Resolution of syringomyelia in ten cases of "up-and-down Chiari malformation" after posterior fossa decompression Resolução de siringomielia em dez casos de malformação de Chiari observada apenas com o paciente em posição sentada durante a descompressão da fossa posterior

The authors describe ten cases of syringomyelia without hindbrain herniation depicted by preoperative magnetic resonance imaging (MRI) in supine position. However, the herniation was observed in all cases during the operation with the patient in sitting position. The postoperative MRI revealed an intense reduction of the syrinx in all patients, as well as it was also observed a clinical amelioration in all cases. The surgical treatment was based on a large craniectomy with the patient in sitting position, tonsillectomy, large opening of the fourth ventricle and duraplasty with creation of a large cisterna magna.Os autores descrevem 10 casos de siringomielia sem herniação do rombencéfalo, observada na ressonância magnética realizada em decúbito dorsal. Por outro lado, a herniação foi observada em todos os pacientes durante a operação com o paciente em posição sentada. A ressonância magnética pós-operatória evidenciou redução da cavidade siringomiélica nos dez pacientes, bem como foi observada melhora clínica em todos os casos. O tratamento cirúrgico consistiu de craniectomia ampla da fossa posterior, tonsilectomia, abertura ampla do quarto ventrículo e duroplastia com a criação de ampla cisterna magna

Suboccipital craniectomy with opening of the fourth ventricle and duraplasty: study of 192 cases of craniovertebral malformations

The prime objective in the surgical treatment of basilar impression (BI), Chiari malformation (CM), and/or syringomyelia (SM) is based on restoration of the normal cerebrospinal fluid (CSF) dynamics at the craniovertebral junction and creation of a large artificial cisterna magna, avoiding the caudal migration of the hindbrain. It is observed that a large craniectomy might facilitate an upward migration of the posterior fossa structures. There are many surgical techniques to decompress the posterior fossa; however, a gold standard approach remains unclear. The authors present the results of 192 cases of BI, CM, and SM treated between 1975 and 2008 and whose surgical treatment was characterized by a large craniectomy without tonsillectomy with the patient in the sitting position, large opening of the fourth ventricle, and duraplasty