INTRODUCTION:

Cervical spondylosis (CS) is a common disease in adults and may coexist with amyotrophic lateral sclerosis (ALS). It is important to detect ALS coexisting with CS (ALS-cs) at an early stage, especially when surgical treatment of CS is planned.

METHODS:

Single-fiber electromyography was performed in 26 patients with ALS, 19 with ALS-cs, and 22 with CS.

RESULTS:

Mean jitter, percentage of jitter >55 μs, and percentage of impulse blocking were not statistically different between ALS and ALS-cs cases, but they were significantly lower in CS. Mean fiber density was not statistically different among the 3 groups. The percentage of pairs with jitter >55 μs exceeding 40% and mean jitter exceeding 55 μs had high sensitivity and specificity in the diagnosis of ALS.

CONCLUSIONS:

Single-fiber electromyography can supply valuable information in helping to differentiate ALS from CS. Muscle Nerve, 2013.

INTRODUCTION:

In patients with obstructive sleep apnea (OSA), intermittent apnea and hypopnea might cause different adaptations in inspiratory and peripheral muscles. In this study we aimed to determine the changes that occur in muscle activation characteristics during incremental exercise testing in patients with severe OSA. Surface electromyography of inspiratory muscles and knee extensors was performed.

METHODS:

Eleven men with severe OSA and 11 matched controls were recruited. Changes in muscle activity were compared by determining root mean square (RMS) and median power frequency (MPF) values obtained at different exercise intensities.

RESULTS:

The ratios of RMS to oxygen consumption in inspiratory muscles and vastus lateralis increased significantly at peak workload in the control group (P < 0.05), but not in the OSA group.

CONCLUSIONS:

Patients with severe OSA demonstrated an inability to increase motor unit recruitment of inspiratory muscles and knee extensors during incremental exercise. Muscle Nerve, 2013.

Introduction: Dystrophinopathies are X-linked recessive neuromuscular diseases caused by mutations in the dystrophin gene. This study aimed to detect mutations within the dystrophin gene in DMD patients, to determine the carrier status of women, and to perform a prenatal diagnosis.

Methods:

We analyzed 17 individuals from 2 unrelated families with a history of DMD. We used multiplex PCR, Multiplex Ligation-dependent Probe Amplification (MLPA), and Short Tandem-Repeat (STR) segregation analysis to accurately detect and characterize the mutations and to identify the at-risk haplotype.

Results:

The selected methodology allowed for the characterization of 2 single-exon out-of-frame deletions in the affected patients. 9/13 women and a fetus were excluded from being carriers. Three recombination events were found and suggested that germline mosaicism had occurred in both families. Discussion: This methodology proved to be efficient for characterizing the disease-causing mutation in affected individuals and for assessing the carrier status in healthy relatives. These findings helped inform precise genetic counseling and contributed to characterization of the disease in the Argentine population. © 2013 Wiley Periodicals, Inc.

In this review, we present an overview of the role of exercise in neuromuscular disease (NMD). We demonstrate that despite the different pathologies in NMDs, exercise is beneficial, whether aerobic/endurance or strength/resistive training, and we explore whether this benefit has a similar mechanism to that of healthy subjects. We discuss further areas for study, incorporating imaginative and novel approaches to training and its assessment in NMD. We conclude by suggesting ways to improve future trials by avoiding previous methodological flaws and drawbacks in this field. Muscle Nerve, 2013.

Introduction: An open label trial suggested that valproic acid (VPA) improved strength in adults with spinal muscular atrophy (SMA). We report a 12 month, double blind, crossover study of VPA in ambulatory SMA adults.

Methods:

There were 33 subjects aged 20-55 years. After baseline assessments subjects were randomized to receive VPA (10-20 mg/kg/daily) or placebo. At 6 months, patients were switched to the other group. Assessments were performed at 3, 6, and 12 months. The primary outcome was the 6-month change in maximum voluntary isometric contraction testing with pulmonary, electrophysiologic, and functional secondary outcomes.

