Subarachnoid hemorrhage as shown on a CT scan. It is denoted by the arrow. This type of injury may result in damage to the brainstem, which could initiate or worsen the symptoms of the<unk>  Whenever a<unk>  occurs, there is a high probability of death in seconds to minutes. As a result, a<unk>  indicates a need for immediate care. Since its presence is a good detector of high ICP, it is often useful in the medical field, particularly during surgery. During any neurosurgery being performed on the brain, there is always a likelihood that raised intracranial pressure may occur. Early recognition of this is crucial to the well being of the patient. Although direct measurement of ICP is possible, it is not always accurate. In the past, physicians and nurses have relied on hemodynamic changes or bradycardia, the late phase of the reflex, to identify the ICP increase. Once the initial stage of the<unk>  (bradycardia combined with hypertension) was discovered, it offered a much more reliable and swift warning sign of high ICP. It was found that hypertension and bradycardia occurred 93% of the time when cerebral perfusion pressure (CPP) dropped below 15 mmHg due to raised ICP. Also, the<unk>  is known to arise only from acute prolonged raises in ICP. Thus, it can be used as a tool by physicians to differentiate acute and chronic rises in ICP. It has also been reported that the presence of a<unk>  due to an ICP increase could allow one to conclude that ischemia has occurred in the posterior cranial fossa. Finally, the<unk>  may be one of many ways to identify if a patient has rejected a transplanted organ. Aside from the innate autoimmune response, ischemia in the cranial region has been detected with a transplanted organ that is being rejected. As such, the presence of a<unk>  due to ICP can indicate that ischemia may be occurring due to foreign organ rejection. As first postulated by Harvey<unk> , raised intracranial pressure is the primary cause of the<unk> . Furthermore, continued moderate increases in cranial pressure allows for the<unk>  to occur. In contrast, rapid and dramatic pressure rises do not allow for the mechanism of the reflex to sufficiently take place. Elevated intracranial pressure can result from numerous pathways of brain impairment, including: subarachnoid hemorrhages, ischemia, meningitis, trauma, including concussions, hypoxia, tumors, and stroke. In one study, it was confirmed that raised ICP due to subarachnoid hemorrhaging causes mechanical distortion of the brainstem, specifically the medulla. Due to the mechanism of the<unk> , brainstem distortion is then swiftly followed by sympathetic nervous system over activity. In addition, during typical neurosurgical procedures on patients, especially those involving neuroendoscopic techniques, frequent washing of the ventricles have been known to cause high intracranial pressure. The<unk>  can also result from low CPP, specifically below 15 mmHg. CPP normally falls between 70-90 mmHg in an adult human, and 60-90 mmHg in children. Brain plateau wave changes are also associated with the<unk> . These waves are characterized by acute rises of the ICP, and are accompanied by a decrease of the cerebral perfusion pressure. It has been found that if a<unk>  occurs, brain plateau wave changes can be erased due to disappearance of high ICP.
Cushing reflex
Abdominal reflex
Diving reflex
Snout reflex
Red reflex
Galant reflex
Vagovagal reflex
Cough reflex