The evolution of electroencephalographic features in lissencephaly syndrome

Identification and clinical characteristics of a novel missense ADGRG1 variant in bilateral Frontoparietal Polymicrogyria: The electroclinical change from infancy to adulthood after Callosotomy in three siblings

OBJECTIVE

Bilateral frontoparietal polymicrogyria (BFPP) is a rare genetic-related migration disorder. It has been attributed to loss-of-function of the ADGRG1 gene, which encodes an adhesion G protein-coupled receptor, ADGRG1/GPR56. We report the EEG findings of BFPP in three Asian patients, and confirmed that change in protein function was caused by the novel missense variant (p.Leu290Pro).

METHODS

We reviewed the medical records of three siblings with BFPP including one elder girl and two identical twin boys from birth to adulthood. The clinical symptoms, electroencephalography (EEG), brain MRI, whole-exome sequencing, treatment including medications, neuromodulation, and epilepsy surgery, and clinical outcomes were reviewed. The protein structure of a novel missense variant (p.Leu290Pro) was predicted by in silico studies, and molecular analysis was performed via typical flow cytometry and Western blotting.

RESULTS

The elder girl (Patient 1) was 22 years old and the twin boys (Patients 2 and 3) were 20 years old at the time of publication. All of them presented with typical clinical symptoms/signs and MRI findings of BFPP. Whole-exome sequencing followed by Sanger confirmation showed that all three patients had compound heterozygous variants in the ADGRG1 gene. The missense variant (p.Leu290Pro) was confirmed to be related to a reduction in cell surface GPR56 expression. High-amplitude rhythmic activity was noted in sleep EEG during infancy, which may have been due to excessive sleep spindle, and the rhythm disappeared when they were of pre-school age. Partial callosotomy provided short-term benefits in seizure control in Patients 1 and 2, and combined vagus nerve stimulation and partial callosotomy provided longer benefits in Patient 3.

SIGNIFICANCE

Sleep EEG findings of high-amplitude rhythmic activity in our BFPP cases were only noted during infancy and childhood. We also confirmed that the missense variant (p.Leu290Pro) led to loss of function due to a reduction in cell surface GPR56 expression.

Seizures and EEG characteristics in a cohort of pediatric patients with dystroglycanopathies

PURPOSE

To delineate the seizure type, phenotype and V-EEG patterns of dystroglycanopathy (DGP) and correlate them with the neuroradiological and genetic results.

METHODS

Patients with seizures were screened from our dystroglycanopathy database from January 2010 to March 2021. Detailed clinical information, including seizure type, brain magnetic resonance imaging (MRI), EEG and genetic analysis, was collected.

RESULTS

Thirteen patients (15.1%, 13/86) had seizures. Most patients had a severe phenotype. The mean age at first seizure onset was 2 years and 8 months. The most common seizure type was generalized tonic-clonic seizure (GTCS), with 92.3% (12/13) induced by fever. Three patients were diagnosed with epilepsy. Most patients did not take any medicine. A few patients had irregular use of antiseizure medications (ASMs). Of the 13 patients, seven patients were diagnosed with MEB, four patients with POMGNT1 mutations, two with ISPD mutations, and one with POMT1 mutation. Three patients were diagnosed with FCMD with FKTN mutations. Two patients were diagnosed with CMD-MR, one patient with ISPD mutation, and one with POMT1 mutation. One patient was diagnosed with LGMD with FKRP mutation. Nine patients underwent EEG examination, and eight patients had abnormal EEG results, including abnormal background activities in three patients, abnormal background activities combined with paroxysmal discharges in three patients, pure paroxysmal discharges in one patient and positive phase sharp waves in the occipital region in one patient. For radiology, brain MRI was available for 12 patients. The brain MRI of nine patients showed type II lissencephaly. Two patients showed cerebellar hypoplasia and brainstem hypoplasia. One patient had a normal brain MRI result. Patients with type II lissencephaly usually had abnormal background activities and paroxysmal discharges.

CONCLUSION

The seizure phenotype of dystroglycanopathy (DGP) is characterized by GTCS, which was the most common seizure type, while focal seizures and epileptic spasms could also occur in DGP patients. Most seizures were induced by fever. Seizures were relatively more frequent in severe phenotypes of DGP, such as FCMD and MEB. Abnormal background activities were the most common EEG patterns, which were closely related to type II lissencephaly.

CASK related disorder: Epilepsy and developmental outcome

OBJECTIVE

CASK pathogenic variants are associated with variable features, as intellectual disability, optic atrophy, brainstem/cerebellar hypoplasia, and epileptic encephalopathy. Few studies describe the electroclinical features of epilepsy in patients with CASK pathogenic variants and their relationship with developmental delay.

