Pedunculopontine nucleus stimulation: A novel therapeutic technique in intractable epilepsy

Intractable epilepsy accounts for approximately 30% cases of epilepsy worldwide, and continues to pose a medical challenge even today. Several studies have demonstrated the strong anti-epileptic influence of rapid eye movement (REM) sleep in humans, some researchers even claiming it as the most potent anti-epileptic state in human sleep–wake cycle. A reduction of REM sleep is a common feature reported in various forms of intractable epilepsy. Several studies have reported reduction to total disappearance of even the severe EEG abnormalities in West syndrome during REM sleep suggesting an explorable relation between the reduction of REM sleep and severity/intractability of seizures. In autopsy examination of the cases of West syndrome, the total number of neurons in pedunculopontine nucleus (PPN) and the number of acetylcholine neurons (AChN) in PPN in particular have been found to be reduced with comparative preservation of catecholaminergic neurons and GABAergic interneurons suggesting a specific change and displaying a strong indication of significance of lesions of AChN in epileptogenesis. Stimulation of AChN in PPN has been observed to induce REM sleep. Therefore, in view of the strong anti-epileptic influence of REM sleep, it is postulated that PPN may be electrically stimulated (with programmable and manual modes) for enhancing the genesis of REM sleep throughout the night sleep time when the susceptibility to seizure generation and occurrence is maximum. Thus, the postulated technique does hold promise as an effective anti-epileptic technique warranting an insightful study of its prospects and the success that may ensue from its preliminary trials.