Ecchordosis physaliphora presenting as hypnic headache.

Ecchordosis physaliphora (EP) is a rare benign congenital hamartomatous lesion originating from remnants of the notochord. EP has never been associated with hypnic headache before. We report for the first time two cases of EP associated with an hypnic headache. The latter is a form of sleep-related nocturnal headache whose pathogenesis has not been fully elucidated. A 61-year-old woman and a 41-year-old man had been complaining of a dull headache that woke them up every night for many months. In both cases, an enlarged cystic lesion in the prepontine cistern, compatible with ecchordosis physaliphora, was found on brain MRI. A diagnosis of hypnic headache secondary to EP was made. Ecchordosis physaliphora presenting as hypnic headache had never been described before. The low prevalence of both conditions (EP and HH) and their presence in two cases might suggest a possible causal association between the two conditions.