METHODS

this national multicentre cohort included genetically confirmed patients with different CASK pathogenic variants. Our findings were compared with cohorts reported in the literature.

RESULTS

we collected 34 patients (29 females) showing from moderate (4 patients) to severe (22) and profound (8) developmental delay; all showed pontine and cerebellar hypoplasia, all except three with microcephaly. Seventeen out of 34 patients (50%) suffered from epileptic seizures, including spasms (11 patients, 32.3%), generalized (5) or focal seizures (1). In 8/17 individuals (47.1%), epilepsy started at or beyond the age of 24 months. Seven (3 males) out of the 11 children with spasms showed EEG features and a course supporting the diagnosis of a developmental and epileptic encephalopathy (DEE). Drug resistance was frequent in our cohort (52.9% of patients with epilepsy). EEG abnormalities included poorly organized background activity with diffuse or multifocal epileptiform abnormalities and sleep-activation, with possible appearance over the follow-up period. Developmental delay degree was not statistically different among patients with or without seizures but feeding difficulties were more frequent in patients with epilepsy.

CONCLUSIONS

epilepsy is a frequent comorbidity with a high incidence of spasms and drug resistance. Overall developmental disability does not seem to be more severe in the group of patients with epilepsy nor to be linked to specific epilepsy/EEG characteristics. A childhood onset of epilepsy is frequent, with possible worsening over time, so that serial and systematic monitoring is mandatory.

Electrographic pattern recognition: A simple tool to predict clinical outcome in children with lissencephaly

PURPOSE

To describe and correlate the clinical, radiological and EEG findings in children with lissencephaly.

METHOD

Retrospective record analysis of children with lissencephaly presenting to tertiary health centre in Northern India was performed. Radiological classification and severity scoring were done. EEG findings were categorized into three patterns and its association with clinical severity was studied.

RESULTS

Twenty-eight children (males = 17) with lissencephaly were enrolled. Median age at diagnosis was 6.5months (range 3days-3years). Global developmental delay (median social quotient (SQ) = 25 (range15-68) was seen in all; motor deficits in 23 (82 %); epilepsy in 21 (75 %); behavioural problems in 18 (64 %); ophthalmic problems in 17 (61 %); microcephaly in 13 (46 %); feeding difficulty in 12 (43 %). Radiologically, classical Type I lissencephaly was seen in 18(64 %), cobblestone variant (Type II) in 5 (18 %) and microlissencephaly in 5 (18 %). Grade 4 (diffuse pachygyria) radiologic severity was most common (severity grade 1-6); no cases with severity score 5 or 6 were seen. The clinical profile did not correspond with radiological severity grading. EEG pattern recognition revealed pattern I in 14 (50 %); pattern II in 6 (21 %); pattern III in 8 (29 %). Children with pattern III EEG had drug resistant epilepsy and severe developmental delay. No relationship between EEG patterns and radiological severity grading was evident.

CONCLUSION

EEG is better predictor of clinical status and outcome rather than radiological severity grading. EEG pattern III is associated with severe developmental delay and drug resistant epilepsy.

EEG and neuroimaging correlations in children with lissencephaly

PURPOSE

To study the usefulness of EEG in the diagnosis of lissencephaly, a rare cortical developmental disorder associated with abnormal cellular proliferation. Currently, the clinical emphasis is placed on the radiological and genetic aspects for the diagnosis of lissencephaly.

METHODS

This is a retrospective review of consecutive EEG recordings and imaging data from 14 children, with the diagnosis of lissencephaly, who were admitted from January 1998 to January 2010. All EEG recordings were performed with the 10-20 system of electrode placement, in both awake and sleep states. All EEG recordings were reviewed using anterior-posterior bipolar and transverse montages and then they were interpreted blindly, with respect to the imaging and genetic investigations for each patient.

RESULTS

All children showed one of the three characteristic EEG patterns reported in the literature of lissencephaly. The EEG pattern I, showed an anterior posterior gradient that corresponded to the severity of the imaging study abnormality. All patients were on two or more AEDs and reported to continue having active epilepsy.

CONCLUSION

In a child with clinical characteristics of lissencephaly, one of these three reported EEG patterns can prove useful in making the diagnosis very probable, preceding imaging and genetic testing.

Interictal regional polyspikes in noninvasive EEG suggest cortical dysplasia as etiology of focal epilepsies

PURPOSE

To evaluate the clinical significance of interictal regional polyspikes in focal epilepsies secondary to cortical dysplasia.

