Elaine Hughes - Academia.edu (original) (raw)

Papers by Elaine Hughes

Research paper thumbnail of Molybdenum cofactor deficiency - phenotypic variability in a family with a late-onset variant

Develop Med Child Neurol, 2008

Research paper thumbnail of Paroxysmal episodes, re-build up phenomenon and moyamoya disease

Epileptic Disorders International Epilepsy Journal With Videotape, Nov 1, 2009

Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progress... more Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progressive. Non-idiopathic forms with an associated disease are called moyamoya-like syndrome. The electroencephalographic finding characteristically seen after hyperventilation in about 50% of children with cerebrovascular disease includes gradual frequency decrease and activation of amplitude of slow waves which appear after the disappearance or attenuation of ordinary build up. This is termed the "re-build up" phenomenon, which is rarely seen and therefore may be under-recognized. We present video telemetry during a transient ischaemic event of a child subsequently diagnosed with moyamoya-like syndrome. We highlight the potential for misdiagnosis of organic non-epileptic events. Hyperventilation during EEG should be avoided in children with known moyamoya disease.

Research paper thumbnail of Effects of Inhibitory Concentrations of 3-Indolylacetic Acid and 3-Indolylacetonitrile on Cell Division and Tissue 2

Research paper thumbnail of Risk factors for reading disability in families with rolandic epilepsy

Epilepsy & Behavior, 2015

The high prevalence and impact of neurodevelopmental comorbidities in childhood epilepsy are now ... more The high prevalence and impact of neurodevelopmental comorbidities in childhood epilepsy are now well known, as are the increased risks and familial aggregation of reading disability (RD) and speech sound disorder (SSD) in rolandic epilepsy (RE). The risk factors for RD in the general population include male sex, SSD, and ADHD, but it is not known if these are the same in RE or whether there is a contributory role of seizure and treatment-related variables. An observational study of 108 probands with RE (age range: 3.6-22years) and their 159 siblings (age range: 1-29years; 83 with EEG data) were singly ascertained in the US or UK through a proband affected by RE. We used a nested case-control design, multiple logistic regression, and generalized estimating equations to test the hypothesis of an association between RD and seizure variables or antiepileptic drug treatment in RE; we also assessed an association between EEG focal sharp waves and RD in siblings. Reading disability was reported in 42% of probands and 22% of siblings. Among probands, RD was strongly associated with a history of SSD (OR: 9.64, 95% CI: 2.45-37.21), ADHD symptoms (OR: 10.31, 95% CI: 2.15-49.44), and male sex (OR: 3.62, 95% CI: 1.11-11.75) but not with seizure or treatment variables. Among siblings, RD was independently associated only with SSD (OR: 4.30, 95% CI: 1.42-13.0) and not with the presence of interictal EEG focal sharp waves. The principal risk factors for RD in RE are SSD, ADHD, and male sex, the same risk factors as for RD without epilepsy. Seizure or treatment variables do not appear to be important risk factors for RD in probands with RE, and there was no evidence to support interictal EEG focal sharp waves as a risk factor for RD in siblings. Future studies should focus on the precise neuropsychological characterization of RD in families with RE and on the effectiveness of standard oral-language and reading interventions.

Research paper thumbnail of External Trigeminal Nerve Stimulation (Etns) for Epilepsy

Journal of Neurology, Neurosurgery & Psychiatry, 2014

Research paper thumbnail of Epilepsy in chromosomal and related disorders

Introduction to Epilepsy, 2012

Research paper thumbnail of Paroxysmal episodes, "re-build up" phenomenon and moyamoya disease

Epileptic disorders : international epilepsy journal with videotape, 2009

Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progress... more Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progressive. Non-idiopathic forms with an associated disease are called moyamoya-like syndrome. The electroencephalographic finding characteristically seen after hyperventilation in about 50% of children with cerebrovascular disease includes gradual frequency decrease and activation of amplitude of slow waves which appear after the disappearance or attenuation of ordinary build up. This is termed the "re-build up" phenomenon, which is rarely seen and therefore may be under-recognized. We present video telemetry during a transient ischaemic event of a child subsequently diagnosed with moyamoya-like syndrome. We highlight the potential for misdiagnosis of organic non-epileptic events. Hyperventilation during EEG should be avoided in children with known moyamoya disease.

