A recent post contained a picture of cystic degeneration of the cerebellar tonsil in an adult patient. Stevenson et al. studied this phenomenon in children in 2009. On review of a database of 400 pediatric patients undergoing posterior fossa decompression for the Chiari I malformation, the investigators found 3 in which cystic degeneration was subtly evident in the pre-operative MRI and more clearly seen on intraoperative ultrasonography. Regarding treatment:
In each patient, the tonsillar cyst was resected. Histological examination revealed areas of cystic degenerative change characterized by distortion of the normal cerebellar architecture with absent Purkinje and internal granular cell layers. All children experienced improvement in their symptoms, without complication, postoperatively.
The investigators conclude:
Cystic degeneration of the tonsils in pediatric patients with CM-I is an uncommon pathological process most likely resulting from long-standing and excessive compression. Based on their experience, the authors advocate expeditious surgical treatment, including intradural exploration and capacious duraplasty, for patients in whom there is evidence of this phenomenon on preoperative imaging.