METHODS

We performed a data search for the term "regional polyspikes" in the database of our epilepsy-monitoring unit. Patients with generalized epilepsies including Lennox-Gastaut syndrome were excluded. Regional interictal epileptiform discharges were recorded in 513 patients with noninvasive EEG.

RESULTS

We identified 29 patients with interictal regional polyspikes and focal epilepsies. Another 484 patients showed regional epileptiform discharges other than polyspikes. The etiology of the epilepsy was significantly more frequently cortical dysplasia in the group of patients with regional polyspikes (35%, 10 of 29 patients) than in the patients with other regional epileptiform discharges (5%, 24 of 484 patients) (p < 0.01). The polyspikes were significantly more frequently localized to the extratemporal (72%; n = 21) than temporal (28%; n = 8) regions (p < 0.01). In contrast, regional epileptiform discharges other than polyspikes were significantly more frequently localized to the temporal lobe (75%; n = 362) than extratemporal regions (25%; n = 122) (p < 0.01). Eight of the 10 patients with focal cortical dysplasia had extratemporal polyspikes.

DISCUSSION

Noninvasively recorded regional polyspikes suggest cortical dysplasias as etiology of predominantly extratemporal epilepsies.

Enhanced capacity of epilepsy in brain malformation produced during early development

This study investigates the clinical features of epilepsy in 20 patients with brain malformation. Epileptic seizures were recognized in 15 patients, 12 of whom had their first seizure by 1 year of age. Partial seizure was the initial seizure type in 10 patients. Epileptic seizures were controlled in only four patients. Patients with holoprosencephaly and lissencephaly had seizure onset by 3 months of age, resulting in the most severe neurologic outcome. Only two patients with porencephaly had epileptic seizures, and in one of those patients the seizures were well controlled. A wide variety of clinical features of epilepsy in patients with brain malformation was found. More immature anomalous brain lesions may be associated with an enhanced capacity of epilepsy and resultant refractory seizures.

A new paradigm for West syndrome based on molecular and cell biology

Symptomatic West syndrome has heterogeneous backgrounds. Recently, two novel genes, ARX and CDKL5, have been found to be responsible for cryptogenic West syndrome or infantile spasms. Both are located in the human chromosome Xp22 region and are mainly expressed and play roles in fetal brain. Moreover, several genes responsible for brain malformations including lissencephaly, which is frequently associated with West syndrome or infantile spasms, have been found, and the mechanisms responsible for the neural network disorders in these brain malformations are rapidly being determined. Findings of animal and in vitro studies and mutation analyses in humans are delineating the molecular and cellular basis of West syndrome. Mutations of the ARX gene controlling the development of GABAergic interneurons exhibit pleiotropic effects including lissencephaly with a strong genotype-phenotype correlation. An expansion mutation of the first polyalanine tract of ARX is more strongly related to infantile spasms than is that of the second polyalanine tract. Although the phenotype of CDKL5 mutation is similar to Rett syndrome caused by MECP2 mutation, the former is characterized by early-onset seizures and association with West syndrome. Lissencephaly caused by LIS1 or DCX mutation frequently results in West syndrome, while lissencephaly due to ARX mutation is associated with the most severe form of epilepsy but never results in West syndrome nor infantile spasms. Both LIS1 and DCX participate in the development of GABAergic interneurons as well as pyramidal neurons, while ARX participates only in that of interneurons. Individuals with lissencephaly due to ARX mutation lack non-pyramidal or GABAergic interneurons. ARX is crucial for the development of GABAergic interneuron, so abnormal interneurons in patients with ARX mutation are thought to be implicated in the pathological mechanism, even though brain MRI is normal. Abnormal interneurons appear to play an essential role in the pathogenesis of West syndrome or infantile spasms, which can be considered an interneuronopathy.

Agyria-pachygyria: clinical, neuroimaging, and neurophysiologic correlations

Agyria-pachygyria complex is a disorder of neuronal migration and organization. Patients suffer either motor or intellectual retardation. We report our experiences of 10 patients with agyria-pachygyria complex and evaluate their clinical features, electroencephalography, and evoked potentials. Of nine electroencephalography examinations, five patients demonstrated characteristically high-amplitude fast activity. One of nine patients had an abnormal brainstem auditory-evoked potential. Three of seven patients had abnormal goggled visual-evoked potential. Six patients received somatosensory-evoked potential examinations, and five of these were abnormal, including four with prolonged central conduction times. Of the 10 patients, eight survived with variable intellectual and motor retardation; two died of sepsis. Patients with grades 1-4 agyria-pachygyria had high incidences of somatosensory-evoked potential abnormalities and also suffered worse neurologic outcomes. Normal brainstem auditory-evoked potential but abnormal cortical somatosensory-evoked potential components and prolonged central conduction time in these patients indicate that agyria-pachygyria is a supratentorial disease. We conclude that somatosensory-evoked potential examination is supplemental to neuroimaging in predicting the neurologic prognosis of patients with agyria-pachygyria.

