Diagnostic workup for neuromuscular diseases

Abstract

Clinical symptoms of neuromuscular diseases vary according to age and type of primary involvement (spinal motor neuron, nerve, neuromuscular junction or muscle). Tools at our disposal for diagnostic purposes are graduated based on the age of the patient and diagnostic suspicions generated by the clinical workup. Seven clinical presentations can be identified that all require technical facilities specifically dedicated to pediatric neuromuscular diseases: congenital hypomobility and arthrogryposis, paralytic hypotonia in infancy, motor delay and chronic walking difficulties after the age of 18 months, progressive walking difficulties after the age of 3 years, effort intolerance and acute rhabdomyolysis, acute motor symptoms or fatigability, and variability of symptoms. Electrophysiological investigation, particularly electromyography, is a valuable tool where neurogenic involvement or neuromuscular block is suspected. However, the technique is difficult to perform in children. Muscle biopsy is generally the key investigation and can be performed at any age. Molecular biology helps to improve diagnostic strategy. Muscle MRI, in combination with clinical evaluation, assists the selection of appropriate genetic tests and more generally the identification of genetically distinct forms of neuromuscular disorder. None of these are by any means routine investigations, and only a specialized multidisciplinary clinical approach can permit correct diagnosis and proper follow-up.