What are your preferred second-line medications for trigeminal neuralgia?

My FIRST-LINE medication for trigeminal neuralgia is botulinum toxin. I write about its application in face pain, including trigeminal neuralgia, in Chapter 16 of my book, HEADACHES: Why You Have Them - What You Can Do About Them.

My first line is oxcarbazepine or carbamazepine. The second line is gabapentin. Then, in no particular order, baclofen and lamotrigine. Other options to try: pimozide, tizanidine, phenytoin, valproic acid. If 1 agent does not provide good control, I refer to a surgeon as we try a 2nd agent.

Unclear to me why Botox would work