Phrenic nerve stimulation

A Device for Transcutaneous Stimulation of the Diaphragm

Results obtained during the development of an original device for noninvasive transcutaneous stimulation of the diaphragm using electromagnetic radiation in the terahertz frequency range are presented. The block diagram and design of a terahertz emitter and a controlled current source for its power supply are presented, along with specialized software for selecting and setting the amplitude and time parameters of the stimulating signal.

Dynamic magnetic resonance imaging in unilateral diaphragm eventration: knowledge improvement before and after plication

Background

The assessment before surgical plication for unilateral hemidiaphragm (HD) eventration is not clearly defined and no precise criteria exist to really understand which patient is operated with which results depending on the technique used. The goal of this study was to evaluate the place of dynamic magnetic resonance imaging (dMRI) before and after plication by developing measurement criteria.

Methods

Between 2006 and 2017, 18 patients (group1: Gp1) were operated for eventrations, 15 left-sided (Gp1L) and 3 right-sided (Gp1R). All had preoperative and postoperative evaluations including dMRI and pulmonary function tests. Five healthy volunteer subjects (group2: Gp2) had the same imaging protocol. For each HD, we measured the respiratory excursion at three fixed points (S1, S2, S3) and the height of curvature on sagittal plane. We also searched for upward paradoxical diaphragm movements.

Results

Before surgery, no excursion (n=13) or extremely reduced excursion (n=5) was detected on the injured HD (IHD) in Gp1. Upward paradoxical movements were identified only in Gp1L (n=6). Compared with Gp2 subjects, the healthy HD for Gp1L patients had significantly reduced excursion values at three sites S1 (P=0.038), S2 (P=0.006), and S3 (P=0.004). After plication, the decreasing height of curvature confirmed a tightening of the IHD in all patients (median value from 100 to 39.5 mm in Gp1L and 92 to 74 mm in Gp1R, P=0.0001). All upward paradoxical movements disappeared. Healthy HD excursions in Gp1L normalised their values. All those imaging improvements were correlated with postoperative improvements of dyspnoea score (P<0.0001) and vital capacity (P=0.002).

Conclusions

dMRI and the standardised grid we developed not only improve the knowledge of unilateral diaphragm eventration but also permit to evaluate the quality of its surgical repair. It also demonstrates that a dysfunction of the healthy HD contralateral to eventration is possible and reversible after plication of the IHD.