Lead breakage and vocal cord paralysis following blunt neck trauma in a patient with vagal nerve stimulator

Vagus nerve stimulation: Surgical technique of implantation and revision and related morbidity

“…The complications of VNS therapy are classified as early (related to surgery) and late (related to the device and to the stimulation of the nerve) . Early complications include the following: intraoperative bradycardia and asystole during lead impedance testing (1/1,000 cases), peritracheal hematoma, infections (3–8%), and vagus nerve injury followed by hoarseness, dyspnea, and dysphagia because of left vocal cord paralysis though the paralysis of left vocal cord is usually transient and patients normally recover after a few months . Delayed morbidity due to the device includes mostly late infections or wound dystrophy.…”

“…Delayed morbidity due to the device includes mostly late infections or wound dystrophy. Other rare and anecdotal complications are late injury of the nerve with permanent left vocal cord paralysis because of blunt trauma to the neck, tampering of the device in obese and mentally retarded patients (“twiddler's' syndrome”), or stretching of the nerve because of implantation of the lead electrode without enough strain loop relief . Late complications associated with nerve stimulation are delayed arrhythmias (bradycardia, asystole), laryngopharyngeal dysfunction, obstructive sleep apnea, stimulation of the phrenic nerve due to proximity, tonsillar pain mimicking glossopharyngeal neuralgia, and vocal cord damage during prolonged endotracheal intubation .…”

“…Other rare and anecdotal complications are late injury of the nerve with permanent left vocal cord paralysis because of blunt trauma to the neck, tampering of the device in obese and mentally retarded patients (“twiddler's' syndrome”), or stretching of the nerve because of implantation of the lead electrode without enough strain loop relief . Late complications associated with nerve stimulation are delayed arrhythmias (bradycardia, asystole), laryngopharyngeal dysfunction, obstructive sleep apnea, stimulation of the phrenic nerve due to proximity, tonsillar pain mimicking glossopharyngeal neuralgia, and vocal cord damage during prolonged endotracheal intubation . Laryngopharyngeal dysfunction (hoarseness, dyspnea, and coughing) occurs in about 66% of patients and is usually transitory and due to the stimulation of the inferior (recurrent) laryngeal nerve and directly related to its frequency of stimulation: 20–30 Hz stimulation may cause vocal cord abduction and 40 Hz adduction, whereas >40 Hz may cause a tetanic adduction with larynx hemispasm .…”

“…Late complications associated with nerve stimulation are delayed arrhythmias (bradycardia, asystole), laryngopharyngeal dysfunction, obstructive sleep apnea, stimulation of the phrenic nerve due to proximity, tonsillar pain mimicking glossopharyngeal neuralgia, and vocal cord damage during prolonged endotracheal intubation . Laryngopharyngeal dysfunction (hoarseness, dyspnea, and coughing) occurs in about 66% of patients and is usually transitory and due to the stimulation of the inferior (recurrent) laryngeal nerve and directly related to its frequency of stimulation: 20–30 Hz stimulation may cause vocal cord abduction and 40 Hz adduction, whereas >40 Hz may cause a tetanic adduction with larynx hemispasm . A true late paralysis of the left vocal cord is often partial and rare (1–2.7%), and usually transitory, and may be due to the previous surgical trauma (i.e., damage of nerve fibers and/or of their blood supply) or to a supposed chronic denervation during stimulation of the vagus nerve .…”

Late-onset jaw and teeth pain mimicking trigeminal neuralgia associated with chronic vagal nerve stimulation: case series and review of the literature

“…The problems typically started after an accident (trauma, puncture, traction, excessive manipulations, tight electrode). In most cases of device malfunctions, the lead impedance is too high or too low [38–41]. …”