New-onset seizures after cranioplasty—a different view on a putatively frequently observed phenomenon

Abstract

Background New-onset seizures after cranioplasty (NOSAC) are reported to be a frequent complication of cranioplasty (CP) after decompressive hemicraniectomy (DHC). There are considerable differences in the incidence of NOSAC and contradictory data about presumed risk factors in the literature. We suggest NOSAC to be a consequence of patients’ initial condition which led to DHC, rather than a complication of subsequent CP. We conducted a retrospective analysis to verify our hypothesis. Methods The medical records of all patients ≥ 18 years who underwent CP between 2002 and 2017 at our institution were evaluated including incidence of seizures, time of seizure onset, and presumed risk factors. Indication for DHC, type of implant used, timing of CP, patient age, presence of a ventriculoperitoneal shunt (VP shunt), and postoperative complications were compared between patients with and without NOSAC. Results A total of 302 patients underwent CP between 2002 and 2017, 276 of whom were included in the outcome analysis and the incidence of NOSAC was 23.2%. Although time between DHC and CP differed significantly between DHC indication groups, time between DHC and seizure onset did not differ, suggesting the occurrence of seizures to be independent of the procedure of CP. Time of follow-up was the only factor associated with the occurrence of NOSAC. Conclusion New-onset seizures may be a consequence of the initial condition leading to DHC rather than of CP itself. Time of follow-up seems to play a major role in detection of new-onset seizures.

Outcomes of Cranioplasty: A Single-Center Experience

“…However, interestingly, all patients had their seizures within 24 hours post CP. Which, contrary to Hirschmann et al's argument [ 46 ], suggests that the CP procedure itself may play some role in provoking seizures even in some indirect way, and not entirely caused by the initial disease. Moreover, in contrast to several studies where new onset seizures were found in patients with THI, hemorrhagic or ischemic strokes, our study noted that the surgical site osteomyelitis infection on the previous craniotomy site was the indication for craniectomy in two patients, and the tumor was the indication in the third.…”

“…New onset seizure is another frequently reported complication post CP, with an incidence rate between 2.7% to 30.3% [ 45 ]. Several risk factors have been identified as contributory to its incidence including the time interval between craniectomy and CP, patient age at CP, presence of VP shunt at time of CP, type of material used, the indication for the craniectomy, hypertension (HTN), and diabetes mellitus (DM) [ 46 ]. However, these risk factors once again are inconsistent in the literature, and some even are contradictory.…”

“…However, recently, Hirschmann et al argued that new-onset seizures post CP are independent of the procedure of CP, and are more likely to be caused by the initial disease [ 46 ]. They supported this claim with the findings of their study where they observed that only the time of follow-up was significantly associated with the incidence of new-onset seizures post CP [ 46 ].…”

“…However, recently, Hirschmann et al argued that new-onset seizures post CP are independent of the procedure of CP, and are more likely to be caused by the initial disease [ 46 ]. They supported this claim with the findings of their study where they observed that only the time of follow-up was significantly associated with the incidence of new-onset seizures post CP [ 46 ]. Moreover, based on their argument they suggested the following explanation: timing of CP only resembles a point in time according to which seizures will be classified and determined to be either pre-existing or new-onset seizure post CP.…”

“…Moreover, based on their argument they suggested the following explanation: timing of CP only resembles a point in time according to which seizures will be classified and determined to be either pre-existing or new-onset seizure post CP. Therefore, patients undergoing late CP will be more likely to be classified in the pre-existing group and excluded from the study, while on the other hand, more patients with early CP will be included in the study [ 46 ]. This explanation is based on their findings that the median time of follow-up in patients with new onset post-CP seizure was three times longer than of patients without a new-onset post-CP seizure in addition to the observation that most cohorts reported insufficient time of follow-up, which led to a considerable proportion of late-onset seizures that will not be observed [ 46 ].…”