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F. Dierick1,2, J.-M. Brismée3, O. White4, A.-F. Bouché5, C. Périchon2, N. Filoni2, V. Barvaux2, F. Buisseret2
1Rehazenter, Laboratoire d'Analyse de la Marche et de la Posture, Luxembourg, Luxembourg, 2CeREF, Mons, Belgium, 3Texas Tech University Health Sciences Center, Lubbock, United States, 4Univérsité de Bourgogne, Dijon, France, 5Le Richemont, Bioul, Belgium
Background: Fine dexterity critically depends on information conveyed by the median nerve. While the effects of its compression and vibration are well characterized, little is known about longitudinal tension and excursion. However, these mobilizations are frequently applied during physiotherapy interventions.
Purpose: The purpose of this study was to understand the physiological repercussions of median nerve mobilization on precision grip in healthy participants.
Methods: Using a force-sensitive manipulandum and Semmes-Weinstein monofilaments, we examined the adaptations of precision grip control and fingertips pressure sensation threshold before and immediately after the application of longitudinal tension and excursion mobilizations applied on the median nerve. Grip and load forces (normal and tangential forces, respectively) applied by the thumb, index and major fingers were collected in 40 healthy young participants during three different grip precision tasks along the direction of gravity. For grip-lift-drop task, maximum grip and load forces and their first-time derivatives were computed. For up-down oscillations, means of grip and load forces and their variability were computed. For oscillations with up and down collisions, peaks of grip and load forces, time delay between grip force peak and contact, and values of grip and load forces at contact were collected.
Results: Our findings show that median nerve mobilizations induce significant fine adaptations of precision grip control in the three different tasks but mainly during grip-lift-drop and oscillations with collisions. In the grip-lift-drop task, significant increases of maximal load force and its derivative were observed after the mobilizations. A significant increase of load force standard-deviation was observed after the mobilizations during the oscillations without collisions. A significant decrease of maximal load force and grip force at contact as well as an increase of load force at contact were observed after the mobilizations during oscillations with collisions in upward direction. A significant decrease of maximal grip and load and forces was observed after the mobilizations during oscillations with collisions in downward direction. Fingertips pressure sensation thresholds at index and thumb were significantly reduced after the mobilizations.
Conclusion(s): We conclude that precision grip adaptations observed after median mobilizations could be partly explained by changes in cutaneous median-nerve mechanoreceptive afferents from the thumb and index fingertips. Future works are needed to explore pathological conditions involving the median nerve.
Implications: We provide a better understanding of the physiological effects of median nerve mobilizations practiced in physiotherapy on precision grip control. Our results in healthy participants will serve as a basis for studying neurodynamics and its effects in patients with median nerve injuries.
Funding, acknowledgements: With the financial support of the European Regional Development Fund (Interreg FWVl NOMADe).
Keywords: Prehensile activity, Motor control, Neurodynamics
Topic: Musculoskeletal
Did this work require ethics approval? Yes
Institution: Brussels Alliance for Research and Higher Education
Committee: Academical Ethical Committee
Ethics number: B200-2015-062
All authors, affiliations and abstracts have been published as submitted.
