Epidemiology & Risk Factors

Often diagnosed in children (peak age 2–7 years), but increasingly recognized in adults.
Strongly associated with a personal or family hx of migraines (hypothesized mitochondrial DNA mutations or dysautonomia).
Triggers: Psychological stress (positive or negative), infections (e.g., URI), physical exertion, sleep deprivation, or specific dietary triggers (chocolate, cheese).

Clinical Features

Stereotypical episodes: Each episode is identical in onset, symptoms, and duration within a single patient. c
Divided into 3 phases:
- Prodrome: Intense nausea, pallor, diaphoresis, lethargy.
- Emetic phase: Acute, severe, relentless vomiting/retching (often beginning in early morning, lasting hours to days).
- Recovery phase: Gradual return of appetite and energy.
Symptom-free intervals between episodes (lasting weeks to months).
Accompanying symptoms: Abdominal pain, photophobia, headache.

Primarily a clinical diagnosis of exclusion; no single diagnostic test is available.
Rome IV Criteria:
- $\geq 3$ discrete episodes in the past year (or $\geq 2$ in past 6 months), occurring $\geq 1$ week apart.
- Stereotypic onset and duration (< 1 week).
- Complete absence of vomiting between episodes.
Initial Workup (essential to rule out organic/anatomical causes):
- Key Labs: BMP (assess for hypokalemia, metabolic alkalosis), LFTs, amylase/lipase (to rule out pancreatitis/biliary pathology).
- Imaging: Abdominal US or CT (exclude structural abnormalities like malrotation, intermittent bowel obstruction, or gallstones).
- Upper GI Endoscopy: To exclude severe GERD, gastritis, or PUD.

Cannabinoid Hyperemesis Syndrome (CHS):
- Diff: Chronic, daily marijuana use; vomiting episodes temporarily relieved by hot showers/baths; symptoms resolve completely within weeks of cannabis cessation.
Intestinal Malrotation / Volvulus:
- Diff: Acute-onset bilious vomiting, abdominal distension; diagnosed via upper GI contrast series (corkscrew sign) or abdominal US; represents a surgical emergency.
Inborn Errors of Metabolism (e.g., urea cycle disorders, organic acidemias):
- Diff: Typically presents in infancy/early childhood; associated with developmental delay, hyperammonemia, or metabolic acidosis triggered by fasting or illness.
Abdominal Migraine:
- Diff: Paroxysmal abdominal pain is the predominant symptom rather than vomiting; also associated with migraine FHx.

Acute Phase (Abortive & Supportive):
1. IV Fluid (IVF) resuscitation: Aggressive hydration with normal saline or D5NS + electrolyte replacement (especially K+ and Cl-).
2. Antiemetics: IV ondansetron (5-HT3 antagonist) or IV aprepitant (NK1 receptor antagonist).
3. Migraine Abortives: IV/SC triptans (e.g., sumatriptan) if patient has a personal/family hx of migraines or severe prodromal headache.
4. Supportive: Keep patient in a quiet, dark room; consider sedation with diphenhydramine or lorazepam for severe agitation.
Prophylactic Therapy (Indicated if episodes are frequent, severe, or cause significant loss of school/work days):
1. First-Line (Age ≥ 5 / Adults): Amitriptyline (TCA).
2. First-Line (Age < 5): Cyproheptadine (first-generation antihistamine/antiserotonergic).
3. Alternative Prophylaxis: Propranolol (beta-blocker) or Topiramate.
4. Supplements: Coenzyme Q10 and L-carnitine are frequently used as adjunctive therapies.

Severe dehydration and hypovolemic shock.
Electrolyte abnormalities: Hypokalemia, hypochloremic metabolic alkalosis (due to continuous loss of gastric HCl).
Mallory-Weiss tears (mucosal lacerations at the gastroesophageal junction from repeated retching).
Peptic esophagitis or esophageal perforation (Boerhaave syndrome).
Dental caries/enamel erosion (chronic acid exposure).

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