What could cause symptoms of myalgias, fever, occipital headaches, neck pain, and poor oral intake in a patient with normal CT (computed tomography) brain imaging results?

Meningitis or Encephalitis Until Proven Otherwise

This presentation of fever, myalgias, occipital headache, neck pain, and poor oral intake represents a classic CNS infection syndrome that requires immediate empiric antimicrobial therapy—do not delay treatment while awaiting diagnostic confirmation, as delays worsen outcomes and increase mortality. 1, 2

Immediate Management Priority

• Initiate empiric antibiotics within 1 hour (ceftriaxone plus vancomycin for suspected pneumococcal meningitis, plus dexamethasone to reduce mortality and neurological sequelae) even before lumbar puncture if there will be any delay 2
• The Centers for Disease Control and Prevention emphasizes that empiric antimicrobial therapy should not be delayed while awaiting diagnostic confirmation 1
• Obtain blood cultures, complete blood count, hepatic transaminases, and serum sodium before antibiotics 1

Why CT Brain Was Negative

• Normal CT does not exclude meningitis or encephalitis—CT has poor sensitivity for diagnosing pediatric and adult encephalitis compared to MRI 3
• CT brain is performed primarily to assess for herniation risk before lumbar puncture (90% specificity for identifying dangerous mass effect), not to diagnose infection 2
• The American College of Radiology states that a negative noncontrast CT scan should not conclude the evaluation for suspected encephalitis 3

Diagnostic Algorithm

Step 1: Obtain emergent non-contrast head CT (already done—negative for mass effect) 2

Step 2: Proceed immediately to lumbar puncture, as CSF analysis is the principal diagnostic contributor for bacterial meningitis 2

• Expected findings in bacterial meningitis: polymorphonucleocyte predominance, CSF/blood glucose ratio <0.4, elevated protein (>45 mg/dL), elevated opening pressure (>25 cm H₂O) 2
• Lymphocytic pleocytosis and elevated protein suggest viral encephalitis 1

Step 3: Obtain MRI brain with and without IV contrast as soon as feasible 1

• MRI is superior to CT for suspected CNS infection, showing better sensitivity for encephalitis, meningeal enhancement, and abscess formation 1
• MRI sequences (T2 FLAIR for vasogenic edema, DWI for cytotoxic edema, post-contrast T1 and T2 FLAIR for meningeal enhancement) help identify the extent of inflammation 3, 1

Clinical Reasoning for CNS Infection

• Fever with headache, neck pain, and poor oral intake represents the classical triad of CNS infection 1
• Myalgias and fever with altered neurological function strongly suggest encephalitis or meningitis 1
• The presence of nuchal rigidity (neck pain/stiffness) further supports this diagnosis 1
• Occipital headache location is consistent with dural irritation from meningitis 1

Alternative Diagnoses to Consider (Lower Priority)

If CSF analysis and MRI are negative for infection, consider these secondary causes:

Acute Calcific Tendinitis of Longus Colli Muscle

• Presents with fever, neck pain/stiffness, myalgias, and can mimic meningitis 4
• CT neck shows calcification of the longus colli muscle with prevertebral and retropharyngeal space edema 4
• Benign, self-limited condition treated with anti-inflammatories and corticosteroids 4

Crowned Dens Syndrome (Calcium Pyrophosphate Deposition)

• Characterized by severe occipital pain, neck stiffness, fever, and inflammatory response 5
• Can be misdiagnosed as meningitis due to similar presentation 5
• CT or MRI shows calcification around the odontoid process 5

Spontaneous Intracranial Hypotension

• Presents with orthostatic headache (worse when upright, better when lying down), neck pain, and nausea 3
• MRI shows smooth diffuse dural enhancement, venous sinus engorgement, and possible brain sagging 3
• However, fever is NOT typical of intracranial hypotension, making this diagnosis less likely in this febrile patient 3

Subdural Empyema or Epidural Empyema

• Can present with fever, headache, and neck pain 1
• Often results from sinusitis or otitis media extension 3, 1
• MRI with contrast is superior for detection 1

Critical Pitfalls to Avoid

• Do not delay antibiotics waiting for imaging or LP—treatment should begin within 1 hour if bacterial meningitis is strongly suspected 2
• Do not assume absence of fever rules out meningitis—bacterial meningitis can present without fever, though fever is present in this case 2
• Do not perform lumbar puncture before imaging in patients with meningeal signs—this risks cerebral herniation if mass effect is present (though CT was already negative here) 1, 2
• Do not stop the workup after negative CT—CT has 98% sensitivity for acute subarachnoid hemorrhage but poor sensitivity for encephalitis 3, 1

Mortality Context

• The mortality rate for bacterial meningitis is 20-30%, increasing with diagnostic delays 2
• This makes immediate empiric antibiotic therapy and systematic diagnostic approach critical for reducing morbidity and mortality 2