Paroxysmal sympathetic hyperactivity (PSH) is a relatively common early complication after severe brain injury. It is characterized by episodic generalized sympathetic hyperactivity. We herein present a case of a 29-year-old woman who developed PSH after near-hanging with uncertainty of cardiac arrest. The patient attempted suicide by hanging herself. Her mother found her pulseless and in a deep coma and started chest compressions. Upon arrival at our hospital, spontaneous breathing was restored and her vital signs stabilized; however, she remained in a deep coma. After admission to the intensive care unit, generalized tonic-clonic convulsions developed and her body temperature increased to 39.2 °C despite surface cooling. We presumed that she had been in cardiac arrest when her mother discovered her and initiated 24-hour therapeutic hypothermia (TH) and 24-hour rewarming. After rewarming, her temperature increased to 38.7 °C again despite the disappearance of her convulsions, and she suddenly exhibited a decerebrate posture, muscle stiffness, pupillary dilatation, elevated blood pressure, and tachycardia by repeated extrinsic stimulation. She was diagnosed with PSH, and medical treatment and fever management were begun. The PSH began to resolve, and she was transferred to another hospital for rehabilitation in a persistent vegetative state without PSH on the 42nd hospital day. In this case, TH was utilized for anoxic brain injury after near-hanging with uncertain cardiac arrest. A clinical course of PSH after near-hanging is presented with a brief review of TH indication.