Increasing Hand Opening in Chronic Hemiparetic Stroke Using Nerve Blocks

Research Objectives: We investigated the best-case efficacy of emerging nerve block technologies in improving hand opening in individuals with stroke. Upper limb disability in chronic stroke stems from significant flexor bias and weakness of extensors, with hand opening particularly compromised in moderate to severely impaired individuals with stroke. A complete motor block of the ulnar and median nerves may improve volitional hand opening and/or hand opening with assistive Functional Electrical Stimulation (FES).

Design: A single participant case study, quantifying hand opening before and after administration of the local anesthetic ropivacaine to the median and ulnar nerve.

Setting: Academic research laboratory.

Participants: A 63-year-old male with a unilateral hemorrhagic stroke (> 2 years).

Interventions: The participant’s forearm was attached to a robotic device capable of providing support or applying a load, and their fingers were instrumented with motion-tracking sensors. An FES unit was attached to forearm extensors. We asked the participant to perform multiple hand opening tasks, with the forearm fully supported or under a load (30% of maximum shoulder abduction), and then either volitionally or by FES. These tasks were then undergone again 1.5 hours after the complete nerve block just above the elbow.

Main Outcome Measures: The primary outcome metric is Hand Pentagonal Area (HPA), which is the surface area (mm²) measured by 3 triangles: thumb, index, middle; thumb, middle, ring; and thumb, ring, and pinky.

Results: Mean volitional hand opening in the supported condition increased significantly (two-sample t-test p≪0.001) from 1311.7mm² to 2944.2mm², and significantly (p≪0.001) in the loaded condition from 1383.3mm² to 2387.7mm². Mean FES hand opening in the supported condition increased (no significance) from 1976.1mm2 to 2177.8mm2 and in the loaded condition significantly (p=0.0047) from 1832.7mm² to 2865.8mm².

Conclusions: These preliminary results indicate that a complete motor block of the median and ulnar nerve can improve both the volitional and assistive FES hand opening area in an individual with chronic stroke. Emerging instant and reversible nerve block technologies may thus provide potential benefit to this population.

Author(s) Disclosures: No conflicts of interest to disclose.