Vagus nerve stimulation paired with tactile training improved sensory function in a chronic stroke patient

BACKGROUND: Recent studies indicate that vagus nerve stimulation (VNS) paired with rehabilitation can enhance neural plasticity in the primary sensory and motor cortices, improve forelimb function after stroke in animal models and improve motor function in patients with arm weakness after stroke. OBJECTIVE: To gain "first-in-man" experience of VNS paired with tactile training in a patient with severe sensory impairment after stroke. METHODS: During the long-term follow-up phase of a clinical trial of VNS paired with motor rehabilitation, a 71-year-old man who had made good motor recovery had ongoing severe sensory loss in his left hand and arm. He received VNS paired with tactile therapy in an attempt to improve his sensory function. During twenty 2-hour sessions, each passive and active tactile event was paired with a 0.5 second burst of 0.8mA VNS. Sensory function was measured before, halfway through, and after this therapy. RESULTS: The patient did not report any side effects during or following VNS+Tactile therapy. Quantitative measures revealed lasting and clinically meaningful improvements in tactile threshold, proprioception, and stereognosis. After VNS+Tactile therapy, the patient was able to detect tactile stimulation to his affected hand that was eight times less intense, identify the joint position of his fingers in the affected hand three times more often, and identify everyday objects using his affected hand seven times more often, compared to baseline. CONCLUSIONS: Sensory function significantly improved in this man following VNS paired with tactile stimulation. This approach merits further study in controlled clinical trials.