Revisiting the compound muscle action potential (CMAP).

The compound muscle action potential (CMAP) is among the first recorded waveforms in clinical neurography and one of the most common in clinical use. It is derived from the summated muscle fiber action potentials recorded from a surface electrode overlying the studied muscle following stimulation of the relevant motor nerve fibres innervating the muscle. Surface recorded motor unit potentials (SMUPs) are the fundamental units comprising the CMAP.

Targeted next-generation sequencing study in familial ALS-FTD Portuguese patients negative for C9orf72 HRE.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with clinical and etiological heterogeneity and a complex genetic contribution. Clinical, neuropathological, and genetic evidence revealed that ALS and frontotemporal dementia (FTD) are in part of a single disease continuum. Genetic causes have been identified in sporadic (SALS) and familial patients (FALS) and the recurrent genetic factor underlying ALS and FTD is the C9orf72 hexanucleotide repeat expansion (HRE).

Assessing upper limb function with ALSFRS-R in amyotrophic lateral sclerosis patients.

: Functionality in ALS is usually assessed by the revised functional ALS rating scale (ALSFRS-R). The impact of dominant non-dominant side of upper limb (UL) onset on functionality has not been addressed before. : Consecutive patients with clear UL side dominance and followed in our unit were included.

Motor unit recruitment in myopathy: The myopathic EMG reconsidered.

Motor unit recruitment is abnormal in myopathies. We have addressed this subject by recording motor unit potentials (MUPs) using a standard concentric needle electrode in tibialis anterior muscles of clinically normal strength in a group of patients with myopathy (15 with myositis and 4 with facioscapulohumeral muscular dystrophy Type 1). In each recording site, a minimal voluntary contraction was sought in order to activate only 2 MUPs.

Muscular cramp: causes and management.

Muscular cramp is a common symptom in healthy people, especially among the elderly and in young people after vigorous or peak exercise. It is prominent in a number of benign neurological syndromes. It is a particular feature of chronic neurogenic disorders, especially amyotrophic lateral sclerosis.

Frequency of C9orf72 hexanucleotide repeat expansion and SOD1 mutations in Portuguese patients with amyotrophic lateral sclerosis.

Mutation frequency of the 2 main amyotrophic lateral sclerosis (ALS)-related genes, C9orf72 and SOD1, varies considerably across the world. We analyzed those genes in a large population of Portuguese ALS patients (n = 371) and recorded demographic and clinical features. Familial ALS (FALS) was disclosed in 11.

Motor unit number estimation (MUNE): Where are we now?

Estimation of the number of motor units (MUNE) in specific muscles is important to monitor outcome in progressive neurogenic disorders, with potential application in clinical trials. However, in spite of recent developments to identify the most convenient technique for MUNE, all current methods have individual shortcomings. It is essential to understand the scientific concepts that support MUNE and the many methods already proposed.

Hot-spot KIF5A mutations cause familial ALS.

Heterozygous missense mutations in the N-terminal motor or coiled-coil domains of the kinesin family member 5A (KIF5A) gene cause monogenic spastic paraplegia (HSP10) and Charcot-Marie-Tooth disease type 2 (CMT2). Moreover, heterozygous de novo frame-shift mutations in the C-terminal domain of KIF5A are associated with neonatal intractable myoclonus, a neurodevelopmental syndrome. These findings, together with the observation that many of the disease genes associated with amyotrophic lateral sclerosis disrupt cytoskeletal function and intracellular transport, led us to hypothesize that mutations in KIF5A are also a cause of amyotrophic lateral sclerosis.

Diaphragm motor responses to phrenic nerve stimulation in ALS: Surface and needle recordings.

Objective: In studies of phrenic nerve (PN) conduction in amyotrophic lateral sclerosis (ALS) both motor response amplitude and latency have been reported as abnormal. However, correlation with diaphragm motor unit loss, and with diaphragmatic function has not been fully evaluated.

