Parry and colleagues propose that handgrip dynamometry (HGD) is used as a screening test and that the simplified four-point Medical Research Council (MRC) score with isometric manual muscle test evaluation is reserved to patients with reduced handgrip strength below critical thresholds (< 7 kg for female and <11 Kg for males). The authors also mention the need for simplified electrophysiological tests as third-tier to distinguish between critical illness myopathy and neuropathy. However, distinction between these two entities is not simple and cannot be achieved using simplified tests [2]. Moreover, CIP and CIM often coexist. As for HGD, these tests can indeed be used as screening tests. The peroneal nerve test (PENT) has been shown in two multicenter studies – the CRIMYNE [3] and CRIMYNE-2 study [4] – to have 100% sensitivity against full electromyography. If PENT is normal, further electrophysiological investigations can be avoided.
Simplified, non-volitional electrophysiological could be used at an early stage of critical illness, before definitive nerve-muscle damage occurs. At a later stage, they can differentiate those patients with abnormal electrophysiology (CIP, CIM or both, without distinguishing among these categories) from deconditioned patients that have a better prognosis [5].
Simplified tests to evaluate muscle strength as those proposed by Parry can be helpful to define the association between acute events and short and long-term sequelae of critical illness if they are integrated in a rational diagnostic work-up with other simplified tests evaluating muscle function, volume and structure in representative populations of ICU patients.
Prof. Nicola Latronico
University of Brescia, Italy
References
1. Parry SM, Berney S, Granger CL, Dunlop DL, Murphy L, El-Ansary D, Koopman R, Denehy L: A new two-tier strength assessment approach to the diagnosis of weakness in intensive care: an observational study. Crit Care 2015, 19(1):52.
2. Latronico N, Bolton CF: Critical illness polyneuropathy and myopathy: a major cause of muscle weakness and paralysis. Lancet Neurol 2011, 10(10):931-941.
3. Latronico N, Bertolini G, Guarneri B, Botteri M, Peli E, Andreoletti S, Bera P, Luciani D, Nardella A, Vittorielli E et al: Simplified electrophysiological evaluation of peripheral nerves in critically ill patients: the Italian multi-centre CRIMYNE study. Crit Care 2007, 11(1):R11.
4. Latronico N, Nattino G, Guarneri B, Fagoni N, Amantini A, Bertolini G, Investigators GS: Validation of the peroneal nerve test to diagnose critical illness polyneuropathy and myopathy in the intensive care unit: the multicentre Italian CRIMYNE-2 diagnostic accuracy study. F1000Res 2014, 3:127.
5. Moss M, Yang M, Macht M, Sottile P, Gray L, McNulty M, Quan D: Screening for critical illness polyneuromyopathy with single nerve conduction studies. Intensive Care Med 2014, 40(5):683-690.
6. Latronico N, Smith M: Introducing simplified electrophysiological test of peripheral nerves and muscles in the ICU: choosing wisely. Intensive Care Medicine 2014, 40(5):746-748.
Critical Care
Simplified diagnostic tests in the ICU
5 May 2015
Simplified diagnostic tests in the ICU
Parry and colleagues propose that handgrip dynamometry (HGD) is used as a screening test and that the simplified four-point Medical Research Council (MRC) score with isometric manual muscle test evaluation is reserved to patients with reduced handgrip strength below critical thresholds (< 7 kg for female and <11 Kg for males). The authors also mention the need for simplified electrophysiological tests as third-tier to distinguish between critical illness myopathy and neuropathy. However, distinction between these two entities is not simple and cannot be achieved using simplified tests [2]. Moreover, CIP and CIM often coexist. As for HGD, these tests can indeed be used as screening tests. The peroneal nerve test (PENT) has been shown in two multicenter studies – the CRIMYNE [3] and CRIMYNE-2 study [4] – to have 100% sensitivity against full electromyography. If PENT is normal, further electrophysiological investigations can be avoided.
Simplified, non-volitional electrophysiological could be used at an early stage of critical illness, before definitive nerve-muscle damage occurs. At a later stage, they can differentiate those patients with abnormal electrophysiology (CIP, CIM or both, without distinguishing among these categories) from deconditioned patients that have a better prognosis [5].
Simplified tests to evaluate muscle strength as those proposed by Parry can be helpful to define the association between acute events and short and long-term sequelae of critical illness if they are integrated in a rational diagnostic work-up with other simplified tests evaluating muscle function, volume and structure in representative populations of ICU patients.
Prof. Nicola Latronico
University of Brescia, Italy
References
1. Parry SM, Berney S, Granger CL, Dunlop DL, Murphy L, El-Ansary D, Koopman R, Denehy L: A new two-tier strength assessment approach to the diagnosis of weakness in intensive care: an observational study. Crit Care 2015, 19(1):52.
2. Latronico N, Bolton CF: Critical illness polyneuropathy and myopathy: a major cause of muscle weakness and paralysis. Lancet Neurol 2011, 10(10):931-941.
3. Latronico N, Bertolini G, Guarneri B, Botteri M, Peli E, Andreoletti S, Bera P, Luciani D, Nardella A, Vittorielli E et al: Simplified electrophysiological evaluation of peripheral nerves in critically ill patients: the Italian multi-centre CRIMYNE study. Crit Care 2007, 11(1):R11.
4. Latronico N, Nattino G, Guarneri B, Fagoni N, Amantini A, Bertolini G, Investigators GS: Validation of the peroneal nerve test to diagnose critical illness polyneuropathy and myopathy in the intensive care unit: the multicentre Italian CRIMYNE-2 diagnostic accuracy study. F1000Res 2014, 3:127.
5. Moss M, Yang M, Macht M, Sottile P, Gray L, McNulty M, Quan D: Screening for critical illness polyneuromyopathy with single nerve conduction studies. Intensive Care Med 2014, 40(5):683-690.
6. Latronico N, Smith M: Introducing simplified electrophysiological test of peripheral nerves and muscles in the ICU: choosing wisely. Intensive Care Medicine 2014, 40(5):746-748.
Competing interests
I do not have conflicts of interest to declare.