neuron signs. Predictors for delay in the diagnosis were age between 65 and 75 years and spinal onset while fasciculations and cramps as first symptoms were predictors of exclusion from trials.

CONCLUSIONS

In this population-based series, diagnostic delay was longer in subjects with spinal onset and age between 65 and 75 and fasciculation as first symptoms. About 80% of incident cases were trial eligible with AHC criteria. However, a significant number of subjects with ALS, characterized by a limited spread of signs, were not trial eligible while alive.

Laser Doppler spectroscopy towards the detection of spontaneous muscle activity

OBJECTIVE

We used laser Doppler spectroscopy to detect hyperactivity of muscle fibers caused by the presence of fibrillations, positive waves and fasciculations.

METHODS

The proposed method relies upon the dynamic scattering of light by moving particles, which causes a Doppler shift of the original frequency. For resolution of small alterations in frequency the heterodyne detection was used. One hundred seventy-three normal and 109 EMG diagnosed denervated first dorsal interosseous muscles were examined.

RESULTS

Denervated muscles with fasciculations showed significant differentiation from control muscles, whereas denervated muscles without fasciculations were not significantly differentiated. The smallest differentiation compared to controls was seen in chronic denervated muscles without spontaneous activity.

CONCLUSIONS

Presence of fasciculations in denervated muscles allowed Doppler spectroscopy to differentiate them from normal muscles. Presence of atrophy reduced the diagnostic potential of the method.

SIGNIFICANCE

Our findings can be used as a basis for further improving painless and noninvasive laser Doppler spectroscopy to be used clinically as an alternative to painful and invasive EMG.

Persistent idiopathic unilateral isolated hypoglossal nerve palsy: a case report

Isolated hypoglossal nerve palsy (IHNP) although a rare condition, has been previously reported. A literature review revealed that in most cases, IHNP indicates the presence of an intracranial or extracranial space occupying lesion, head and neck injury, vascular abnormality, infection, autoimmune disease or neuropathy. Reports of idiopathic cases are rare and the vast majority of IHNP are reversible. We report a case of persistent idiopathic unilateral hypoglossal nerve palsy, with an emphasis on the investigations necessary to be undertaken on presentation of such a lesion.

Prevalence of denervation in paraspinal and foot intrinsic musculature

OBJECTIVE

The primary purpose of this investigation was to determine the prevalence of abnormal spontaneous activity (positive sharp waves (PSWs) and fibrillation potentials (FPs)) in selected lumbosacral paraspinal and foot intrinsic muscles in an asymptomatic healthy population.

DESIGN

This was a prospective assessment of 50 individuals without history or physical findings suggestive of peripheral neuromuscular disease whereby a monopolar needle electrode was located in the unilateral L4 and L5 paraspinal as well as abductor hallucis and extensor digitorum brevis muscles. These muscles were extensively evaluated for the presence of PSWs, FPs, and fasciculation potentials.

RESULTS

Ten subjects per decade from 20-59 yr and ten subjects from 60-80 yr comprised the 50 participants (28 women), resulting in a mean age of 45+/-15.9 (range, 20-76) yr. A single individual (prevalence, 2%) demonstrated fibrillation potentials in the extensor digitorum brevis, and FPs and PSWs were detected in two subjects' (4% prevalence) L4/L5 paraspinal muscles. Ninety-four percent of the subjects had fasciculation potentials in the abductor hallucis, whereas 60% had these waveforms in the extensor digitorum brevis. Only 6% of subjects had fasciculation potentials in the L4 but not L5 paraspinal muscles. All subjects demonstrated both prototypical and "atypical" appearing endplate spikes in all of the muscles examined.

CONCLUSIONS

We failed to confirm the previously reported prevalence of FPs and PSWs in both the paraspinal and foot intrinsic musculature. Atypical appearing endplate spikes, however, display configurations similar to FPs and PSWs and were present in all subjects. Failure to pay close attention to the discharge rate and rhythm of endplate spikes can lead to misinterpreting these waveforms as FPs and PSWs. It is likely that the previously reported high prevalence of spontaneous activity in healthy persons resulted from not fully appreciating the similarity between innervated and denervated spontaneous single muscle fiber discharge configurations.

