Fourth ventricle stent placement for treatment of recurrent syringomyelia in patients with type I Chiari malformations

Abstract

OBJECTIVE In patients with syringomyelia and type I Chiari malformation (CM-I) who have required reoperation because of persistent, recurrent, or expanding syrinx, the senior author placed a stent from the fourth ventricle to the cervical subarachnoid space in hopes of promoting circulation of CSF out of the ventricle and away from the central canal of the spinal cord. This study was undertaken to determine the long-term success of this operative stratagem in eliminating the syrinx, as well as to document the complications that occurred following stent placement. The technique utilized for placement of fourth ventricle stents is presented. METHODS The surgical database of the senior author was reviewed to identify all patients who underwent stent placement at a reexploration of a suboccipital decompression for a CM-I conducted for a recurrent or ineffectively treated syringomyelia. The clinical and radiological data of these patients were analyzed to determine long-term efficacy and complications of the procedure. RESULTS Fourteen patients (average age 10.7 ± 5.2 years, range 2.6–20.1 years) were identified who met these inclusion criteria. They each presented with recurrent, residual, or expanding syringomyelia following a prior decompression for a CM-I. The reoperation with stent placement was complicated by late stent dislodgement and recurrence or persistence of the syrinx in 2 patients (14%) and by neurological deficit in 1 patient (7%). There was 1 perioperative CSF leak (7%). In 1 other patient (7%), the stent dislodged after surgery but required no further intervention, as the syrinx remained collapsed. Two patients (14%) required late reoperation for stent replacement when syrinxes recurred. At the most recent imaging follow-up, the stent was positioned appropriately in 12 patients (86%; average follow-up 6.9 years, range 0.5–18.1 years), and the recurrent or residual syrinx was eliminated or reduced in size by 75% or greater in 13 patients (93%). CONCLUSIONS The placement of a stent from the fourth ventricle to the cervical subarachnoid space was a highly effective treatment for patients with recurrent, residual, or expanding syringomyelia following an initial decompression of an associated CM-I. The sole neurological complication in this series was related to lysis of arachnoid scar rather than stent placement itself, but inability to maintain fixation of the stent in situ led to further surgery to replace the stent in 2 patients.