Causes of Acute Headache with ‘red-Flag’ Features: Fever, Reduced Conscious Level, Papilloedema, Neck Stiffness or Focal Neurological Signs
| Cause | Chapter or reference/comment |
|---|---|
| Vascular | |
| Stroke | Chapter 65 |
| Subarachnoid haemorrhage | Chapter 67 |
| Cerebral venous sinus thrombosis | Headache usually of gradual onset but may be ‘thunderclap’ |
| Subdural haematoma | Table 65.4 |
| Hypertensive encephalopathy | Table 55.4 |
| Pituitary apoplexy | Chapter 93 |
| Cerebral vasculitis | Table 65.4, Chapter 99 |
| Infective | |
| Bacterial meningitis | Chapter 68 |
| Viral encephalitis | Chapter 69 |
| Brain abscess | Headache usually localized to side of abscess; may be of gradual or sudden onset |
| Subdural empyema | Complication of paranasal sinusitis, otitis media, or mastoiditis |
| Tuberculous meningitis | Appendix 68.1 |
| Cryptococcal meningitis | Appendix 68.2 |
| Toxoplasma encephalitis | Chapter 34 |
| Systemic infection with headache/meningism | In returning travellers, include malaria and typhoid in the differential diagnosis (Chapter 33) |
| Others | |
| Poisoning with amphetamine/cocaine | Table 36.2 |
| Other causes of raised intracranial pressure | Chapter 72 |
| Hyperviscosity syndrome | Due to high levels of immunoglobulin (e.g. Waldenstrom macroglobulinaemia) or cells (e.g. polycythaemia, leukaemias) |
| Severe hyponatraemia | Chapter 85 |
| Malignant meningitis (carcinoma, melanoma, lymphoma, leukaemia) | CSF typically shows raised protein concentration and high lymphocyte count; diagnosis confirmed by cytology |