Pupillary response to percutaneous auricular vagus nerve stimulation in alcohol withdrawal syndrome: A pilot trial.

BACKGROUND: Autonomic symptoms in alcohol withdrawal syndrome (AWS) are associated with a sympathetic-driven imbalance of the autonomic nervous system. To restore autonomic balance in AWS, novel neuromodulatory approaches could be beneficial. We conducted a pilot trial with percutaneous auricular vagus nerve stimulation (pVNS) in AWS and hypothesized that pVNS will enhance the parasympathetic tone represented by a reduction of pupillary dilation in a parasympatholytic pharmacological challenge. METHODS: Thirty patients suffering from alcohol use disorder, undergoing AWS, and stable on medication, were recruited in this open-label, single-arm pilot trial with repeated-measure design. Peripheral VNS (monophasic volt impulses of 1 msec, alternating polarity, frequency 1 Hz, amplitude 4 mV) was administered at the left cymba conchae for 72 h, followed by pupillometry under a tropicamide challenge. We assessed craving with a visual analog scale. We used pupillary mean as the dependent variable in a repeated-measures ANOVA (rmANOVA). RESULTS: A repeated-measures ANOVA resulted in a significant difference for pupillary diameter across time and condition (F(2,116) = 27.97, p < .001, ηp2 > .14). Tukey-adjusted post hoc analysis revealed a significant reduction of pupillary diameter after pVNS. Alcohol craving was significantly reduced after pVNS (p < .05, Cohen's d = 1.27). CONCLUSION: Our study suggests that pVNS activates the parasympathetic nervous system in patients with acute AWS, and that this activation is measurable by pupillometry. To this end, pVNS could be beneficial as a supportive therapy for AWS. Potential confounding effects of anti-craving treatment should be kept in mind.

High-resolution blood flow velocity measurements in the human finger.

MR phase contrast blood flow velocity measurements in the human index finger were performed with triggered, nontriggered, and cine acquisition schemes. A strong (G(max) = 200 mT/m), small bore (inner diameter 12 cm) gradient system inserted in a whole body 3 Tesla MR scanner allowed high-resolution imaging at short echo times, which decreases partial volume effects and flow artifacts. Arterial blood flow velocities ranging from 4.9-19 cm/sec were measured, while venous blood flow was significantly slower at 1.5-7.1 cm/sec. Taking into account the corresponding vessel diameters ranging from 800 microm to 1.8 mm, blood flow rates of 3.0-26 ml/min in arteries and 1.2-4.8 ml/min in veins are obtained. The results were compared to ultrasound measurements, resulting in comparable blood flow velocities in the same subjects. Magn Reson Med 45:716-719, 2001.

In vivo magnetic resonance micro-imaging of the human toe at 3 Tesla.

The feasibility of in vivo high-resolution magnetic resonance micro-imaging of fine anatomic structures of human toes was tested. Five healthy subjects were investigated on an experimental 3 Tesla whole body scanner, using standard 3D gradient echo sequences. A radio-frequency surface coil was used for signal detection. Feet, toes and surface coil were comfortably fixed using a home built device for positioning and reduction of motion artifacts. The spatial resolution of 117 x 313 x 375 microm(3) allowed detailed visualization of anatomic structures like skin layers, vessels and nerves. In addition, oval structures with diameters ranging from 500 to 1000 microm were observed in all subjects, which could represent the sensory nerve endings of Vater-Pacinian bodies. Thus, high resolution MR micro-imaging at 3 Tesla may provide improved morphologic information in distal extremities of humans in vivo.