Vagal Nerve Stimulation in Autonomic Dysfunction – A Case Study

      Background: Autonomic nervous system function is influenced by the balance of the parasympathetic and sympathetic systems. Management for imbalance of these components causing dysfunction is largely focused on medications primarily improving cardiovascular tone. However, there appears to be an opportunity for therapy by modulating neurotransmission. Methods: Our patient is a nine year old female with history of intractable epilepsy and developmental delay related to confirmed genetic abnormalities and also complaints of episodic pallor, fatigue, light-headedness and headaches concerning for dysautonomia. Results: Our patient underwent vagal nerve stimulator (VNS) implantation for treatment of epilepsy and showed improvement of these symptoms at typical settings. Head-up tilt test (HUTT) was subsequently performed and revealed normal findings and no subjective symptoms of autonomic dysfunction. A repeat HUTT was performed five months later with VNS output currents set to zero and revealed cardiovascular changes and clinical symptoms consistent with dysautonomia. With resumption of previous VNS settings, clinical symptoms resolved. Conclusions: Neurotransmission from vagal afferents to brainstem nuclei is increased during VNS affecting multiple brainstem areas and the cerebral cortex, including regions controlling autonomic function. Studies have suggested a role for VNS in patients with clinical signs of autonomic dysfunction showing improvement in sympathovagal balance after VNS implantation. In our patient, we observed subjective and objective improvement in autonomic function. This initial case demonstrates a phenomenon that requires further study, may lead to improved understanding of autonomic function and the response to vagal nerve stimulation, and possibly a new indication for VNS therapy.
      To read this article in full you will need to make a payment