Repetitive transcranial magnetic stimulation improves open field locomotor recovery after low but not high thoracic spinal cord compression‐injury in adult rats

Abstract

Electromagnetic fields are able to promote axonal regeneration in vitro and in vivo. Repetitive transcranial magnetic stimulation (rTMS) is used routinely in neuropsychiatric conditions and as an atraumatic method to activate descending motor pathways. After spinal cord injury, these pathways are disconnected from the spinal locomotor generator, resulting in most of the functional deficit. We have applied daily 10 Hz rTMS for 8 weeks immediately after an incomplete high (T4-5; n = 5) or low (T10-11; n = 6) thoracic closed spinal cord compression-injury in adult rats, using 6 high- and 6 low-lesioned non-stimulated animals as controls. Functional recovery of hindlimbs was assessed using the BBB locomotor rating scale. In the control group, the BBB score was significantly better from the 7th week post-injury in animals lesioned at T4-5 compared to those lesioned at T10-11. rTMS significantly improved locomotor recovery in T10-11-injured rats, but not in rats with a high thoracic injury. In rTMS-treated rats, there was significant positive correlation between final BBB score and grey matter density of serotonergic fibres in the spinal segment just caudal to the lesion. We propose that low thoracic lesions produce a greater functional deficit because they interfere with the locomotor centre and that rTMS is beneficial in such lesions because it activates this central pattern generator, presumably via descending serotonin pathways. The benefits of rTMS shown here suggest strongly that this non-invasive intervention strategy merits consideration for clinical trials in human paraplegics with low spinal cord lesions.

Iron oxide nanoparticles and magnetic field exposure promote functional recovery by attenuating free radical-induced damage in rats with spinal cord transection

“…An MF can noninvasively create electric fields in deep underlying structures, thereby modulating oxidative stress, apoptosis, release of neurotransmitters, secretion of neurotrophic factors, and axonal growth. [26][27][28][29][30][31] In rat models of spinal cord injury (SCI), exposure to a low intensity MF results in significant improvement in locomotor, sensorimotor, and autonomic function. [32][33][34][35][36] Stimulation of the motor cortex by repetitive transcranial magnetic stimulation is beneficial, especially in lower thoracic SCI lesions, because it activates the central pattern generator via descending serotonin pathways.…”

“…[32][33][34][35][36] Stimulation of the motor cortex by repetitive transcranial magnetic stimulation is beneficial, especially in lower thoracic SCI lesions, because it activates the central pattern generator via descending serotonin pathways. 28 In vitro, exposure to an MF increases the overall viability of mouse monoclonal hippocampal HT22 cells and has a neuroprotective effect against oxidative stressors.…”

“…These results are comparable with previous reports of repeated low-intensity MF stimulation in SCI rats and may be mediated by the effects of the MF on free radical-induced secondary injury or by activation of the central pattern generator center for locomotion by serotonin pathways. [28][29][30][31][32][33][34][35][36] 5-Hydroxytryptamine has an important role in modulating the excitability of motor and sensory neurons in the spinal cord, thereby influencing locomotion and sensorimotor behavior. [51][52][53][54][55] Exposure to an MF has been shown to restore the metabolism, synthesis, and distribution of 5-hydroxytryptamine in the spinal cord and brain.…”

Combined Effects of Acrobatic Exercise and Magnetic Stimulation on the Functional Recovery after Spinal Cord Lesions

“…There are several recently published reviews and books describing application of rTMS in several disorders of the central nervous system (CNS) (Pascual-Leone, et al, 2002;Walsh and Pascual-Leone, 2003), although reports describing the application of this type of stimulation directly to the site of the spinal cord/nerve injury are rare (Wilson and Jagadeesh, 1976;Orgel et al, 1984). Cranial application of rTMS was reported to significantly improve locomotor recovery after spinal cord lesions in rats (Poirrier et al, 2004) and humans (Belci et al, 2004). The mechanism by which rehabilitation and physical therapy improves function, after SCI, is still not well understood (Thuret et al, 2006), and there are no reports about the influence of skilled motor training, combined with MS, on functional recovery after SCI.…”

Therapeutic effects of acrobatic exercise and magnetic field exposure on functional recovery after spinal cord injury in mice

“…The procedure has been proven to be beneficial in brain [Vorel and Lisanby, 2008;Loo, 2008], and spinal cord pathologies [Wilson and Jagadeesh, 1976;Belci et al, 2004;Poirrier et al, 2004;Ahmed and Wieraszko, 2008]. It has been suggested that this improvement might occur due to rTMS-induced enhancement of cortical neuronal plasticity [Rossi and Rossini, 2004].…”