The Effect of Anaemia on Intra-operative Neuromonitoring Following Correction of Large Scoliosis Curves: Two Case Reports.

The correction of anemia is important in reversing significant intraoperative bilateral motor-evoked potential (MEP) loss following rod placement for correction of large scoliosis curves. This article presents a retrospective review of intraoperative neuromonitoring (IONM) data, anesthesia records, and medical charts of two patients with significant bilateral MEP changes associated with posterior spinal surgery for deformity correction. A 70 kg 12-year-old and a 44 kg 16-year-old female with main thoracic curves underwent a posterior scoliosis correction with multilevel posterior column osteotomies. Following rod insertion, significant reduction in the bilateral lower extremity MEP occurred in both cases despite mean arterial pressure exceeding 70 mmHg, which was presumed to be due to the scale of the correction attempted in the setting of haemorrhage which rendered the patient acutely anaemic, thus compromising cord vasculature and oxygen delivery. The rods were removed and packed red blood cell transfusions were administered in response to acute anaemia as a result of haemorrhage in both cases. Neither was noted to be anaemic preoperatively. Once the MEP signals improved, the rods were reinserted and correction was attempted, limited by neuromonitoring signals and resistance of the bony anchors to pullout. At closure, the MEPs were near baseline in the first case and >50% of baseline in the second. There were no changes in the somatosensory evoked potential signals in either case. Post-operative neurological function was normal in both patients. Correcting the circulating haemoglobin concentration through blood product resuscitation allowed for safe correction of spinal deformity in two cases with significant bilateral MEP loss following the initial placement of rods.

Fusion Extension Leads to Spontaneous Resolution of Symptomatic Disc Herniations Associated With Proximal Junctional Kyphosis: A Report of 3 Cases.

CASES: A retrospective chart and radiographic review was performed of 3 patients presenting with neurological deficits secondary to soft thoracic disc herniation associated with proximal junctional kyphosis. The patients were treated with proximal extension of the construct, correction of the focal sagittal malalignment, and posterior decompressive laminectomy without excision of the herniated disc. All 3 patients made complete neurological recovery and subsequent magnetic resonance imaging showed resolution of the herniated discs. CONCLUSIONS: Laminectomy in conjunction with proximal extension of the construct without formal thoracic discectomy was associated with complete neurological recovery and spontaneous resolution of soft thoracic disc herniations associated with junctional failures.

Responding to Intraoperative Neuromonitoring Changes During Pediatric Coronal Spinal Deformity Surgery.

STUDY DESIGN: Retrospective case study on prospectively collected data. OBJECTIVES: The purpose of this explorative study was: 1) to determine if patterns of spinal cord injury could be detected through intra-operative neuromonitoring (IONM) changes in pediatric patients undergoing spinal deformity corrections, 2) to identify if perfusion based or direct trauma causes of IONM changes could be distinguished, 3) to observe the effects of the interventions performed in response to these events, and 4) to attempt to identify different treatment algorithms for the different causes of IONM alerts. METHODS: Prospectively collected neuromonitoring data in pre-established forms on consecutive pediatric patients undergoing coronal spinal deformity surgery at a single center was reviewed. Real-time data was collected on IONM alerts with >50% loss in signal. Patients with alerts were divided into 2 groups: unilateral changes (direct cord trauma), and bilateral MEP changes (cord perfusion deficits). RESULTS: A total of 97 pediatric patients involving 71 females and 26 males with a mean age of 14.9 (11-18) years were included in this study. There were 39 alerts in 27 patients (27.8% overall incidence). All bilateral changes responded to a combination of transfusion, increasing blood pressure, and rod removal. Unilateral changes as a result of direct trauma, mainly during laminotomies for osteotomies, improved with removal of the causative agent. Following corrective actions in response to the alerts, all cases were completed as planned. Signal returned to near baseline in 20/27 patients at closure, with no new neurological deficits in this series. CONCLUSION: A high incidence of alerts occurred in this series of cases. Dividing IONM changes into perfusion-based vs direct trauma directed treatment to the offending cause, allowing for safe corrections of the deformities. Patients did not need to recover IONM signal to baseline to have a normal neurological examination.