Outcomes of patients with syringomyelia undergoing spine deformity surgery: do large syrinxes behave differently from small?

Abstract

Background context: A paucity of data exists studying outcomes of patients with syringomyelia undergoing spinal deformity correction. The literature does not stratify patients by syrinx size, which is likely a major contributor to outcomes.

Purpose: The study aimed to compare differences in outcomes between patients with large (≥4 mm) and small syrinxes (<4 mm) undergoing spinal deformity correction.

Design: This is a retrospective review.

Patient sample: The sample included 28 patients (11 with large syrinx [LS, >4 mm] and 17 with small syrinx [SS, <4 mm]).

Outcome measures: The outcome measures were radiographic, operative, and neurophysiological measures.

Methods: We retrospectively reviewed 28 patients with syringomyelia who underwent spine deformity surgery with 2-year follow-up. Demographic, surgical, and radiographic data were collected and compared preoperatively and at 2 years.

Results: The LS group (11 patients) trended toward more left-sided thoracic curves (36% vs. 18%, p=.38) and was more likely to have had a Chiari decompression (45% vs. 12%, p=.08). The LS patients had larger preoperative major curves (LS=66° vs. SS=57°, p=.05), more thoracic kyphosis (LS=42°, SS=24°, p<.01), and greater rib prominences (LS=16°, SS=13°, p=.04). The LS patients had more levels fused (LS=12.2, SS=11.2, p=.05), higher estimated blood loss (EBL) (LS=1068 cc, SS=832 cc, p=.04), and a trend toward less percent correction of the major curve (LS=57%, SS=65%, p=.18). Four of 11 LS patients (36%) did not have somatosensory evoked potentials, and one of these also did not have motor evoked potentials. Neuromonitoring changes occurred in 3 of 11 (27%) LS patients and in none of the SS patients, with no postoperative deficits.

Conclusions: Outcomes of patients with syringomyelia undergoing spine deformity surgery are dependent on the size of the syrinx. Those with large syringomyelia are fused longer with more EBL and less correction. Spine surgeons should be aware that these patients are more likely to have less reliable neuromonitoring, with a higher chance of experiencing a change.

Keywords: Neuromonitoring; Pediatric spine; Scoliosis; Spinal deformity; Surgery; Syringomyelia; Syrinx.