In a 73‑year‑old patient with a persistent headache and a normal non‑contrast head CT, what is the appropriate next diagnostic and management approach?

Persistent Headache in a 73-Year-Old with Negative CT

In a 73-year-old patient with persistent headache and normal non-contrast head CT, you must perform lumbar puncture to rule out subarachnoid hemorrhage if the CT was performed more than 6 hours after headache onset, and obtain MRI brain with contrast plus MR venography to evaluate for cerebral venous thrombosis, temporal arteritis-related complications, and other secondary causes that CT cannot detect. 1, 2

Critical Next Steps Based on Timing and Clinical Features

Immediate Lumbar Puncture Indications

• If the CT was performed >6 hours after headache onset, lumbar puncture is mandatory to evaluate for xanthochromia, as CT sensitivity for subarachnoid hemorrhage drops from 98-100% at 12 hours to 93% at 24 hours and 57-85% at 6 days 1

• Spectrophotometry for xanthochromia maintains 100% sensitivity for detecting SAH from 12 hours through 2 weeks, and >70% sensitivity at 3 weeks after the hemorrhage 1, 3

• Opening pressure measurement during LP is essential, as elevated pressure >250 mm H₂O suggests idiopathic intracranial hypertension, which can present with persistent headache in this age group 4

Essential MRI Evaluation

MRI brain with and without IV contrast plus MR venography should be obtained urgently for the following reasons 1, 4, 2:

• Cerebral venous thrombosis (CVT) can present as isolated headache with normal CT and normal CSF in 17% of cases, with the lateral sinus most frequently involved 2

• MRI is far more sensitive than CT for detecting secondary signs of elevated intracranial pressure, including empty sella, posterior globe flattening, and optic nerve sheath dilatation 4

• MRI detects ischemic lesions, subdural collections, and mass lesions that may be isodense on CT in elderly patients 1, 3

Age-Specific Considerations in Patients Over 65

• Up to 15% of patients ≥65 years presenting with new-onset headache have serious pathology including stroke, temporal arteritis, neoplasm, or subdural hematoma 3

• Temporal arteritis must be strongly considered in this age group, as headache occurs in 60-90% of cases, though ESR can be normal in 10-36% of patients 3

• If temporal arteritis is suspected clinically, do not delay treatment while awaiting temporal artery biopsy, as the biopsy can yield false-negative results in 5-44% of cases 3

Red Flags Requiring Urgent Neuroimaging Beyond CT

The following features mandate MRI evaluation even with normal CT 5, 4:

• Progressive worsening over days to weeks
• Headache awakening patient from sleep (suggests elevated ICP) 4
• Headache worsened by Valsalva maneuver (indicates elevated ICP) 4
• Any abnormal neurological finding on examination 4
• Rapidly increasing frequency of headaches 4

Diagnostic Algorithm

1. Determine CT timing relative to headache onset 1

   • If <6 hours and negative: Consider LP if clinical suspicion remains high
   • If >6 hours and negative: LP is mandatory

2. Perform lumbar puncture with 1, 4:

   • Opening pressure measurement
   • Cell count and differential
   • Protein and glucose
   • Xanthochromia by spectrophotometry (not visual inspection alone)

3. Obtain MRI brain with and without contrast plus MRV 1, 4, 2:

   • Evaluate for CVT (can present as isolated headache)
   • Assess for signs of elevated ICP
   • Rule out mass lesions, subdural collections, ischemia

4. Consider additional workup based on age 3:

   • ESR and CRP for temporal arteritis
   • If ESR elevated or high clinical suspicion: start corticosteroids immediately and arrange temporal artery biopsy

Common Pitfalls to Avoid

• Do not assume normal CT excludes all serious pathology - CT has limited sensitivity for CVT, early ischemia, meningitis, and temporal arteritis complications 1, 2

• Do not rely on visual inspection alone for xanthochromia - spectrophotometry is required for accurate detection 1

• Do not delay empiric treatment for temporal arteritis while awaiting confirmatory testing in patients >50 years with suggestive features, as vision loss can occur rapidly 3

• Do not dismiss normal opening pressure - CSF pressure can be normal in spontaneous intracranial hypotension, and absence of low pressure should not exclude this condition 1

If Initial Workup is Negative

When CT, LP, and MRI are all normal but symptoms persist 1:

• Consider spontaneous intracranial hypotension (requires MRI spine with fluid-sensitive sequences to detect epidural fluid collections)
• Evaluate for positional component to headache (orthostatic vs. non-positional)
• Consider alternative diagnoses including new daily persistent headache, cervicogenic headache, or migraine variant