Results:

Thirty subjects completed the study. VPA was well tolerated, and compliance was good. There was no change in primary or secondary outcomes at 6 or 12 months.

Conclusions:

VPA did not improve strength or function in SMA adults. The outcomes used are feasible and reliable and can be employed in future trials in SMA adults. © 2013 Wiley Periodicals, Inc.

Introduction: Duchenne muscular dystrophy (DMD) subjects ≥5 years with nonsense mutations were followed for 48 weeks in a multicenter, randomized, double-blind, placebo-controlled trial of ataluren. Placebo arm data (N=57) provide insight into the natural history of the 6-minute walk test (6MWT) and other endpoints.

Methods:

Evaluations performed every 6 weeks included the 6 minute walk distance (6MWD), timed function tests (TFTs), and quantitative strength using hand-held myometry.

Results:

Baseline age (≥7 years), 6MWD, and selected TFT performance, are strong predictors of decline in ambulation (Δ 6MWD) and time to 10% worsening in 6MWD. A baseline 6MWD of <350 meters was associated with greater functional decline, and loss of ambulation was only seen in those with baseline 6MWD <325 meters. Only 1/42 (2.3%) subjects able to stand from supine lost ambulation. Discussion: Findings confirm the clinical meaningfulness of the 6MWD as the most accepted primary clinical endpoint in ambulatory DMD trials. © 2013 Wiley Periodicals, Inc.

Introduction: Transthyretin familial amyloid polyneuropathy (TTR-FAP) is characterized by early selective involvement of small nerve fibers. Initial clinical diagnosis is complicated by psychosocial factors.

Objective:

To evaluate diagnostic accuracy of sural sensory nerve action potentials, plantar sympathetic skin response (SSR), and cortical laser-evoked potentials (LEP) to dorsal foot stimulation in early diagnosis of TTR-FAP.

Methods:

Sixty-three subjects with TTR-FAP (Val30Met) mutation were split into 2 groups (asymptomatic carriers and early-symptomatic patients) and compared with 33 healthy controls.

Results:

The diagnostic accuracy of plantar SSR amplitude and LEP N2 latency was similar; all had very high specificity (94 to 97%) but low sensitivity (22 to 32%) in distinguishing controls from carriers and early-symptomatic patients. No control had abnormal results on both tests.

Conclusions:

Plantar SSR and LEPs have similar diagnostic performance in detecting small-fiber dysfunction in early TTR-FAP; we propose that both tests should be used to investigate this population. © 2013 Wiley Periodicals, Inc.

Neuromuscular ultrasound involves the use of high-resolution ultrasound to image the peripheral nervous system of patients with suspected neuromuscular diseases. It complements electrodiagnostic studies well by providing anatomic information regarding nerves, muscles, vessels, tendons, ligaments, bones, and other structures that cannot be obtained with nerve conduction studies and electromyography. Neuromuscular ultrasound has been studied closely over the past 10 years and has been used most often in the assessment of entrapment neuropathies. This review focuses on the use of neuromuscular ultrasound in 4 of the most common entrapment neuropathies: carpal tunnel syndrome, ulnar neuropathy at the elbow and wrist, and fibular neuropathy at the knee. © 2013 Wiley Periodicals, Inc.

INTRODUCTION:

Focal peripheral neuropathy of the median nerve is mainly caused by a traumatic event or pressure, but it may also be produced by systemic illnesses. Among the latter, leprosy is a rare cause.

METHODS:

Six cases of isolated median neuropathy as the first sign of leprosy were selected from patients with an exclusively neurological complaint as the initial symptom. The patients, evaluated at the National Leprosy Reference Center in Rio de Janeiro, Brazil, followed routine and specialized procedures.

RESULTS:

Three of the patients had pure neural leprosy, and 3 had skin lesions. Clinical median nerve function impairment was confirmed by neurophysiological testing and histopathology. Both mononeuritis and mononeuritis multiplex were observed.

CONCLUSIONS:

This case series demonstrates an additional form of presentation of leprosy, which, if not diagnosed and treated in time, may lead to permanent disability. Muscle Nerve, 2013.