Pediatric Chiari I malformation: novel and traditional measurements associated with syrinx and surgery

Natural history of Chiari I malformation with syrinx and dilatation of the central canal in the pediatric population: the CHEO experience

PURPOSE

Given that syrinx is often considered an indication of surgery in children with Chiari I malformation (CM1), understanding of the natural history of these patients is very challenging. In this study, we investigate the natural history of children with CM1 that have syrinx and/or prominence of the central canal on presentation.

METHODS

All pediatric Chiari I patients who had syrinx and/or prominence of the central canal who underwent MR imaging of the head and spine from 2007 to 2020 were reviewed. Patients were divided into 3 groups (early surgery, delayed surgery, and conservative management). We focused on those patients who did not initially undergo surgery and had at least 1 year of clinical follow-up. We assessed if there were any radiological features that would correlate with need for delayed surgical intervention.

RESULTS

Thirty-seven patients met the inclusion criteria. Twenty-one patients were female and 16 were male. The mean age at presentation was 8.7 (5.8 SD). Fourteen (38%) patients had early surgical intervention, with a mean of 2.5 months after initial presentation, 8 (16%) had delayed surgery due to new or progressive neurological symptoms and 46% of patients did not require intervention during follow-up. The length of tonsillar herniation and the position of the obex were associated with the need of surgery in patients who were initially treated conservatively.

CONCLUSION

In pediatric patients with CM1 with syringomyelia and prominence of the central canal, conservative treatment is initially appropriate when symptoms are absent or mild. Close follow-up of patients with CM1 and dilatation of the central canal who have an obex position below the foramen magnum and greater tonsillar herniation is suggested, as these patients show a trend towards clinical deterioration over time and may require earlier surgical intervention.

Chiari I malformation: management evolution and technical innovation

BACKGROUND AND DEFINITION

In recent years thanks to the growing use of radiological assessment, Chiari I malformation became one of the major diseases for a neurosurgeon to deal with. CIM can be classified according to the extent of cerebellar tonsil tip into the foramen magnum being a protrusion over five mm considered pathological. Such a disease is a heterogeneous condition with a multifactorial pathogenetic mechanism that can subdivided into a primary and secondary form. Regardless of the form, it seems that CIM is the result of an imbalance between the volume of the braincase and its content. Acquired CIMs are secondary to conditions causing intracranial hypertension or hypotension while the pathogenesis of primary forms is still controversial.

PATHOGENESIS AND TREATMENT

There are several theories in the literature but the most accepted one implies an overcrowding due to a small posterior cranial fossa. While asymptomatic CIM do not need treatment, symptomatic ones prompt for surgical management. Several techniques are proposed being the dilemma centered in the need for dural opening procedures and bony decompression ones.

CONCLUSION

Alongside the paper, the authors will address the novelty presented in the literature on management, diagnosis and pathogenesis in order to offer a better understanding of such a heterogeneous pathology.