Clinical Significance of Neonatal Parafrontal Horn Cysts Detected by Cranial Sonography

ABSTRACT

PURPOSE: To describe the significance, incidence and characteristics of sonographic findings and long term outcomes of parafrontal horn cysts detected by screening cranial sonography done within the first week following birth. MATERIALS AND METHODS: 2122 first cranial ultrasound scans performed over a five year period were retrospectively evaluated and 23 neonates with parafrontal horn cysts were found (which are different from secondary cystic lesions). 17 cases had a birth weight of 2400 gm with gestation between 34 and 41 weeks. The size, shape and location of the parafrontal horn cysts and other associated abnormalities shown on the cranial sonogram were evaluated and sequential ultrasound study, maternal records, neonatal events and neurodevelopmental evaluations were retrospectively assessed. RESULTS: Of the 23 subjects, 21 had isolated parafrontal horn cysts and 2 had subependymal hemorrhages. There was no record of any abnormal perinatal history. The cysts were bilateral in 20 neonates and unilateral in the others. The size of the cysts ranged from 3 to 18 mm in diameter (mean 9 mm). Sonographic features of the parafrontal horn cysts were distinctive morphology (elliptical, thin walled) and location (adjacent to the tip of the frontal horn). In 17 of the cases a follow-up cranial sonography was performed, and all parafrontal horn cysts disappeared within 3 to 6 months. Neurodevelopmental outcomes were normal in those 17 cases. CONCLUSION: Screening cranial sonography of neonates discovers isolated parafrontal horn cyst. The incidence of parafrontal horn cysts in neonates in our study was 1.1%. They are present in the first week following birth and resolve themselves without medical treatment within a few months. In addition, they show normal neurodevelopment. The parafrontal cysts are suspected to be a benign variant of normal neurodevelopment.