INFANTILE SPASMS - RECOVERY. It common?

Dear Doctor's, My 1.5yr old son had involuntary movements just 3weeks ago and after EEG & MRI, pediatric neurologist confirmed that it is infantile spasms and initially started giving Valparin 2.5ml. after one week, pediatric neurologist suggested to give ACTH injection and B-Long prolongatam tablet for a week and he started showing really active. Then Doctor changed from ACTH injection to SABRIL 500mg tablet  (1/4th twice for 3days and 1/2 twice to continue) + Omnacortil syrup 5ml Twice a day along with 3.5ml Valparin after food. Now he is really recovered and not showing involuntary movements since 2days... As per the prescription, we need to increase the dosage of SABRIL 500mg tablet from 1/4th of the tablet twice to 1/2 of the tablet twice a day. (As per prescription we need to increase the dosage from 1/4th to 1/2 after 3days and 3days over) My questions is, As per our observation, my son is not showing involuntary movements, but he is getting saliva in his mouth. is it common??