Many masterpieces owe their immortality to the substances enjoyed by their creators in their creation. Samuel Taylor Coleridge admitted writing Kubla Khan under the influence of opium. Georgette Heyer found gin and dexedrine helped her write throughout the night.
But writing under the influence of back pain? The consequences are spasmodic. Voltaren washed down with red wine makes me sleepy rather than productive. However it's not the first time chronic back pain has reared its ugly head and I'm sure I'll be working away at my book, raise my head in contemplation and think, "I wonder when the pain went away." Pain is like that.