Focal cortical dysplasias: surgical outcome in 67 patients in relation to histological subtypes and dual pathology

Abstract

The purpose of this study was to assess whether the histological subtype of focal cortical dysplasia and dual pathology affect surgical outcome in patients with medically intractable epilepsy due to focal cortical dysplasia (FCD). We retrospectively analysed the outcome of 67 patients from 2 to 66 years of age at follow-up periods of 6 to 48 months after epilepsy surgery. Histological subtypes were classified according to Palmini and included a few cases with mild histological abnormalities corresponding to the definition of mild malformations of cortical development. The seizure outcome was classified according to Engel and evaluated at the last follow-up visit as well as at follow-up periods of 12 and 24 months after surgery. The outcome in patients with FCD and additional hippocampal pathology (dual pathology) was analysed separately. Distribution of histological subtypes differed in temporal and extratemporal localization, with a significantly higher extratemporal prevalence of FCD type 2. There was a tendency towards better postsurgical outcome related to the last follow-up visit in patients with more subtle abnormalities classified as mild malformations of cortical development (mMCD) (63% Engel Ia), FCD type 1a (67% Engel Ia) and FCD type 1b (55% Engel Ia) compared with patients with FCD type 2a (43% Engel Ia) and FCD type 2b (Taylor type) (50% Engel Ia). Considering the outcome at follow-up periods over 12 and 24 months, complete seizure-freedom was achieved significantly more often in patients with FCD type 1 and mMCD than with FCD type 2, and seizure reduction by less than 75% (Engel IV) occurred in more patients with FCD type 2a compared with the other subgroups. This tendency was seen in the whole patient group and in the extratemporal subgroup. Patients with dual pathology almost always had temporal lobe epilepsy; the outcome in this patient group was generally favourable (66% complete seizure-freedom at the last follow-up visit). The outcome remained almost constant with longer periods of follow-up. We conclude that patients with FCD type 1 and mMCD had a better outcome compared with those with more severe forms of cortical dysplasia. A higher incidence of FCD type 1 in temporal localization did not allow the effects of histological subtype and localization to be separated. A subanalysis of extratemporal FCDs, however, revealed a similar tendency for a better outcome with FCD type 1, suggesting that the histological subtype itself seems to be at least a relevant cofactor influencing postsurgical outcome.

Magnetic resonance imaging abnormalities in the resection region correlate with histopathological type, gliosis extent, and postoperative outcome in pediatric cortical dysplasia

“…5,14,19,21,28,31,32 Some studies, however, have shown better outcomes for patients with Type I CD, 5,8 and other studies have shown no difference in outcome between patients with milder and those with more severe CD subtypes. 13 The few studies specifically evaluating children are less conclusive.…”

The influence of lesion volume, perilesion resection volume, and completeness of resection on seizure outcome after resective epilepsy surgery for cortical dysplasia in children

“…Several clinical research groups have studied the impact of different radiological or clinicopathological factors on seizure outcome after extirpative surgery for FCD. [4][5][6][7][8][9][11][12][13][14][15]23,24,26,28,29 Recently, Rowland et al 22 reported on their meta-analysis of predictors of seizure freedom in the surgical management of FCD on the basis of results from 37 selected studies. They noted that complete resection of the anatomical or electrographic abnormality was the most important treatment-related factor predictive of seizure freedom.…”

Coexistent pathology in chronic epilepsy patients with neoplasms

“…[7][8][9][10] In a subset of these tumors, which are generally low-grade glial or glioneuronal neoplasms, multiple pathologies, which potentially may contribute to the genesis of these seizures, are identifiable (dual pathology). [11][12][13][14][15][16] Among these, there is a well-established association of certain neoplasms with malformations of cortical development (cortical dysplasia), particularly dysembryoplastic neuroepithelial tumors and gangliogliomas. [17][18][19][20] The purpose of this study is to systematically review one institution's experience with neoplasms associated with identifiable coexistent pathology arising in the setting of chronic epilepsy.…”