Research paper thumbnail of The CHRNB2 mutation I312M is associated with epilepsy and distinct memory deficits

Neurobiology of Disease, 2005

Mutations in nAChRs are found in a rare form of nocturnal frontal lobe epilepsy (ADNFLE). Previou... more Mutations in nAChRs are found in a rare form of nocturnal frontal lobe epilepsy (ADNFLE). Previously, some nAChR mutations have been described that are associated with additional neurological features such as psychiatric disorders or cognitive defects. Here, we report a new CHRNB2 mutation located in transmembrane region 3 (M3), outside the known ADNFLE mutation cluster. The CHRNB2 mutation I312M, which occurred de novo in twins, markedly increases the receptor's sensitivity to acetylcholine. Phenotypically, the mutation is associated not only with typical ADNFLE, but also with distinct deficits in memory. The cognitive problems are most obvious in tasks requiring the organization and storage of verbal information. D

Research paper thumbnail of Mutations in GRIN2A cause idiopathic focal epilepsy with rolandic spikes

Nature Genetics, 2013

Idiopathic focal epilepsy (IFE) with rolandic spikes is the most common childhood epilepsy, compr... more Idiopathic focal epilepsy (IFE) with rolandic spikes is the most common childhood epilepsy, comprising a phenotypic spectrum from rolandic epilepsy (also benign epilepsy with centrotemporal spikes, BECTS) to atypical benign partial epilepsy (ABPE), Landau-Kleffner syndrome (LKS) and epileptic encephalopathy with continuous spike and waves during slow-wave sleep (CSWS). The genetic basis is largely unknown. We detected new heterozygous mutations in GRIN2A in 27 of 359 affected individuals from 2 independent cohorts with IFE (7.5%; P = 4.83 × 10(-18), Fisher's exact test). Mutations occurred significantly more frequently in the more severe phenotypes, with mutation detection rates ranging from 12/245 (4.9%) in individuals with BECTS to 9/51 (17.6%) in individuals with CSWS (P = 0.009, Cochran-Armitage test for trend). In addition, exon-disrupting microdeletions were found in 3 of 286 individuals (1.0%; P = 0.004, Fisher's exact test). These results establish alterations of the gene encoding the NMDA receptor NR2A subunit as a major genetic risk factor for IFE.

Research paper thumbnail of Trihexyphenidyl for acute life-threatening episodes due to a dystonic movement disorder in Rett syndrome

Movement Disorders, 2010

In Rett syndrome (RS), acute life-threatening episodes (ALTEs) are usually attributed to epilepsy... more In Rett syndrome (RS), acute life-threatening episodes (ALTEs) are usually attributed to epilepsy or autonomic dysfunction but they can represent a movement disorder (MD). We describe three girls with RS who experienced ALTEs from an early age. These were long considered epileptic until video-EEG in Patients 1 and 3 revealed their non-epileptic nature. A primary dystonic mechanism was suspected and Patients 1 and 2 were treated with Trihexyphenidyl with significantly reduced frequency of the ALTEs. Patient 3 died before Trihexyphenidyl was tried. Trihexyphenidyl in RS patients with similar presentations can modify the dystonia and prevent ALTEs.

Research paper thumbnail of Molybdenum cofactor deficiency presenting with a parkinsonism-dystonia syndrome

Research paper thumbnail of Paediatric autoimmune encephalopathies: clinical features, laboratory investigations and outcomes in patients with or without antibodies to known central nervous system autoantigens

Journal of Neurology, Neurosurgery & Psychiatry, 2013

Research paper thumbnail of Hyperkalaemic cardiac arrest in a manifesting carrier of Duchenne muscular dystrophy following general anaesthesia

European Journal of Pediatrics, 2001

Potentially fatal adverse reactions to depolarising muscle relaxants and volatile inhalational ag... more Potentially fatal adverse reactions to depolarising muscle relaxants and volatile inhalational agents may occur in children with neuromuscular disorders. A history of motor delay may indicate a neuromuscular disorder in a child of either sex and must be thoroughly explored. It is vital to assess serum creatinine kinase levels when presented with such a history.

