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The extent of investigation should depend on the degree and duration of illness, the most likely causes and the clinical findings. In a patient who has an obvious cause for their catatonia or an established history of catatonia, minimal investigation beyond the basics might be appropriate.
Bedside investigations
- Physical observations (pulse, blood pressure, respiratory rate, temperature, oxygen saturation). Repeat at least 3 times daily.
- Food and fluid chart
Lorazepam challenge
If the diagnosis of catatonia is uncertain, the lorazepam challenge can help distinguish.
- Assess for features of catatonia at baseline, ideally using a scoring system such as the Bush-Francis Catatonia Rating Scale.
- Administer 1-2mg lorazepam by the intravenous, intramuscular or oral route.
- Re-assess after 5 minutes (intravenous), 15 minutes (intramuscular) or 30 minutes (oral). A 50% improvement suggests that catatonia is likely and that there is likely to be a good response to further treatment with benzodiazepines.
- If there is limited response, repeat the test with one further dose of lorazepam.
Blood tests
- Full blood count
- Electrolytes
- Renal function
- Bone profile
- Liver function
- Glucose
- Thyroid function
- Vitamin B12/folate
- Creatine kinase
- Iron
- Copper and caeruloplasmin
- HIV and syphilis serology
- Antinuclear antibodies
- Anti-NMDA receptor antibodies
Other
- Urinalysis for ketones
- Urine drug screen
- Electrocardiogram
- Neuroimaging (MRI preferred to CT)
- Electroencephalograph (EEG)
- Lumbar puncture