Background: This is an updated version of a Cochrane Review previously published in 2019. Catamenial epilepsy describes worsening seizures in relation to the menstrual cycle and may affect around 40% of women with epilepsy. Vulnerable days of the menstrual cycle for seizures are perimenstrually (C1 pattern), at ovulation (C2 pattern), and during the luteal phase (C3 pattern). A reduction in progesterone levels premenstrually and reduced secretion during the luteal phase is implicated in catamenial C1 and C3 patterns. A reduction in progesterone has been demonstrated to reduce sensitivity to the inhibitory neurotransmitter in preclinical studies, hence increasing risk of seizures. A pre-ovulatory surge in oestrogen has been implicated in the C2 pattern of seizure exacerbation, although the exact mechanism by which this surge increases risk is uncertain. Current treatment practices include the use of pulsed hormonal (e.g. progesterone) and non-hormonal treatments (e.g. clobazam or acetazolamide) in women with regular menses, and complete cessation of menstruation using synthetic hormones (e.g. medroxyprogesterone (Depo-Provera) or gonadotropin-releasing hormone (GnRH) analogues (triptorelin and goserelin)) in women with irregular menses. Catamenial epilepsy and seizure exacerbation is common in women with epilepsy. Women may not receive appropriate treatment for their seizures because of uncertainty regarding which treatment works best and when in the menstrual cycle treatment should be taken, as well as the possible impact on fertility, the menstrual cycle, bone health, and cardiovascular health. This review aims to address these issues to inform clinical practice and future research.

Objectives: To evaluate the efficacy and tolerability of hormonal and non-hormonal treatments for seizures exacerbated by the menstrual cycle in women with regular or irregular menses. We synthesised the evidence from randomised and quasi-randomised controlled trials of hormonal and non-hormonal treatments in women with catamenial epilepsy of any pattern.

Search methods: We searched the following databases on 20 July 2021 for the latest update: Cochrane Register of Studies (CRS Web) and MEDLINE Ovid (1946 to 19 July 2021). CRS Web includes randomised controlled trials (RCTs) or quasi-RCTs from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, the Cochrane Central Register of Controlled Trials (CENTRAL), and the specialised registers of Cochrane Review Groups including Cochrane Epilepsy. We used no language restrictions. We checked the reference lists of retrieved studies for additional reports of relevant studies.

Selection criteria: We included RCTs and quasi-RCTs of blinded or open-label design that randomised participants individually (i.e. cluster-randomised trials were excluded). We included cross-over trials if each treatment period was at least 12 weeks in length and the trial had a suitable wash-out period. We included the following types of interventions: women with any pattern of catamenial epilepsy who received a hormonal or non-hormonal drug intervention in addition to an existing antiepileptic drug regimen for a minimum treatment duration of 12 weeks.

Data collection and analysis: We extracted data on study design factors and participant demographics for the included studies. The primary outcomes of interest were: proportion seizure-free, proportion of responders (at least 50% decrease in seizure frequency from baseline), and change in seizure frequency. Secondary outcomes included: number of withdrawals, number of women experiencing adverse events of interest (seizure exacerbation, cardiac events, thromboembolic events, osteoporosis and bone health, mood disorders, sedation, menstrual cycle disorders, and fertility issues), and quality of life outcomes.

Main results: Following title, abstract, and full-text screening, we included eight full-text articles reporting on four double-blind, placebo-controlled RCTs. We included two cross-over RCTs of pulsed norethisterone, and two parallel RCTs of pulsed progesterone recruiting a total of 192 women aged between 13 and 45 years with catamenial epilepsy. We found no RCTs for non-hormonal treatments of catamenial epilepsy or for women with irregular menses. Meta-analysis was not possible for the primary outcomes, therefore we undertook a narrative synthesis. For the two RCTs evaluating norethisterone versus placebo (24 participants), there were no reported treatment differences for change in seizure frequency. Outcomes for the proportion seizure-free and 50% responders were not reported. For the two RCTs evaluating progesterone versus placebo (168 participants), the studies reported conflicting results for the primary outcomes. One progesterone RCT reported no significant difference between progesterone 600 mg/day taken on day 14 to 28 and placebo with respect to 50% responders, seizure freedom rates, and change in seizure frequency for any seizure type. The other progesterone RCT reported a decrease in seizure frequency from baseline in the progesterone group that was significantly higher than the decrease in seizure frequency from baseline in the placebo group. The results of secondary efficacy outcomes showed no significant difference between groups in the pooled progesterone RCTs in terms of treatment withdrawal for any reason (pooled risk ratio (RR) 1.56, 95% confidence interval (CI) 0.81 to 3.00, P = 0.18, I² = 0%) or treatment withdrawals due to adverse events (pooled RR 2.91, 95% CI 0.53 to 16.17, P = 0.22, I² = 0%). No treatment withdrawals were reported from the norethisterone RCTs. The RCTs reported limited information on adverse events, although one progesterone RCT reported no significant difference in the number of women experiencing adverse events (diarrhoea, dyspepsia, nausea, vomiting, fatigue, nasopharyngitis, dizziness, headache, and depression). No studies reported on quality of life. We judged the evidence for outcomes related to the included progesterone RCTs to be of low to moderate certainty due to risk of bias, and for outcomes related to the included norethisterone RCTs to be of very low certainty due to serious imprecision and risk of bias.

Authors' conclusions: This review provides very low-certainty evidence of no treatment difference between norethisterone and placebo, and moderate- to low-certainty evidence of no treatment difference between progesterone and placebo for catamenial epilepsy. However, as all the included studies were underpowered, important clinical effects cannot be ruled out. Our review highlights an overall deficiency in the literature base on the effectiveness of a wide range of other hormonal and non-hormonal interventions currently being used in practice, particularly for those women who do not have regular menses. Further clinical trials are needed in this area.