Article

Focal cortical dysplasia – review

Department of Diagnostic Imaging, Mazowiecki Regional Hospital in Siedlce, Siedlce, Poland.
Polish journal of radiology / Polish Medical Society of Radiology 04/2012; 77(2):35-43.
Source: PubMed

ABSTRACT Focal cortical dysplasia is a malformation of cortical development, which is the most common cause of medically refractory epilepsy in the pediatric population and the second/third most common etiology of medically intractable seizures in adults.
Both genetic and acquired factors are involved in the pathogenesis of cortical dysplasia. Numerous classifications of the complex structural abnormalities of focal cortical dysplasia have been proposed – from Taylor et al. in 1971 to the last modification of Palmini classification made by Blumcke in 2011. In general, three types of cortical dysplasia are recognized.
Type I focal cortical dysplasia with mild symptomatic expression and late onset, is more often seen in adults, with changes present in the temporal lobe.
Clinical symptoms are more severe in type II of cortical dysplasia usually seen in children. In this type, more extensive changes occur outside the temporal lobe with predilection for the frontal lobes.
New type III is one of the above dysplasias with associated another principal lesion as hippocampal sclerosis, tumor, vascular malformation or acquired pathology during early life.
Brain MRI imaging shows abnormalities in the majority of type II dysplasias and in only some of type I cortical dysplasias.
The most common findings on MRI imaging include: focal cortical thickening or thinning, areas of focal brain atrophy, blurring of the gray-white junction, increased signal on T2- and FLAIR-weighted images in the gray and subcortical white matter often tapering toward the ventricle. On the basis of the MRI findings, it is possible to differentiate between type I and type II cortical dysplasia. A complete resection of the epileptogenic zone is required for seizure-free life. MRI imaging is very helpful to identify those patients who are likely to benefit from surgical treatment in a group of patients with drug-resistant epilepsy.
However, in type I cortical dysplasia, MR imaging is often normal, and also in both types the lesion seen on MRI may be smaller than the seizure-generating region seen in the EEG. The abnormalities may also involve vital for life brain parts, where curative surgery will not be an option. Therefore, other diagnostic imaging techniques such as FDG PET, MEG, DTI and intra-cranial EEG are widely used to establish the diagnosis and to decide on management.
With advances in both genetics and neuroimaging, we may develop a better understanding of patients with drug-resistant epilepsy, which will help us to provide more successful pharmacological and/or surgical treatment in the future.

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    • "There is considerable evidence that there is an underlying genetic contribution to this condition and indeed a substantial subgroup of the epilepsies are specifically classified as 'genetic' epilepsies (Berg et al., 2010). Furthermore at the other end of the spectrum, there is mounting evidence that even lesional and post-traumatic epilepsies are underpinned by a genetic predisposition (Scher et al., 2011; Kabat and Krol, 2012) . While a complex interaction between genetic and possibly environmental factors is likely to influence the particular seizure phenotype seen in these syndromes ( Berkovic et al. , 2006 ) , alter - ation of ion channels arising from genetic variation or functional modification , is a potential unifying theme for the hyperexcitability seen in individuals with epilepsy ( Helbig et al . "
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    • "There is considerable evidence that there is an underlying genetic contribution to this condition and indeed a substantial subgroup of the epilepsies are specifically classified as 'genetic' epilepsies (Berg et al., 2010). Furthermore at the other end of the spectrum, there is mounting evidence that even lesional and post-traumatic epilepsies are underpinned by a genetic predisposition (Scher et al., 2011; Kabat and Krol, 2012) . While a complex interaction between genetic and possibly environmental factors is likely to influence the particular seizure phenotype seen in these syndromes ( Berkovic et al. , 2006 ) , alter - ation of ion channels arising from genetic variation or functional modification , is a potential unifying theme for the hyperexcitability seen in individuals with epilepsy ( Helbig et al . "
    Brain 01/2013; · 10.23 Impact Factor
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    ABSTRACT: We used transcranial magnetic stimulation to investigate whether the cortical excitability changes observed amongst the different generalized and focal epilepsy syndromes are reflected in their asymptomatic siblings and if these changes depended on the clinical phenotype. We studied 157 patients with epilepsy (95 generalized and 62 focal) and their asymptomatic siblings (138 and 82, respectively). Motor threshold and paired pulse transcranial magnetic stimulation at short (2, 5, 10 and 15 ms) and long (100-300 ms) interstimulus intervals were measured. Results were compared to those of 12 control subjects and 20 of their siblings. There were no differences in cortical excitability between healthy control subjects and their siblings. Compared with control subjects, cortical excitability was higher in siblings of patients whether generalized (P < 0.05; short and long interstimulus intervals) or focal (P < 0.05; long interstimulus intervals). Compared with epilepsy, motor threshold was lower (P < 0.05) in patients with juvenile myoclonic epilepsy compared with their siblings only early at onset in the drug naïve state. In all groups (generalized and focal) cortical excitability was lower in siblings only at the long interstimulus intervals (250 and 300; P < 0.05). Cortical excitability is higher in asymptomatic siblings of patients with generalized and focal epilepsy in a similar manner. The disturbance seems to involve intracortical inhibitory circuits even in the siblings of patients with a structural abnormality (acquired epilepsy). This implies there are certain genetic factors that predispose to both generalized and focal epilepsies and a complex genetic/environmental interaction then determines the clinical phenotype.
    Brain 03/2013; 136(4). DOI:10.1093/brain/awt047 · 10.23 Impact Factor
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