Journal of Pediatric Orthopaedics - 2026-09-21 - Journal Article
Low Sensitivity of Neurological Examination, Curve Laterality, and Thoracic Kyphosis for Detecting Chiari I Malformation and Syrinx in Operative Pediatric Scoliosis.
Budd LR, Strahle JM, Vorhies JS, Kelly BA, Chen L, Tang SY, Montgomery BK
Topics
Key Takeaway
Standard screening criteria (abnormal neuro exam, left-sided curve, thoracic hyperkyphosis) collectively missed 34% of patients with confirmed Chiari I malformation and/or syrinx in operative pediatric scoliosis, yielding a combined sensitivity of only 66%.
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Summary
This study evaluated the sensitivity of three standard preoperative MRI screening triggers—abnormal neurological exam, left-sided thoracic curve, and thoracic hyperkyphosis—in 47 surgical scoliosis patients with confirmed CM1 and/or syrinx. Individually, these criteria performed poorly: abnormal neuro exam 19%, left-sided curve 26%, T5-T12 hyperkyphosis 22%, and T2-T5 hyperkyphosis 12%. Combined sensitivity of any one criterion being present was 66%, leaving 34% of neural axis anomaly patients undetected by current screening practice.
Key Limitation
The absence of a control group of MRI-screened operative scoliosis patients without CM1/syrinx prevents calculation of specificity, making it impossible to quantify the trade-off between increased MRI utilization and false-positive rate.
Original Abstract
BACKGROUND
For pediatric patients with presumed adolescent idiopathic scoliosis, surgeons rely on abnormal neurological exam, left-sided thoracic curve, or thoracic hyperkyphosis to initiate preoperative magnetic resonance imaging; however, the sensitivity of these screening criteria for detecting neural axis anomalies of Chiari malformation type I (CM1) and syrinx is not well understood. We aim to determine the frequency of abnormal neurological exam, left-sided thoracic curve, and hyperkyphosis of thoracic curves in patients with operative scoliosis and CM1 and/or syrinx.
METHODS
A retrospective analysis was conducted with patients who underwent surgical management for pediatric scoliosis and were diagnosed with either CM1 (n=4), syrinx (n=23), or both conditions (n=20). Neurological exams before surgery were reviewed and screened for abnormal deep tendon reflexes, abnormal abdominal reflexes, motor disturbance, sensory disturbance, muscle mass asymmetry, spasticity/contracture, abnormal gait, abnormal balance, and ankle clonus. Thoracic curvature direction, T2-T5 kyphosis, and T5-T12 kyphosis were also obtained.
RESULTS
Across all patients with CM1 and/or syrinx that underwent surgery for scoliosis, 9 of 47 (19%) had an abnormal preoperative neurological exam, 11 of 43 (26%) had a left-sided thoracic curve, 5 of 41 (12%) had a T2-T5 hyperkyphosis, and 9 of 41 (22%) had a T5-T12 hyperkyphosis. The T1-T12 kyphosis across the whole cohort averaged 38 degrees. In patients with known CM1 and/or syrinx, the sensitivity of neurological exam abnormality, left-sided curve, or hyperkyphosis was 27 of 41 (66%). Patients with both CM1 and syrinx were not more likely to have an abnormality on imaging or physical exam compared to patients with isolated CM1 or syrinx conditions.
CONCLUSIONS
These results indicate that neurological exam abnormalities, left-sided thoracic curve, and thoracic hyperkyphosis have a relatively low sensitivity when used as a screening metric for detecting CM1 and/or syrinx in patients with scoliosis. Thirty-four percent of patients with CM1/syrinx and operative scoliosis had a normal neurological exam, right-sided curve, and a normal amount of kyphosis. Surgeons should consider the sensitivity of these screening metrics when determining which patients should obtain a preoperative MRI before scoliosis surgery.
LEVELS OF EVIDENCE
Diagnostic studies-investigating a diagnostic test level III with a retrospective analysis.