I have never seen this side effect. Physiologically, Dysport attaches to the SNAP receptors of nerve endings, and there is no relationship between the nerve endings and hair growth or loss. We see decreased sweating in the forehead with Botox, but there is no reason why it should effect your hair.There are many, many reasons why one could have hair loss at the frontal area, and a dermatologist will help you with this.
I have no good explanation as to why this might be true, but a few patients have asked me about it.