Research paper thumbnail of Acute sensory neuropathy in an adolescent girl following BCG vaccination

European Journal of Paediatric Neurology, 1999

A 13-year-old girl developed a sensory neuropathy following bacille Calmette-Gukin (BCG) vaccinat... more A 13-year-old girl developed a sensory neuropathy following bacille Calmette-Gukin (BCG) vaccination, consistent with acute inflammatory demyelinating polyradiculoneuropathy or acute sensory axonal neuropathy.

Research paper thumbnail of Encephalopathy and SCN1A mutations

Epilepsia, 2011

We describe three children with genetically different sodium channel alpha 1 subunit (SCN1A) muta... more We describe three children with genetically different sodium channel alpha 1 subunit (SCN1A) mutation associated epilepsy who experienced a sudden and sustained neurologic regression following status epilepticus in two and acute sepsis in one. Neuroimaging showed evidence of cerebral ischemia in one, but the other two cases showed cerebellar signal abnormalities. The selectivity of cerebellar white matter change suggests a different mechanism of injury or increased susceptibility of this brain region to injury in at least some patients with SCN1A mutations. This report adds to the spectrum and mechanism of acute neurologic deterioration and functional deficit associated with SCN1A mutations, which remains to be fully understood.

Research paper thumbnail of Mortality Rates and Causes of Death in Children with Epilepsy Prescribed Antiepileptic Drugs

Drug Safety, 2011

Background: Patients with epilepsy, including children, have an increased risk of mortality compa... more Background: Patients with epilepsy, including children, have an increased risk of mortality compared with the general population. Antiepileptic drugs (AEDs) were the most frequent class of drugs reported in a study looking at fatal suspected adverse drug reactions in children in the UK. Objective: The objective of the study was to identify cases and causes of death in a paediatric patient cohort prescribed AEDs with an associated epilepsy diagnosis.

Research paper thumbnail of Molybdenum cofactor deficiency - phenotypic variability in a family with a late-onset variant

Developmental Medicine & Child Neurology, 2008

Research paper thumbnail of N-methyl-D-aspartate receptor antibody-associated movement disorder without encephalopathy

Developmental Medicine & Child Neurology, 2014

N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a well-recognized clinico-immunolo... more N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a well-recognized clinico-immunological syndrome that presents with a movement disorder, cognitive decline, psychiatric symptoms, and epileptic seizures. A pure monosymptomatic presentation is rare; however, some patients present predominantly with a movement disorder in the absence of encephalopathy. Here, we describe three paediatric patients with an NMDAR antibody-mediated movement disorder: a 5-year-old female with acute onset hemichorea, a 10-year-old female with generalized chorea, and a 12-year-old male with abdominal myoclonus. These patients did not develop the characteristic encephalopathy syndrome seen in NMDAR encephalitis, but all three had other associated subtle cognitive deficits. The patients demonstrated good responses to immunotherapy.

Research paper thumbnail of Paroxysmal disorders in infancy: a diagnostic challenge

Developmental Medicine & Child Neurology, 2010

This commentary is on the article by Visser et al. on pages 1014-1020 of this issue

Research paper thumbnail of EEG latency analysis for hemispheric lateralisation in Landau–Kleffner syndrome

Clinical Neurophysiology, 2011

To determine the reliability of latency analysis in lateralising the origin of epileptiform disch... more To determine the reliability of latency analysis in lateralising the origin of epileptiform discharges in pre-surgical assessment of Landau-Kleffner syndrome (LKS). A computer aided-method was developed to identify leading regions and measure inter-hemispheric latencies before and after averaging discharges. Scalp and intracranial EEG recordings were studied from seven patients undergoing surgical treatment. The laterality suggested by latency analysis was compared with that suggested by pharmacological tests. Latency analysis of bilateral discharges showed a consistent leading hemisphere. The earliest low-amplitude deflections were located in temporal regions in all patients. Contralateral low-amplitude deflections, and ipsilateral and contralateral earliest large negative peaks were recorded in temporal and less frequently in parasagittal regions. Presurgical inter-hemispheric latencies ranged between 8 and 48 ms for the deflections and between 4 and 30 ms for the peaks. The leading hemisphere identified by latency analysis of the earliest low-amplitude deflections coincided with that suggested by pharmacological tests in all 7 patients, whereas latency of later components coincided in 6. Latency analysis appears to be a reliable method to estimate the hemisphere driving bilateral discharges in LKS. It can be carried out non-invasively and could be used to confirm, and eventually replace, results from pharmacological tests.

