The Reality of Benefit in Surgical Removal for Spinal Cord Cavernous Malformation: Commentary on “Acceptance of Early Surgery for Treatment of Spinal Cord Cavernous Malformation in Contemporary Japan”

Spinal cord cavernous malformations (SCCMs) are relatively common intramedullary lesions characterized by thin, sinusoidal vascular channels without intervening neural tissue. Recent multicenter study from Japan has reported surgical removal of SCCMs was performed in 15.4% of total intramedullary tumor surgeries [1]. The incidence of initial hemorrhagic event is not high, which is estimated about 2.1% per year by meta-analysis [2], however, the risk of rebleeding will increase up to 66% [3]. From the recent analysis of 305 symptomatic patients (83% of patients presented with hemorrhage), an annual hemorrhage rate was calculated to be 8.5% per person-year with 35.1% of 5-year cumulative hemorrhage risk. In this study, prior hemorrhage was independent predictors of subsequent hemorrhage and subsequent hemorrhage events were independent risk factors for worsening of neurological function [4]. Moreover, even in conservative management for SCCMs, 11.3% of cases presented exacerbation of neurological function suggesting the natural history of SCCMs totally seems to be progressive deterioration over time [2].

Therefore, it become a reasonable consensus on surgical removal in symptomatic patients of SCCMs in spite of exiting the potential risk of operative neurological complication. However, the optimal timing for SCCMs is still controversial. Early surgery is generally recommended for symptomatic SCCMs [5,6] and Li et al. [7] have indicated the surgical timing within 3 months provides a higher improved outcome. On the other hand, emergent operation includes some problems because conditions of the spinal cord are not ordinarily suitable for intramedullary perilesional dissection especially in acute phase after hemorrhage. Zevgaridis et al. [6] recommended that 4–6 weeks after a hemorrhage seems to be the optimal timing if lesion is in critical areas. In this phase, lesion removal become easier by a glial scar formation and hematomas in resolution with minimal damage to the spinal cord. Imagama et al. [5] also suggested SCCMs resection after hemorrhage should be conducted after primary and secondary damage to the spinal cord are reduced as much as possible. They concluded surgery may be postponed after maximum motor recovery if patients have preoperative paresis. In addition, surgical outcome is highly influenced by spinal cord level and location presumed to be negative factors especially in thoracolumbar and deep-seated lesion [4,8]. The potential of neurological recovery is also controversial in accordance with preoperative neurological severality. The reality of benefit in surgical removal of SCCMs is also unclear, if patients had tetraplegia of paraplegia without any sign of recovery.

Kurokawa et al. [9] demonstrated the results of surgical timing and outcome for symptomatic SCCMs from multicenter survey. This article has provided contemporary practice pattern in surgical treatment among neurosurgical spine centers in Japan. Kurokawa et al. [9] have found that neurological function was more likely to improve in patients with preoperative modified McCormick scale grade V if they had surgery within 3 months from symptom onset. Although no relationship was found between surgical timing and outcome except for this neurological grade, this result supports early surgery can be beneficial even in patients with critical neurological deficit. And more advanced surgical techniques including neuromonitoring which assist complete and safe operation can provide more aggressive surgical indication and urgent surgical timing.