No, you don't need to have a nerve block. There are multiple techniques to anesthetize that area prior to injection. As with everything in medicine there are pluses and minuses.

The most low tech would be icing.

• Pros - provides a brief anesthesia (seconds), doesn't distort the anatomy, short acting.
• Con - short acting, it will hurt soon after.

The next method is being experimented with - vibration. This provides brief anesthesia by confusing your pain and vibration receptors in order to decrease the sensation of pain.

• Same Pros and Cons as ice.

Topical anesthetic

• Pros - anesthesia will last longer than with icing, will not affect underlying muscles, doesn't distort anatomy.
• Cons - not always 100% numb, takes 20-30 minutes to set after being applied, may cause allergic/skin reactions

Local anesthetic - in the area

• Pros - provides good anesthesia for a sufficient duration, can be mixed with fillers (off label for some, pre-mixed with others).
• Con - distorts the anatomy.

Nerve block

• Pros - excellent anesthesia usually 100% numb.
• Cons - may distort local anatomy as the muscles may be paralyzed making the fold shallower than it normally is, takes hours to wear off, involves additional injections. Hope that helps