HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Correspondence to:

ARTICLES: R.A.B. Badawy, J. M. Curatolo, M. Newton, S. F. Berkovic, and R. A.L. Macdonell Sleep deprivation increases cortical excitability in epilepsy: Syndrome-specific effects Neurology 2006; 67: 1018-1022 [Abstract] [Full text] [PDF]

Correspondence: Submit a response to this article

Correspondence published:

Re: Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects

Roberto M. Cantello   (24 April 2007)

Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects

Carlo Civardi, MD, Alessandra Collini, MD   (14 January 2007)

Reply from the Authors

Richard Macdonell, .A.B. Badawy, J. M. Curatolo, M. Newton, S. F. Berkovic   (14 January 2007)

Re: Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects 24 April 2007
Roberto M. Cantello, Università del Piemonte Orientale Clinica Neurologica. Ospedale Maggiore, Corso Mazzini 18, 28100 Novara, Italy. Send Correspondence to journal: Re: Re: Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects cantello{at}med.unipmn.it Roberto M. Cantello	I am writing in reference to the Correspondence by Civardi and Collini commenting on the paper by Badawy et al. [1] Civardi and Collini base the comments in the Correspondence on previous work carried out in the laboratory for which I am responsible. Although Civardi was a collaborator on previous work in the laboratory, neither he nor Collini are currently involved in research activity in the laboratory. Their Correspondence does not represent my opinion or that of others working in the laboratory. References 1. Civardi C, Collini A. Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects [e-online Letter]. Neurology 14 January 2007. Disclosure: The author reports no conflicts of interest.
Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects 14 January 2007
Carlo Civardi, MD, Azienda Ospedaliera “Maggiore della Carità”. Università del Piemonte Orientale “A. Avogadro” C.so Mazzini 18, 28100 Novara, Italy., Alessandra Collini, MD Send Correspondence to journal: Re: Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects c_civardi{at}yahoo.com Carlo Civardi, MD, et al.	We read the Badawy et al [1] article with great interest. The authors described the effects of sleep deprivation (SD) in normal subjects and in two groups of epileptic patients with idiopathic generalized (IGE) and focal epilepsy. In the control group, they reported a slight increase of cortical excitability due to SD at 250 ms interstimulus interval (ISI)recovery curve. In epileptic patients,they cortical excitability increased at short (1, 2, 5, 10 and 15 ms) and long ISIs (200, 250 and 300 ms). In IGE, these changes were roboust in both hemispheres, while in focal epilepsy were localized in the seizure focus hemisphere. We described consistent and significant changes in cortical excitability due to SD in normal subjects.[2] To analyze the effects of SD on cortical excitability, Badawy et al chose a different protocol from ours. They used a round coil instead of a focal coil and they stimulated the dominant hemisphere in the control group. However, in epileptic patients they considered both. Badawy et al did not include short ISIs that in our study showed statistical changes: ISIs 3 and 16 ms. Badawy’s study [1] lasted for 60-90 minutes for each subject while we analyzed a few number of TMS variables in order to reduce the time of the exam. In such a long period of time, the variability of cortical excitability could be significant, especially after 24 hours of SD, thus only ten control stimuli could not be enough. In addition, we are surprised by specific changes of cortical excitability related to the epileptic focus. It is known that in epileptic patients SD "activates EEG" in a specific and diffuse way [3] and in focal epilepsy TMS discloses a bilateral increase of cortical excitability [4,5] in a significant number of patients. The selective activation on seizure focus hemisphere [1] represents an intriguing but unexplained finding. References 1. Badawy RA, Curatolo JM, Newton M, Berkovic SF, Macdonell RA. Sleep deprivation increases cortical excitability in epilepsy: syndrome-specific effects. Neurology 2006; 67: 1018-1022. 2. Civardi C, Boccagni C, Vicentini R, et al. Cortical excitability and sleep deprivation: a transcranial magnetic stimulation study. J Neurol Neurosurg Psychiatry 2001; 71: 809-812. 3. Rodin E. Sleep deprivation and epileptological implications. In: Degen R, Rodin EA, eds. Epilepsy, sleep and sleep deprivation. Epilepsy Res 1991; suppl 2: 265–273. 4. Varrasi C, Civardi C, Boccagni C, et al. Cortical excitability in drug-naive patients with partial epilepsy. A cross-sectional study. Neurology 2004; 63: 2051-2055. 5. Cantello R, Civardi C, Cavalli A, et al. Cortical excitability in cryptogenic localization-related epilepsy: interictal transcranial magnetic stimulation studies. Epilepsia. 2000; 41: 694-704. Disclosure: The authors report no conflicts of interst.
