Activation of inspiratory muscles via spinal cord stimulation

Abstract

Diaphragm pacing is a clinically useful modality providing artificial ventilatory support in patients with ventilator dependent spinal cord injury. Since this technique is successful in providing full-time ventilatory support in only ~50% of patients, better methods are needed. In this paper, we review a novel method of inspiratory muscle activation involving the application of electrical stimulation applied to the ventral surface of the upper thoracic spinal cord at high stimulus frequencies (300 Hz). In an animal model, high frequency spinal cord stimulation (HF-SCS) results in synchronous activation of both the diaphragm and inspiratory intercostal muscles. Since this method results in an asynchronous pattern of EMG activity and mean peak firing frequencies similar to those observed during spontaneous breathing, HF-SCS is a more physiologic form of inspiratory muscle activation. Further, ventilation can be maintained on a long-term basis with repetitive stimulation at low stimulus amplitudes (<1 mA). These preliminary results suggest that HF-SCS holds promise as a more successful method of inspiratory muscle pacing.

High frequency spinal cord stimulation—New method to restore cough

“…If similar to HF-SCS of the upper thoracic spinal cord, which causes in activation of the inspiratory muscles, this method described herein causes activation of expiratory motoneurons rather than motor roots (DiMarco and Kowalski, 2009, 2013). Whether expiratory motoneurons are activated directly or via a spinal network is uncertain.…”

“…In prior studies utilizing HF-SCS applied to the upper thoracic SCS to activate the inspiratory muscles, we demonstrated that electrical stimulation with stimulus frequencies in the range of ~300 Hz with low currents (~1–2 mA) results in very large inspired volumes approximating the inspiratory capacity (DiMarco and Kowalski, 2009, 2013). Our results suggested that upper thoracic HF-SCS results in activation of the phrenic and intercostal motoneuron pools allowing processing of the signal, and the activation of the inspiratory muscles at physiological firing frequencies.…”

Temperature increases by kilohertz frequency spinal cord stimulation

“…The emergence of kilohertz frequency (1–10 KHz ) spinal cord stimulation (kHz-SCS) 1–7 for the treatment of neuropathic pain has engendered studies on new mechanisms of actions (MoA) 5,8–11 . Divergent clinical observations for conventional rate SCS and kHZ-SCS suggest difference in MoA which could in turn inform distinct programming optimization strategies.…”

Spinal cord injury (SCI) rehabilitation: systematic analysis of communication from the biopsychosocial perspective

“…Various management regimes and interventions for respiratory impairment have been documented in the literature, including direct and indirect targeting of respiratory muscle strength and endurance, and interventions through environmental adaptations (mechanical ventilation, pacing of the phrenic nerve or diaphragm ± intercostal muscles, abdominal binders, pharmaceuticals, e.g. theophylline and baclofen) [20,[25][26][27][28][29][30][31][32][33][34][35][36]. In general, the outlook appears positive for some degree of functional respiratory improvement, with flow-on effects to verbal communication and related areas of activity and participation, given continued collaboration between multiple disciplines (e.g.…”