Study	Reason for exclusion
Avanzini 1982	Not a clinical trial
Beenen 1999	Trial with random allocation that compared two anticonvulsants (phenytoin and valproic acid)
Boarini 1985	Retrospective chart review
Byrne 1983	Retrospective study
Cohen 1988	Retrospective study
De Santis 2002	Inclusion of participants with history of seizures
Dent 1996	Retrospective study with historical controls
Foy 1992	Outcome data not extractable for patients with brain tumors in the results section
Franceschetti 1988	It is a duplicate of Franceschetti 1990 with fewer patients
Hagen 1990	Retrospective chart review
Holland 1995	A double‐blind, randomized trial using valproic acid for prevention of seizures after craniotomy or head injury, this trial has not been fully published, and no data about brain tumors are in the abstract
Hung 1991	Retrospective chart review
Levati 1996	Study with random allocation comparing three different doses of phenytoin for prevention of postoperatory seizures in participants with supratentorial brain tumors, there was no placebo or suitable control group
Mahaley 1981	Not a controlled clinical trial, but a retrospective study
Mauro 2007	Retrospective study
Moots 1995	A retrospective review
Nakamura 1999	Double‐blind trial with random allocation comparing zonisamide with phenobarbital
North 1980	This trial was later expanded and published elsewhere, North 1983
Pagani 1983	Prevention of seizures induced by contrast media in patients with brain metastases
Pagani 1984	Prevention of seizures induced by contrast media in patients with glioma
Tsuji 1993	Observational study of 20 patients with meningioma who received valproic acid for seizure prevention, this study did not use a control group
Zhang 2000	A controlled clinical trial with random allocation that compared phenytoin and valproic acid for the prevention of postoperatory seizures