Posterior fossa decompression with tonsillectomy in 104 cases of basilar impression, Chiari malformation and/or syringomyelia

Abstract

The prime objective in the surgical treatment of basilar impression (BI), Chiari malformation (CM) and/or syringomyelia (SM) is based on the restoration of the normal cerebrospinal fluid (CSF) dynamics at the craniovertebral junction through the creation of a large artificial cisterna magna. A small suboccipital craniectomy has been emphasized to avoid caudal migration of the hindbrain structures into the vertebral canal. Nevertheless, the results showed downward migration of the hindbrain related to that type of craniectomy. The authors present, otherwise, the results of 104 cases of BI, CM and/or SM, whose surgical treatment was characterized by a large craniectomy with the patient in the sitting position, tonsillectomy, large opening of the fourth ventricle and duraplasty with creation of a large artificial cisterna magna. A significant upward migration of the posterior fossa structures was detected by postoperative magnetic resonance imaging. Key words: basilar impression, Chiari malformation, hindbrain herniation, tonsillectomy, craniovertebral decompression, syringomyelia.Descompressão da fossa posterior com tonsilectomia em 104 casos de impressão basilar, malformação de Chiari e/ou siringomielia RESUMO O principal objetivo no tratamento cirúrgico da impressão basilar, malformação de Chiari e/ou siringomielia fundamenta-se na restauração dinâmica do líquido cefalorraqueano ao nível da transição craniovertebral e criação de ampla cisterna magna. Uma craniectomia suboccipital de pequenas dimensões foi proposta para evitar a migração caudal de estruturas rombencefálicas no canal vertebral. Entretanto, os resultados evidenciaram migração caudal do rombencéfalo. Os autores apresentam, por outro lado, os resultados de 104 casos de malformação de Chiari e/ou siringomielia, nos quais o tratamento cirúrgico se baseou em ampla craniectomia com o paciente em posição sentada, tonsilectomia, abertura ampla do quarto ventrículo e enxerto dural com consequente criação de ampla cisterna magna. Uma significante migração cranial das estruturas da fossa posterior foi detectada pelo emprego pós-operatório da ressonância magnética. Palavras-Chave: impressão basilar, malformação de Chiari, herniação rombencefálica, tonsilectomia, descompressão craniovertebral, siringomielia.

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

“…One of the most uncommon signs in BI was fasciculation as described by Raupp et al 15 The authors emphasized the compression-ischemic etiology and ruled that Pozo et al described one similar associated with BI. We have observed three patients with fasciculation in our present paper and four other cases in a recently published paper 16 . A comparative study of symptoms in isolated cases of BI and CM showed that in BI the association of motor and rence of BI, the authors found three couples of relatives in the work: brother and sister, two sisters, and mother and son.…”

“…In six cases of CSF fistula, four were transient, one associated with hydrocephalus underwent a ventriculoperitoneal shunt with complete closure of the CSF leakage, and, finally, one patient died due to meningitis. The authors observed one patient with sensory disturbances is the most frequent, while in CM cases, the cerebellar and vestibular signs predominate with the involvement of the lower cranial nerves 9,16 . Regarding the surgical technique, all 192 patients of our work were operated in the sitting position.…”

“…They recommend tonsillectomy as a protection against slump, eliminating the compressive effect over the medulla and spinal cord, as described by Williams 20 . It also contributes to the creation of a large artificial cisterna magna, which can facilitate an upward migration of the hindbrain structures, as we recently published a report of 104 cases 16 in whom a large artificial cisterna magna was created and an upward migration of the posterior fossa structures was depicted by the postoperative MRI. Batzdorf 27 recommends lightly diathermying of the pia mater over the surface of the tonsils.…”

“…On the other side, Gonçalves da Silva et al 16 using a large craniectomy with the patient in the sitting position, tonsillectomy, large opening of the fourth ventricle, and duraplasty with creation of a large artificial cisterna magna in 104 cases of BI, CM, and/or SM observed a significant upward migration of the posterior fossa structures.…”

Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study

“…It is secondary to a caudal rhombencephalon abnormality with displacement of the cerebellar tonsils into the cervical canal, also commonly associated with syringomyelia 6,7,8 . Diagnosis of CM is mainly based on finding of tonsillar ectopia.…”