Complex sentence: One was an operation in which a nerve (recurrent nerve) that controls the vocal-cord movement is sectioned (severed), which neutralizes the spasming vocal cord; another option involved injecting a paralyzing toxin--botox--into the same nerve.
Split into simpler sentences: One was an operation in which a nerve (recurrent nerve) that controls the vocal-cord movement is sectioned (severed), which neutralizes the spasming vocal cord. Another option involved injecting a paralyzing toxin--botox--into the same nerve.