Do Reactive Post‐Resection “Injury” Spikes Exist?

Abstract

Summary:Purpose: New post-resection spikes on electrocorticography (ECoG) after lesionectomy in patients with seizures may represent residual epileptogenic tissue or presumed reactive injury spikes. We investigated the existence of postresection injury spikes by eliminating the possibility of residual epileptogenic tissue.Methods: Preresection and post-resection ECoG was performed on seven patients with an intra-axial neocortical tumor (glioblastoma multiforme or metastasis) and no history of seizures. All tumors were gross-totally resected.Results: The mean age of the patients was 59 years. The tumor location was frontal in four patients, parietal in two, and temporal in one. Two patients had preresection spikes with an average rate of 68 spikedmin that disappeared after surgery. Two different patients had new post-resection spikes, with an average firing rate of 4 spikedmin, despite normal preresection ECoG. In one of these patients, the new spikes were superimposed over a burst suppression pattern. Neither patient developed seizures after surgery.Conclusions: Surgical irritation of the neocortex is sufficient to produce reactive post-resection epileptogenic discharges surrounding an intra-axial neocortical tumor even in the absence of preoperative seizures and spikes. Injury spikes fire at a slow rate and are not predictive of clinical seizures.

Significance of New Postresection Spikes

“…We believed that this observation was most in keeping with “activation by partial excision,” as first described by Penfield and Jasper (5), related to a decreased threshold for the expression of epileptiform activity in acutely disconnected epileptogenic cortex (4). As no preresection chemical activation was carried out at ECoG in the study of Schwartz et al (1), the existence of new postresection spikes cannot with certainty be taken as evidence of their induction by surgical injury during lesionectomy. Nevertheless, there is evidence that transient epileptic foci can be induced by nonresective surgical manipulation of the neocortex, albeit with a different high firing rate, compared to the low firing rate of postresection spikes (6), and so questions remain.…”

“…Nevertheless, there is evidence that transient epileptic foci can be induced by nonresective surgical manipulation of the neocortex, albeit with a different high firing rate, compared to the low firing rate of postresection spikes (6), and so questions remain. As suggested by Schwartz et al (1), larger follow‐up studies using their design, preferably including preresection chemical activation, may hopefully provide more definitive conclusions.…”

“…Schwartz et al (1) describe new postresection spikes appearing at the surgical margins in two patients with solitary cerebral metastases immediately after gross‐total lesionectomy. Because neither patient had suffered from seizures and no preresection spikes were recorded at ECoG, the findings were interpreted as evidence that surgical irritation of the neocortex is sufficient to produce reactive “injury” spikes, which are not predictive of clinical seizures.…”

Residual fast ripples in the intraoperative corticogram predict epilepsy surgery outcome

“…[3][4][5][6][7] Especially ictiform spike patterns, consisting of recruiting, repetitive bursting, and continuous rhythmic spiking patterns, are considered markers of epileptic brain tissue, and it is advocated that those areas should be removed to achieve seizure freedom. 16 Discriminating between epileptic red and meaningless green spikes is difficult. [12][13][14][15] Residual spikes in post-ECoG may arise from surgical manipulation of the neocortex at the resection margin.…”

Brain tumor epilepsy: A reappraisal and six remaining issues to be debated

“…It is well-known that epileptiform discharges are not pathognomonique for epilepsy and could be observed in subjects without any seizures (Sam and So 2001). Moreover, it has been shown that interictal « injury » spikes eventually recorded in the postoperative period are not associated with an increased risk of seizures (Schwartz, Bazil et al 2000),a result further confirmed in patients with meningioma undergoing surgery (Rothoerl, Bernreuther et al 2003).…”