Cardiovascular autonomic and hemodynamic responses to vagus nerve stimulation in drug-resistant epilepsy.

PURPOSE: Vagus nerve stimulation (VNS) is used as an adjunctive therapy for treating patients with drug-resistant epilepsy. The impact of VNS on cardiovascular autonomic function remains to be fully understood. We determined changes in cardiovascular sympathetic and parasympathetic, and hemodynamic function in association with VNS in patients with drug-resistant focal epilepsy. METHOD: Longitudinal (n=15) evaluation of beat-to-beat blood pressure (BP) and heart rate variability (HRV), baroreflex sensibility, and hemodynamic function performed before VNS implantation, 6-months after implantation, and a mean of 12-months after implantation; and cross-sectional study (n=14) of BP and HR variability and baroreflex sensitivity during VNS on and VNS off. RESULTS: In the longitudinal study, no differences were observed between the baseline, the 6-month visit, and the final visit in markers of parasympathetic cardiovagal tone or baroreflex sensitivity. Systolic and diastolic BP upon 5-min of head-up tilt increased significantly after VNS implantation (Systolic BP: -16.69±5.65mmHg at baseline, 2.86±16.54mmHg at 6-month, 12.25±12.95mmHg at final visit, p=0.01; diastolic BP: -14.84±24.72mmHg at baseline, 0.86±16.97mmHg at 6-month, and 17±12.76mmHg at final visit, p=0.001). CONCLUSION: VNS does not seem to produce alterations in parasympathetic cardiovagal tone, regardless of the laterality of the stimulus. We observed a slight increase in sympathetic cardiovascular modulations. These changes had no significant hemodynamic implications. These findings contribute to the understanding of potential mechanisms of action of VNS.

Tako-tsubo cardiomyopathy in a patient with bilateral lesions in the dorsal medulla.

Tako-tsubo-like cardiomyopathy (TTC) is much more common than originally thought. The exact pathophysiology of TTC is unclear. The most accepted theory proposes myocardial stunning of neurogenic origin, supported by the frequent antecedent of emotional or physical stress, suggesting a catecholamine-mediated mechanism. We present a patient with this syndrome and bilateral damage of the dorsal medulla oblongata likely affecting both solitary tract nuclei. Our case points to a link between baroreflex failure and TTC, highlighting the important role of sympathetic discharge in the pathophysiology of TTC.

Neuroleptic malignant syndrome and serotonin syndrome in a female patient: a clinicopathologic case.

We report the case of a 24-year-old female patient who initially developed a neuroleptic malignant syndrome after haloperidol exposure and experienced 6 years later a serotonin syndrome after repeated fluoxetine exposure. The patient did not respond to symptomatic treatment and died in this latter episode. At necropsy, no gross or microscopic changes were seen with conventional histological stains, and immunohistochemical stains were negative. This is the first clinicopathologic case of a patient who experienced both neuroleptic malignant and serotonin syndromes. We speculate that this case argue in favor that both syndromes share some fundamental pathogenetic mechanisms.