(Research Hub Theater) Evaluating the Relationship Between the Extent of Cerebellar Tonsillar Ectopia and Post-Mild Traumatic Brain Injury Clinical Symptoms

Background and/or Objectives: Cerebellar tonsillar ectopia (CTE) represents a caudal or rostral displacement of the cerebellar tonsils in reference to the base of the skull. Of several pathological associations, CTE is also noted as an incidental finding in mild traumatic brain injury (mTBI). This study focuses on the relationship of CTE descent and the survival of clinical symptomatology reported in mTBI.

Design: Retrospective cohort study

Setting: MRI scanners

Participants: 289 mTBI patients diagnosed using the DSM V by a board-certified neurologist specializing in head trauma.

Interventions: Chart reviewed patients underwent a head-trauma MRI protocol with a 3.0 Tesla MR Signa HDxt system. Axial and sagittal T1, T2, and fluid-attenuated inversion recovery images were used to identify the McRae line, drawn in sagittal plane from the basion to the opisthion, to locate the maximum caudal extent of tonsillar descent. A perpendicular line was then drawn to measure the point of maximal descent of the cerebellar tonsils.

Main Outcome Measures: CTE length and its relation to variability on symptom occurrence and survival.

Results: Dates of symptom presentation/improvement were codified, and interval-censored for survival analysis. In cases where symptoms did not improve during clinical assessment, data were right-censored. Parametric Interval-Censored Cox-Proportional Hazard analysis revealed that caudal cerebellar tonsillar displacement is protective (i.e., associated with prolonged survival) of post-concussive balance deficits (Est.: -0.1017, P=0.00099).

Conclusions: Our study suggests that greater CTE descent is significantly associated with documented balance deficiencies. Clinicians should consider the assessment of CTE in addition to protocol mTBI evaluation to improve diagnostic and therapeutic practices in rehabilitation settings.