Characteristics of Prolonged Afterdischarges in Children With Malformations of Cortical Development

Abstract

We investigated aberrant cortical excitability in malformations of cortical development. From subdural electrodes, we recorded afterdischarges lasting ≥ 6 seconds in 12 of 13 patients with malformations of cortical development and 6 of 10 pediatric patients with nonmalformations of cortical development and reviewed amperage thresholds, distribution of afterdischarges, and motor responses. In patients with malformation of cortical development, motor response thresholds were high; afterdischarge and motor response thresholds, which essentially overlapped, inversely correlated with age (P < .01); afterdischarge thresholds declined with age; and 8 patients showed afterdischarges in remote sites. In nonmalformation of cortical development, afterdischarge thresholds did not significantly correlate with age; motor response thresholds tended to decline with age; and 2 patients had remote afterdischarges. Adolescent patients with malformations of cortical development had lower afterdischarge thresholds than adolescents with nonmalformation of cortical development (P < .05). From their high afterdischarge (and motor response) thresholds, we concluded that preadolescent patients with malformation of cortical development have less excitable, immature cortices, whereas adolescent patients with malformation of cortical development with low afterdischarge thresholds have hyperexcitable cortices. Remote afterdischarges over focal dysplastic cortex suggest aberrant cortical excitability and neural circuits.(J Child Neurol 2003;18:247—253).

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References

Walker AE : Posttraumatic Epilepsy. Springfield, IL, Thomas,1949, 23—69.

Penfield WJ , Jasper HH : Epilepsy and the Functional Anatomy of the Human Brain. Boston, Little Brown, 1954, 712—733.

Gloor P. : Contributions of electroencephalography and electrocorticography to the neurosurgical treatment of the epilepsies. Adv Neurol 1975 ;8:59—105.

Lesser RP , Kim SH , Byderman L. , et al: Brief bursts of pulse stimulation terminate afterdischarges caused by cortical stimulation. Neurology 1999;53:2073—2081.

Walker AE , Marshall C. : Stimulation and depth recording in man, in Sheer DE (ed): Electrical Stimulation of the Brain. Austin, TX, University of Texas Press, 1961, 498—518.

Crandall PH , Walter RW , Rand RW : Clinical application of studies on stereotactically implanted electrodes in temporal lobe epilepsies. J Neurosurg 1963 ;20:827—840.

Bancaud J. , Talairach J. , Bonis A. , et al: La Stereoencephalographie dans l'Epilepsie. Paris, Masson, 1965.

Lesser RP , Gordon B. , Fisher R. , et al: Subdural grid electrodes in surgery of epilepsy, in Lüders HO (ed): Epilepsy Surgery. New York, Raven Press, 1991, 399—408.

Bernier GP , Richer F. , Giard L. , et al: Electrical stimulation of the human brain in epilepsy. Epilepsia 1990;32:513—520.

10.

Jayakar P. : Invasive EEG monitoring in children. When, where, and what? J Clin Neurophysiol 1999;16:408—418.

11.

Lesser RP , Luders H. , Klem G. , et al: Extraoperative cortical functional localization in patients with epilepsy. J Clin Neurophysiol 1987;4:27—53.

12.

Wyllie E. , Luders H. , Morris HH , et al: Subdural electrodes in the evaluation for epilepsy surgery in children and adults. Neuropediatrics 1988; 19:80-86.

13.

Jayakar P. , Alvarez LA , Duchowny MS , Resnick TJ : A safe and effective paradigm to functionally map the cortex in childhood . J Clin Neurophysiol 1992;9:288—293.

14.

Chitoku S. , Otsubo H. , Harada Y. , et al: Extraoperative cortical stimulation of motor function in children . Pediatr Neurol 2001;24:344—350.

15.

Wyllie E. , Awad I. : Invasive neurophysiologic techniques in the evaluation for epilepsy surgery in children, in Lüders HO (ed): Epilepsy Surgery. New York, Raven Press, 1991, 409—412.

16.

Palmini A. , Gambardella A. , Andermann F. , et al: Intrinsic epileptogenicity of human dysplastic cortex as suggested by corticography and surgical results. Ann Neurol 1995;37:476—487.

17.

Rosenow F. , Luders HO , Dinner DS , et al: Histopathological correlates of epileptogenicity as expressed by electrocorticographic spiking and seizure frequency. Epilepsia 1998;39:850—856.

18.

Morioka T. , Nishio S. , Ishibashi H. , et al: Intrinsic epileptogenicity of focal cortical dysplasia as revealed by magnetoencephalography and electrocorticography. Epilepsy Res 1999;33:177—187.

19.

Otsubo H. , Ochi A. , Elliott I. , et al: MEG predicts epileptic zone in lesional extrahippocampal epilepsy: 12 pediatric epilepsy surgery cases. Epilepsia 2001;42:1523—1530.

20.

Duchowny M. , Jayakar P. , Levin B. : Aberrant neural circuits in malformations of cortical development and focal epilepsy. Neurology 2000;55:423—428.

21.

Tassi L. , Pasquier B. , Minotti L. , et al: Cortical dysplasia: Electro-clinical, imaging, and neuropathologic study of 13 patients. Epilepsia 2001;42:1112—1123.

22.

Lesser RP , Luders H. , Klem G. , et al: Cortical afterdischarge and functional responses thresholds: Results of extraoperative testing. Epilepsia 1984;25:615—621.

23.

Barth PG : Disorders of neuronal migration. Can J Neurol Sci 1987;14:1—16.

24.

Sarnat HB : Disturbances of late neuronal migrations in the perinatal period. Am J Dis Child 1987;141:969—980.

25.

Duggal N. , Iskander S. , Hammond RR : Nestin expression in cortical dysplasia. J Neurosurg 2001;95:459—465.

26.

Walker AE : Electrocorticography in epilepsy. A surgeon's appraisal. Electroencephalogr Clin Neurophysiol 1951;1(Suppl):S2.

27.

Jacobs KM , Gutnick MJ , Prince DA : Hyperexcitability in a model of cortical maldevelopment. Cerebr Cortex 1996;6:511—523.

28.

Holmes GL , Sarkisian M. , Ben-Ari Y. , et al: Consequences of cortical dysplasia during development in rats . Epilepsia 1999;40:537—544.

29.

Mikuni N. , Babb T. , Ying Z. , et al: NMDA receptor 1 and 2 A/B coassembly increased in human epileptic focal cortical dysplasia. Epilepsia 1999;40:1683—1687.

30.

Marusic P. , Najm IM , Ying Z. , et al: Focal cortical dysplasias in eloquent cortex: Functional characteristics and correlation with MRI and histopathologic changes. Epilepsia 2002;43:27—32.

31.

Akai T. , Otsubo H. , Pang EW , et al: Complex central cortex in pediatric patients with malformations of cortical development. J Child Neurol 2002 ;17:347—352.

32.

Gotman J. , Marciani MG : Electroencephalographic spiking activity, drug levels, and seizure occurrence in epileptic patients. Ann Neurol 1985;17:597—603.