Pneumosinus Dilatans and Hypercalcification of the Falx and Ligamentum Petroclinoideum in Myotonic Dystrophy 1

Objectives: Pneumosinus dilatans (PSD) is a rare condition characterized by abnormally enlarged aerated sinuses, but normal thickness and preserved integrity of the sinus walls. PSD occurs most commonly in young men. Its etiology remains elusive but has been associated with various conditions, such as hydrocephalus, trauma, Dyke-Davidoff syndrome, meningocele, arachnoidal cyst, meningioma, neurofibromatosis 2, and neurolemmoma. PSD has not been reported in myotonic dystrophy type 1 (MD1). Case Report: We present a 43-year-old man with MD1 because of a CTG-expansion of 1333 repeats in the DMPK gene. A computed tomography scan of the cerebrum, carried out for assessment of central nervous system involvement in MD1, surprisingly demonstrated PSD. Because PSD was asymptomatic no surgical treatment was recommended to the patient. Whether PSD was a manifestation of MD1 or a mere coincidence remains elusive. Conclusion: This case shows that PSD may occur together with MD1. Whether this association is causal or coincidental remains to be elucidated. It also remains speculative whether PSD contributes to the facial dysmorphism frequently present in MD1 patients. If PSD becomes symptomatic surgical intervention should be considered.