METHODS OF TESTING NEUROMUSCULAR-TRANSMISSION IN THE INTENSIVE-CARE UNIT

All disorders of neuromuscular transmission (NMT) may cause ventilator y failure, albeit rarely. Respiratory muscle weakness is occasionally the presenting feature of myasthenia gravis (MG), the Lambert-Eaton my asthenic syndrome (LEMS), hypermagnesemia and botulism. Chronic MG, co ngenital myasthenic syndromes and LEMS may be acutely exacerbated by v arious intercurrent conditions and by drugs which interfere with NMT. Finally, in the ICU, difficulty ill weaning from the ventilator may be caused by prolonged use of neuromuscular blocking agents. Electrophys iological studies of NMT disorders in the Intensive care unit have rar ely been reported. Nevertheless, the available data indicates that the electrodiagnosis of severe NMT disorders can be misleading, With seve re NMT defects, the electrophysiological distinction between post-syna ptic and pre-synaptic disorders is blurred and the differential diagno sis with myopathies may be difficult. A clinically suspected NMT disor der should therefore not be ruled out when electrodiagnosis fails to d emonstrate the expected abnormalities.