Background: Critical illness neuromyopathy is a significant clinical problem of multifactorial origin causing morbidity in critically ill children admitted to a paediatric intensive care unit. 
Objective: To describe the pattern of nerve conduction and electromyographic abnormalities in children suspected of critical illness neuromyopathy.  
Methods: Nerve conduction and electromyography (EMG) tests were performed in children in an intensive care setting who have been on prolonged mechanical ventilation with the suspicion of critical illness neuromyopathy (CINM). Nerve conduction was performed in the lower limb and in the phrenic nerve. EMG testing was done in the lower limb muscles and in the diaphragmatic muscles. Neurophysiological tests were done at the bedside in the Paediatric Intensive Care Unit, Sirimavo Bandaranaike Specialised Children’s Hospital, Peradeniya, Sri Lanka using a portable nerve conduction/EMG machine using standard techniques. 
Results: Of 26 children with ages from 5 days to 7 years, 13 were females.
In 11 patients (42%) critical illness neuropathy or myopathy was diagnosed on clinical and neurophysiological findings. Phrenic nerve compound muscle action potentials were absent in 6 of those patients. Abnormal diaphragmatic EMG pattern was seen in 8 of those patients. Common peroneal nerve stimulation to tibialis anterior muscle stimulation, N/M ratio (nerve to muscle ratio) was abnormal in 5 of those patients (recording from tibialis anterior muscle).
In the remaining 15 patients who were not categorized as CINM, generalized myopathy was diagnosed based on the neurophysiological findings in 5 patients, diaphragmatic paralysis was seen in one patient and a traumatic phrenic nerve lesion was seen in another patient. The remaining 8 patients had normal neurophysiological findings.     
Conclusion: Bedside nerve conduction and electromyographic tests are useful in assessing the pattern of neurophysiological abnormalities in children on prolonged mechanical ventilation and will help in better management of these critically ill patients.