Items in AFP with MESH term: Electromyography
Infant Botulism - Article
ABSTRACT: Although the worldwide incidence of infant botulism is rare, the majority of cases are diagnosed in the United States. An infant can acquire botulism by ingesting Clostridium botulinum spores, which are found in soil or honey products. The spores germinate into bacteria that colonize the bowel and synthesize toxin. As the toxin is absorbed, it irreversibly binds to acetylcholine receptors on motor nerve terminals at neuromuscular junctions. The infant with botulism becomes progressively weak, hypotonic and hyporeflexic, showing bulbar and spinal nerve abnormalities. Presenting symptoms include constipation, lethargy, a weak cry, poor feeding and dehydration. A high index of suspicion is important for the diagnosis and prompt treatment of infant botulism, because this disease can quickly progress to respiratory failure. Diagnosis is confirmed by isolating the organism or toxin in the stool and finding a classic electromyogram pattern. Treatment consists of nutritional and respiratory support until new motor endplates are regenerated, which results in spontaneous recovery. Neurologic sequelae are seldom seen. Some children require outpatient tube feeding and may have persistent hypotonia.
ABSTRACT: Muscle weakness is a common complaint among patients presenting to family physicians. Diagnosis begins with a patient history distinguishing weakness from fatigue or asthenia, separate conditions with different etiologies that can coexist with, or be confused for, weakness. The pattern and severity of weakness, associated symptoms, medication use, and family history help the physician determine whether the cause of a patient's weakness is infectious, neurologic, endocrine, inflammatory, rheumatologic, genetic, metabolic, electrolyte-induced, or drug-induced. In the physical examination, the physician should objectively document the patient's loss of strength, conduct a neurologic survey, and search for patterns of weakness and extramuscular involvement. If a specific cause of weakness is suspected, the appropriate laboratory or radiologic studies should be performed. Otherwise, electromyography is indicated to confirm the presence of a myopathy or to evaluate for a neuropathy or a disease of the neuromuscular junction. If the diagnosis remains unclear, the examiner should pursue a tiered progression of laboratory studies. Physicians should begin with blood chemistries and a thyroid-stimulating hormone assay to evaluate for electrolyte and endocrine causes, then progress to creatine kinase level, erythrocyte sedimentation rate, and antinuclear antibody assays to evaluate for rheumatologic, inflammatory, genetic, and metabolic causes. Finally, many myopathies require a biopsy for diagnosis. Pathologic evaluation of the muscle tissue specimen focuses on histologic, histochemical, electron microscopic, biochemical, and genetic analyses; advances in technique have made a definitive diagnosis possible for many myopathies.
ABSTRACT: The diagnosis of peripheral neuropathies can be frustrating, time consuming and costly. Careful clinical and electrodiagnostic assessment, with attention to the pattern of involvement and the types of nerve fibers most affected, narrows the differential diagnosis and helps to focus the laboratory evaluation. An algorithmic approach to the evaluation and differential diagnosis of a patient with peripheral neuropathy is presented, based on important elements of the clinical history and physical examination, the use of electromyography and nerve conduction studies, autonomic testing, cerebrospinal fluid analysis and nerve biopsy findings. The underlying cause of axonal neuropathies can frequently be treated; demyelinating neuropathies are generally managed with the assistance of a neurologist.
ABSTRACT: Peripheral neuropathy has a variety of systemic, metabolic, and toxic causes. The most common treatable causes include diabetes mellitus, hypothyroidism, and nutritional deficiencies. The diagnosis requires careful clinical assessment, judicious laboratory testing, and electrodiagnostic studies or nerve biopsy if the diagnosis remains unclear. A systematic approach begins with localization of the lesion to the peripheral nerves, identification of the underlying etiology, and exclusion of potentially treatable causes. Initial blood tests should include a complete blood count, comprehensive metabolic profile, and measurement of erythrocyte sedimentation rate and fasting blood glucose, vitamin B12, and thyroid-stimulating hormone levels; specialized tests should be ordered if clinically indicated. Lumbar puncture and cerebrospinal fluid analysis may be helpful in the diagnosis of Guillain-Barré syndrome and chronic inflammatory demyelinating neuropathy. Electrodiagnostic studies, including nerve conduction studies and electromyography, can help in the differentiation of axonal versus demyelinating or mixed neuropathy. Treatment should address the underlying disease process, correct any nutritional deficiencies, and provide symptomatic treatment.
Carpal Tunnel Syndrome - Article
ABSTRACT: Carpal tunnel syndrome is the most common entrapment neuropathy, affecting approximately 3 to 6 percent of adults in the general population. Although the cause is not usually determined, it can include trauma, repetitive maneuvers, certain diseases, and pregnancy. Symptoms are related to compression of the median nerve, which results in pain, numbness, and tingling. Physical examination findings, such as hypalgesia, square wrist sign, and a classic or probable pattern on hand symptom diagram, are useful in making the diagnosis. Nerve conduction studies and electromyography can resolve diagnostic uncertainty and can be used to quantify and stratify disease severity. Treatment options are based on disease severity. Six weeks to three months of conservative treatment can be considered in patients with mild disease. Lifestyle modifications, including decreasing repetitive activity and using ergonomic devices, have been traditionally advocated, but have inconsistent evidence to support their effectiveness. Cock-up and neutral wrist splints and oral corticosteroids are considered first-line therapies, with local corticosteroid injections used for refractory symptoms. Nonsteroidal anti-inflammatory drugs, diuretics, and pyridoxine (vitamin B6) have been shown to be no more effective than placebo. Most conservative treatments provide short-term symptom relief, with little evidence supporting long-term benefits. Patients with moderate to severe disease should be considered for surgical evaluation. Open and endoscopic surgical approaches have similar five-year outcomes.