Cystic Degeneration of Cerebellar Tonsil 1 Year After Chiari I Malformation Surgery: A Case Report and Review of the Literature

Chiari malformation results from a bony structural anomaly of the skull base. The structural defect causes downward displacement of the cerebellar tonsils through the foramen magnum. The herniated tonsils block the normal flow of cerebrospinal fluid, which causes a wide spectrum of clinical symptoms. In May 2015, a 16-year-old girl was referred to our center because of a 1-year history of occipital headache, most often triggered by exercise and physical activity at school. She had experienced new-onset numbness in both hands, more severe on the right side, associated with some degrees of weakness. Eventually, an evaluation of her condition included magnetic resonance imaging in T1 and T2 sequences, which revealed a 20-mm downward migration of the cerebellar tonsils, associated with a cervical cord syrinx at the level of the fourth and fifth cervical vertebrae. The patient underwent posterior fossa decompression and C1 and partial C2 laminectomies. Postoperatively there were no complications, and the patient was discharged on day 3. Postoperatively, she experienced some improvement in her symptoms. After 2 months of routine outpatient follow-up, she was better, the headaches had subsided, she could resume some activities, and there was no paresis in her limbs. In cases of progressive symptoms of Chiari malformation, surgical decompression is important and should be considered after shunt insertion to the hindbrain.