NEUROIMAGING FEATURES OF NEURENTERIC CYSTS - ANALYSIS OF 9 CASES AND REVIEW OF THE LITERATURE

PURPOSE: To gain a better understanding of neurenteric (NE) cysts via correlation of imaging findings and surgical and pathologic data. METH ODS: The medical records, imaging studies, surgical information, and p athologic material were retrospectively reviewed in nine patients with NE cysts, including seven proved and two very probable cases. RESULTS : NE cysts occurred in the cerebellopontine angle in one case and exte nded from the cerebellopontine angle to the C2 level in a second. In t he latter patient and the remaining seven with intraspinal lesions, th e NE cyst was always located anterior to the spinal cord. The most com mon myelographic and CT myelographic appearance was that of a lobulate d intradural extramedullary (IDEM) mass. Two patients had an intramedu llary NE cyst with a somewhat unusual appearing exophytic IDEM-appeari ng expansion that can be a characteristic feature of these lesions. MR imaging demonstrated the NE cyst to be isointense to hyperintense rel ative to cerebrospinal fluid on long TR sequences and isointense or sl ightly hyperintense to cerebrospinal fluid on T1-weighted images. Thes e signal characteristics correlate with the high-protein-content fluid within the cysts, usually described at surgery as milky or mucinous i n character. CONCLUSION: The diagnosis of NE cyst should be considered when imaging studies reveal the presence of a lobulated IDEM or an ex ophytic intramedullary cystic mass, especially in association with ant erior spina bifida or other vertebral anomalies. MR can uniquely confi rm the cystic nature of these masses and is the method of choice for t heir imaging investigation. Because cyst recurrence can occur, MR shou ld also be used for long-term patient follow-up.