Effect of localized muscle fatigue on vertical ground reaction forces and ankle joint motion during running

The purpose of this study was to examine the changes in the vertical ground reaction force (VGRF) and ankle joint motion during the first 50% of the stance phase of running following fatiguing exercise of either the dorsiflexors or the invertors of the foot. VGRFs, sagittal and rearfoot kinematic data were collected from 11 female recreational runners running at 2.9 m/second on a treadmill prior to and following localized muscle fatigue of either the invertors or dorsiflexors of the right foot. Loading rate of the impact peak force significantly increased following fatiguing exercise of the dorsiflexors, while the peak magnitudes of the impact and push-off forces remained unchanged. There were significant decreases in dorsiflexion at heel contact, but no significant difference in any rearfoot motion parameters tested following dorsiflexor fatigue. Following fatiguing exercise of the invertors, impact peak magnitude, push-off peak magnitude and the rate of decline of the impact peak force significantly decreased; there was no change in the loading rate of the impact peak force. Invertor fatigue also resulted in a less inverted foot position at heel contact, but there were no significant differences in any other kinematic parameters tested. The results demonstrate that localized muscle fatigue of either the invertors or dorsiflexors can have a significant effect on the loading rates, peak magnitudes and ankle joint motion seen during running. These changes, due to localized muscle fatigue, may play a role in many common lower extremity running injuries.

[Myoclonus in the adult: diagnostic approach]

Myoclonus, defined as shock-like involuntary movement, may be physiological or caused by a very wide variety of hereditary and acquired conditions. Because myoclonus can originate from different disorders and lesions affecting quite varied levels of the central and peripheral nervous systems, it represents from many points of view a diagnostic challenge. Moreover, new entities have been recently individualized, such as cortical tremor, which deserve renewed attention. The aim of this review is to propose a rationale for a diagnostic approach based on clinical and electrophysiological grounds. In this setting, we successively address 1) the clinical features allowing a positive diagnosis of myoclonus; 2) the clinical clues to the etiology; 3) the relevance of the clinical context to the diagnosis; and 4) the contribution of neurophysiology. Differentiating myoclonus from tics, spasm, chorea and dystonia can be difficult, and a careful reappraisal of clinical features allowing precise identification is presented. Moreover, the topographical distribution of myoclonus, the temporal pattern of muscle recruitment, the condition of occurrence and the rhythm of the event, may provide clinical clues relevant to the diagnosis. Myoclonus without associated epilepsy, myoclonus with epilepsy, myoclonus with encephalopathy, parkinsonism and/or dementia represent overlapping clinical categories, although they remain useful for the diagnostic approach. Using electrophysiology (including back-averaging EEG, MEG, SEP, C-reflex studies) to determine the origin of myoclonus may not allow us to focus on the underlying condition. Indeed, in many instances, the myoclonus is cortical in origin, but the pathology is found elsewhere.

Pathophysiological significance of fasciculations in the early diagnosis of ALS

In amyotrophic lateral sclerosis (ALS), muscles with preserved strength can have fasciculation potentials (FPs) as the only abnormality. The FPs in strong muscles are predominantly simple and stable, and can often be recruited by a slight voluntary contraction. In weak and atrophic muscles, the FPs are generally complex and unstable, tend to have a slower firing rate and are not recruited by voluntary contraction. Macro-electromyography studies suggest that these FPs are part of a more complex motor unit, as opposed to simple FPs which can represent all the motor unit. FPs driven by transcranial magnetic stimulation (TMS) were observed in 13 ALS patients. TMS-driven fasciculations had a simple morphology and were stable. Complex potentials were never cortically driven. These observations strengthen the conviction that fasciculations in ALS can have different origins. Simple, stable FPs arise proximally and are probably related to excitotoxicity phenomena, while complex, unstable FPs are most likely to originate in distal axonal sprouts that are associated with the reinnervation process. Some ALS patients with fatigue and mild weakness can have profuse fasciculations at an early phase in the evolution of the disease. Patients with denervation localized in one region and diffuse FPs should be strongly suspected of having ALS. With this strategy it should be possible to shorten the diagnosis time.

Fasciculations without fibrillations: the dilemma of early diagnosis

The challenge of identifying patients at the earliest stage of disease has highlighted the role of subtle markers of clinical pathology. Electrophysiological changes usually precede evidence of clinical weakness and have, therefore, been implicated. Specifically, the onset of fasciculations, particularly those widespread in distribution, in the absence of fibrillation potentials, have been suggested as an early indicator of motor neuron disease. Several cases will be presented here to highlight instances where diffuse fasciculations were not enough to accurately implicate the current diagnostic criteria for amyotrophic lateral sclerosis (ALS). In two instances, alternative diagnoses were eventually supported. If the purpose of early diagnosis is to lead to early treatment with experimental therapy, we must be certain that we study as homogenous a population of patients as possible. Fasciculations by themselves are not enough to implicate early diagnosis; disease progression is probably the single most important historical characteristic for diagnosis. Signs of active denervation (i.e. fibrillation potentials) are critical. Chronic weakness should be proportional to either atrophy or upper motor neuron signs in the affected muscle. This should be true for both early and late recognition of the disease.

