A charcot-marie-tooth type 1B kindred associated with hemifacial spasm and trigeminal neuralgia.

Introduction: Charcot-Marie-Tooth (CMT) phenotypes can be distinguished by electrophysiology and genetic analysis but few can be identified by their clinical characteristics. Distinctive phenotypes are useful in identifying affected individuals and providing additional clues about the mechanism of the neuropathy. Cranial neuropathies are uncommon features of CMT, and few reports of familial hemifacial spasm (HFS) and trigeminal neuralgia (TN) have been published.

Fibromyalgia syndrome and small fiber, early or mild sensory polyneuropathy.

Introduction: Pain mechanisms in fibromyalgia syndrome (FMS) are not clearly understood. Growing evidence appears to suggest a role for small fiber polyneuropathy (SFPN) in some FMS patients, as measured by epidermal nerve fiber density (ENFD). We aimed to better characterize and distinguish the subset of patients with both fibromyalgia and small fiber, early or mild sensory polyneuropathy (FM-SFSPN).

The management and treatment of children with Fabry disease: A United States-based perspective.

Fabry disease is an inherited X-linked disorder that presents during childhood in male and female patients. Young patients may initially experience pain, hypohidrosis, and gastrointestinal symptoms. Other manifestations of Fabry disease, such as renal and cardiac disease, manifest later in adolescence or adulthood.

Neuromuscular junction disorders mimicking myopathy.

Introduction: Small-amplitude, short-duration motor unit action potentials are non-specific findings seen in myopathies and neuromuscular junction (NMJ) disorders. NMJ studies (repetitive nerve stimulation and single-fiber electromyography) can determine if such findings are related to NMJ abnormalities but are not considered routinely in atypical cases.

Methods: Medical records of 338 patients with confirmed NMJ disorders were reviewed to identify cases with a clinical or electrodiagnostic impression of myopathy during initial evaluation.

Multifocal motor neuropathy: a review of pathogenesis, diagnosis, and treatment.

Multifocal motor neuropathy (MMN) is an uncommon, purely motor neuropathy associated with asymmetric deficits with predilection for upper limb involvement. Even in the early descriptions of MMN, the associations of anti-GM1 antibodies and robust response to immunomodulatory treatment were recognized. These features highlight the likelihood of an underlying autoimmune etiology of MMN.

Bent spine syndrome as an early manifestation of myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is highly variable systemic disorder with prominent myopathic involvement in distal limb, facial, and jaw muscles. Bent spine syndrome presents a diagnostic challenge, and usually, DM1 is not included in the differential. We report 2 cases of DM1 with bent spine syndrome.

Ethambutol toxicity exacerbating the phenotype of CMT2A2.

Introduction: CMT2A2 is associated with mutations in the mitofusin 2 gene, which encodes a protein involved in mitochondrial fusion. Ethambutol is an antimycobacterial agent associated with toxic optic neuropathies. Ethambutol-induced optic neuropathy occurs in patients with mutations in a related fusion gene, OPA1, which is responsible for autosomal dominant optic atrophy.

Diagnostic nerve ultrasound in Charcot-Marie-Tooth disease type 1B.

Ultrasound is emerging as a useful tool for evaluation of neuromuscular conditions, because it can provide high-resolution anatomic information to complement electrodiagnostic data. There have been few studies in which ultrasound was used to assess the peripheral nerves of individuals with Charcot-Marie-Tooth (CMT) disease and none involving CMT type 1B. In this study we compared nerve cross-sectional area in individuals from a single large family with CMT 1B with normal, healthy controls.

Mitochondrial fusion and function in Charcot-Marie-Tooth type 2A patient fibroblasts with mitofusin 2 mutations.

Charcot-Marie-Tooth Type 2A is a dominantly inherited peripheral neuropathy characterized by axonal degeneration of sensory and motor nerves. The disease is caused by mutations in the mitochondrial fusion gene MFN2. Mfn2 is an integral outer mitochondrial membrane protein composed of a large GTPase domain and two heptad repeat (HR) domains that face the cytoplasm.

Clinical and electrophysiologic features of CMT2A with mutations in the mitofusin 2 gene.

Background: Axonal neuropathy linked to the CMT2A locus was originally associated with a mutation in the KIF1B gene. However, mutations in this gene have not been described associated with any other CMT2A families. Recently, mutations in the MFN2 gene, encoding the mitochondrial GTPase mitofusin 2 (Mfn2), have been identified as causative of CMT2A in seven families.

Comparison of conventional and decomposition-enhanced spike triggered averaging techniques.

Objective: Spike triggered averaging (STA) is a technique to extract an estimate of a recurring motor unit potential from a complex electromyographic (EMG) signal. In conventional STA (C-STA), potentials related to the discharges of single intramuscular motor units are isolated and used to trigger an averager to obtain an individual surface-detected motor unit potential (S-MUP) from an EMG signal. In decomposition-enhanced STA (DE-STA), EMG signal decomposition algorithms determine discharges of a number of different motor units (4 to 10) that can be used to trigger an averager to obtain their corresponding S-MUPs.

Assessment of axonal loss in Charcot-Marie-Tooth neuropathies.

Sensory loss and weakness in Charcot-Marie-Tooth (CMT) neuropathy is due to axonal loss. However, the pattern and degree of axonal loss cannot be accurately determined from routine electrodiagnostic or strength testing due to collateral reinnervation. We sought to quantify axonal loss in two upper extremity muscles in CMT1A and CMT2 subjects using the electrophysiologic endpoint measure of motor unit number estimation (MUNE).

Counting motor units in chronic motor neuropathies.

The degree of motor unit loss can not be accurately quantified in chronic motor neuropathies with routine electrodiagnostic testing or with pathologic examination. We used motor unit number estimation (MUNE), which is a unique electrophysiologic method that can estimate the number of surviving motor units innervating a muscle, to study axonal loss in spinal muscular atrophy (SMA) and Charcot-Marie-Tooth (CMT) neuropathies. MUNE is based on the ratio of the maximal compound muscle action potential (CMAP) to the average surface-recorded motor unit potential (S-MUP).