Mastering the brain in critical conditions: an update

Intensive Care Medicine Experimental

Table 1 Primary investigations in case of coma of unknown origin

Test	Indication	Scope
Neurological examination, temperature, pulse, BP, EKG, RR, SpO₂	All patients
Blood
Blood glucose	All patients	Rule out hypoglycemia
Electrolytes	All patients	Rule out severe hypo- or hypernatremia
Blood gas analysis	All patients	Rule out hypercapnia
Blood cultures	On clinical suspicion	Rule out systemic infection
Toxicology screening (from blood and urine)	On clinical suspicion	Rule out intoxications
Ammonemia and liver function	On clinical suspicion	Rule out hepatic encephalopathy
Cortisol	On clinical suspicion	Rule out adrenal insufficiency
Thyroid function	On clinical suspicion	Rule out hypothyroidism
CSF: routine cell count, protein, Glucose, Gram staining, India ink stain; cultures, including tuberculosis and fungal agents; cytology. HSV and VZV PCR; other agents depending on presentation	On clinical suspicion	Rule out CNS infections, neuroinflammatory diseases or cancer and leukemia dissemination
Non-contrast CT	All patients	Diagnosis of neurosurgical emergencies and massive stroke
CTA	On clinical suspicion	Rule out basilar artery occlusion
MRI	On clinical suspicion	Indicated in case of brainstem symptoms, unexplained coma, or suspected encephalitis
EEG	On clinical suspicion	Rule out nonconvulsive status epilepticus; may identify electrical patterns typical in some etiologies (e.g., triphasic waves in metabolic encephalopathy)

CNS central nervous system, CT computer tomography, CTA computed tomography angiography, EEG electroencephalogram, GCS Glasgow coma scale, FOUR Full Outline of UnResponsiveness coma scale, TBI traumatic brain injury