Secondary dystonias and experimental models of dystonia suggest that mechanisms responsible for primary dystonias may lie in the basal ganglia or brainstem. A histological study has been done in three patients with cranial dystonia (blepharospasm with oromandibular dystonia in two, blepharospasm alone in one), and one patient with craniocervical dystonia (oromandibular dystonia with retrocollis). In the patient with blepharospasm alone, an angioma, 0.5 mm in diameter, was found in the dorsal pons at the site of the central tegmental tract, confirming that some patients presenting with primary dystonias may have longstanding lesions in the brainstem. In the three other cases, the striatum, pallidum, thalamus, and brainstem were examined and cell populations in the putamen, substantia nigra, and inferior olives were compared with age-matched controls, but no significant abnormality was found.