Diagnosis of amyotrophic lateral sclerosis

This review of the differential diagnosis of amyotrophic lateral sclerosis focuses on two themes. The first is practical, how to establish the diagnosis based primarily on clinical findings buttressed by electrodiagnosis. The main considerations are multifocal motor neuropathy and cervical spondylotic myelopathy. The second theme is the relationship of motor neuron disease to other conditions, including benign fasciculation (Denny-Brown, Foley syndrome), paraneoplastic syndromes, lymphoproliferative disease, radiation damage, monomelic amyotrophy (Hirayama syndrome), as well as an association with parkinsonism, dementia and multisystem disorders of the central nervous system.

Single fibre electromyography in multifocal motor neuropathy with persistent conduction blocks

OBJECTIVE

To study the process of denervation-reinnervation in multifocal motor neuropathy with persistent conduction blocks in clinically affected and unaffected muscles.

METHOD

Volitional single fibre electromyography (SFEMG) was performed in the extensor digitorum communis (EDC) of seven patients. The jitter, the fibre density, and the mean interpotential interval were determined. The results before and after treatment with intravenous immunoglobulin (IVIg) between the unaffected EDC and affected EDC examined during the same SFEMG session were also compared. In addition the values of jitter, fibre density, and mean interpotential interval were analysed for correlation with the strength score on the MRC scale, the duration of the neuropathy, the number of IVIg treatment periods, and the radial nerve conduction block values.

RESULTS

Mean jitter, percentage of jitters >60 micros, and impulse blocking percentage, were higher than normal in both the affected EDCs and to a lesser degree in unaffected EDCs. Jitter decreased significantly after IVIg and correlated only with the MRC score. Fibre density and mean interpotential interval were higher than normal equally in the affected EDC and unaffected EDCs, but no correlation was found with strength, duration of the neuropathy, number of treatment periods, and conduction block values.

CONCLUSION

The major finding is the presence of SFEMG abnormalities in clinically unaffected EDCs. This shows a process of denervation-reinnervation even in the absence of clinical symptoms, probably more frequent than commonly supposed in this neuropathy. The rapid clinical improvement after IVIg infusions could be due to remyelination after demyelination and to an interference of IVIg with the blocking effect of antibodies on the Na+ channels at the motor nerve endings.

Surface EMG and myosonography in the detection of fasciculations: a comparative study

Surface electromyography (EMG) and muscle sonography both facilitate the detection of fasciculations. This study was conducted to evaluate the prevalence of fasciculations in 10 lower extremity muscles in 58 subjects 47 +/- 18 years of age without and 54 patients 52 +/- 15 years of age with various neuromuscular diseases (3 with inflammatory myopathy, 15 with lower motor neuron disease, 22 with acquired and 11 with hereditary motor and sensory neuropathy (HMSN), and 3 with adrenomyeloneuropathy). When each muscle was screened by means of myosonography for 10 seconds, fasciculations were found in up to 8 muscles in 11 control subjects (19%) and in up to 10 muscles in 41 patients (76%). Within the same recording period surface EMG revealed fasciculations in 5 control subjects (9%) and 30 patients (56%), whereas during a recording time of 20 minutes fasciculations were detected in 55 (95%) control subjects and all patients. An amplitude of 400 microV proved to be the optimum cutoff between fasciculations for healthy subjects and patients with neuromuscular disease (accuracy, 74%). Myosonography allowed differentiation of both groups with an accuracy of 79%. Surface EMG was more liable to artifacts than myosonography. The average interval between subsequent fasciculations cannot be used to differentiate patients with acquired and hereditary polyneuropathy and with lower motor neuron disease. Long-term surface EMG recording indicates fasciculations to occur in almost all patients with neuromuscular disease and the vast majority of healthy subjects. Muscle ultrasonography was more convenient and reliable than surface EMG in differentiating patients and healthy subjects.

