Complete Restoration of Respiratory Muscle Function in Subjects With Spinal Cord Injury

To the Editor:

We appreciate the interest in our article by this reader of the Journal.

Several years ago, Christopher Reeve, the famous actor who had experienced a cervical spinal cord injury (SCI) and dependent on mechanical ventilation, approached our research team to pursue diaphragm pacing (DP). He had investigated noninvasive ventilation (NVS) as an alternative to tracheostomy mechanical ventilation and pursued this modality at a major medical center, which advocated this treatment option. After several months, he found NVS to be uncomfortable, difficult to tolerate, and to interfere significantly with his activities of daily living. For these reasons, he ultimately abandoned this option and was maintained on tracheostomy mechanical ventilation. Subsequently, he underwent minimally invasive placement of intramuscular diaphragm electrodes for DP. He described DP as life changing in terms of ease of breathing, improved mobility, improved speech, level of comfort, lack of need for any mechanical devices, improved sense of smell, and overall improvement in life quality. Basically, he found DP to be far more advantageous compared with NVS. This person is worth mentioning because he was known to be an intelligent, well informed, and discriminating individual. In our experience, this person is exemplary of many other individuals who have pursued DP as an alternative to mechanical ventilation and are extremely satisfied with their outcomes.^1–3 In contrast, we know of no individuals who have undergone successful DP, who wish to abandon this modality in favor of NVS.

As described in our article, the three patients who entered our study of spinal cord stimulation (SCS) to restore cough were already being ventilated with DP systems for several years.⁴ Each was extremely satisfied with DP and had no interest in pursuing NVS. Moreover, the positive outcome of electrical diaphragm stimulation was one of the reasons that they were interested in SCS to restore cough.

Although it is true that the removal of tracheostomy tubes results in a reduction in secretion production, there are many SCI patients without tracheostomies who still have difficulty managing secretions, experience intermittent episodes of aspiration while eating and drinking (as we all do), and are dependent on mechanical devices, such as suction machines and mechanical insufflator-exsufflator and/or manual assisted cough.^5–9 These methods are cumbersome, require an experienced caregiver, are uncomfortable for many patients, and are also expensive to administer. In addition, despite use of these devices, respiratory tract infections are a major cause of morbidity and mortality in the SCI population.^10–16 In our studies to date, more than 29 patients have been implanted with SCS to restore cough with a mean achieved peak flow rate of approximately 9 l/sec.^4,17–22 With use of SCS, our patients no longer require mechanical methods to manage airway secretions and find that SCS to restore cough much more effective and comfortable. As with DP, this method has also been shown to be cost effective.¹⁷

Finally, we recognize that there are individuals who may prefer NVS compared with DP. Therefore, after review of the advantages and disadvantages of each modality, individuals with SCI should be given a choice between treatment options. Clearly, DP and SCS should remain as valuable treatment options to restore respiratory muscle function for persons in the SCI population.