epilepsy and focal gyral anomalies detected by mri: electroclinico-morphological correlations and...

EPILEPSY AND FOCAL GVRAL ANOMALIES

MORPHOLOGICAL CORRELATIONS AND DETECTED BY M RI : ELECTROCLI N ICO-

FOLLOW-UP

Renzo Guerrini Agatino Battaglia Charlotte Dravet ,Marie-Odile Livet Charles Raybaud Danielle Gambarelli Joseph Roger Olivier Robain Michelle Bureau

The widespread availability of advanced imaging techniques, particularly magnetic resonance imaging (MRI), has contributed much to the detection of brain lesions underlying human epilepsy (McLachlan et al. 1985, Conlon et al. 1988). In a growing number of patients with childhood-onset epilepsy, MRI can now show the developmental nature of such lesions by precisely defining the gyral pattern and digitations between grey and white matter (Barkovich e! a/ . 1987). Nevertheless, focal gyral anomalies with different pathological substrates are still difficult to differentiate by MRI alone. Areas of thick pachygyric cortex, polymicrogyria, and focal cortical dysplasia may have a similar macrogyric-like appearance on MRI (Barkovich et al. 1987, Kuzniecky et al. 1988, Titelbaum et al. 1989, Aicardi 1991). In addition, some intracortical lesions with both malformative and neoplastic characteristics may be ac- companied by loss of the normal gyral pattern (Altman 1988, Daumas-Duport et a/. 1988, Duchowney et al. 1989).

Different cortical developmental ab- normalities occuring in the same site and to the same extent can produce the same clinical features (Becker 1990). However, ( 1 ) different developmental lesions detectable by MRI may occur together with more widespread changes that are not detectable by MRI; and (2) clinically

these lesions are consistently complicated by epilepsy, the severity and type of which do not necessarily correlate with their ex tent.

To illustrate these points, we report the clinical and EEG findings for 10 patients with focal malformations of cortical gyri detected by M R I , and the MRI-anatomical correlates for two of these patients for whom pathological studies were available.

Patients and method The 10 patients (four male, six female) were aged between 40 days and 30 years (mean age 15 years 6 months). They have been followed at three institutions which deal with unselected populations of epilepsy patients (Centre Saint Paul, Marseille), or with children and ado- lescents with neurological disorders, developmental. delay and cognitive dis- abilities (Paediatric Neurology Depart- ment, CHU La Timone, Marseille; Institute of Child Neurology and Psychiatry, University of Pisa). In these institutions, neuroradiological investi- gations are performed largely for diag- nostic purposes. The 10 patients came from a consecutive series of 50 patients presenting with a developmental gyral abnormality which had been diagnosed by computed tomography (CT) scan, MRI, or both, between 1975 and 1990. We classified the abnormality as diffuse (22

TABLE I Age and diagnosis at first referral P d

Patient Sex Age Diagnosis (yrs:mths)

1 F 3:O 2 M 1O:O 3 F 2 6

4 F 1:0 5 M 8:O

6 F 0:5

7 M 0:l

8 M 3:O 9 F 6:O

10 F 15:O

Cerebral palsy (hemiparetic) Complex partial seizures Cerebral palsy (hemiparetic). absent speech Partial seizures Mild learning disability and arthrogryposis multiplex congenita Infantile spasms and arthrogryposis multiplex congenita Situation-related seizures and multiple congenital malformations Complex partial seizures Complex partial seizures Complex partial seizures

patients), bilateral localized (lo), hemi- spheric (eight) and focal (10). The distribution of cases among these categories and clinical findings of patients with bilateral localized gyral abnormality are reported in an accompanying paper (Guerrini et al. 1992). The criteria for inclusion in the present study was the demonstration by MRI of a focal area of abnormal gyral pat!ern, with no change in cortical thickness and finger-like extensions of white matter in the remaining brain. Gyral anomalies resulting from scarring, atrophic or destructive lesions and those bordering a cleft in the cerebral mantle were excluded. Heterotopia was defined as an island of grey matter surrounded by white matter, located between the ventricular wall and the cortical mantle.

Ages and diagnoses at first referral were diverse (Table I). Mean duration of clinical follow-up from first referral was 10 years 8 months (from one month to 27 years). Seizures, present in all cases and associated or not with neurological signs, were the main complaints which led to neuroradiological investigations. All patients had had a CT scan, using first- to third-generation apparatus (EM1 1010, CGR FS 200 and GE 9800) before the advent of MRI. Either a normal CT scan or insufficient characterization of the

morphology and extent of the cortical abnormality prompted us to carry out further investigations by MRI in all patients. We also performed video-EEG polygraphic monitoring, classified types and severity of seizures and types of epilepsy, and assessed the patients cognitive level. Methods for these clinical, EEG, neuroradiological and neuropsycho- logical investigations are reported in an accompanying paper (Guerrini el a!. 1992).

The nine patients presenting with epilepsy have been followed from the onset of the disease, for a mean of 10 years 3 months (three to 27 years). A description of the clinical sympto- matology of seizures was available for all nine, and seizures were recorded in six.

Patient 7 (see Table 11) died at 40 days, following open-heart surgery. At autopsy, the brain was removed and fixed in 10 per cent formalin. Representative samples were embedded in paraffin. Sections were stained with cresyl violet and haematoxylin and eosin.

Patient 8 (see Table 11) underwent right partial frontal lobectomy because of medically-resistant complex partial seizures. The seizure focus was defined as the constant site of onset of ictal EEG activity recorded during several seizures from scalp ,electrodes, consistent with

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