Many women who are considering a breast augmentation, reduction or lift are often concerned about how the surgery will affect their nipple sensitivity. For some people, breast surgery leads to lost or reduced sensation in the nipples. However, for others it causes the nipple and areola area to become more sensitive, sometimes to the point of pain. Usually these changes are temporary, lasting from a matter of weeks to a few years, but sometimes they can be permanent. It all depends on what happened to the nerves during surgery. Plastic surgeons take great care to protect the nerves found in the breast during any cosmetic procedure. Unfortunately, sometimes nerve pathways are impaired or damaged. The surgeon’s choice of technique often plays a key role in the patient’s postoperative nipple sensitivity.
The U.S. Food and Drug Administration (FDA) has reported that a minority of women who received saline-filled breast implants approved in May 2000 experienced nipple sensation changes after having a breast augmentation. Three years following surgery 5 to 9% of women had intense nipple sensation while 8 to 10% lost nipple sensation. Five years following surgery 10% of women had intense or lost sensation. 
During a breast augmentation, the surgeon may take three common approaches to insert the implant intramamary (in the breast crease), sub areaolar (around the nipple), transaxillary (armpit) often will cut around the edge of the nipple in order to insert the implant. Because this incision is made very close to where the fourth intercostal nerve branch enters the nipple, it is more likely to cause nipple sensation changes than other techniques. However, changes in nipple sensation are possible with any type of incision, but higher with the sub areaolar incision. Nipple sensitivity also seems to be affected more if the implant is placed under the glandular tissue rather than under the muscle tissue.
For many years it was thought that loss of sensitivity depended on how much weight was removed from the breasts. However, more recently, researchers have linked postoperative nipple sensitivity with the surgical technique used. A 2005 study compared five different breast reduction techniques and revealed that removing tissue from the base of the breast leads to significantly lower postoperative nipple and areola sensitivity. In fact, the only people who ended up with completely insensitive nipples were those who underwent this type of surgery, and it occurred 48% of the time. 
Researchers have found that sagging breasts have less nipple-areola sensitivity.  This means that sensation changes caused by a breast lift may actually improve nipple sensitivity. However, as with any breast surgery, there is also a risk of permanent sensation loss.
Generally, minor lifts carry less of a risk than dramatic ones, as dramatic lifts can involve completely reshaping and/or resizing the breast, as well as nipple repositioning. These invasive techniques have a greater chance of causing nerve damage that leads to changes in nipple sensitivity.
The most important step in the decision to have any breast surgery is to choose an experienced plastic surgeon. Look for one like Dr. Rajagopal in San Francisco that has had several years of doing the procedure weekly, plus few to no patients with changes in nipple sensitivity.
FDA Breast Implant Consumer Handbook 2004: Local Complications and Reoperations. http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/ImplantsandProsthetics/BreastImplants/ucm064106.htm. Updated May 20, 2009.
Schlenz I, Rigel S, Schemper M, Kuzbari R. Alteration of Nipple and Areola Sensitivity by Reduction Mammaplasty: A Prospective Comparison of Five Techniques. Plast Reconstr Surg. 2005;115(3):743-751.
Schlenz I, Kuzbari R, Gruber H, Holle J. The Sensitivity of the Nipple-Areola Complex: An Anatomic Study. Plast Reconstr Surg. 2000;105(3):905-909.