Reply from the Authors 14 January 2007
Richard Macdonell, Austin Health Studley Road, Heidelberg, Victoria 3084, Australia, .A.B. Badawy, J. M. Curatolo, M. Newton, S. F. Berkovic Send Correspondence to journal: Re: Reply from the Authors Richard.Macdonell{at}austin.org.au Richard Macdonell, et al.	We thank Civardi et al for their interest in our study [1] and agree that our study differs in several respects from their study. [2] The primary focus of our study was to look at changes after sleep deprivation in patients suffering from epilepsy, rather than in controls. There may be subtle changes in excitability in controls that only appear at specific ISI’s, not included in our study rather than the more robust changes seen in patients with epilepsy. The 3msec and 16msec ISIs were not ignored but rather were not included in our experimental paradigms as this was not the focus. In response to the comment about unilateral versus bilateral stimulation in the control group, we relied on previous publications. [4,6] together with our own unpublished data which indicate that there are no inter side differences in excitability in a control population using paired pulse TMS at various interstimulus intervals. It appears intuitively unlikely that sleep deprivation causes more excitability in one hemisphere than another in a control group but this has not yet been studied. In the IGE group, there was no interside difference in excitability after sleep deprivation, this only occurred in the focal group when referenced to the side of seizure focus. There was also no difference between dominant and non-dominant hemispheres were compared pre and post sleep deprivation in either epilepsy group. It is conjecture that using a round coil rather than a figure eight coil had some impact on the findings. There are no studies to support this. A round coil is an accepted method of investigating cortical excitability [7] and interhemispheric asymmetries [8] using TMS. In any such study, cortical excitability varies over time; one reason that a much larger group of subjects were included than in the Civardi et al study. We feel it is unlikely that this explains the differences between those with focal and generalized epilepsy and controls given the random order of stimulation at various ISIs. We agree that sleep deprivation activates the EEG in a specific and diffuse way, but it is also discriminatory in patients with epilepsy. Sleep deprivation enhances the probability of detecting specific focal or generalized EEG abnormalities.[9] Our findings are consistent with this. We are currently exploring the phenomenon of lateralized excitability in patients with focal epilepsy in a larger number of patients than in the references quoted. References 6. Hamer HM, Reis J, Mueller HH, Knake S, Overhof M, Oertel WH, Rosenow F. Motor cortex excitability in focal epilepsies not including the primary motor area-a TMS study. Brain. 2005;128:811-818. 7. Manganotti P, Bongiovanni LG, Fuggetta G, et al. Effects of sleep deprivation on cortical excitability in patients affected by juvenile myoclonic epilepsy: a combined transcranial magnetic stimulation and EEG study. J Neurol Neurosurg Psychiatry 2006;77:56-60. 8. Garry MI Kamen G, Nordstrom MA Hemispheric differences in the relationship between corticomotor excitability changes following a fine- motor task and motor learning. J Neurophysiol 2004;91:1570-1578. 9. Leach J P, Stephen L J, Salveta C, Brodie M J. Which electroencephalography (EEG) for epilepsy? The relative usefulness of different EEG protocols in patients with possible epilepsy. J Neurol Neurosurg Psychiatry 2006; 77: 1040-1042. Disclosure: The authors report no conflicts of interest.