Electrophysiologic assessment of autonomic function in epilepsy
Drake J ME, Andrews JM, and Castleberry CM (1998) Electrophysiologic assessment of autonomic function in epilepsy. Seizure 7:2 91–6.
Abstract: Sudden unexpected death associated with epilepsy (SUDEP) is an important clinical problem. Peri-ictal autonomic dysfunction is thought to play a role in SUDEP and few means exist for clinical identification of patients at risk. Sympathetic function was assessed by measuring sympathetic skin responses (SSR) elicited in the hand by auditory or tactile stimulation or by inspiration. Parasympathetic function was assessed by recording the R-R interval (RRI) and determining its variability in subsequent heartbeats. Fifty epilepsy patients had significantly greater SSR amplitudes and latencies than controls. The RRI was shorter in patients than in controls and the mean successive difference (MSD) was less, but significance was not reached. Twenty patients at possible risk for SUDEP (male, generalized seizures, intermittent medication noncompliance, drug and alcohol abuse, traumatic or structural aetiology) differed significantly from controls in SSR and RRI. Epilepsy patients may differ in autonomic function from the general population, and these differences may be relevant to SUDEP. The SSR and the RRI may be a simple means of assessing autonomic function in epilepsy outpatients.
Keywords: epilepsy; autonomic; sympathetic; parasympathetic; electrophysiology
- Sympathetic function measured by skin conductance changes, parasympathetic by HRV. Skin conductance changes were larger in epilepsy patients, HRV was not, but if a subgroup of patients with SUDEP risk factors was considered, the differences were more pronounced. Some statistical results seem unlikely, for example, the standard deviation of heart rate was almost 20 times less in these SUDEP-risk patients than in controls, even though the SD for all epilepsy patients was about 85% that of controls.