Diagnosing PSH can be very difficult due to the lack of common terminology in circulation and a lack of diagnostic criteria. Different systems for diagnosis have been proposed, but a universal system has not been embraced. One example of a proposed system of diagnosis requires observation confirmation for four of the six following symptoms: fever greater than 38.3 degrees Celsius, tachycardia classified as a heart rate of 120 bpm or higher, hypertension classified as a systolic pressure higher than 160 mmHg or a pulse pressure higher than 80 mmHg, tachypnea classified as respiration rate higher than 30 breaths per minute, excess sweating, and severe dystonia. Ruling out other diseases or syndromes that show similar symptoms is imperative to diagnosis as well. Sepsis, encephalitis, neuroleptic malignant syndrome, malignant hyperthermia, lethal catatonia, spinal cord injury (not associated with PSH), seizures, and hydrocephalus (this can be associated with PSH) are examples of diagnoses that should be considered due to the manifestation of similar symptoms before confirming a diagnosis of PSH. PSH has no simple radiological features that can be observed or detected on a scan.
Paroxysmal sympathetic hyperactivity
Cholinergic crisis
Parasympathetic rebound
Postural orthostatic tachycardia syndrome
False awakening
Postanesthetic shivering
Heat syncope
Thalamocortical dysrhythmia