Research paper thumbnail of Molybdenum cofactor deficiency - phenotypic variability in a family with a late-onset variant

Develop Med Child Neurol, 2008

Research paper thumbnail of Paroxysmal episodes, re-build up phenomenon and moyamoya disease

Epileptic Disorders International Epilepsy Journal With Videotape, Nov 1, 2009

Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progress... more Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progressive. Non-idiopathic forms with an associated disease are called moyamoya-like syndrome. The electroencephalographic finding characteristically seen after hyperventilation in about 50% of children with cerebrovascular disease includes gradual frequency decrease and activation of amplitude of slow waves which appear after the disappearance or attenuation of ordinary build up. This is termed the "re-build up" phenomenon, which is rarely seen and therefore may be under-recognized. We present video telemetry during a transient ischaemic event of a child subsequently diagnosed with moyamoya-like syndrome. We highlight the potential for misdiagnosis of organic non-epileptic events. Hyperventilation during EEG should be avoided in children with known moyamoya disease.

Research paper thumbnail of Effects of Inhibitory Concentrations of 3-Indolylacetic Acid and 3-Indolylacetonitrile on Cell Division and Tissue 2

Research paper thumbnail of Risk factors for reading disability in families with rolandic epilepsy

Epilepsy & Behavior, 2015

The high prevalence and impact of neurodevelopmental comorbidities in childhood epilepsy are now ... more The high prevalence and impact of neurodevelopmental comorbidities in childhood epilepsy are now well known, as are the increased risks and familial aggregation of reading disability (RD) and speech sound disorder (SSD) in rolandic epilepsy (RE). The risk factors for RD in the general population include male sex, SSD, and ADHD, but it is not known if these are the same in RE or whether there is a contributory role of seizure and treatment-related variables. An observational study of 108 probands with RE (age range: 3.6-22years) and their 159 siblings (age range: 1-29years; 83 with EEG data) were singly ascertained in the US or UK through a proband affected by RE. We used a nested case-control design, multiple logistic regression, and generalized estimating equations to test the hypothesis of an association between RD and seizure variables or antiepileptic drug treatment in RE; we also assessed an association between EEG focal sharp waves and RD in siblings. Reading disability was reported in 42% of probands and 22% of siblings. Among probands, RD was strongly associated with a history of SSD (OR: 9.64, 95% CI: 2.45-37.21), ADHD symptoms (OR: 10.31, 95% CI: 2.15-49.44), and male sex (OR: 3.62, 95% CI: 1.11-11.75) but not with seizure or treatment variables. Among siblings, RD was independently associated only with SSD (OR: 4.30, 95% CI: 1.42-13.0) and not with the presence of interictal EEG focal sharp waves. The principal risk factors for RD in RE are SSD, ADHD, and male sex, the same risk factors as for RD without epilepsy. Seizure or treatment variables do not appear to be important risk factors for RD in probands with RE, and there was no evidence to support interictal EEG focal sharp waves as a risk factor for RD in siblings. Future studies should focus on the precise neuropsychological characterization of RD in families with RE and on the effectiveness of standard oral-language and reading interventions.

Research paper thumbnail of External Trigeminal Nerve Stimulation (Etns) for Epilepsy

Journal of Neurology, Neurosurgery & Psychiatry, 2014

Research paper thumbnail of Epilepsy in chromosomal and related disorders

Introduction to Epilepsy, 2012

Research paper thumbnail of Paroxysmal episodes, "re-build up" phenomenon and moyamoya disease

Epileptic disorders : international epilepsy journal with videotape, 2009

Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progress... more Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progressive. Non-idiopathic forms with an associated disease are called moyamoya-like syndrome. The electroencephalographic finding characteristically seen after hyperventilation in about 50% of children with cerebrovascular disease includes gradual frequency decrease and activation of amplitude of slow waves which appear after the disappearance or attenuation of ordinary build up. This is termed the "re-build up" phenomenon, which is rarely seen and therefore may be under-recognized. We present video telemetry during a transient ischaemic event of a child subsequently diagnosed with moyamoya-like syndrome. We highlight the potential for misdiagnosis of organic non-epileptic events. Hyperventilation during EEG should be avoided in children with known moyamoya disease.

