The impact of the COVID-19 pandemic on patients awaiting spinal cord stimulation surgery in the United Kingdom: a multi-centre patient survey by Baranidharan, G, Bretherton, B, Eldabe, S, Mehta, V, Thomson, S, Sharma, ML, Vajramani, G, Bojanic, S, Gulve, A, FitzGerald, J, Hall, S, Firth, J