Electromyographic tools to assess hemidiaphragm paralysis Yves Jammes 1,2 , Ce ´cile Budin-Poirier 1,2 and Fabienne Bre ´geon 1,2 1 UMR MD2 (P2COE), Jean Roche Institute, Faculty of Medicine, University of Me ´diterrane ´e, and 2 Lung Function Laboratory, North Hospital, Assistance Publique-Ho ˆpitaux de Marseille, Marseille, France Correspondence Pr. Yves Jammes, UMR MD2 (P2COE), Jean Roche Institute, Faculty of Medicine, University of Me ´diterrane ´e, Marseille, France E-mail: yves.jammes@univmed.fr; JammesYves48@aol.com Accepted for publication Received 12 June 2009; accepted 15 October 2009 Key words diaphragm electromyogram; diaphragm paralysis; maximal inspiration; phrenic nerve; sniff Abbreviations ANOVA, analysis of variance; CT, phrenic nerve conduction time; Edi, integrated diaphragmatic electromyogram; EMG, surface electromyogram; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; M-wave, evoked compound muscle action potential; PaCO 2 , arterial partial pressure of carbon dioxide; PaO 2 , arterial partial pressure of oxygen; PImax, maximal inspiratory mouth pressure; TLC, total lung capacity; VC, vital capacity. Summary Non-invasive measurements of the phrenic nerve conduction time (CT) and diaphragmatic electromyographic response to voluntary inspiratory efforts may help to document an abnormal diaphragmatic function in the presence of hemidia- phragm elevation on chest radiographs. Twenty-one patients were addressed for the diagnosis of abnormal placement and motion of the right (13) or left (8) cupola on chest radiographs. CT was measured by recording the diaphragmatic M-wave evoked by electrical transcutaneous phrenic nerve stimulation. The integrated diaphragmatic surface electromyogram (Edi) was recorded during sniff and Mu ¨ller manoeuvres. Four patients were followed up during the next 8–16 months. Among the twenty- one patients, five (24%) had a lengthened or absent CT. A right-to-left peak Edi asymmetry was measured in fourteen (67%), including those having abnormal CT. Agreement between side-related radiographic abnormalities and Edi asymmetry was high in the cases of an elevation of the right cupola (12 ⁄ 13, 92%) but poor when the left cupola was suspected (1 ⁄ 8, 13%). Long-term follow-up of Edi asymmetry showed a partial or total recovery. Thus, the combination of measurements of phrenic nerve CT and Edi recordings during voluntary inspiratory efforts confirmed 67% of the radiographic suspicion of diaphragmatic dysfunction. Introduction The causes, clinical manifestations and exploration of diaphrag- matic dysfunction are widely documented (Laghi & Tobin, 2003). Diaphragmatic dysfunction may result from the reduc- tion or the suppression of the motor command through a phrenic nerve compression or section or neuronal lesions at the spinal or supraspinal level. They may also result from an impaired muscle contractility, accompanying inflammatory, infectious or haemorrhagic pleurisy (Malucelli & Mariano, 1980; Zifko et al., 2002) or simply result from a mechanical impairment of the diaphragmatic motion (through a disruption of the muscle structure or a decreased compliance of the surrounding tissues) (Laghi & Tobin, 2003). In routine medical practise, diaphragmatic dysfunction is often simply called Ôdiaphragm paralysisÕ and suspected from hemidiaphragm elevation on chest radiographs. The radiographic and radio- scopic criteria for diaphragmatic cupolae abnormality are well defined (Tarver et al., 1989; Laghi & Tobin, 2003; Verhey et al., 2007). Although more appropriate (Laghi & Tobin, 2003), ultrasonography is rarely primarily used to explore diaphrag- matic function in our country, because of the higher cost and because it requires a trained practitioner. For about four decades, physiologists have developed non- invasive means to explore the motor command to the diaphragm using electrical or magnetic stimulation of the phrenic motoneurones (cervical stimulation) or the supraspinal structures (transcranial stimulation). The contractile diaphrag- matic response is then assessed from recordings of the twitch mouth or trans-diaphragmatic pressure (Laroche et al., 1988), or the evoked electromyographic (EMG) potential called the M-wave (Newsom Davis, 1967; De Troyer & Vanderhoeft, 1982; Markand et al., 1984; McKenzie & Gandevia, 1985; Mier et al., 1987; Similowski et al., 1989, 1997; Chen et al., 1995; Zifko et al., 1996; Verin et al., 2002; Demoule et al., 2003; Glerant et al., 2006; Resman-Gaspersc & Podnar, 2008). How- ever, twitch pressure changes or M-wave recordings have been rarely reported as diagnostic tools to complete the exploration of a diaphragmatic dysfunction (Newsom Davis, 1967; Moorthy et al., 1985; Gandevia, 1987; Mier et al., 1987; Wilcox & Pardy, 1989; Chetta et al., 2005). There is a dearth of data in the literature on the ability of physiological tools to explore the Clin Physiol Funct Imaging (2010) 30, pp107–115 doi: 10.1111/j.1475-097X.2009.00911.x Ó 2009 The Authors Journal compilation Ó 2009 Scandinavian Society of Clinical Physiology and Nuclear Medicine 30, 2, 107–115 107