"Long-term stability of stimulating spiral nerve cuff electrodes on human peripheral nerves".
Breanne P Christie, Max Freeberg, William D Memberg and 4 others
PMID 28693584WHAT IT FOUND
In people with implanted spiral nerve cuff electrodes, most stimulation contacts still produced motor or sensory responses, and stimulation settings changed little over 5 to 11 years.
Key findings
01In the eight active participants, 44 of 45 independent contacts were operational and evoked a motor or sensory response.
02Charge thresholds were stable in most contacts followed over 5 to 11 years, and 20 of 27 contacts changed by less than 5nC per year.
03At 4.2 and 6.3 years, percent overlap among tested femoral cuff contacts ranged from 5.5% to 47.4%.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study followed only 14 participants, and only eight were active in recent testing. The recruitment curves and percent overlap were not measured soon after implantation or repeatedly over multiple years. Only two multi-contact cuffs were tested for motor unit overlap because of time constraints. One cuff pulled off a nerve, one stimulator was explanted, and one contact did not evoke a response. Some charge thresholds increased over time, and one threshold jump may be misleading because the device could only test amplitudes from 2.1 mA to 18 mA. The safety limits for charge density at 100 Hz were not clear. Subject 10 did not regularly use her system, so muscle deconditioning may explain low plantarflexion moments.
Declared interests
The funding statement names the National Institute of Biomedical Imaging and Bioengineering and a U.S. named funder. The supplied text does not name a commercial sponsor of the electrodes or report author conflicts.
The easy way to misread this
Do not read the long-term electrode stability as proof that these neuroprostheses improve function in new patients. The study reports device performance in 14 already implanted participants, not a controlled trial of therapy outcomes.