Cardiac autonomic neuropathy in adult epilepsy patients in a tertiary hospital in South-Western Nigeria.

Abstract

Cardiac autonomic neuropathy (CAN) resulting from seizures has been implicated in sudden unexpected death in epilepsy in persons with epilepsy (PWE), however, there are no previous studies of CAN in PWE from Nigeria. This study sought to determine the frequency and pattern of CAN in adult PWE in a tertiary hospital in South-western Nigeria and to determine the relationship between seizure variables and CAN. A cross-sectional study of 80 adult PWE and 80 matched controls aged between 18 and 60 years was carried out between March 2012 and June 2013 at the Obafemi Awolowo University Teaching Hospital Complex, Ile-Ife, Nigeria. Demographic and clinical data were obtained from all the study participants. Anxiety was excluded using the Hamilton Anxiety Scale. Those with conditions that could affect autonomic function, such as chronic renal failure, heart failure, Parkinson's disease, diabetes mellitus, anxiety, and psychiatric disorders and pregnant women were excluded. Five bedside cardiovascular reflex tests were performed on each subject after baseline heart rate and blood pressure (BP) had been recorded. The mean age of onset of epilepsy was 19 ± 10 years, whereas the mean duration of epilepsy was 10 ± 8 years. The mean seizure frequency was 14 ± 30 per month (median three seizures per month). Of the 80 patients evaluated, 42 (52.5%) had CAN, whereas none of the controls had CAN. Majority (69%) of the PWE with CAN had purely parasympathetic dysfunction, whereas 3% had purely sympathetic dysfunction and 10% had combined autonomic dysfunction. The PWE in this study had significantly lower tilt ratios and diastolic BP change with Isometric Hand grip as well as significantly higher systolic BP change on standing than the controls. Patients who had more than four seizures per month had higher odds of CAN than those with less frequent seizures (odds ratio 0.275, P value 0.023). Also, patients who had received treatment for less than 10 years were found to have greater odds of CAN than those who had received treatment for a longer period (odds ratio 11.676, P value 0.046). CAN is common in adult PWE in South-Western Nigeria and the major predictors are short duration of treatment and frequent seizure episodes. Routine screening of these patients may help with early detection of autonomic dysfunction and provide an opportunity for intervention.