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Compound Motor Action Potential Measures Acute Changes in Laryngeal Innervation
Neel K Bhatt1, Wee Tin K Kao1, Randal C Paniello1
11 Department of Otolaryngology-Head and Neck Surgery, Washington University in Saint Louis, Saint Louis, Missouri, USA.
Compound motor action potentials (CMAP) can quantitatively measure laryngeal innervation after recurrent laryngeal nerve (RLN) injury. This method may help assess nerve recovery and patient prognosis in vocal fold paralysis cases.
Area of Science:
- Neurology
- Otolaryngology
- Biomedical Engineering
Background:
- Vocal fold paralysis often results from recurrent laryngeal nerve (RLN) damage.
- Existing clinical assessments of laryngeal innervation lack quantitative precision.
- Compound motor action potentials (CMAP) offer a potential method for measuring motor nerve function.
Purpose of the Study:
- To evaluate the utility of CMAP in quantifying laryngeal innervation following acute RLN injury.
- To establish a correlation between CMAP amplitude and the degree of nerve damage.
Main Methods:
- Canine hemilaryngeal preparations underwent serial RLN stimulation to determine maximal response.
- CMAP amplitude was measured and correlated with stimulation intensity.
- The RLN was partially transected, and the reduction in CMAP amplitude was correlated with the percentage of transected axons, verified by horseradish peroxidase staining.
Main Results:
- Submaximal RLN stimulation showed a linear correlation with CMAP amplitude (r = 0.83).
- Following partial RLN transection, remaining axon percentage linearly correlated with CMAP amplitude (r = 0.87).
Conclusions:
- CMAP amplitude serves as a quantitative indicator of laryngeal innervation in canines.
- Post-RLN injury, CMAP can potentially quantify intact axons, predict recovery, and inform patient counseling.
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