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CLINICAL TRIAL article

Front. Neurol.
Sec. Neurorehabilitation
Volume 16 - 2025 | doi: 10.3389/fneur.2025.1486591
This article is part of the Research Topic New approaches for central nervous system rehabilitation - Volume II View all 4 articles

Stable Improvement in Hand Muscle Strength in Incomplete Spinal Cord Injury Patients by Long-term Paired Associative Stimulation -a Case Series Study

Provisionally accepted
Kirsi Holopainen Kirsi Holopainen 1Anastasia Shulga Anastasia Shulga 1Bersch-Porada Ines Bersch-Porada Ines 2Piia Haakana Piia Haakana 1*Markus Pohjonen Markus Pohjonen 3*Erika Kirveskari Erika Kirveskari 4*Jari Arokoski Jari Arokoski 3*Anastasia Shulga Anastasia Shulga 1*
  • 1 BioMag Laboratory, Helsinki University Hospital, Helsinki, Uusimaa, Finland
  • 2 Swiss Paraplegic Centre, Nottwil, Switzerland
  • 3 Helsinki University Hospital Internal Medicine and Rehabilitation, Helsinki, Finland
  • 4 Department of Clinical Neurophysiology, Helsinki University Hospital, Helsinki, Uusimaa, Finland

The final, formatted version of the article will be published soon.

    Introduction: Paired associative stimulation (PAS) consists of high-intensity transcranial magnetic stimulation and high-frequency electric stimulation of peripheral nerve (high-PAS) and can induce plastic changes in spared corticospinal connections in individuals with spinal cord injury (SCI), leading to restoration of motor function. The objective of this study was to investigate the long-term effect of high-PAS on hand function and muscle strength.Materials and methods: High-PAS was applied to four patients with chronic, incomplete, cervical-level SCI multiple times a week for as long as hand muscle strength improved. Median, ulnar, and radial nerves of one hand chosen by the patient were stimulated. Patients underwent Medical Research Council manual muscle testing (MRC) monthly during the stimulation period and were followed for 12 months after the stimulation.Results: Strength increased both in the stimulated and non-stimulated hand. In muscles innervated by stimulated nerves, strength increased on average by 24.5% from pre to post condition (p=0.013). The achieved strength level was maintained for a minimum of 6 months after completing the stimulations. Patients were also evaluated with motor point (MP) integrity testing to estimate the extent of lower motor neuron damage. High MP integrity testing scores (low extent of damage) correlated positively with good MRC outcomes of the stimulated hand after high-PAS (r=0.52, p≤0.001).Conclusions: High-PAS may improve muscle strength of both the stimulated and contralateral side. Stable results were achieved when stimulation was delivered as long as MRC improved progressively. The optimal duration of high-PAS treatment remains unknown.

    Keywords: Paired associative stimulation, Transcranial Magnetic Stimulation, Electric Stimulation, motor point integrity testing, spinal cord injury

    Received: 26 Aug 2024; Accepted: 09 Jan 2025.

    Copyright: © 2025 Holopainen, Shulga, Ines, Haakana, Pohjonen, Kirveskari, Arokoski and Shulga. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Piia Haakana, BioMag Laboratory, Helsinki University Hospital, Helsinki, 00290, Uusimaa, Finland
    Markus Pohjonen, Helsinki University Hospital Internal Medicine and Rehabilitation, Helsinki, Finland
    Erika Kirveskari, Department of Clinical Neurophysiology, Helsinki University Hospital, Helsinki, Uusimaa, Finland
    Jari Arokoski, Helsinki University Hospital Internal Medicine and Rehabilitation, Helsinki, Finland
    Anastasia Shulga, BioMag Laboratory, Helsinki University Hospital, Helsinki, 00290, Uusimaa, Finland

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