What is the appropriate management for an adult patient with sudden onset neuropsychiatric symptoms and headache?

Sudden Onset Neuropsychiatric Symptoms with Headache: Management Approach

Obtain urgent non-contrast head CT immediately to rule out subarachnoid hemorrhage, intracranial hemorrhage, and other life-threatening causes, followed by brain MRI with contrast if CT is negative and clinical suspicion remains high. 1, 2

Immediate Diagnostic Workup

First-Line Imaging

• Non-contrast head CT is the mandatory first test when sudden onset headache accompanies neuropsychiatric symptoms, as it has 98% sensitivity and 99% specificity for detecting acute subarachnoid hemorrhage (SAH). 3
• CT must be performed emergently because 11.3% of patients with sudden onset ("thunderclap") headache have SAH, and clinical features alone cannot distinguish SAH from benign causes. 4
• The combination of sudden onset headache with neuropsychiatric symptoms represents a red flag requiring immediate imaging, as focal neurologic deficits, altered mental status, and personality changes indicate serious underlying pathology. 5, 2

Second-Line Imaging When CT is Negative

• Brain MRI with and without IV contrast should follow if CT is negative but clinical suspicion remains high, as MRI has superior sensitivity for detecting encephalitis, arterial dissection, cerebral venous thrombosis, and subtle SAH. 1, 3
• MRI sequences must include FLAIR, SWI/GRE, and blood-sensitive sequences to detect SAH (sensitivity 50-94% for acute SAH), superficial siderosis, and venous abnormalities. 3
• MRI is particularly critical when autoimmune encephalitis is suspected, as this can present with acute psychosis and headache. 1, 6

Critical Ancillary Testing

Lumbar Puncture Indications

• Perform lumbar puncture after negative CT if SAH remains suspected, as CT sensitivity decreases after 6 hours and LP can detect xanthochromia. 4
• LP is essential when meningitis or encephalitis is in the differential, particularly if fever, neck stiffness, or altered consciousness accompanies the neuropsychiatric symptoms. 4, 2

EEG Requirements

• Order emergent EEG if altered consciousness, encephalopathy, or fluctuating mental status is present, as 25% of patients with status epilepticus have continuing electrical seizures without convulsive movements. 6
• EEG is mandatory when autoimmune encephalitis is suspected, as specific findings like extreme delta brush suggest NMDAR-antibody encephalitis. 6
• Do not order routine EEG if consciousness is normal and there is no seizure history, as this has inadequate supporting evidence. 6

Vascular Imaging

• Add CT angiography (CTA) or MR angiography (MRA) if SAH is detected or if arterial dissection is suspected, as CTA is comparable to conventional angiography for detecting aneurysms. 3
• Consider MR venography (MRV) or CT venography when cerebral venous thrombosis is suspected, particularly in patients with risk factors like oral contraceptive use or prothrombotic states. 3

Specific Dangerous Causes to Exclude

High-Priority Diagnoses

• Subarachnoid hemorrhage from aneurysm rupture or arteriovenous malformation (11.3% of sudden onset headache cases). 4
• Spontaneous intracranial hypotension with subdural hematoma or cerebral venous thrombosis, which can present with sudden neuropsychiatric changes. 3
• Autoimmune encephalitis (particularly NMDAR or LGI1 antibody), which presents with acute psychosis, altered consciousness, and headache. 1, 6
• Arterial dissection (carotid or vertebral), especially if unilateral headache with Horner syndrome or focal deficits. 3
• Cerebral infarction (5 of 137 patients with sudden onset headache in one series). 4
• Intracerebral hemorrhage (3 of 137 patients with sudden onset headache). 4

Additional Organic Causes

• Temporal lobe tumors or infarcts can present with psychosis and headache. 1
• Encephalitis (viral, bacterial, or autoimmune) must be excluded with MRI, LP, and potentially EEG. 1, 6
• Multiple sclerosis, particularly with acute demyelinating lesions affecting temporal or frontal regions. 1
• Systemic lupus erythematosus with CNS involvement. 1

Critical Clinical Pitfalls

Do Not Rely on Clinical Features Alone

• Nausea, neck stiffness, occipital location, and impaired consciousness are more frequent with SAH but do not occur in all cases and cannot exclude benign causes. 4
• Sexual activity preceded the headache in 8% of sudden onset cases, with 18% of these having SAH. 4
• Clinical features cannot distinguish SAH from benign causes—imaging is mandatory. 4

Avoid Premature Reassurance

• 24% of patients with benign sudden onset headache have recurrent attacks, but no delayed SAH occurred in follow-up. 4
• However, first presentation always requires full workup regardless of subsequent benign course. 4

Do Not Skip Contrast

• Contrast-enhanced MRI is necessary when autoimmune disorders or definitive lesion characterization is needed. 1
• Non-contrast studies alone may miss encephalitis, vasculitis, or enhancing lesions. 1

Age-Specific Considerations

• Patients ≥50 years with new onset psychosis and headache have higher risk of organic pathology and warrant more aggressive imaging. 1
• Consider temporal arteritis in elderly patients with new headache and neuropsychiatric symptoms. 2

When Advanced Testing is Needed

• FDG PET should only be considered after structural imaging if diagnostic uncertainty remains regarding neurodegenerative causes (Alzheimer's, frontotemporal dementia, Lewy body dementia). 7
• Conventional angiography is reserved for cases where CTA/MRA results are unclear and strong suspicion for small vessel disease or dissection persists. 3