Involvement of the esophagus in the cramp-fasciculation syndrome

A 35-year-old male patient presented with symptoms of a cramp-fasciculation syndrome, but also reported difficulties swallowing. Esophageal manometry showed spontaneous nonperistaltic contractions, pathologically increased amplitudes and duration of the contractile complexes, and an asynchronous propagation. Electromyographic evidence of fasciculations in the sternocleidomastoid and pectoralis muscles was found. Apparently all types of peripheral motor fibers can be involved in this heterogeneous syndrome, including cranial motor nerves, the vagal nerve, and enteric motor fibers of the gastrointestinal tract.

The use of botulinum toxin in localizing neuromyotonia to the terminal branches of the peripheral nerve

In 2 patients with neuromyotonia, nerve blocks had no effect on the abnormal activity, while intramuscular injection of the botulinum toxin abolished the discharges in one and greatly diminished them in the other. Botulinum toxin thus helps to localize the origin of the neuromyotonic discharges to the terminal regions of the peripheral nerve in those cases where the more proximal portions cannot be held responsible.

[Isaacs syndrome: long-term improvement with intravenous polyvalent immunoglobulins]

A 35 year-old man developed a syndrome with muscle cramp, myokimia, generalized, fasciculations, excessive sweating, sleep disorders and severe impairment. It was a syndrome of continuous muscle fiber activity--or Isaacs syndrome--with central disorders (this may be called "Maladie de Morvan"). Previous reports have suggested that Isaac's syndrome might be an autoimmune disorder. Moreover, high doses intravenous immunoglobulins were given resulting in a substantial improvement six months after the onset of this treatment.

A case of Isaacs' syndrome with associated central nervous system findings

We report a 44-year-old female with Isaacs' syndrome, peripheral motor neuropathy, and features of central pontine myelinolysis (CPM). The patient presented with stiffness and muscle spasms accompanied by profound sweating. She also had bilateral Babinski signs. Electrodiagnostic abnormalities were characteristic of Isaacs' syndrome. Magnetic resonance imaging demonstrated features of CPM. She gained modest relief from baclofen, valproate, and diazepam. She improved dramatically following plasmapheresis and continued to recover on prednisone. She was weaned from steroids without relapse.

Muscle pain, fatigue, and fasiculations

This article discusses muscle pain, fatigue, and fasiculations. Muscle pain and fatigue are common problems in general medicine and in neurology, while fasiculations raise concern about a potentially ominous disease. The author reviews the conditions that cause pain and similar conditions arising from nonmuscular soft tissues. The article includes a general evaluation to be used for each of these clinical problems.

Facial myokymia in multiple system atrophy

Two patients are described with clinical and neuroimaging features consistent with a diagnosis of multiple system atrophy (MSA). The patients are unusual in that facial myokymia became apparent clinically at some stage in their illness. In each patient, the nature and severity of the involuntary facial movements evolved over the course of the illness. Electrophysiologically the movement pattern was consistent with myokymia, and studies of blink-reflex responses suggested that the myokymic discharges were of brainstem origin. Involuntary facial movements described as facial action myoclonus with electrical characteristics consistent with myoclonus have been described previously in hereditary olivopontocerebellar atrophy (OPCA). Our report describes electrical and clinical features of facial myokymia in MSA with electrical features suggesting hyperexcitability of the facial motorneurons in the brainstem. Such myokymic movements may occur more frequently in MSA than previously recognised but may be missed clinically because of their evolving nature.

Systemic juvenile rheumatoid arthritis and associated Isaacs' syndrome

We describe a patient with systemic onset juvenile chronic arthritis who developed clinical and electromyographic features of acquired Isaacs' syndrome. This association has not been reported before and possible links between the 2 diseases are discussed.

Differential diagnosis of limb girdle syndromes

The term limb girdle syndrome includes a variety of neuromuscular disorders like the scapulohumeral and pelvifemoral types of muscular dystrophy, quadriceps myopathy and Wohlfart-Kugelberg-Welander syndrome. There may be considerable difficulty in distinguishing between different types of limb girdle syndrome, even with the aid of electromyographic and muscle biopsy examinations. The aim of this investigation was to reestablish the clues for distinguishing between different types of limb girdle syndrome. Fifty-four patients with limb girdle syndromes took part in this investigation. They were subdivided into two groups according to EMG and muscle biopsy data. The first group consisted of 39 patients with limb-girdle type of muscular dystrophy and the second group consisted of 15 patients with juvenile type of spinal muscular atrophy. Our results revealed that neurological examination was not enough to distinguish the different types of limb girdle syndrome. The most important electromyographic findings in patients with muscular atrophy are the neurogenic action potentials and fasciculations. Fibrillations, positive sharp waves and bizzare discharges may be found also in some patients with muscular dystrophy. Myogenic action potentials are found in some patients with muscular atrophy and so may cause confusion. Muscle biopsy may also reveal some myogenic features in patients with muscular atrophy. In conclusion electromyography and muscle biopsy are useful in the differentiation of different types of limb girdle syndrome, as well as, in determining the exact pattern of muscle involvement.