Structure-function correlations in patients with malformations of cortical development

Malformations of cortical development (MCD) are a diverse group of diseases that exhibit both genetic and phenotypic heterogeneity. While previous studies have described the clinical, MRI, and/or EEG features of specific malformations, structure and function have not been correlated across a wide spectrum of these disorders. We reviewed the medical records of 22 patients with MCD due to abnormal neuronal migration and cortical organization, and correlated levels of clinical disability with specific MRI and EEG findings. The extent of abnormality on MRI was significantly correlated with clinical disability. Compared with patients with other lesions, those with lissencephaly were more disabled. Although background slowing, suppression, fast activity, and interictal epileptiform activity were not individually predictive, the overall degree of EEG abnormality was significantly correlated with clinical disability, as were alterations in the posterior head rhythm and physiologic sleep features.

Epilepsy and genetic malformations of the cerebral cortex

Malformations of the cerebral cortex are an important cause of developmental disabilities and epilepsy. Here we review those malformations for which a genetic basis has been elucidated or is suspected and the types of associated epilepsy. Schizencephaly (cleft brain) has a wide anatomo-clinical spectrum, including partial epilepsy in most patients. Familial occurrence is rare. Heterozygous mutations in the EMX2 gene were reported in 13 patients. X-linked bilateral periventricular nodular heterotopia (BPNH) consists of typical BPNH with epilepsy in females and prenatal lethality in males. About 88% of patients have partial epilepsy. Filamin A mutations, all leading to a truncated protein, have been reported in three families and in sporadic patients. The most frequent forms of lissencephaly (agyria-pachygyria) are caused by mutations of LIS1. XLIS mutations cause classical lissencephaly in hemizygous males and subcortical band heterotopia (SBH) in heterozygous females. The thickness of the heterotopic band and the degree of pachygyria correlate with the likelihood of developing Lennox-Gastaut syndrome. Mutations of the coding region of XLIS were found in all reported pedigrees and in 38-91% of sporadic female patients with SBH. With few exceptions, children with LIS1 mutations have isolated lissencephaly, with severe developmental delay and infantile spasms. Autosomal recessive lissencephaly with cerebellar hypoplasia, accompanied by severe developmental delay, seizures, and hypotonia has been associated with mutations of the reelin gene. Fukuyama congenital muscular dystrophy is due to mutations of the fukutin gene and is accompanied by polymicrogyria. Febrile seizures and epilepsy with generalized tonic-convulsions appear in about 50% of children but are usually not severe. Tuberous sclerosis (TS) is caused by mutations in at least two genes, TSC1 and TSC2; 75% of cases are sporadic; 60% of patients have epilepsy, manifested in 50% of them as infantile spasms. TSC1 mutations seem to cause a milder disease with fewer cortical tubers and lower frequency of seizures. Among several syndromes featuring polymicrogyria, bilateral perisylvian polymicrogyria had familial occurrence on several occasions. Genetic heterogeneity is likely, including autosomal recessive, X-linked dominant, X-linked recessive inheritance, and association with 22q11.2 deletions. About 65% of patients have severe epilepsy, often Lennox-Gastaut syndrome.

Epileptogenic brain malformations: clinical presentation, malformative patterns and indications for genetic testing

