Ketharnath is the sacred spiritual place where Goddess Ambigai got blessings of Lord siva by observing kethara Gowri Pooja. Near Ketharnath, Mandagini river is flowing. People who want their family members affected by coma should pay and bring the mandagini river water here and should offer pooja for kabaleeswarar for 48 days. One should bring Komuga prasadam after the pooja and should give little drops to the people affected by coma.
Thanks to agasthiar blog.