Potential Side Effects of Electrical Stimulation Therapy for Vocal Cord Paresis
Electrical stimulation therapy for vocal cord paresis may cause headache, discomfort at the stimulation site, muscle aches, and in rare cases can trigger swallowing reflexes or coughing. While generally considered safe, understanding these potential side effects is crucial for proper patient management and informed consent.
Common Side Effects
- Discomfort at stimulation site: Most patients experience some level of discomfort during the procedure, particularly as stimulation amplitude increases 1
- Muscle aches: Stimulation of laryngeal muscles can cause soreness similar to that experienced after exercise 2
- Headache: Can occur following electrical stimulation sessions, typically resolving within the same day 2, 3
- Transient confusion: May occur immediately after treatment but typically resolves quickly 2
Procedure-Specific Side Effects
Non-selective muscle activation
- Stimulation parameters must be carefully controlled to avoid triggering:
- Unwanted strap muscle or platysma responses
- Swallowing reflexes
- Coughing 1
Optimal parameters to minimize side effects
- Pulse widths between 50-100 milliseconds with amplitudes of approximately 7.1-7.2 mA appear to provide the best balance between effectiveness and minimizing side effects 1
- Higher amplitudes increase risk of non-selective muscle activation
Rare but Serious Side Effects
- Seizure risk: While rare, electrical stimulation carries a theoretical risk of seizure induction, particularly in patients with pre-existing neurological conditions 2
- Auditory complications: Prolonged stimulation or improper parameters could potentially affect auditory thresholds 2, 3
Contraindications
Electrical stimulation is contraindicated in patients with:
- Cardiac pacemakers or other implanted electrical devices
- Implanted metal in the neck/head region
- Epilepsy (relative contraindication)
- Known intracranial pathology 2
Monitoring Recommendations
During electrical stimulation therapy for vocal cord paresis:
- Vital signs should be monitored during and immediately after the procedure
- Patients should be observed for adverse events including:
- Excessive discomfort
- Unexpected muscle contractions
- Signs of airway compromise 2
- Flexible laryngoscopy should be used to monitor laryngeal responses during stimulation to ensure proper muscle activation 1
Risk Minimization Strategies
- Start with lower stimulation parameters and gradually increase as tolerated
- Use appropriate electrode placement techniques
- Ensure proper training of personnel administering the therapy
- Select appropriate patients without contraindications
- Use charge-balanced pulse widths to minimize tissue damage 1
Despite these potential side effects, electrical stimulation therapy has shown superior outcomes compared to traditional voice exercise therapy alone in patients with unilateral recurrent laryngeal nerve paresis 4, with evidence suggesting it can effectively reverse muscle fiber atrophy produced by denervation 5.