We review here those malformations of the cerebral cortex which are most often observed in epilepsy patients, for which a genetic basis has been elucidated or is suspected and give indications for genetic testing. There are three forms of lissencephaly (agyria-pachygyria) resulting from mutations of known genes, which can be distinguished because of their distinctive imaging features. They account for about 85% of all lissencephalies. Lissencephaly with posteriorly predominant gyral abnormality is caused by mutations of the LIS1 gene on chromosome 17. Anteriorly predominant lissencephaly in hemizygous males and subcortical band heterotopia (SBH) in heterozygous females are caused by mutations of the XLIS(or DCX) gene. Mutations of the coding region of XLIS were found in all reported pedigrees, and in most sporadic female patients with SBH. Missense mutations of both LIS1 and XLIS genes have been observed in some of the rare male patients with SBH. Autosomal recessive lissencephaly with cerebellar hypoplasia has been associated with mutations of the reelin gene. With few exceptions, children with lissencephaly have severe developmental delay and infantile spasms early in life. Patients with SBH have a mild to severe mental retardation with epilepsy of variable severity and type. X-linked bilateral periventricular nodular heterotopia (BPNH) consists of typical BPNH with focal epilepsy in females and prenatal lethality in males. About 88% of patients have focal epilepsy. Filamin A (FLNA) mutations have been reported in some families and in sporadic patients. Additional, possibly autosomal recessive gene(s) are likely to be involved in causing BPNH non-linked to FLN1. Tuberous sclerosis (TS) is a dominant disorder caused by mutations in at lest two genes, TSC1 and TSC2. 75% of cases are sporadic. Most patients with TS have epilepsy. Infantile spasms are a frequent early manifestation of TS. Schizencephaly (cleft brain) has a wide anatomo-clinical spectrum, including focal epilepsy in most patients. Familial occurrence is rare. Heterozygous mutations in the EMX2 gene have been reported in some patients. However, at present, there is no clear indication on the possible pattern of inheritance and on the practical usefulness that mutation detection in an individual with schizencephaly would carry in terms of genetic counselling. Amongst several syndromes featuring polymicrogyria, bilateral perisylvian polymicrogyria had familial occurrence on several occasions. Genetic heterogeneity is likely, including autosomal recessive, X-linked dominant, X-linked recessive inheritance and association to 22q11.2 deletions. FISH analysis for 22q11.2 is advisable in all patients with perisylvian polymicrogyria. Parents of an affected child with normal karyotype should be given up to a 25% recurrence risk.

Clinical spectrum of cortical dysplasia in childhood: diagnosis and treatment issues

Disorders of cortical development form a spectrum of lesions produced by insults to the developing neocortex. These conditions typically first manifest in childhood with epilepsy, developmental delay, and focal neurologic signs. Although the clinical and electrophysiologic findings are often nonspecific, high-resolution magnetic resonance imaging facilitates diagnosis during life, and assists in delineating specific clinical syndromes. While many patients are dysmorphic and severely affected by mental retardation and epilepsy, some have normal or near-normal cognitive function and no seizures. Molecular studies of dysplastic cortex are providing new insights into the basic mechanisms of brain function and development, while pathologic analysis of tissue removed at surgery is helping to define epileptic circuitry. Treatment of the epilepsy associated with cortical dysplasia is often frustrating, but surgical approaches based on accurately defining epileptogenic regions are proving increasingly successful. Genetic diagnosis is important for accurate counseling of families.

EEG features of focal malformations of cortical development

Recent advances in neuroimaging have allowed the detection and characterization of focal malformations of cortical developmental in a significant proportion of patients with epilepsy, many of whom were previously labelled as cryptogenic, allowing a better description of the associated electroencephalogram (EEG) features. Alpha activity is usually preserved, although superficial gyral abnormalities are often associated with overlying localized polymorphic delta activity, and occasionally abnormal fast activity. Most affected patients with epilepsy show interictal spikes. These are often broadly concordant with the structural abnormality but may show a wider anatomic distribution and be multifocal, or occasionally appear only in anatomically distant sites. In many patients the spikes are frequent and sometimes they occur continuously or in long trains. EEG findings are often stable over time, but some patients only show the development of slow wave changes or interictal spikes when followed serially for several years. A small proportion of patients with focal malformations of cortical development have EEG features mimicking idiopathic generalized epilepsy, and occasionally patients exhibit continuous generalized spike and slow wave activity in sleep. Electrocorticography studies confirm the often widespread nature of interictal spiking, but may also show highly epileptogenic patterns recorded directly from dysplastic cortex. The intrinsic epileptogenicity of areas of cortical developmental abnormalities has also been demonstrated by chronic intracranial studies and in vitro recordings of slices obtained from resected human dysplastic cortex. In this regard such developmental abnormalities are fundamentally different from acquired lesions such as tumors/vascular anomalies that usually exert their effects through changes in adjacent cortex.

Cortical dysgenesis: serial EEG findings in children and adults

Cortical dysgenesis (CD) is becoming increasingly recognised as a cause of epilepsy in otherwise cryptogenic cases. We describe the serial EEG findings in 22 patients with focal/localised CD. The EEGs covered a minimum period of 5 years in each case (median = 13 years, range: 5-30 years), beginning in childhood. Median age at seizure onset was 3 years (range: 3 weeks-10 years, n = 21). The EEG was normal in the one patient, a 6 year old, who did not have epilepsy. Background rhythms appropriate for age were preserved in the majority of patients (18/22). Slow activity localised to the area of CD was seen in 11 patients; in 3 patients, this did not appear until the second decade of life. Epileptiform discharges were seen in at least one EEG in 20 patients: these were continuous or near-continuous (6 patients) or occurred recurrently in short runs (6 patients). In 6 patients, these discharges appeared only after the second decade of life and in 11 patients, they became more widespread over time. In the remaining patients, the EEG changes did not evolve. Sleep failed to produce new abnormalities (n = 15). None of the patients showed EEG features characteristic of lissencephaly or evolution to the Lennox-Gastaut syndrome. Even in this selected cohort of patients who had undergone serial clinical EEGs, the EEG abnormalities in focal/localised CD appeared relatively stable and showed only moderate changes over time. CD must be included in the differential diagnosis of any patient who presents with localised slow activity on EEG.

