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Nerve Conduction Studies of Phrenic Nerve: Normative Data
José Castro1,2, Mamede de Carvalho1,2
1Instituto de Fisiologia, Centro de Estudos Egas Moniz, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal ; and.
Summary
Nerve conduction studies of the phrenic nerve (PN) are a reliable method to assess diaphragm function in neuromuscular diseases. Results show that sex and age significantly influence diaphragm motor responses, with higher amplitudes on the left side.
Area of Science:
- Neurology
- Respiratory Medicine
- Clinical Electrophysiology
Background:
- Respiratory failure is a significant complication in neuromuscular diseases.
- Pulmonary function tests are standard but can be affected by various factors.
- Phrenic nerve (PN) conduction studies offer a noninvasive method to evaluate diaphragm compromise.
Purpose of the Study:
- To assess diaphragm motor responses via PN conduction studies.
- To determine the influence of anthropometric variables (sex, age, height, weight) on diaphragm motor responses.
- To analyze side-to-side differences in PN compound muscle action potential (CMAP).
Main Methods:
- Studied 132 healthy subjects (78 males, aged 23-90 years).
- Performed bilateral PN stimulation and recorded diaphragm motor responses.
- Collected anthropometric data and analyzed its effect on CMAP and side-to-side variations.
Main Results:
- Left PN CMAP amplitude and area were significantly higher than the right.
- Men exhibited longer latency and higher amplitude/area compared to women.
- Age significantly impacted CMAP latency (0.25 ms increase per decade). Established normative values for men and women.
Conclusions:
- PN conduction studies are a simple, reliable, and clinically applicable technique.
- Diaphragm CMAP parameters are significantly influenced by sex and age.
- Left-sided PN demonstrates greater CMAP amplitude and area.
