In a 60-year-old man with a 10-year history of abrupt loud thundering noises awakening him shortly after sleep onset, causing anxiety and tachycardia but no pain, who snores, has an Epworth Sleepiness Scale score of 14, and a home sleep study showing a respiratory event index of 10 events per hour with mild hypoxemia while on continuous positive airway pressure (CPAP), is the most likely diagnosis exploding head syndrome rather than early‑morning headache, migraine, or hypnic headache?

Exploding Head Syndrome

This is exploding head syndrome (EHS), not early-morning headache, migraine, or hypnic headache. The clinical presentation—loud thundering noises occurring during sleep-wake transitions, causing anxiety and tachycardia without pain—is pathognomonic for EHS 1, 2.

Diagnostic Reasoning

The key distinguishing features that confirm EHS include:

• Timing: Episodes occur specifically during wake-sleep or sleep-wake transitions, not during established sleep 2, 3
• Phenomenology: Loud explosive or thundering noises without actual pain 1, 2
• Associated symptoms: Tachycardia, anxiety, and fear are characteristic accompanying features 4, 2
• Polysomnographic findings: When captured, EHS attacks occur during stage N1 and N2 sleep transitions 1, 3

Why Not the Other Diagnoses?

Hypnic headache is excluded because it presents with actual headache pain that awakens patients from sleep, typically occurs in older adults (>50 years), and has a predictable "alarm clock" pattern 5. This patient has no pain.

Migraine is ruled out because there is no headache, no typical migraine features (photophobia, phonophobia, nausea), and the episodes lack the characteristic temporal profile of migraine attacks.

Early-morning headache would present with actual head pain upon awakening, often related to sleep apnea or other causes, which is absent here.

The OSA Connection

An important clinical consideration: This patient has documented mild OSA (respiratory event index of 10/hour) with an elevated Epworth Sleepiness Scale score of 14, indicating significant daytime sleepiness 6, 7. Notably, one case report demonstrated complete resolution of EHS after treatment of concurrent OSA with an oral appliance 1. The soft snoring preceding EHS attacks on polysomnography in that case suggests a potential mechanistic link.

Management Algorithm

1. Reassure the patient: EHS is benign and not associated with neurological disease 2, 3
2. Optimize OSA treatment: Given the documented OSA and the case report showing EHS resolution with OSA treatment 1, ensure adequate CPAP therapy or consider alternative OSA treatments
3. If EHS persists despite OSA optimization: Consider clomipramine, which has shown immediate symptom relief in multiple patients 3
4. Monitor: Most patients experience spontaneous improvement over time 2, 3

Clinical Pitfalls

• Don't dismiss as insignificant: While benign, EHS causes clinically significant fear and distress in affected patients 4, 8
• Don't assume it's rare: EHS affects approximately 16-18% of young adults with recurrent episodes 8, though it was historically thought to primarily affect older individuals
• Don't overlook the OSA: The concurrent OSA requires treatment regardless (ESS of 14 indicates significant sleepiness), and treating it may resolve the EHS 1
• Don't order extensive neurological workup: Polysomnographic studies show no epileptiform activity, and the condition has no association with neurological disorders 3

The patient should be informed that only 11% of EHS sufferers report their symptoms to professionals 4, so acknowledgment and validation of the experience is therapeutically important.