Metabolic screens, inflammatory markers, or autoantibodies may reveal reversible medical causes of catatonia.Vital signs should be frequently monitored as catatonia can progress to malignant catatonia which is life-threatening. Malignant catatonia is characterized by fever, hypertension, tachycardia, and tachypnea. Rating scale
Various rating scales for catatonia have been developed, however, their utility for clinical care has not been well established. The most commonly used scale is the Bush-Francis Catatonia Rating Scale (BFCRS) (external link is provided below). The scale is composed of 23 items with the first 14 items being used as the screening tool. If 2 of the 14 are positive, this prompts for further evaluation and completion of the remaining 9 items. A diagnosis can be supported by the lorazepam challenge or the zolpidem challenge. While proven useful in the past, barbiturates are no longer commonly used in psychiatry; thus the option of either benzodiazepines or ECT. Differential diagnosis
The differential diagnosis of catatonia is extensive as signs and symptoms of catatonia may overlap significantly with those of other conditions. Therefore, a careful and detailed history, medication review, and physical exam are key to diagnosing catatonia and differentiating it from other conditions. Furthermore, some of these conditions can themselves lead to catatonia. The differential diagnosis is as follows:

Neuroleptic malignant syndrome (NMS) and catatonia are both life-threatening conditions that share many of the same characteristics including fever, autonomic instability, rigidity, and delirium. Lab values of low serum iron, elevated creatine kinase, and white blood cell count are also shared by the two disorders further complicating the diagnosis.
Mood disorders such as a bipolar disorder and depression are the most common etiologies to progress to catatonia. Other psychiatric associations include schizophrenia and other primary psychotic disorders. It also is related to autism spectrum disorders.Catatonia is also seen in many medical disorders, including infections (such as encephalitis), autoimmune disorders, meningitis, focal neurological lesions (including strokes), alcohol withdrawal, abrupt or overly rapid benzodiazepine withdrawal, cerebrovascular disease, neoplasms, head injury, and some metabolic conditions (homocystinuria, diabetic ketoacidosis, hepatic encephalopathy, and hypercalcaemia). Pathogenesis
The pathophysiology that leads to catatonia is still poorly understood and a definite mechanism remains unknown. Neurologic studies have implicated several pathways; however, it remains unclear whether these findings are the cause or the consequence of the disorder.Abnormalities in GABA, glutamate signaling, serotonin, and dopamine transmission are believed to be implicated in catatonia.Furthermore, it has also been hypothesized that pathways that connect the basal ganglia with the cortex and thalamus is involved in the development of catatonia. Diagnosis
There is not yet a definitive consensus regarding diagnostic criteria of catatonia. In the American Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the World Health Organizations eleventh edition of the International Classification of Disease (ICD-11) the classification is more homogeneous than in earlier editions. Prominent researchers in the field have other suggesions for diagnostic criteria.DSM-5 classification
The DSM-5 does not classify catatonia as an independent disorder, but rather it classifies it as catatonia associated with another mental disorder, due to another medical condition, or as unspecified catatonia.