Serial EEG and sleep polygraphic studies on lissencephaly (agyria-pachygyria)

We carried out serial EEG studies on 12 cases of lissencephaly (6 of agyria and 6 of pachygyria), polysomnograms being recorded in 8 of the 12 cases. Fourteen Hz sleep spindles appeared from early infancy in all cases. They were poorly observed after the age of 1 year, and 5-11 Hz high-amplitude rhythmic activity (HARA) of more than 300 microV appeared predominantly in place of the 14 Hz spindles. Both the 14 Hz spindles and HARA showed asymmetry, but the dominant cerebral area for both types of waves was much the same. Four of the 6 agyria cases showed hypsarrhythmia within the first 6 months after birth, 3 of the 4 cases showing asymmetric hypsarrhythmia at first. Their hypsarrhythmia consisted of very high-voltage 5-7 Hz slow sharp waves and delta waves. The EEG abnormalities transformed from hypsarrhythmia to focal spikes in the 6 pachygyria cases. The polygraphic study on 8 cases revealed that the proportion of REM sleep decreased in 3 cases and the REMs/min values decreased in 7. Infantile spasms occurred in 4 of the 8 cases. The REM/min values decreased in all of these 4 cases, and, furthermore, the proportion of REM sleep decreased in 3 of the 4 cases. These findings suggest that lissencephaly involves a disorder of the brainstem, and that the combination of brainstem lesions and severe cerebral dysplasia is important for the manifestation of infantile spasms in lissencephaly.

Lissencephaly syndromes: clinical aspects

We report clinical and neurophysiological findings in six children (three female, three male) with type I lissencephaly and three children (all female) with type II lissencephaly (Walker-Warburg syndrome). In type I lissencephaly the diagnosis is based only on electroencephalographic (EEG) signs, whereas in type II lissencephaly the diagnosis rests on clinical signs. In type I lissencephaly the EEG typically shows high alpha-beta activity, which is not seen in type II lissencephaly.

Reappraisal of interictal electroencephalograms in infantile spasms

To delineate interictal electroencephalographic (EEG) features before treatment of patients with clinically defined infantile spasms, EEGs of 82 infants having tonic spasms in clusters were analyzed by type of paroxysmal abnormalities, continuity, interhemispheric synchrony, topography, and wave component of hypsarrhythmia during wakefulness and sleep. Hypsarrhythmia occurred less frequently in wakefulness than in non-rapid eye movement (NREM) sleep at any age, least frequently in wakefulness after 1 year of age, and disappeared in rapid eye movement (REM) sleep at any age. The continuity of hypsarrhythmia changed with states, but did not change with age, and was greatest in wakefulness and stage 1 and decreased in stage 2-3. Interhemispheric synchrony increased with increasing age but decreased with advancing sleep stage. The term modified hypsarrhythmia should be discarded, and unusual features, if present, should be specified.

Neurological findings and seizure outcome in children with bilateral opercular macrogyric-like changes detected by MRI

The authors studied 10 patients aged between six and 23 years (mean age 14 years 5 months) with magnetic resonance imaging, which detected bilateral 'macrogyric-like' maldevelopment of the insulo-opercular regions. The data confirm that biopercular gyral anomaly, associated with mental retardation, pseudobulbar palsy (cortical or central) and epilepsy, represents an anatomo-clinical syndrome. Nevertheless, a wide clinical spectrum was found varying from pictures correlating with the topography and extent of the MRI-detected anomaly to conditions indicating wider cerebral involvement. Epilepsy, varying greatly in age at onset and severity, consistently influenced the prognosis for five patients with diffuse EEG abnormalities and intractable seizures with falls. Anterior callosotomy relieved such seizures in one case.

