Abstract Purpose To examine the associations between cerebellar tonsillar ectopia and syrinx size on bony spinal canal diameter in pediatric patients to explore the impact of CM with or without SM on the developing spine. Methods Cohorts of patients with CM + SM, CM-only, and neither condition were compared. Anteroposterior (AP) syrinx diameter was measured at C2 (SX 2 ) and C7 (SX 7 ) for patients with syringomyelia. Tonsillar ectopia was measured for all patients in the CM + SM and CM-only cohorts. AP diameter of the bony spinal canal at C2 (SC 2 ) and C7 (SC 7 ) was measured for all patients. Patients were stratified by age and sex in secondary analyses. Results 357 patients had CM + SM and 217 patients had CM-only. Both cohorts had larger SC 2 (p < 0.0001) and SC 7 (p < 0.0001) compared to controls. CM + SM had larger SC 7 (p < 0.0001) but not SC 2 (p = 0.10) compared to CM-only. Increased SX 2 was associated with increased SC 2 (p < 0.0001); both SX 2 and SX 7 were significantly associated with increases in SC 7 (p < 0.0001). Syringes ≥ 3 mm were associated with larger SC 2 and SC 7 compared to syringes < 3 mm (p ≤ 0.002). SC 2 and SC 7 for syringes < 3 mm were not significantly different from CM-only. Children with CM + SM in early childhood/adolescence experienced the greatest percentage spinal canal dilation. Females experienced greater spinal canal dilation than similarly-aged males. Conclusions Patients with CM ± SM experience significant increases in bony cervical spinal canal diameter during development. Syringes ≥ 3 mm with CM are associated with further canal dilation of the spinal canal at syrinx level. The degree of spinal canal dilation appears to be age- and sex-dependent.
Yahanda et al. (Thu,) studied this question.