A woman who stabbed her son--a quadriplegic with cerebral palsy--was ordered to serve five years’ probation because she suffers from psychiatric problems. Santa Clara County Superior Court Judge Read Ambler also ordered Janice Purnell to perform 200 hours of public service, to stay away from her son unless she gets permission from her probation officer, and to continue psychiatric treatment. Purnell, 47, pleaded no contest to assault charges after she stabbed her son, Christopher, 24, twice with a kitchen knife on Nov. 17. She told police she wanted to end his misery. Christopher, who was born with cerebral palsy and needs constant care, has recovered and now lives with his father in Santa Cruz County. “Both the Probation Department and the psychiatrist recommended stringent conditions designed to protect the victim and closely monitor the defendant, who is clearly a troubled woman,” Deputy Dist. Atty. Ron Rico said.