What is pressure alopecia?

Hair loss from pressure?

Pressure alopecia doesn't refer to hair loss caused by stress! Rather if refers to hair loss from prolonged positioning on one's back, usually during prolonged surgeries (cardiovascular surgery, gynaecological surgery, abdominal surgery.)

Nowadays, it's pretty standard in the operating room for someone to be in charge of making sure the patient's head is turned frequently during surgery. If not, the tiny blood vessels get occluded and skin ulceration and hair loss can occur.

Hair loss on post op day 7

Hair loss occurring a 7-14 days after the surgery from the middle back of the scalp usually indicates pressure alopecia. Patients may develop tenderness and crusting a few days before the hair loss. Fortunately for most - the hair loss is temporary and grows back in 1-2 months. However, for a small number of individuals the hair loss is permanent. Hair transplantation provides an option to restore density. 

Reference

Davies and Yesudian. Pressure alopecia. Int J Trichol 2012; 4(2): 64-68