The agyria-pachygyria complex: a spectrum of cortical malformations

Agyria-pachygyria is a relatively common brain malformation in humans as shown by the recent experience with CT scan and MR imaging. However, the specificity of imaging is not completely established and it is not known whether all cases with a thick cortical ribbon and a smooth surface correspond histologically to actual agyria-pachygyria or may belong to different pathological anomalies such as polymicrogyria. The extent, distribution and detailed structure of agyria-pachygyria vary widely and the clinical features are accordingly very diverse. Rather than one entity, pachygyric cortical abnormalities form a broad spectrum that raises different clinical, nosological and genetic problems. Therefore, a precise analysis of each case is necessary to establish the prognosis and risk of recurrence.

Diagnostic features and clinical signs of 21 patients with lissencephaly type 1

Lissencephaly type I has been described as either the cerebral expression of a complex malformation syndrome such as Miller-Dieker syndrome (MDS), or as isolated lissencephaly sequence (ILS). In a nation-wide study in The Netherlands, of 21 patients with lissecephaly type I, four were found to have MDS and 17 ILS. New clinical aspects were as follows: the mean life-span of the entire group was longer than previously reported; patients with lissencephaly grades 3 or 4 (mixture of agyria and pachygyria, or complete pachygyria) developed seizures later than those with grades 1 and 2 (complete and almost complete agyria); microcephaly was not always present in patients with grades 3 and 4 lissencephaly; and patients with lissencephaly grades 1 and 2 had hardly any psychomotor development, while those with grades 3 and 4 were severely retarded.

Special etiologies in the classification of epilepsy--with special reference to brain malformations

I analyzed 18 cases of brain malformations detected by autopsy and five cases of lissencephaly diagnosed by CT scan or MRI. 1) Autopsy Cases Brain malformations were highly complicated, and many cases showed more than one type of brain malformation. Epileptic seizures were observed in 13 of 18 cases. In most cases, the seizures were characterized by infantile onset, a high incidence of tonic seizures and difficulties in controlling them. 2) Patients with Lissencephaly They all had severely retarded psychomotor development. Tonic seizures were observed in all the five patients, two of whom had a past history of infantile spasms. The EEG patterns of these patients were varied. It is thought that a relationship exists between the severity of CT or MRI findings and that of EEG findings.

Lissencephaly, abnormal lymph nodes, and T-cell deficiency in one patient

We report on a child with lissencephaly type I, abnormal lymph nodes, and immunodeficiency, associated with recurrent infections, autoimmune disease, spastic tetraplegia, and psychomotor retardation. Diagnostic measures included cranial computer tomography (CT) and magnetic resonance imaging (MRI) scanning, several in vivo and in vitro immunological tests, and histology of skin, lymph nodes, and liver including electron microscopy and immunohistology. Despite medical supervision, the child died at age 4 years. A common pathogenetic mechanism of defective migration of neurons and the dysmaturation of lymph nodes is most probable. The T-cell deficiency may represent a common defect of the development of both neuronal and lymphatic tissue, as the six-layered cerebral cortex and the B-cell areas in lymph nodes develop at about the same gestational age. A common defect could also be assumed involving genetically determined cell surface proteins.

Bilateral central macrogyria: epilepsy, pseudobulbar palsy, and mental retardation--a recognizable neuronal migration disorder

The neuronal migration disorders comprise several morphological entities that are recognizable during life using current imaging techniques. We studied 4 patients who had a characteristic bilateral central rolandic and sylvian macrogyria. The patients had pseudobulbar palsy with oromotor incoordination and developmental delay and were mildly retarded. Minor seizures developed between the ages of 8 and 9 years. Subsequently, atonic drop attacks became the predominant epileptic pattern. Epileptogenic electrographic abnormalities were secondary generalized or multifocal. The lesions were detected by computed tomography and magnetic resonance imaging in all patients. Bilateral symmetrical areas of thick cortex surrounding a large sulcus were seen. This syndrome consists of specific clinical, imaging, electroencephalographic, and epileptic features. It can be suspected clinically and confirmed by imaging studies. Callosotomy in two patients helped the intractable seizures.

Lissencephaly (agyria-pachygyria): clinical findings and serial EEG studies

Fifteen cases of lissencephaly were studied and the literature reviewed. The authors conclude that the clinical findings of lissencephaly in infancy are non-specific, consisting of developmental delay and hypotonia. While the CT scan establishes the diagnosis, it may also be strongly suggested by an EEG showing 'major fast dysrhythmia', characterized by abnormally rapid, very high-voltage activity, predominantly in the alpha and beta frequency bands. Some possible mechanisms for this highly suggestive EEG pattern are proposed.