[Muscle cramps and fasciculations not always ominous: muscle cramp-fasciculation syndrome]

In three patients, men of 43, 44 and 55 years old with muscle cramps, fasciculations and easy fatiguability of muscles, cramp-fasciculation syndrome was diagnosed. This is a benign disorder which has to be differentiated from amyotrophic lateral sclerosis. Response to treatment (benzodiazepines or carbamazepine) is good.

Fasciculations: clinical, electromyographic, and ultrasonographic assessment

Widespread fasciculations are an important clinical sign in, for example, degenerative lower motor neuron diseases (LMND). Usually they are detected by clinical inspection and electromyography. Recently myosonography has been proposed for the detection of fasciculations. This prospective study compares the value of these three modes of examination in patients with degenerative LMND. Seventy healthy control persons and 34 patients (11 women, 23 men; aged 43-78 years; median age 60.5) with LMND were included in the study. All participants were subjected to thorough visual screening for the presence of fasciculations. Fourteen muscles were examined bilaterally by myosonography and a median of 8 muscles were screened electromyographically (only in the patients); the investigators were blinded to the other findings. Clinical inspection and ultrasonography exhibited fasciculations in up to 5 and 8 muscles, respectively, in 8 healthy persons. Ultrasonography demonstrated fasciculations in all patients, clinical inspection in all but 2, and electromyography in 26 of 33 patients (1 patient was not examined electromyographically). Comparing the three methods, clinical observation revealed fasciculations in 42%, electromyography in 39%, and ultrasonography in 67% of all muscles. Thus, ultrasonography was significantly more sensitive than the other techniques (P < 0.001). The interrater agreement (correlation coefficient) r in respect of the presence or absence of fasciculation was 0.71 for the clinical, 0.85 for the electromyographic and 0.84 for the myosonographic examinations. Ultrasonography and electromyography were more reliable than the clinical examination (P < 0.001 and P < 0.01, respectively). Our study indicates that ultrasonography is more sensitive than clinical and electromyographic examination in visualizing fasciculations in patients with LMND. Additionally, it is more reliable than clinical examination.

[A case of myokymia with abnormal F responses]

We reported a case of myokymia with abnormal F response. A 60-year-old male with chronic alcoholism was admitted to our hospital with complaint of muscle cramp in both legs just after drinking. Neurological examination revealed muscle pain and weakness of the legs, absence of bilateral Achilles tendon reflexes and prominent myokymia in his right quadriceps femoris and left calf muscles. The electrophysiological examination showed reduced conduction velocity, high amplitude, increased number of phases and long duration of F responses suggesting increased excitability of motoneuron pool. The epidural nerve block brought about a disappearance of the myokymia and an improvement of the abnormal features of F response. The myokymia gradually tended to be milder in the clinical course. The relationship between the myokymia and the abnormal F responses indicated that the increased excitability of spinal motoneurons might play an important role on the generation of myokymia of this patient.

Degenerative disorders of the central nervous system. An integrated approach to the differential diagnosis

Neurodegenerative disorders are gaining increasing importance as the average age of the population progressively increases. It is therefore important to continue developing imaging techniques that will noninvasively, rapidly, and accurately diagnose such disorders. The major role of imaging in neurodegenerative disorders is to exclude the presence of treatable causes. By combining functional and anatomic imaging approaches, imaging has become a critical tool in the evaluation of these disorders.

Neuromyotonia in alcoholic patients with gastrectomy

Four patients with severe muscle cramps were reported. In two of them the electrical signs of neuromyotonia were demonstrated. All the patients had undergone gastrectomy and all were immoderate consumers of alcohol. The neuromuscular disorder was reversible in all the patients.

A patient with one limb interstitial myositis with localised lipoatrophy presenting with severe cramps and fasciculations

A case of interstitial myositis associated with a localised lipoatrophy is reported. The patient is a 24 year old man who presented with severe painful cramps and fasciculations localised to one limb. The rarity of both disorders, and their likely common autoimmune mechanism, suggest that this is not a chance association.