Incidence of idiopathic syrinx in pediatric patients diagnosed with VACTERL association

Objective: While the association of a syrinx with a tethered spinal cord in the context of VACTERL (vertebral defects [V], imperforate anus or anal atresia [A], cardiac malformations [C], tracheoesophageal defects [T] with or without esophageal atresia [E], renal anomalies [R], and limb defects [L]) association is known, the incidence of idiopathic syrinxes among these patients has not previously been reported. The authors aimed to characterize the incidence of syrinxes and the pattern of congenital anomalies in pediatric patients with VACTERL association, with a specific focus on the presence of idiopathic syrinxes in this population.

Methods: An institutional database was retrospectively queried for all pediatric patients with VACTERL association. Patients were assessed for the presence of a syrinx. Those with no accompanying lesion to which the syrinx could be ascribed were designated idiopathic. Descriptive statistics and qualitative analyses characterized the clinical presentation and outcomes of this population.

Results: The authors retrospectively identified 186 patients between 1993 and 2023 with VACTERL association. Of these 186 patients, 141 (75.8%) had a tethered spinal cord and 44 (23.7%) had a syrinx. Most syrinxes could be ascribed to the presence of a tethered spinal cord and/or Chiari malformation; however, 4 (9.1%) of the 44 appeared idiopathic, suggesting the incidence of idiopathic syrinxes in this patient population may be as high as 2.2% (4/186). Most patients remained asymptomatic aside from a single patient who presented with mild gait dysfunction that resolved over time. All syrinxes were managed conservatively, and all but one decreased or remained stable in size on follow-up imaging.

Conclusions: Although limited, current estimates suggest the general incidence of an idiopathic syrinx is between 5.6 and 8.4 per 100,000 people; these findings in a pediatric cohort with VACTERL association suggest an incidence of 2200 per 100,000 (i.e., 2.2%). Thus, an idiopathic syrinx may be 200-400 times as prevalent in the pediatric VACTERL population.