What is the differential diagnosis for a 17-year-old patient presenting with headache, neck pain, Upper Respiratory Infection (URI) symptoms, and diarrhea?

Differential Diagnosis for a 17-Year-Old with Headache, Neck Pain, URI Symptoms, and Diarrhea

Bacterial meningitis must be excluded immediately in this patient, as the combination of headache and neck pain represents a life-threatening emergency with 20-30% mortality that requires urgent cerebrospinal fluid examination and empiric antibiotics within 1 hour of presentation. 1, 2

Critical Life-Threatening Diagnosis to Rule Out First

Bacterial Meningitis

• This is the most urgent diagnosis to exclude given the combination of headache and neck pain, even with concurrent URI symptoms and diarrhea. 1
• Classic clinical signs (fever, neck stiffness, altered mental status) are present in only 41-51% of patients, and bacterial meningitis can present with nonspecific symptoms including gastrointestinal complaints. 1
• Neck stiffness has only 51% sensitivity in adolescents, meaning its absence does NOT rule out meningitis. 1
• Obtain emergent non-contrast head CT immediately before lumbar puncture if any neurologic signs are present (nuchal rigidity, altered consciousness) to prevent herniation complications. 2
• If bacterial meningitis is suspected, initiate empiric antibiotics (ceftriaxone plus vancomycin plus dexamethasone) within 1 hour, even before imaging or lumbar puncture if there will be any delay. 2

Key Clinical Pitfall

• Do NOT assume this is simply a viral URI with coincidental neck pain—the presence of headache with neck pain mandates exclusion of meningitis regardless of other symptoms. 1, 2

Most Likely Benign Diagnosis

Viral Meningitis or Aseptic Meningitis

• Accounts for 50-80% of meningitis cases and commonly presents with headache, neck stiffness, photophobia, and nonspecific symptoms including diarrhea, vomiting, and sore throat. 1, 3
• Enteroviruses (transmitted via fecal-oral route) are the most common cause and frequently present with gastrointestinal symptoms. 1
• Fever is not always present in viral meningitis. 1
• CSF examination is essential for diagnosis, showing lymphocytic pleocytosis (versus neutrophilic in bacterial), normal glucose ratio, and mildly elevated protein. 1, 2
• CSF PCR should test for enteroviruses, HSV-1, HSV-2, and VZV. 1

Other Differential Considerations

Uncomplicated Viral Upper Respiratory Infection with Myalgia

• URI symptoms with headache and neck pain (from muscle tension/myalgia) plus diarrhea can occur with viral URIs. 4, 5
• Gastrointestinal symptoms are common in viral URIs and do not change management when no red flags are present. 4
• However, this diagnosis can only be considered AFTER meningitis has been excluded, particularly given the combination of headache and neck pain. 1

Cervical Musculoskeletal Pain with Concurrent URI

• Mechanical neck pain from facet joints, muscles, or fascia can occur but would be unusual in a 17-year-old without trauma. 1
• The presence of concurrent headache, URI symptoms, and diarrhea makes isolated musculoskeletal pain unlikely. 1

Otogenic Meningitis

• Meningitis secondary to otitis media can present with headache, neck pain, and nausea after several days of ear infection. 6
• Consider if patient has history of recent ear pain or otitis media. 6

Diagnostic Algorithm

1. Immediate assessment for meningeal signs (neck stiffness, Kernig sign, Brudzinski sign, altered mental status, fever). 1

2. If ANY meningeal signs present or high clinical suspicion:

   • Obtain emergent non-contrast head CT immediately (98-100% sensitivity for acute pathology). 2
   • If CT negative, proceed immediately to lumbar puncture. 2
   • Initiate empiric antibiotics within 1 hour if bacterial meningitis suspected, even before LP if any delay anticipated. 2

3. CSF analysis to differentiate:

   • Bacterial: neutrophilic pleocytosis, CSF/blood glucose <0.4, elevated protein >45 mg/dL, elevated opening pressure >25 cm H₂O. 2
   • Viral: lymphocytic pleocytosis, normal glucose, mildly elevated protein. 1, 2
   • CSF PCR for enteroviruses, HSV-1, HSV-2, VZV. 1

4. Only if meningitis definitively excluded, consider viral URI with symptomatic management:

   • Analgesics (acetaminophen or ibuprofen) for headache. 4
   • Pseudoephedrine for nasal congestion. 4
   • Adequate hydration and rest. 4

Red Flags Requiring Immediate Action

• Any combination of headache and neck pain in an adolescent mandates urgent evaluation for meningitis. 1, 2
• Altered mental status, focal neurologic deficits, or papilledema. 1, 3
• High fever (≥39°C) with purulent discharge for ≥3 consecutive days. 5
• Symptoms persisting beyond 10 days without improvement or worsening after initial improvement. 4, 5

Critical Clinical Reasoning

The presence of URI symptoms and diarrhea does NOT exclude bacterial meningitis, as nonspecific symptoms are common presentations, particularly in adolescents. 1 The 20-30% mortality rate of bacterial meningitis and the potential for permanent neurologic sequelae make this the absolute priority diagnosis to exclude before considering more benign etiologies. 2