Research paper thumbnail of The CHRNB2 mutation I312M is associated with epilepsy and distinct memory deficits

Neurobiology of Disease, 2005

Mutations in nAChRs are found in a rare form of nocturnal frontal lobe epilepsy (ADNFLE). Previou... more Mutations in nAChRs are found in a rare form of nocturnal frontal lobe epilepsy (ADNFLE). Previously, some nAChR mutations have been described that are associated with additional neurological features such as psychiatric disorders or cognitive defects. Here, we report a new CHRNB2 mutation located in transmembrane region 3 (M3), outside the known ADNFLE mutation cluster. The CHRNB2 mutation I312M, which occurred de novo in twins, markedly increases the receptor's sensitivity to acetylcholine. Phenotypically, the mutation is associated not only with typical ADNFLE, but also with distinct deficits in memory. The cognitive problems are most obvious in tasks requiring the organization and storage of verbal information. D

Research paper thumbnail of Mutations in GRIN2A cause idiopathic focal epilepsy with rolandic spikes

Nature Genetics, 2013

Idiopathic focal epilepsy (IFE) with rolandic spikes is the most common childhood epilepsy, compr... more Idiopathic focal epilepsy (IFE) with rolandic spikes is the most common childhood epilepsy, comprising a phenotypic spectrum from rolandic epilepsy (also benign epilepsy with centrotemporal spikes, BECTS) to atypical benign partial epilepsy (ABPE), Landau-Kleffner syndrome (LKS) and epileptic encephalopathy with continuous spike and waves during slow-wave sleep (CSWS). The genetic basis is largely unknown. We detected new heterozygous mutations in GRIN2A in 27 of 359 affected individuals from 2 independent cohorts with IFE (7.5%; P = 4.83 × 10(-18), Fisher's exact test). Mutations occurred significantly more frequently in the more severe phenotypes, with mutation detection rates ranging from 12/245 (4.9%) in individuals with BECTS to 9/51 (17.6%) in individuals with CSWS (P = 0.009, Cochran-Armitage test for trend). In addition, exon-disrupting microdeletions were found in 3 of 286 individuals (1.0%; P = 0.004, Fisher's exact test). These results establish alterations of the gene encoding the NMDA receptor NR2A subunit as a major genetic risk factor for IFE.

Research paper thumbnail of Trihexyphenidyl for acute life-threatening episodes due to a dystonic movement disorder in Rett syndrome

Movement Disorders, 2010

In Rett syndrome (RS), acute life-threatening episodes (ALTEs) are usually attributed to epilepsy... more In Rett syndrome (RS), acute life-threatening episodes (ALTEs) are usually attributed to epilepsy or autonomic dysfunction but they can represent a movement disorder (MD). We describe three girls with RS who experienced ALTEs from an early age. These were long considered epileptic until video-EEG in Patients 1 and 3 revealed their non-epileptic nature. A primary dystonic mechanism was suspected and Patients 1 and 2 were treated with Trihexyphenidyl with significantly reduced frequency of the ALTEs. Patient 3 died before Trihexyphenidyl was tried. Trihexyphenidyl in RS patients with similar presentations can modify the dystonia and prevent ALTEs.

Research paper thumbnail of Molybdenum cofactor deficiency presenting with a parkinsonism-dystonia syndrome

Research paper thumbnail of Paediatric autoimmune encephalopathies: clinical features, laboratory investigations and outcomes in patients with or without antibodies to known central nervous system autoantigens

Journal of Neurology, Neurosurgery & Psychiatry, 2013

Research paper thumbnail of Hyperkalaemic cardiac arrest in a manifesting carrier of Duchenne muscular dystrophy following general anaesthesia

European Journal of Pediatrics, 2001

Potentially fatal adverse reactions to depolarising muscle relaxants and volatile inhalational ag... more Potentially fatal adverse reactions to depolarising muscle relaxants and volatile inhalational agents may occur in children with neuromuscular disorders. A history of motor delay may indicate a neuromuscular disorder in a child of either sex and must be thoroughly explored. It is vital to assess serum creatinine kinase levels when presented with such a history.

