Delayed neurological deterioration after surgery for intraspinal meningiomas: Ischemia-reperfusion injury in a rat model

Delayed neurological deterioration in the absence of direct cord insult following surgical removal and cord decompression is a rare but severe postoperative complication in a small subset of patients with intraspinal meningiomas. To date, the underlying pathophysiology of such a finding remains unclear and ischemia-reperfusion injury (IRI) is considered as the potential etiology in the literature. However, no experimental research has been reported to prove this hypothesis. The present study investigated whether IRI occurs following decompression surgery using an experimental rat model of chronic compressive spinal cord injury (SCI). A chronic spinal cord compression model was developed with various sizes of polymer sheets (mild and severe compression) that were microsurgically implanted underneath the T8-9 laminae, and occurrence of IRI in the spinal cord following decompression was determined by measuring superoxide dismutase (SOD) level and malondialdehyde (MDA) concentration. In the mild compression groups, after decompression SOD activities significantly increased along with a reduction in MDA content compared with the non-decompression group (P<0.05), which exhibited diminishment of lipid peroxidation and relief of the secondary injury. These findings indicated that decompression is effective to improve neurological recovery and may deliver improved outcomes for chronic mild compression of the spinal cord. However, in severe compression groups, after decompression, SOD activities markedly reduced further along with a significant increase in MDA content compared with non-decompression group (P<0.05). The results indicated that lipid peroxidation increased immediately after decompression surgery which resulted from reperfusion of the spinal cord. These findings demonstrated IRI may occur as a result of chronic severe compression of the spinal cord. In clinical practice, sudden cord expansion and reperfusion may have lead to disruption in the blood spinal cord barrier, and triggered a cascade of IRI resulting in postoperative neurologic deterioration. Recognition of this neurological deterioration following removal for intraspinal meningiomas may improve preoperative patient counseling and merits further study for determination of the precise pathophysiology.