Abstract MP23: Arterial Depressor Responses Induced By Neuromodulation Of Deep Peroneal Nerve In Spontaneously Hypertensive Rats

Hypertension affects nearly half of the US population but only 43% achieved blood pressure control with medication alone. Medical devices for hypertension include implantable lead electrodes that stimulate the carotid baroreceptors with promising results, albeit with significant adverse complications. To address these limitations, we have proposed the use of deep peroneal nerve stimulation (DPNS), which elicited a depressor response in anesthetized, breathing supported, spontaneously hypertensive rats (SHR). In this study, we further define the electrical stimulation parameters that optimize the DPNS depressor response, and demonstrated that increasing the pulse duration from 0.15 ms to 1ms, of 1.0 mA pulses at 2 Hz for 10 sec, significantly reduced the mean arterial pressure (MAP) by 8±4 mmHg (p<0.005; n=4) in this animal model. DPNS also caused an immediate increase in renal nerve activity (RNA; p< 0.004, n=5), which may represent afferent sensory axons from the kidney, although this possibility needs to be further investigated. In a separate cohort of anesthetized SHR animals, breathing spontaneously, we demonstrated that optimal DPNS stimulation reduced the MAP from 121±3 to 108±4; p=0.02; n=10). To confirm if DPNS is able to evoke a depressor response in fully awake SHR animals, we developed a novel miniaturized wireless microchannel electrode (w-μCE) with a L-shaped microchannel, through which the DPN slides and locks into a recording/stimulation chamber, causing no discomfort to the animal during locomotion. Two weeks after implantation of the w-μCE neural stimulation device, animals were movement-retrained to received wireless DPNS for 10 min daily for 2 weeks. Blood pressure was measured by tail-cuff at baseline, 10 days after device implantation, and 1 and 2-hr 15 days after DPNS. After two weeks of DPNS, the acute neuromodulation treatment reduced the initial systolic BP of 154±20 mmHg to 127±7 and 119±2 mmHg at 1 and 2 hr; respectively (p< 0.001, n=15-19 measurements; n=2 animals). These results provide evidence of the effectiveness and reliability of DPN neuromodulation as a possible treatment for drug-resistant hypertension.

Painful legs and moving toes

A 40-year-old woman reported involuntary and irregular movements of her left toes accompanied by pain. This arose following arthroscopy after a sprained left ankle. She had involuntary flexion–extension and abduction and adduction movements of the hallux and the other toes, with reduced pinprick sensation on the skin web between the left hallux and the second toe. Nerve conduction studies confirmed a deep peroneal nerve axonal injury. We diagnosed the syndrome of painful legs and moving toes, provoked by a peripheral nerve injury. Her symptoms have persisted despite pregabalin, gabapentin and amitriptyline.

Foot Reanimation Using Double Nerve Transfer to Deep Peroneal Nerve: A Novel Technique for Treatment of Neurologic Foot Drop

Background: Our primary objective was to assess the efficacy of a new technique for foot reanimation in patients with neurologic foot drop using double nerve transfer from the tibial to the deep peroneal nerve. Our secondary objective was to document the technical nuances of our technique. Methods: Thirty-one patients with common peroneal nerve injury between October 2015 and March 2019 were prospectively enrolled in the study. Patients underwent a transfer of the tibial nerve branches to flexor digitorum longus and lateral head of gastrocnemius to the deep peroneal nerve. Motor recovery, range of ankle dorsiflexion, pain, leg girth, and complications were examined as outcome measures. The modified Medical Research Council (MRC) scale was adopted to assess the motor power recovery. All patients were followed up for a minimum of 1 year. Results: Motor recovery of M3 or M4 grade of tibialis anterior, extensor hallucis longus, and extensor digitorum longus was achieved in 15 of 31, 13 of 31, and 12 of 31 patients, respectively. Those patients could discontinue use of orthosis. Most patients with high-energy traumas or knee-level injuries failed to recover antigravity function. Only 2 patients reported weak postoperative toe plantarflexion. Our patients achieved significant improvement of the pain perception and range of active ankle motion at the final follow-up. Conclusion: The double nerve transfer technique represented a feasible and safe surgical option. It has been shown to improve function in some patients with neurologic foot drop resulting from a less than 12-month injury of the deep peroneal nerve. Level of Evidence: Level IV, therapeutic.