<prompt> In pneumatic dilatation for the treatment of achalasia, the cylindrical balloon dilator is dilated upto:1-2 cm2-3cm3-4 cm5-6 cm  <response>: The only effective therapies for achalasia are pneumatic dilatation and Heller myotomy. Pneumatic dilatation - Efficacy is 32-98, The cylindrical balloon dilator is positioned across the LES and inflated to a diameter of 3-4 cm. The major complication is perforation Also note: The most common surgical procedure for achalasia is laparoscopic Heller myotomy, usually performed with an antireflux procedure paial fundoplication. Ref: Harrison, Edition-18, Page-2432 