Short-lasting unilateral neuralgiform headache (SUNCT) and first division trigeminal neuralgia (TN) are rare and very similar periorbital unilateral pain syndromes. Few cases of SUNCT are associated with posterior skull lesions. We describe a 54-year-old man with symptoms compatible with both the previous painful syndromes, associated with a small posterior skull and a cerebellar hypoplasia. The short height and the reported bone fractures could be compatible with a mild form of osteogenesis imperfecta, previously described in one case associated with SUNCT. However, a hypoplastic posterior cranial fossa characterizes also Chiari I malformation. The difficult differential diagnosis between SUNCT and TN and their relation with posterior skull malformations is debated.