Eleven-Year Diagnostic Delay in Episodic Cluster Headache With a Characteristic International Classification of Headache Disorders, 3rd Edition (ICHD-3) Clinical Pattern: A Case of Migraine Misdiagnosis and Otologic Confusion.

Cluster headache is a primary headache disorder characterized by recurrent attacks of severe unilateral headache accompanied by ipsilateral cranial autonomic symptoms. Despite well-established diagnostic criteria, it remains one of the most frequently misdiagnosed primary headache disorders, resulting in substantial diagnostic delay. We report a diagnostic dilemma involving a 31-year-old man with episodic cluster headache who remained undiagnosed for 11 years despite a clinical presentation highly consistent with the International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria. Throughout the disease course, he experienced recurrent severe unilateral orbital pain lasting 30-60 minutes, occurring more than three times daily during annual cluster periods and accompanied by ipsilateral lacrimation, nasal congestion, rhinorrhea, and marked restlessness. However, he was repeatedly diagnosed with migraine without aura and later underwent ophthalmologic and otolaryngologic evaluations, further delaying recognition of the characteristic headache pattern. Detailed reassessment of the clinical history ultimately led to a clinical diagnosis of episodic cluster headache, and guideline-recommended therapy was followed by substantial clinical improvement. The principal educational feature of this case is how prominent ipsilateral ear pain and distracting otologic and ophthalmologic findings contributed to delayed recognition of an otherwise characteristic cluster headache presentation. Careful assessment of attack duration, periodicity, cranial autonomic symptoms, and restlessness remains essential for timely recognition of cluster headache, particularly when apparently relevant local findings do not adequately explain the overall headache pattern.