J Neurol (2011) 258:212–217 DOI 10.1007/s00415-010-5712-3 O R I G I N A L C O M M U N I C A T I O N Cold paresis in multifocal motor neuropathy Dirk C. G. Straver • Jan-Thies H. van Asseldonk • Nicolette C. Notermans • John H. J. Wokke • Leonard H. van den Berg • Hessel Franssen Received: 25 May 2010 / Revised: 9 August 2010 / Accepted: 11 August 2010 / Published online: 28 August 2010 The Author(s) 2010. This article is published with open access at Springerlink.com Abstract Increased weakness during cold (cold paresis) was reported in single cases of multifocal motor neuropa- thy (MMN). This was unexpected because demyelination is a feature of MMN and symptoms of demyelination improve, rather than worsen, in cold. It was hypothesized that cold paresis in MMN does not reﬂect demyelination only, but may indicate the existence of inﬂammatory nerve lesions with permanently depolarized axons that only just conduct at normal temperature, but fail at lower tempera- tures. We investigated symptoms of cold paresis in 50 MMN patients, 48 chronic inﬂammatory demyelinating polyneuropathy (CIDP) patients, 35 progressive spinal muscular atrophy (PSMA) patients, and 25 chronic idio- pathic axonal polyneuropathy patients. We also investi- gated symptoms of increased weakness during warmth (heat paresis). Cold paresis was reported more often than heat paresis. Cold paresis was most frequently reported in MMN. Multivariate analysis indicated that MMN patients had a 4- to 6-fold higher risk of reporting cold paresis than CIDP or PSMA patients. Because cold paresis is not consistent with demyelination, the lesions in MMN may involve other mechanisms than demyelination only. In conclusion, symptoms of cold paresis are common in D. C. G. Straver J.-T. H. van Asseldonk N. C. Notermans J. H. J. Wokke L. H. van den Berg H. Franssen Neuromuscular Disease Group, Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands H. Franssen (&) Department of Neurology, F02.230, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands e-mail: H.Franssen@umcutrecht.nl 123 peripheral nervous system disorders, particularly in MMN. This supports the above-described hypothesis. Keywords Multifocal motor neuropathy Chronic inﬂammatory demyelinating polyneuropathy Chronic idiopathic axonal polyneuropathy Progressive spinal muscular atrophy Cold paresis Abbreviations CB Conduction block CIAP Chronic idiopathic axonal polyneuropathy CIDP Chronic inﬂammatory demyelinating polyneuropathy MMN Multifocal motor neuropathy PSMA Progressive spinal muscular atrophy Introduction The effect of temperature on symptoms of neurological disorders is complicated and has not been fully explored, neither in patients, nor in physiological research. A well- known effect is the worsening of symptoms in multiple sclerosis after a hot bath [20, 25]. In peripheral neuropa- thies, similar effects were described. In a patient with chronic inﬂammatory demyelinating polyneuropathy (CIDP), symptoms considerably increased during fever and in seven patients with various demyelinating neuropathies, electrophysiological signs of conduction block increased after warming and decreased after cooling [4, 8, 20]. This so-called heat paresis may occur in demyelinating disor- ders and is caused by an unfavorable combination of fac- tors that block saltatory conduction between an active node