Feature Review Article Critical illness polyneuropathy and myopathy in pediatric intensive care: A review Stephen Williams, MB, BS, MRCPCH, FJFICM; Iain A. Horrocks, MB, ChB, MRCP (UK); Robert A. Ouvrier, MD, FRACP; Jonathan Gillis, PhD, FJFICM; Monique M. Ryan, M Med, FRACP C ritical illness polyneuropathy (CIP) and myopathy (CIM) are syndromes causing weakness and failure to successfully wean from mechanical ventilation in crit- ically ill adults. First described by Bolton et al. in (1) 1984, CIP and CIM have been the subject of several recent reviews (2– 4). The literature is complex, with significant variation in nomenclature and classifica- tion rendering comparison of the various series difficult. Many authors now argue that CIP and CIM are on a continuum of neuromuscular disorders associated with critical illness. Definitive differentiation be- tween disorders of the peripheral nerve, neuromuscular junction, and muscle in this setting is often dependent on detailed clinical, neurophysiologic, and patho- logic testing (Table 1). These conditions have repeatedly been shown to cause sig- nificant long-term morbidity in as many as 100% of adults with critical illness, resulting in weakness and fatigability that may be more limiting than respiratory dysfunction (5, 6). A number of unresolved issues per- taining to adult critical illness polyneu- ropathy and myopathy (CIPNM) are rele- vant to studies of these disorders in childhood, in which their incidence and clinical significance are not known. This review summarizes the literature on CIP and CIM with special reference to what is known of these disorders in childhood. CLINICAL FEATURES The term critical illness polyneurop- athy and myopathy (CIPNM) represents a spectrum of conditions affecting criti- cally ill patients in which generalized weakness and respiratory dysfunction are common. Distinct subtypes are recog- nized (4, 7, 8) but can be difficult to differentiate clinically. Examination shows weakness, muscle atrophy, and re- duced or absent reflexes with sensory def- icit being less prominent (2, 3, 7, 9). CIPMN is frequently cited as a cause for failure of extubation when lung disease no longer mandates continuing mechan- ical ventilation. The variability of inci- dence figures in reported series reflects a lack of uniformity of clinical, neurophys- iologic, and pathologic criteria in these studies (reviewed in Ref. 4). CIPNM man- ifests as early as the first 3 days of illness in some cases (2). There are no reliable data on the incidence of CIPNM in criti- cally ill children, in whom only one pro- spective study has been reported. There are, however, several case reports of CIPNM developing within the first week of critical illness in childhood (10 –13). RISK FACTORS AND PATHOGENESIS Risk factors for development of CIP and CIM in adults include sepsis and the systemic inflammatory response syn- From the Helen McMillan Paediatric Intensive Care Unit (SW, JG) and the Institute for Neuromuscular Research (IAH, RAO, MMR), The Children’s Hospital at Westmead, NSW, Australia; and the Discipline of Pae- diatrics and Child Health, University of Sydney (RAO, JG, MMR). No financial support was obtained for the prepa- ration of this article. Copyright © 2007 by the Society of Critical Care Medicine and the World Federation of Pediatric Inten- sive and Critical Care Societies DOI: 10.1097/01.pcc.0000256623.01254.40 Objective: To review the medical literature on critical illness polyneuropathy and myopathy in childhood. Data Source: Medline and EMBASE were searched using the following terms: critical illness (neuropathy, polyneuropathy, and myopathy), critical care (neuropathy, polyneuropathy, and myop- athy), acute myopathy, acute necrotizing myopathy, children, and pediatric. The references listed in publications thus identified were also reviewed. Study Selection and Data Extraction: All studies relating to pediatric critical illness polyneuropathy and myopathy were in- cluded. The adult literature was also reviewed as to the current understanding of critical illness polyneuropathy and myopathy. Data Synthesis: Critical illness polyneuropathy and critical illness myopathy are well recognized in adults, in whom they commonly cause generalized weakness and muscle wasting, with failure to wean from mechanical ventilation. Critical illness poly- neuropathy and critical illness myopathy are reported in 32–100% of critically ill adult patients ventilated for >3 days. There is significant clinical and neurophysiologic overlap between the two conditions, such that the term critical illness polyneuropathy and myopathy (CIPNM) is often used. Critical illness polyneuropathy and critical illness myopathy have only occasionally been re- ported in childhood, and little is known of their prevalence or clinical significance in this population. This article summarizes the pediatric literature on critical illness polyneuropathy and critical illness myopathy and highlights areas for future research in critically ill children. Conclusions: Critical illness polyneuropathy and myopathy may cause significant morbidity in critically ill children. These conditions seem to be clinically and electrophysiologically similar in children and adults, but prospective studies of these entities are required to better characterize their frequency, natural his- tory, and clinical significance in pediatric practice. (Pediatr Crit Care Med 2007; 8:18 –22) 18 Pediatr Crit Care Med 2007 Vol. 8, No. 1