Rationale:
Identical twins share a unique genome, and similarities in their genotype offer opportunities for medical research. Many studies have been performed on identical twins for a variety of disease processes, including epilepsy. We are discovering that many forms of epilepsy are genetic, and identical twins sharing an epilepsy disorder seems expected. While the twins in this case report displayed expected similarities in seizure phenotype and medication responses (something previous studies have focused on), we present the near identical changes on ictal and interictal EEG patterns over time as the twins aged. This case report seeks to illustrate these parallel changes.
Methods:
This is a retrospective case report. After obtaining consent from the parents of the twins, their electronic medical records were reviewed from the time of birth to present, as well as their electroencephalograms (EEGs). We also reviewed literature that has been published on twins with epilepsy. Afterwards, we compared the findings of our twins to other published cases of twins with epilepsy, with a focus on EEG changes over time.
Results:
The twins in our case report developed seizures close to the same age of three years. Importantly, they both displayed similar interictal and ictal changes in the EEG pattern over time. Both displayed bifrontal spike and wave, with maximum negativity Fp1 greater than Fp2 (Figure 1), early on in their course. Over time the interictal EEGs for both showed evolution to parieto-occipital spike and wave, P3/O1 greater than P4/O2 (Figure 2).
Both showed a sustained photo-paroxysmal response lasting approximately 19 seconds with 3Hz generalized spike and wave activity with their hands and arms clenched, and their right leg flexed. No changes were observed during hyperventilation. During sleep, there were poorly organized bursts of generalized spikes and waves, consistent with primary generalized epilepsy. MRI brain w/wo contrast for both was unremarkable. Genetic workup is pending.
Both were treated with levetiracetam with identical efficacy and adverse events. They were switched to topiramate due to inadequate efficacy and side effects of cognitive changes and insomnia on levetiracetam after six months. Currently, both twins are doing well at age 11 years on topiramate.
Conclusions:
Identical twins are known to show similar seizure phenotype and treatment responses. This case report highlights that EEG changes over time can also be expected to be similar. Further investigations into the EEG specifically over time in identical twins is needed, as the field of genetic epilepsy continues to grow.
Funding: No funding was received for this project.