Talipes equinovarus congênito e tálus vertical congênito decorrente de doença do corno anterior da medula espinhal: lições da síndrome congênita associada a infecção pelo vírus Zika

Abstract

ABSTRACT Idiopathic congenital talipes equinovarus (iCTEV) and congenital vertical talus (CVT) are structural foot deformities whose etiologies remain incompletely understood. Clinical and histopathological findings described in classic cases have long raised the possibility of neurogenic mechanisms involving the anterior horn of the spinal cord. Similarly, neurogenic arthrogryposis multiplex congenita (AMC) is characterized by congenital joint contractures and muscular and medullary patterns compatible with early motor neuron impairment. Congenital Zika Syndrome (CZS), in turn, represents a contemporary model of congenital viral injury to the central and peripheral nervous systems, including selective neural depletion and calcification of the anterior horn of the spinal cord, frequently associated with foot deformities. Given these convergences, this study aimed to describe and analyze congenital foot deformities in patients with CZS, with clinical, etiological, and pathophysiological emphasis, to support the hypothesis of anterior horn injury as an etiological factor in orthopedic deformities. Secondarily, it illustrates clinical, anatomopathological, and histopathological findings from two pre-Zika stillborns diagnosed with iCTEV and CVT, compares these findings with those observed in CZS and neurogenic AMC, and describes additional foot deformities identified in this case series. Thus, an observational, descriptive, prospective, uncontrolled study was conducted, composed of two complementary subgroups. Subgroup 1 included a coorte of children with CZS followed between December 2016 and June 2019 in a multidisciplinary clinic in Fortaleza, Ceará, with 30-month follow-up and semiannual clinical and radiographic evaluations. Subgroup 2 consisted of an illustrative retrospective analysis of two pre-2015 stillborns with bilateral iCTEV and CVT who underwent autopsy. The evaluation included macroscopic examination of the lumbar spine, histologic analysis of the lumbar spinal cord and lower-limb muscles, and documentation of “ghost fascicles” as well as neural depletion and calcification of the anterior horn. Orthopedic clinical assessments were performed by a team of three pediatric orthopedic surgeons. Among 130 patients with CZS, 11 (8.46%) presented isolated rigid iCTEV, isolated CVT, or both deformities; four (3.08%) met diagnostic criteria for AMC. The pre-Zika iCTEV case showed neural depletion and spinal cord calcification, while both pre-Zika cases exhibited muscular patterns with “ghost fascicles”, characteristic of neurogenic atrophy, similar to those observed in neurogenic AMC and CZS. The foot deformities identified demonstrate a clinical and pathophysiological pattern consistent with motor neuron injury of the anterior horn. The analysis of pre-Zika cases reinforces etiological similarities among iCTEV/CVT, neurogenic AMC, and CZS. The diversity of deformities observed in CZS suggests focal spinal cord involvement capable of producing multiple orthopedic phenotypes. These findings support the hypothesis of a neurogenic etiology for iCTEV and CVT—or at least for a subset of cases—and indicate new directions for etiological, diagnostic, and preventive investigation.