EEG and seizure threshold in normal and lissencephalic ferrets

Changes in EEG and susceptibility to electrically induced seizures were examined in the ferret with lissencephaly produced by exposure to a single injection of methylazoxymethanol acetate (MAM Ac) given to the pregnant jill on gestation day 32. Ten lissencephalic and 11 normal ferrets were chronically implanted with 14 cortical stainless steel electrodes. EEG records were sampled from various stages of the sleep/awake cycle. Six of each group were subjected to electrical stimulation for seizure threshold. Although the number of stimulations and the current intensity required to produce epileptiform afterdischarges (AD) and seizures were not different between the two groups, the lissencephalic ferrets had significantly longer AD and seizures, and a greater number of generalized seizures, indicating an enhanced seizure susceptibility. The EEG of the lissencephalic ferrets was characterized by increased slow wave activity within the low theta band range, extreme spindle activity, focal or multifocal slow and sharp waves, spikes, or spike and slow wave complexes. The differences in the EEG were more pronounced during drowsiness and sleep stages. The brains of all of the treated animals were lissencephalic and hydrocephalic, and weighed significantly less than those of the normals. The cerebral cortex was thin and flattened, with the parieto-occipital region most severely affected. Heterotopic foci were found in the cerebellum as well as in the cerebral cortex. Abnormalities in the configuration of the cerebellar folia were also seen. Comparison between the electrophysiological and neuropathological data suggests that the extent of the extreme spindle activity, and longer AD and seizure duration depended on the degree of cerebellar dysplasia, whereas the EEG focal abnormalities were related to lesions in the cerebral hemispheres.

Drug effects on afterdischarge and seizure threshold in lissencephalic ferrets: an epilepsy model for drug evaluation

In normal and lissencephalic ferrets with chronically implanted electrodes, two antiepileptic drugs, (E)-2-[(amino)phenylmethylen]-benzo [b] thiophen-3(2H)-on (AF-CX 921 XX) and carbamazepine (CBZ), were compared. The variables included afterdischarges (AD) and seizures induced by cortical electrical stimulations (ES). Both drugs were given orally, 100 mg/kg of pure substance. ES was applied before and 1, 2, 3, 4, 5, and 24 h after drug administration. Lissencephaly was produced by a single intraperitoneal injection of 15 mg methylazoxymethanol acetate to pregnant animals. The administration of both drugs resulted in increases of the AD threshold current to 240% in the normal and to 170% in the lissencephalic ferrets, in comparison with control stimulations (the difference significant at p less than 0.001). Moreover, duration of the AD was shorter (p less than 0.01) than before the drugs. Seizure threshold also increased 170% after AF-CX 921 XX and 175% after CBZ in normal and 153% and 138% in lissencephalic ferrets, respectively. The difference between the two drugs was significant. However, in contrast to the threshold, duration of seizures during AF-CX 921 XX administration was significantly shorter (p less than 0.05) than during CBZ. In general, lissencephalic ferrets responded less than normal ferrets to both drugs, but AF-CX 921 XX had a greater inhibitory effect on the duration of seizures. The lissencephalic ferret is proposed as an animal model of epilepsy with diffuse developmental defects.

A spectrum of gyral anomalies in Miller-Dieker (lissencephaly) syndrome

Four unrelated patients who had the clinical appearance of Miller-Dieker syndrome, also called lissencephaly syndrome, were studied. All four had a typical clinical course with failure to thrive, severe psychomotor retardation, opisthotonos, seizures, and death early in life. None of these children had lissencephaly, the anticipated central feature of this disorder. One of the four had pachygyria, one had polymicrogyria, and two had both pachygyria and polymicrogyria. The brain weights were normal to decreased. The ventricles were dilated in all cases. The cerebral cortex was thickened in each, with decreased white matter and diminution or distortion of the cellular layers, and there were neuroglial heterotopias. The corpus callosum was partially absent in one and thinned in three. The neuropathy found in these children with Miller-Dieker syndrome suggests a spectrum of gyral anomalies resulting from a single type of embryonic error.

Lissencephaly: two distinct clinico-pathological types

The present study is a review of four new cases of lissencephaly and two others previously reported. This study demonstrates that lissencephaly is a gross feature of the brain occurring in two different groups of cortical malformations. The first group, the classic agyria syndrome extensively analyzed by Jellinger and Rett [8] includes two types of abnormal cortical organization. They may be found in familial syndromes and also can appear sporadically. The second group includes smooth brains with the internal features of polymicrogyria and a more severely disorganized cortex. This type appears in familial lissencephaly in the cerebro-oculo-muscular syndrome, belonging to the same group as Fukuyama congenital-cerebro-muscular dystrophy. The other incidences of this type of cortical malformation require further investigation. The clinico-pathological differential diagnosis of two types of lissencephaly are also discussed.