Methods: We studied 83 patients with ALS, and 21 patients referred with clinically suspected phrenic nerve lesions whose studies were normal.

Interplay of upper and lower motor neuron degeneration in amyotrophic lateral sclerosis.

Objective: We studied motor unit recruitment to test a new method to identify motor unit firing rate (FR) variability.

Methods: We studied 68 ALS patients, with and without upper neuron signs (UMN) in lower limbs, 24 patients with primary lateral sclerosis (PLS), 13 patients with spinal cord lesion and 39 normal subjects. All recordings were made from tibialis anterior muscles of normal strength.

Comparison of slow and forced vital capacities on ability to predict survival in ALS.

Introduction: Slow (SVC) and forced (FVC) vital capacities are the most used pulmonary function tests in amyotrophic lateral sclerosis (ALS). It is unknown if they equally predict survival in ALS. The aim of the present study was to compare both measures in predicting survival in this disease.

Correlation between Forced Vital Capacity and Slow Vital Capacity for the assessment of respiratory involvement in Amyotrophic Lateral Sclerosis: a prospective study.

Introduction: Slow vital capacity (SVC) and forced vital capacity (FVC) are the most frequent used tests evaluating respiratory function in amyotrophic lateral sclerosis (ALS). No previous study has determined their interchangeability.

Objective: To evaluate SVC-FVC correlation in ALS.

Physiology of the fasciculation potentials in amyotrophic lateral sclerosis: which motor units fasciculate?

We set out to study whether in amyotrophic lateral sclerosis (ALS) fasciculation potentials (FPs) arise from the most excitable motor units (MUs). We studied 70 patients with ALS and 18 subjects with benign fasciculation syndrome (BFS). Of the 56 eligible ALS patients, 31 had signs of reinnervation in the right first dorsal interosseous muscle selected for study, and 25 did not.

Fasciculation discharge frequency in amyotrophic lateral sclerosis and related disorders.

Objective: In amyotrophic lateral sclerosis (ALS), fasciculations are believed to become less frequent during disease progression, associated with the loss of motor units. To address this issue, we studied the variation of fasciculation potential (FPs) frequency as evaluated by surface electromyography of the first dorsal interosseous muscle (1st DI) in patients with ALS and other related disorders, and to relate this change with the neurophysiological index (NI), a surrogate measure of functional motor units.

Methods: We measured the FP frequency and mean amplitude during a two minute recording of the relaxed right first dorsal interosseous muscle (1st DI) in 34 ALS patients, 9 subjects with benign fasciculations (BFS), 6 with primary lateral sclerosis (PLS) and 4 with spinal muscle atrophy (SMA).

Origin of fasciculations in root lesions.

Objective: Fasciculations are occasionally observed in root lesions, but their site of origin is uncertain.

Methods: We studied the origin of fasciculations (FPs) in consecutive patients with mild chronic L5 root lesions, excluding peripheral nerve lesion. We used a novel technique of double-EMG needle recording, in which each needle was placed in the territory of separate motor units.

Origin of fasciculations in amyotrophic lateral sclerosis and benign fasciculation syndrome.

Importance: Fasciculation potentials (FPs) may arise proximally or distally within the peripheral nervous system. We recorded FPs in the tibialis anterior using 2 concentric needle electrodes, ensuring by slight voluntary contraction and electrical nerve stimulation that each electrode recorded motor unit potentials innervated by different axons.

Observations: Time-locked FPs recorded from both electrodes, suggesting a spinal origin, were most frequent in benign fasciculation syndrome (44%) (P < .

Sensitivity of MUP parameters in detecting change in early ALS.

Objectives: We aimed to identify the most appropriate MUP parameter to evaluate reinnervation in very early ALS.

Methods: We studied tibialis anterior (TA), initially of normal strength with normal MUP analysis parameters, in 15 patients with ALS of recent onset. They were studied at the initial diagnostic assessment, and then 3 and 6 months later.