Parasympathetic hyperactivity is a condition that causes episodes of excessive sympathetic nervous system activity, which often follows a severe brain injury.
Parasympathetic hyperactivity is not just an overactive parasympathetic system, but instead is an imbalance, where your sympathetic nervous system overreacts as a result of a disruption in the normal inhibitory control from your brain.
As a result it lead to symptoms such as rapid heart rate, increased body temperature, high blood pressure and muscle stiffness.
Episodes of parasympathetic hyperactivity are often sudden and can also be triggered by various different stimuli including pain, movement or even routine care.
And although it's called parasympathetic hyperactivity, the core issue is excessive sympathetic nervous system activity.
Parasympathetic hyperactivity is most commonly associated with severe traumatic brain injury, although it can also occur after other brain injuries such as stroke or hypoxic brain injury.
Symptoms of parasympathetic hyperactivity can also vary in combination and severity, although the symptoms of parasympathetic hyperactivity often include rapid heart rate, high blood pressure, rapid breathing, high temperature or hyperthermia and sweating and muscle rigidity.
Possible triggers of parasympathetic hyperactivity include pain, coughing, repositioning, suctioning and loud noises.