Causes of a Reduced Conscious Level
| Without localizing signs or meningism | With meningism (+/– localizing signs) | With localizing signs |
|---|---|---|
| Toxic | ||
| Alcohol, drugs, carbon monoxide | ||
| Metabolic/endocrine | ||
| Hypoxia, hypercapnia, hypoglycaemia, hyperglycaemic ketoacidosis/hyperosmolar states, hypo/hypernatraemia, uraemia, hepatic encephalopathy, hypercalcaemia, Addisonian crisis, dysthyroidism, hypo/hyperthermia, Wernicke's | Pituitary apoplexy | Wernicke's encephalopathy, hypo/hyperglycaemia, sodium shifts |
| Vascular | ||
| Shock, hypertensive encephalopathy, eclampsia, venous sinus thrombosis | Subarachnoid haemorrhage | Brainstem infarction, cerebral infarction with mass effect, venous sinus thrombosis, cerebral/pontine/cerebellar haemorrhage |
| Infective | ||
| Severe systemic infection | Bacterial meningitis, viral meningo-encephalitis, cerebral malaria | Herpes simplex encephalitis, subdural empyema, abscess, septic emboli |
| Inflammatory | ||
| Paraneoplastic or autoimmune encephalitis (limbic encephalitis (with or without VGKC, GABABR, or AMPAR antibodies)), NMDAR encephalitis, Hashimoto's encephalopathy | Bickerstaff's brainstem encephalitis, acute disseminated encephalo-myelitis (ADEM), autoimmune encephalitis | |
| Seizure | ||
| Post-ictal state, status epilepticus | Post-ictal, status epilepticus | |
| Tumour | ||
| Paraneoplastic, acute hydrocephalus | Carcinomatous meningitis | Brain tumour |
| Trauma | ||
| Concussion | SDH, EDH, other traumatic brain injury |