Magnetic resonance imaging–based measures predictive of short-term surgical outcome in patients with Chiari malformation Type I: a pilot study

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>This study identifies quantitative imaging-based measures in patients with Chiari malformation Type I (CM-I) that are associated with positive outcomes after suboccipital decompression with duraplasty.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Fifteen patients in whom CM-I was newly diagnosed underwent MRI preoperatively and 3 months postoperatively. More than 20 previously described morphological and physiological parameters were derived to assess quantitatively the impact of surgery. Postsurgical clinical outcomes were assessed in 2 ways, based on resolution of the patient's chief complaint and using a modified Chicago Chiari Outcome Scale (CCOS). Statistical analyses were performed to identify measures that were different between the unfavorable- and favorable-outcome cohorts. Multivariate analysis was used to identify the strongest predictors of outcome.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>The strongest physiological parameter predictive of outcome was the preoperative maximal cord displacement in the upper cervical region during the cardiac cycle, which was significantly larger in the favorable-outcome subcohorts for both outcome types (p &lt; 0.05). Several hydrodynamic measures revealed significantly larger preoperative-to-postoperative changes in the favorable-outcome subcohort. Predictor sets for the chief-complaint classification included the cord displacement, percent venous drainage through the jugular veins, and normalized cerebral blood flow with 93.3% accuracy. Maximal cord displacement combined with intracranial volume change predicted outcome based on the modified CCOS classification with similar accuracy.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Tested physiological measures were stronger predictors of outcome than the morphological measures in patients with CM-I. Maximal cord displacement and intracranial volume change during the cardiac cycle together with a measure that reflects the cerebral venous drainage pathway emerged as likely predictors of decompression outcome in patients with CM-I.</jats:p></jats:sec>

Chiari malformation and syringomyelia

“…24 Some, including us, believe that reducing the size of the cerebellar tonsils contributes to the enlargement of the cisterna magna and initiates ascent of the tonsils. 13 Duraplasty may affect intracranial compliance 5 and appears to be associated with a lower risk of reoperation. 54…”

“…Intracranial compliance and pressure relationships offer an important area of study. 5 Further study of fluid hydrodynamics and pulsatility may also add to our understanding of both the Chiari anomaly and syringomyelia. The relationship of Chiari anomaly to HCTDs and craniocervical instability is in need of clarification, and there would be advantages to a clearer definition of the genetic bases of Chiari anomalies.…”

Predictive value of posterior cranial fossa morphology in the decompression of Chiari malformation type I

“…They found that ∼80% of the patients experienced relief from the symptoms and signs of CMI, whereas the remaining 20% showed no improvement after surgery. [7] In some studies, the percentage of unfavorable outcomes after PFD was as high as 30%, [8] although a subsequent report noted that postoperative magnetic resonance imaging (MRI) reflected adequate decompression in two-thirds of the patients with unfavorable outcomes. [9] The high rate of unfavorable outcomes has been attributed to poor patient selection rather than to the surgical procedure.…”

“…[9] The high rate of unfavorable outcomes has been attributed to poor patient selection rather than to the surgical procedure. [8–10] As people are always skeptical and prudent regarding health-related services, they will definitely not choose to have surgery if they find that PFD cannot bring them improvement. [11] Most studies of CMI decompression efficacy have considered symptoms, syringomyelia, CSF dynamics, or PCF volumetric changes, whereas few studies have attempted to predict surgical outcome based on preoperative PCF morphology.…”

Effectiveness of modified dural incision to preserve the patency of the occipital sinus in foramen magnum decompression for a patient with Chiari malformation type I

“…Chiari malformation type I (CM-I) is a well-known hindbrain disorder that is characterized by cerebellar tonsillar herniation behind the cervicomedullary junction, which is associated with the hypoplastic posterior cranial fossa, and often accompanied by syringomyelia. [ 1 2 5 ] Foramen magnum decompression (FMD) has been acknowledged as a standard surgical procedure for most of the symptomatic pediatric and adult patients with CM-I. [ 5 6 ] Incision of the dura mater at the posterior fossa is frequently required to relieve the symptoms; a Y-shaped dural incision is usually applied for effective decompression.…”