J Neurol (2005) 252 : 916–920 DOI 10.1007/s00415-005-0780-5 ORIGINAL COMMUNICATION Dario Cocito Palma Ciaramitaro Eugenia Rota Gianluca Isoardo Silvana Cannizzo Fabio Poglio Alessia Tavella Lorys Castelli Ilaria Paolasso Bruno Bergamasco Sergio Baldi Subclinical electrophysiological alterations of phrenic nerve in chronic inflammatory demyelinating polyneuropathy JON 1780 Introduction Chronic inflammatory demyelinating polyneuropathy (CIDP) is characterized by proximal and distal weak- ness, associated with sensitive involvement and has a chronic course [14]. Although respiratory failure is a rare occurrence in CIDP patients [7], a few cases of CIDP have recently been described in which the clinical hall- mark was phrenic nerve (PN) dysfunction associated with respiratory failure or death due to respiratory fail- ure [6]. A recent study [9] demonstrated a positive correla- tion between a low amplitude of the diaphragmatic compound muscle action potential (CMAP) and altered pulmonary function tests (PFTs) in those CIDP patients who showed clinical signs of respiratory failure. Fur- thermore, abnormal values of conduction velocity of PN, even in the absence of respiratory dysfunction, have been reported in patients with acquired [3] or inherited neuropathies [1], suggesting that PN conduction studies may be able to disclose subclinical changes. Therefore, whether or not a PN involvement may be able to predict or cause respiratory failure in CIDP patients is a ques- tion still to be answered. We ourselves doubt that conduction alterations or ax- onal damage of the PN in patients suffering from chronic polyneuropathy could be responsible for respi- ratory failure, which is often characterized by a late on- set after diagnosis. Received: 11 May 2004 Received in revised form: 1 December 2004 Accepted: 20 December 2004 Published online: 21 March 2005 D. Cocito, MD () · E. Rota, MD · F. Poglio, MD · A. Tavella, MD · L. Castelli, MD · I. Paolasso, MD · B. Bergamasco, MD U.O. Neurofisiologia Clinica Dipartimento di Neuroscienze Università di Torino Via Cherasco 15 10126 Torino, Italy Tel.: + 39-011/6335243 Fax: +39-011/6963487 E-Mail: dariococito@yahoo.it D. Cocito, MD · B. Bergamasco, MD I.R.C.C.S. Fondazione S. Maugeri Pavia, Italy P. Ciaramitaro, MD Neurofisiologia Clinica Div. Neurochirurgia, Ospedale CTO Torino, Italy G. Isoardo, MD S.O.C. Neurologia Ospedale Civile Asti, Italy S. Baldi, MD · S. Cannizzo, MD S.O.C. Pneumologia A.S.O. San Giovanni Battista Torino, Italy ■ Abstract Alterations of the phrenic nerve (PN) and pulmonary function tests (PFTs) have been described in patients with chronic inflammatory demyelinating poly- neuropathy (CIDP). This study was aimed at assessing the relationship between PN and respiratory func- tion in CIDP patients without clini- cal signs of respiratory failure. Bilateral PN and right median nerve conduction studies were carried out along with blood gas analysis and PFTs: maximal inspi- ratory pressure; maximal expira- tory pressure; forced vital capacity. The amplitude of the compound muscle action potential of the PN was seen to be altered in 19/24 (79 %) patients and latency in 22 (92 %). Eighteen patients (75 %) showed at least one abnormal PFTs or CO 2 partial pressure value. Electrophysiological alterations of the PN were observed in a high percentage of the CIDP patients studied. No statistically significant correlation was observed between PN and PFTs alterations. ■ Key words phrenic nerve conduction · chronic inflammatory demyelinating polyneuropathy · CIDP · pulmonary function · electrodiagnosis