The benefits of CC to prevent recurrence of SE have been previously described.5
To our knowledge, this is the first reported case of successful surgical treatment of ongoing pediatric RSE with CC alone: previous reports describe CC as part of a resective procedure, such as hemispherectomy or focal resection with CC. In our report, anticonvulsant medications which were ineffective preoperatively were sufficient to prevent relapse into RSE postoperatively while the same anesthetic agents were weaned. There are only six case reports of successful disconnective or disruptive epilepsy surgery (excluding hemispherectomy) for pediatric RSE.6,7
There is little evidence-based guidance for treating RSE. Treatment strategies may follow from consideration of the differential diagnosis—in our patient with a history of prior RSE, an infectious or inflammation-mediated encephalopathy was considered unlikely. Pharmacologic coma is often initiated, but in some cases cerebral suppression proves ineffective when the patient re-emerges from coma with SE. Ma et al. recommend consideration of surgical treatment after failure of three trials of pharmacologic coma therapy over 2 weeks.8
In the setting of focal epilepsy, particularly with lesional findings on magnetic resonance imaging (MRI), RSE is clearly amenable to focal resection or hemispherectomy. In a retrospective study of 10 patients with focal epileptogenesis, all were treated surgically, successfully aborting RSE and without mortality.9
In our case, a prior presurgical workup identified the patient as a poor resective surgical candidate. Since resective surgery could not be accomplished, additional trials of anesthetic agents were attempted before a palliative procedure was considered.
In the absence of a clear anatomical focus for seizures or in the presence of signs suggestive of generalized epilepsy, resective surgery is not an option. Disconnective or disruptive procedures, including CC, multiple subpial transections, vagal nerve stimulation (VNS) and electroconvulsive therapy may effectively abort RSE. Complete CC was chosen in our case, since it is probably superior in the treatment of tonic seizures, the patient’s habitual seizure type.10
For this indication, the added benefit of complete disconnection in complete CC compared to anterior two-thirds sectioning may outweigh the difference in surgical risk, as some reports demonstrate lower relapse rate in tonic and drop seizures with complete CC.11,12
Complete callosal section is associated with improved seizure outcome in prepubescent children and children with global cerebral dysfunction.13,14
Our patient’s young age and cognitive impairment were factors favoring complete CC in clinical decision-making. While the extent of callosal section correlates with the risk for development of a disconnection syndrome, studies in prepubescent children show that functional gain and family satisfaction post-callosotomy are most strongly correlated with seizure control, not extent of callosal section.13–15
The mechanism by which CC may abort seizures, rather than simply prevent generalization, is unclear. However, it is well-documented that CC can reduce partial seizures, indicating that it may have some antiepileptic effect.16,17
Further, presurgical evaluation after CC may identify a resectable focus in some patients; favorable seizure outcome can be obtained from subsequent surgery following CC.18,19
The limitations of the report include a lack of direct evidence that CC was responsible for terminating the patient’s RSE. It is possible that the natural history of the RSE episode was such that it would have relented without surgical intervention. Since patients with RSE are typically in a pharmacologic coma necessitated by the diagnosis, it is not always practical to demonstrate direct evidence of termination of RSE intraoperatively. The most common anesthetic agent used is a barbiturate; even after discontinuation barbiturates continue to cause cerebral suppression for several hours. That the same medications tried ineffectually preoperatively were sufficient postoperatively, and that pharmacologic coma was able to be discontinued, is indicative of the benefit of CC to terminate RSE in this case.