Comorbidity between epilepsy and sleep disorders

Despite being relatively common and potentially able to have clinical and pathophysiological consequences, the comorbidity between epilepsy and sleep disorders is poorly investigated in the literature and rarely taken into consideration by clinicians in general practice. There is increasing evidence that obstructive sleep apnoea (OSA) coexists in epilepsy (in 10% of unselected adult epilepsy patients, 20% of children with epilepsy and up to 30% of drug-resistant epilepsy patients). A few lines of evidence suggest that continuous positive airway pressure treatment of OSA in epilepsy patients improves seizure control, cognitive performance and quality of life. Parasomnias and epileptic seizures can coexist in the same subject making the differential diagnosis of these conditions particularly challenging. In childhood, a frequent association between epilepsy and NREM arousal parasomnias, enuresis and rhythmic movement disorder has been documented. A particular pattern of association has been found between nocturnal frontal lobe epilepsy (NFLE) and NREM arousal parasomnias, the latter being found in the personal or family history of up to one third of NFLE patients. As far as REM parasomnias are concerned, REM sleep behaviour disorder, unrecognised or misdiagnosed, has been found to co-occur in 12% of elderly epilepsy patients. Patients with epilepsy often complain of poor, non-restorative sleep; however, insomnia in epilepsy is poorly investigated, with the literature giving conflicting prevalence data and no information on the impact of this disorder on seizure control, or on the best therapeutic approach to insomnia in this particular group of patients. A greater awareness, among clinicians, of the comorbidities between sleep disorders and epilepsy may help to prevent misdiagnosis and mistreatment. Sleep hygiene measures in epilepsy need to be more comprehensive, taking into account the various pathologies that may underlie disordered sleep in epilepsy patients.