Anterior Thalamic Stimulation Induced Relapsing Encephalitis.

Deep brain stimulation of the anterior thalamic nucleus is one of the promising therapeutic options for epilepsy. Several studies are still under way to further strengthen and clarify the mechanism, efficacy, and complications. Contrary to hardware-related and operation-related events, the stimulation-related adverse effect is mild, target-dependent, and adjustable. We present a case of relapsing herpes simplex encephalitis (HSE) as a newly reported and potentially fatal stimulation-related adverse effect following stimulation of the anterior thalamic nucleus (ANT-DBS) accompanied by fever, confusion, and cognitive impairment in a 32-year-old epileptic patient with a history of herpes meningoencephalitis 31 years earlier. The T2-weighted/FLAIR high-signal intensity in the temporal lobe developed at a "distance" from the stimulation target. The positive polymerase chain reaction of herpes virus deoxyribonucleic acid in the cerebrospinal fluid confirmed the diagnosis. The condition improved partially on acyclovir and stimulation stopped. Seizures disappeared and then returned after few months. The unique case report presents a rationale for considering history of herpes encephalitis as a relative contraindication for ANT-DBS, and HSE relapse should be suspected in patients with post-stimulation fever and/or altered consciousness.