Differential Diagnoses: 6-year-old female with Headache, Dizziness, Vomiting (x2), Loose Stools (x3)

Tier 1 - Most Likely (Common, Must Not Miss)

1. Acute Gastroenteritis (AGE) - Most Common Diagnosis

• Viral (norovirus, rotavirus): sudden onset, low-grade or no fever, self-limiting; norovirus is now the leading cause of AGE in the US since rotavirus vaccination. Headache and dizziness can occur as systemic viral symptoms or from early dehydration.
• Bacterial (Salmonella, Campylobacter, E. coli, Shigella): more likely if diarrhea is bloody, fever is prominent, or there is a food/exposure history.
• Key concern: dehydration driving the dizziness and headache.
• Tintinalli's Emergency Medicine notes that vomiting + diarrhea are the defining features of AGE; Swanson's Family Medicine Review confirms norovirus as the top cause in this age group.

2. Bacterial Meningitis - Must Not Miss

• Classic triad: fever, headache, neck stiffness - but early or partially treated cases may lack the full triad.
• Roberts and Hedges' states: "An older child may complain of a headache. At all ages, patients generally appear ill and drowsy." Kernig's and Brudzinski's signs are more reliable in children >3 years.
• At age 6, N. meningitidis and S. pneumoniae are the dominant organisms. H. influenzae is important in unvaccinated children.
• Vomiting and loose stools can accompany meningococcemia (GI manifestations precede purpuric rash).
• A petechial or purpuric rash in a febrile child with these symptoms is a red flag for meningococcal disease.
• Jawetz Microbiology 28E and Harrison's 22E: bacterial meningitis in older children presents with fever, headache, vomiting, photophobia, and altered sensorium.

3. Viral Meningitis / Aseptic Meningitis

• Enteroviruses (echovirus, coxsackievirus) are the most common cause in this age group.
• Milder course than bacterial meningitis; GI symptoms (nausea, vomiting, diarrhea) are a hallmark of enteroviral infection.
• Headache and neck stiffness present but patient appears less toxic.

Tier 2 - Important Differentials

4. Food Poisoning / Toxin-Mediated Illness

• Staphylococcal enterotoxin: rapid onset vomiting, diarrhea within 1-6 hrs of ingestion, often with headache.
• Bacillus cereus (emetic type): similar rapid-onset picture.
• Often affects multiple family members simultaneously - ask for exposure history.

5. Increased Intracranial Pressure (ICP) - from any cause

• Headache + vomiting in a child should always prompt consideration of raised ICP.
• Causes include: brain tumor (posterior fossa tumors like medulloblastoma are most common in children), brain abscess, pseudotumor cerebri.
• Vomiting from raised ICP is classically projectile, often without nausea, and worse in the morning.
• The diarrhea in this case is less typical for raised ICP alone - consider if vomiting is disproportionate to nausea.
• Cummings Otolaryngology: intracranial complications present with "persistent headache, lethargy, malaise, irritability, nausea and vomiting."

6. Febrile Illness with Systemic Symptoms (any viral infection)

• Non-specific viral illnesses (influenza, adenovirus, EBV) commonly cause headache, dizziness, vomiting, and diarrhea together.
• Influenza particularly causes prominent headache, myalgia, GI symptoms.

7. Typhoid Fever (in endemic regions)

• Enteric fever (Salmonella typhi) can present with GI symptoms, headache, dizziness in a step-ladder fever pattern.
• Bradycardia relative to fever is a clue.
• Should be high on the list if the child lives in or recently traveled to an endemic area.

Tier 3 - Less Common but Clinically Significant

8. Malaria (in endemic/travel context)

• Classic triad: headache, vomiting, fever. Diarrhea can occur.
• Goodman & Gilman's documents headache, vomiting, diarrhea, dizziness as prominent features of malaria treatment and infection patterns.
• Ask about travel history.

9. Vestibular Neuritis / Benign Paroxysmal Vertigo of Childhood

• Dizziness is the hallmark; can trigger nausea and vomiting.
• Benign Paroxysmal Vertigo of Childhood (BPVC) is a migraine-related disorder in children aged 2-12.
• No loss of consciousness; episodes brief (seconds to minutes).

10. Abdominal Migraine

• A well-recognized pediatric entity in school-age children.
• Episodic vomiting, central abdominal pain, headache, pallor - often with a family history of migraine.
• Diagnosis of exclusion; diarrhea is less typical but can occur.

11. Diabetic Ketoacidosis (DKA)

• Headache, vomiting, abdominal pain, and altered mental status in a child.
• Diarrhea is less common but can occur.
• Check blood glucose; ketotic smell on breath is a clue.

12. Intussusception (less typical at age 6 but possible)

• More common in 6 months to 3 years, but can occur up to school age.
• Episodic, colicky abdominal pain, vomiting, "currant jelly" stools; headache not typical unless secondary to pain/distress.

Red Flag Features to Assess Immediately

Suggested Immediate Workup

1. Vitals + temperature - fever points to infection
2. Neurological exam - GCS, meningeal signs, fundoscopy
3. Blood glucose - rule out DKA/hypoglycemia
4. CBC, CRP, ESR - infection/inflammation markers
5. Stool microscopy and culture - if diarrhea prominent
6. Blood culture - before antibiotics if meningitis suspected
7. LP (lumbar puncture) - if meningitis is clinically suspected, after ruling out raised ICP
8. CT head - if raised ICP or focal neurology suspected before LP