Research paper thumbnail of Acute sensory neuropathy in an adolescent girl following BCG vaccination

European Journal of Paediatric Neurology, 1999

A 13-year-old girl developed a sensory neuropathy following bacille Calmette-Gukin (BCG) vaccinat... more A 13-year-old girl developed a sensory neuropathy following bacille Calmette-Gukin (BCG) vaccination, consistent with acute inflammatory demyelinating polyradiculoneuropathy or acute sensory axonal neuropathy.

Research paper thumbnail of Encephalopathy and SCN1A mutations

Epilepsia, 2011

We describe three children with genetically different sodium channel alpha 1 subunit (SCN1A) muta... more We describe three children with genetically different sodium channel alpha 1 subunit (SCN1A) mutation associated epilepsy who experienced a sudden and sustained neurologic regression following status epilepticus in two and acute sepsis in one. Neuroimaging showed evidence of cerebral ischemia in one, but the other two cases showed cerebellar signal abnormalities. The selectivity of cerebellar white matter change suggests a different mechanism of injury or increased susceptibility of this brain region to injury in at least some patients with SCN1A mutations. This report adds to the spectrum and mechanism of acute neurologic deterioration and functional deficit associated with SCN1A mutations, which remains to be fully understood.

Research paper thumbnail of Mortality Rates and Causes of Death in Children with Epilepsy Prescribed Antiepileptic Drugs

Drug Safety, 2011

Background: Patients with epilepsy, including children, have an increased risk of mortality compa... more Background: Patients with epilepsy, including children, have an increased risk of mortality compared with the general population. Antiepileptic drugs (AEDs) were the most frequent class of drugs reported in a study looking at fatal suspected adverse drug reactions in children in the UK. Objective: The objective of the study was to identify cases and causes of death in a paediatric patient cohort prescribed AEDs with an associated epilepsy diagnosis.

Research paper thumbnail of Molybdenum cofactor deficiency - phenotypic variability in a family with a late-onset variant

Developmental Medicine & Child Neurology, 2008

Research paper thumbnail of N-methyl-D-aspartate receptor antibody-associated movement disorder without encephalopathy

Developmental Medicine & Child Neurology, 2014

N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a well-recognized clinico-immunolo... more N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a well-recognized clinico-immunological syndrome that presents with a movement disorder, cognitive decline, psychiatric symptoms, and epileptic seizures. A pure monosymptomatic presentation is rare; however, some patients present predominantly with a movement disorder in the absence of encephalopathy. Here, we describe three paediatric patients with an NMDAR antibody-mediated movement disorder: a 5-year-old female with acute onset hemichorea, a 10-year-old female with generalized chorea, and a 12-year-old male with abdominal myoclonus. These patients did not develop the characteristic encephalopathy syndrome seen in NMDAR encephalitis, but all three had other associated subtle cognitive deficits. The patients demonstrated good responses to immunotherapy.

Research paper thumbnail of Paroxysmal disorders in infancy: a diagnostic challenge

Developmental Medicine & Child Neurology, 2010

This commentary is on the article by Visser et al. on pages 1014-1020 of this issue

Research paper thumbnail of EEG latency analysis for hemispheric lateralisation in Landau–Kleffner syndrome

Clinical Neurophysiology, 2011

To determine the reliability of latency analysis in lateralising the origin of epileptiform disch... more To determine the reliability of latency analysis in lateralising the origin of epileptiform discharges in pre-surgical assessment of Landau-Kleffner syndrome (LKS). A computer aided-method was developed to identify leading regions and measure inter-hemispheric latencies before and after averaging discharges. Scalp and intracranial EEG recordings were studied from seven patients undergoing surgical treatment. The laterality suggested by latency analysis was compared with that suggested by pharmacological tests. Latency analysis of bilateral discharges showed a consistent leading hemisphere. The earliest low-amplitude deflections were located in temporal regions in all patients. Contralateral low-amplitude deflections, and ipsilateral and contralateral earliest large negative peaks were recorded in temporal and less frequently in parasagittal regions. Presurgical inter-hemispheric latencies ranged between 8 and 48 ms for the deflections and between 4 and 30 ms for the peaks. The leading hemisphere identified by latency analysis of the earliest low-amplitude deflections coincided with that suggested by pharmacological tests in all 7 patients, whereas latency of later components coincided in 6. Latency analysis appears to be a reliable method to estimate the hemisphere driving bilateral discharges in LKS. It can be carried out non-invasively and could be used to confirm, and eventually replace, results from pharmacological tests.