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of an amnesic syndrome. However developments in functional MRI, assessed in combination
with full neuropsychology assessment in experienced hands, mean that the WADA test is
now rarely performed for assessment of language in children, particularly in the evaluation
for temporal resection.

The role of invasive monitoring

Despite the improved techniques in non-invasive presurgical evaluation, there remains a
small proportion of children who benefit from invasive EEG monitoring, whether with
subdural grids with or without depth electrodes or in stereo EEG. These are children in whom
there is concern that the seizure focus lies within a functionally eloquent area, in children
with extratemporal epilepsy in whom all data are concordant but there is no structural
abnormality on MRI, and those in whom data are suggestive of a single focus but there may
be some doubt.

The role of neuropsychiatry

The exact aims of surgery require discussion to review whether expectations on the part of
the patient and family are realistic. This has particular relevance in childhood, as the group
under consideration is clinically heterogeneous, and outcome aims are diverse. In particular,
in a young child with severe developmental delay and extremely frequent seizures, the aims
of surgery may be more related to improved developmental progress and quality of life with,

Table 1. Seizure-free outcome according to procedure and pathology.

Hemispherectomy Wyllie et al 199813 Mathern et al 199914 GOSH15,16,17
- Cortical dysplasia F/up 17.4 years F/up 6m10 years F/up >2 year
16/28 (57%)
- Other 11/16 (69%) 40/62 (64%) 5/15 (33%)8
18/26 (69%) (HME 20%, other
Temporal resection 14/21 (67%)
22/36 (61%) 50%)
- Hippocampal
13/20 (65%) 11/13 (82%)
sclerosis 5/9 (56%) 34/59 (58%)
7/8 (87%)
- Cortical } 16/30 (53%)
} 6/12 (50%) }
dysplasia } } 18/26 (69%)
}
- Tumour 24/28 (86%) 16/29 (55%)
22/37 (59.5%)
Extratemporal/ 0
5/13 (38%) 15/22 (68.2%)
multilobar resection

- Cortical 11/22 (50%)

dysplasia

- Tumour 12/16 (75%)

- Other

GOSH: Great Ormond Street Hospital