2 The procedure

2.1 Indications

2.1.1 Vagus nerve stimulation is indicated for use as an adjunctive therapy in reducing the frequency of seizures in patients who are refractory to anti-epileptic medication. This includes patients whose epileptic disorder is dominated by partial seizures (with or without secondary generalisation) or generalised seizures.

2.2 Outline of the procedure

2.2.1 A battery-powered pulse-generating device is implanted under the skin of the upper left chest. A wire is tunnelled under the skin and connected to the left vagus nerve in the neck. The stimulation parameters (pulse width and frequency, current intensity, and on/off cycles) are programmed into the pulse generator via a programming wand. Patients or carers can give additional stimulation or temporarily inhibit stimulation. The battery lasts 8–10 years and can be replaced under local anaesthesia. A typical treatment regimen might comprise intermittent stimulation for 30 seconds every 5 minutes throughout the day and night.

2.3 Efficacy

2.3.1 In one study of 50 children aged 12 years and younger, 23 (46%) experienced a greater than 50% reduction in seizure frequency. In a study of 28 children aged 12 years and younger, a mean reduction of 62% in seizure frequency was reported at 1 year. There was some evidence to suggest that quality of life improved following the procedure. Comparisons are difficult to make between the studies because of variations in the patient populations, the methods of outcome assessment and the reporting of outcomes. For more details, refer to the Sources of evidence section.

2.3.2 The Specialist Advisors also noted that the procedure seemed to have some benefits in terms of mood and quality of life.

2.4 Safety

2.4.1 The most commonly reported complications were hoarseness, sore throat and cough. In a case series of 125 children, 73 children (58%) experienced voice alteration and 48 children (38%) experienced coughing during stimulation. More serious adverse events included infection (requiring device removal) in 3% (3/100) to 6% (1/16) of patients, and breathing irregularities in 19% (3/16) of patients. For more details, refer to the Sources of evidence section.

2.4.2 The Specialist Advisors believed that this is a safe procedure with no major complications.