Effects of chronic electrical stimulation on paralyzed expiratory muscles

J Appl Physiol, 2008 · DOI: 10.1152/japplphysiol.01321.2007 · Published: June 1, 2008

Spinal Cord Injury Pulmonology Neurology

Simple Explanation

Following spinal cord injury, expiratory muscles weaken due to disuse. This study investigates whether electrical stimulation can prevent this atrophy. Cats with spinal cord injuries received electrical stimulation to their lower thoracic spinal cord for 15 minutes, twice daily, five days a week, for six months. The study found that electrical stimulation helped maintain the strength and size of the expiratory muscles, which are important for coughing.

Study Duration

6 Months

Participants

10 cats (5 chronic, 5 acute spinalized controls)

Evidence Level

Level II: Animal Study

Key Findings

1
Chronic electrical stimulation prevented significant reductions in expiratory muscle weight and fiber cross-sectional area.
2
Electrical stimulation maintained the global pressure-generating capacity of expiratory muscles near control values over the vital capacity range.
3
Fiber-type characteristics of expiratory muscles were also maintained with electrical stimulation, based on phenotypic expression techniques.

Research Summary

This study assessed the effects of chronic expiratory muscle stimulation, via lower thoracic spinal cord stimulation, in a chronic cat model of spinal cord injury. The results indicate that intermittent high-frequency electrical stimulation via lower thoracic spinal cord stimulation is sufficient to maintain the global pressure-generating capacity of this muscle group near control values. Electrical stimulation served to prevent the development of muscle atrophy as evidenced by the lack of any significant decrement in expiratory muscle weight or fiber CSA.

Practical Implications

Preservation of Cough Function

Electrical stimulation could help maintain an effective cough mechanism in patients with spinal cord injury, reducing respiratory complications.

Dual Purpose Application

Daily electrical stimulation could serve the dual purpose of maintaining expiratory muscle function and aiding airway clearance.

Clinical Use Consistency

The stimulation paradigm used is consistent with the expected pattern of clinical use for secretion removal.

Study Limitations

1
Lower thoracic spinal cord stimulation may not fully activate the lower portions of the abdominal muscles.
2
The evaluation of electrical stimulation was limited to a single-stimulus paradigm.
3
The study lacks a control group in which animals were spinalized but not stimulated.

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