Rationale:
Catamenial epilepsy refers to worsening of seizures in relation to the menstrual cycle. Brain responsive neurostimulation (RNS® System), is a device that can detect epileptiform activity and deliver stimulation for the treatment of refractory epilepsy. It also
provides chronic ambulatory monitoring of ictal patterns which can guide treatment. Our objective is to determine the feasibility of diagnosing catamenial epilepsy patterns with RNS data in patients of childbearing age. Methods:
We identified all patients with childbearing capacity with intractable epilepsy and an RNS system at our center. Patients with hysterectomies were excluded. Patients who recorded their menstrual cycle dates from February 15, 2023 through May 15, 2023 were included and their opinion on whether their seizures worsened during their menstrual cycle was recorded. Daily long episode (LE) data (objective ictal pattern detections by the RNS system) was reviewed and tabulated for the same time interval for each patient. Demographic data including ASMs and contraception use were collected and descriptive analysis was performed. Results:
Four patients with medical intractable epilepsy kept records of their menstrual cycle and met inclusion criteria. All four patients believed their epilepsy worsened during or around the time of their menstruation. Most LE lengths ranged from 30 to 45 seconds. Patient 3 and 4’s LEs correlated to clinical seizures. Patient 2, 3, and 4 LEs correlated to electrographic seizures. RNS implantation time averaged 3.1 years (range 2-4 years).
Patient 1 was a 32-year-old Black woman with bilateral independent temporal lobe epilepsy since infancy. She was on lamotrigine, brivaracetam and progesterone-only contraceptive. Figure 1A shows an increase of her LEs by 38.4 % during cycles.
Patient 2 was 40-year-old White woman with bitemporal lobe epilepsy and psychogenic non-epileptic spells for 17 years. She was on clonazepam, brivaracetam, and phenytoin. She was not taking any contraception. A mid-cycle spike not associated with menstruation was noted but there were no significant differences in the number of LEs in the three-month study period (Fig B).
Patient 3 was a 31-year-old White woman with right temporal epilepsy for 10 years. She was on lacosamide, lamotrigine, levetiracetam and no contraception. There was a mild spike during the first cycle and then in the week after the second and third cycle (Fig C).
Patient 4 was a 38-year-old Black woman with left temporal lobe epilepsy for 7 years. During this time period, she was on clobazam, eslicarbazepine, lamotrigine and topiramate. She was not taking any contraception. There were no significant differences between her cycles and inter-cycle LEs.
Conclusions:
While many patients feel an increase in the severity or frequency around the times of menstruation, objective data collection can be biased by observational data and true catamenial epilepsy diagnosis and rates may be unreliable. Using the RNS® system data as an objective way to estimate seizure burden is a reasonable method to correlate menstrual cycles in patients of childbearing potential for further evaluation and treatment methodologies.
Funding: No funding was used.