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Phrenic nerve conduction in infancy and early childhood
T Imai1, H Shizukawa, H Imaizumi
1Department of Neurology, School of Medicine, Sapporo Medical University, South 1, West 16, Chuo-ku, Sapporo 060-8543, Japan. toimai@sapmed.ac.jp
Insights
Diaphragmatic action potentials (DAPs) in infants show decreasing latencies with age, indicating normal phrenic nerve development. These findings aid in diagnosing phrenic nerve palsy.
Area of Science:
- Neurology
- Pediatrics
- Physiology
Background:
- Diaphragmatic action potentials (DAPs) are crucial for assessing respiratory function.
- Understanding normal DAP development in infants is essential for clinical diagnosis.
Purpose of the Study:
- To map DAPs in neurologically normal infants and young children.
- To establish reference values for DAP latency and amplitude.
- To evaluate DAPs as indicators of normal phrenic nerve development.
Main Methods:
- Mapping DAPs on the thorax bilaterally using transcutaneous phrenic nerve stimulation.
- Recording DAPs in 16 infants and 8 children (1-4 years) during artificial ventilation.
- Analyzing DAP latency and amplitude in relation to age and conduction distance.
Main Results:
- DAPs were recorded on the anterolateral chest wall, with peak amplitude in the 7th intercostal space.
- DAP latencies decreased from 6-8 ms at birth to ~5 ms by 1 year.
- DAP amplitude showed no correlation with age, and minimal interside variation was observed.
Conclusions:
- DAP latency decreases with age, reflecting normal phrenic nerve maturation.
- These findings provide valuable reference data for diagnosing phrenic nerve palsy in children.
- DAP characteristics serve as indicators of healthy phrenic nerve development.
Abstract:
Diaphragmatic action potentials (DAPs) were mapped on the thorax bilaterally in 16 neurologically normal infants and 8 boys aged 1 to 4 years during artificial ventilation after thoracic surgery. Transcutaneous stimulation was used to activate the phrenic nerve at the supraclavicular fossa at the end of an artificial inspiration. The DAPs were of positive polarity and were recorded on the ipsilateral anterolateral chest wall over the sixth to the eighth intercostal spaces, with a maximal peak at the seventh intercostal space. The DAP latencies gradually decreased from 6 to 8 ms at birth to about 5 ms at the age of 1 year, despite an increase of conduction distance. Statistical analyses revealed that DAP amplitude did not correlate with age. The latencies and amplitudes of the DAPs displayed little interside variation. The results are valuable not only as a reference for the diagnosis of patients with phrenic nerve palsy, but also as an indicator of the normal development of the phrenic nerve.