Neuromuscular Disorders in Neonate

Abstract

Neuromuscular (NM) disorders in neonates are an abnormality of the lower motor neuron system comprising of anterior horn motor neurons and nerves, NM junction, and the muscle. The neonate with NM disorders presents with hypotonia, weakness, often associated with respiratory insufficiency, swallowing difficulty and is at high risk of perioperative complications. The underlying myopathy requires a proper detailed preoperative assessment of all systems, especially the respiratory and the NM systems. This is possible in children and adult patients, but the situation is different in the newborns and neonates, because there may be no history, presenting features of myopathy may not be very diagnostic and may be superimposed by the those of surgical condition and its associated metabolic and biochemical changes, making diagnosis, or even suspicion of a myopathy more difficult. Hence, anesthesiologist needs to be very vigilant in evaluation, as undiagnosed myopathy may increase the risk of postoperative morbidity and mortality, in such babies. In the developed countries, a detailed neonatal screening may be able to detect these disorders early, but in other countries, such as India, neonatal screening is still not a routine. Approach to a neonate suspected with NM disorders include Creatinine phosphokinase (CP kinase) and lactate measurements, electromyography, muscle biopsy, and genetic testing. Elevated CP kinase levels are an alert for a muscular disorder, significantly high levels point toward a congenital muscular dystrophy, while in myopathies and spinal muscular atrophy, the levels may be normal or mildly elevated. Lactate levels are elevated in mitochondrial disease. In such cases, caution should be exercised in the use of muscle relaxants and halogenated anesthetic agents. Combination of muscle weakness of myopathy and general anesthesia is a good concoction for respiratory depression, delayed recovery from anesthesia, need for postoperative ventilation, and prolonged NICU stay. Even in case, there is no preoperative diagnosis, all due precautions should be taken in neonates. Neonatal NM disorders and their anesthetic implications are discussed in this chapter, though the evidence-based literature in neonates is still scarce.