Treatment of “idiopathic” syrinx by atlantoaxial fixation: Report of an experience with nine cases

Abstract

Objective:The authors evaluate the significance of atlantoaxial instability in the management of idiopathic syringomyelia.Background:We recently observed that atlantoaxial dislocation can be present even when the atlantodental interval was within normal range. Atlantoaxial instability can be identified on the basis of facetal mal-alignment or even by direct observation of status of joint during surgery. Our observations are discussed in nine patients where we identified and treated atlantoaxial instability in cases that would otherwise be considered as having “idiopathic” syrinx.Materials and Methods:The authors report experience with nine cases that were diagnosed to have “idiopathic” syrinx. The main bulk of the syrinx was located in the cervico-dorsal spinal region in all cases. One patient had been treated earlier by syringo-subarachnoid shunt surgery and one patient had undergone foramen magnum decompression.Results:On radiological evaluation, eight patients had posterior atlantoaxial facetal (Type B) dislocation. In one patient there was no facetal mal-alignment and was labeled to have axial or central (Type C) facetal instability. All patients were treated by atlantoaxial fixation. All patients improved symptomatically in the immediate postoperative period and the improvement was progressive and sustained on follow-up. In one case, the size of syrinx reduced in the immediate postoperative imaging. In the period of follow-up (range 6–42 months - average 19 months), reduction in the size of syrinx was demonstrated on imaging in three cases.Conclusions:The positive clinical outcome suggests that atlantoaxial instability may be the defining phenomenon in development of previously considered “idiopathic” syringomyelia.

Central atlantoaxial instability as a cause of syringomyelia mimic intramedullary lipoma

“…Identification of central instability as a nodal point of the pathogenesis of a number of clinical entities can have a defining impact on their surgical management. [ 4 5 6 7 8 ] We identified that following atlantoaxial fixation, apart from recovery from neurological symptoms, there can be the reversal of secondary musculoskeletal changes and neural alterations such as short neck, torticollis, basilar invagination, Chiari formation, and syringomyelia. [ 5 6 7 8 9 ] In addition, the patient had C3-4 fusion.…”

“…It was recently identified that atlantoaxial fixation can be the treatment for “idiopathic” syringomyelia and for syringomyelia associated with Chiari formation. [ 5 7 8 ] It was reported that following atlantoaxial fixation, the clinical symptoms recovered dramatically, and the syringomyelia cavity regressed in size in a significant number of cases. [ 5 7 8 ] Our current observation is that when the follow-up imaging is done after more than a year, the syringomyelia cavity regressed in 100 percent cases.…”

Atlantoaxial fixation for failed foramen magnum decompression in patients with Chiari formation

“…[ 1 2 14 ] Our further evaluations of craniovertebral junction-related issues conclude that atlantoaxial instability is the basis of a number of musculoskeletal abnormalities, such as basilar invagination, bone fusions or Klippel-Feil abnormality, assimilation of atlas, C2-3 fusion, bifid posterior arch of atlas, platybasia, short neck, and torticollis, as well as neural abnormalities, such as Chiari formation and syringomyelia, when they are present in conjunction or in isolation. [ 33 34 35 36 37 ] The observation has significant clinical relevance and suggests the need for atlantoaxial fixation in all the mentioned clinical entities and futility of foramen magnum decompression surgery as the mode of surgical treatment. As we identified decrease in the size of syrinx and reversal of tonsillar herniation, we identified reversal of musculoskeletal changes of basilar invagination that begins in the immediate postoperative period following atlantoaxial fixation.…”

Basilar Invagination: Instability Is the Cause and Stabilization Is the Treatment

“…Chronic or longstanding atlantoaxial instability is associated with a host of ‘secondary’ musculoskeletal and neural ‘alterations.’ Musculoskeletal alterations include a number of morphological changes that include platybasia, Klippel-Feil abnormality, assimilation of atlas, bifid arch of atlas and C2–3 fusion and neural alterations that include Chiari formation and syringomyelia [ 13 - 15 ]. The term ‘basilar invagination’ in general is an umbrella term that includes a range of alterations.…”