Spinal cord cavernous malformations (SCCM) are relatively rare entities comprising 5%– 12% of all spinal cord vascular lesions, affecting mostly the cervical and thoracic segments. It is estimated that 12% of patients affected by this condition will have positive family history of SCCM and up to 16.5% will have associated intracranial cavernomas [1]. Diagnosis is usually made at the midages and data on sex predilection is divergent, although gathered evidenced supports the existence of an equilibrium [1]. They may be asymptomatic or present as variable degrees of myelopathy. Chronic progressive symptoms seem to originate from microhemorrhage, microcirculatory variations, and partial thrombosis, whereas acute presentations are often related to frank hemorrhage [2]. Surgery is the mainstay treatment for symptomatic cases, although the appropriate timing and patient selection is subject of debate [1].
In this elegant study, Cai et al. [3] describe their experience on microsurgical treatment of symptomatic SCCM. Clinical presentation, surgical outcomes, and factors related to spontaneous hemorrhage and neurological outcomes were assessed. The neurological outcome was measured using the modified McCormick scale (MMCS). Surgeries were performed by 2 experienced surgeons using a posterior approach with either laminectomy or laminoplasty. Microsurgical technique was used in all cases and the myelotomy was performed in the midline or along the posterior lateral sulcus, depending on SCCM position inside the parenchyma.
The present study analyses the outcome in 29 consecutive patients (12 females and 17 males) treated in a single center from June 2014 to May 2021. The current cohort is similar in many aspects to prior studies [1,4], however, they differ in a male predominance (1.4:1 ratio) and an increased prevalence of bladder/bowel dysfunction over motor/sensory dysfunction. Seven patients (24.1%) presented severe preoperative deficits (MMCS IV/V). It is important to highlight that the MMCS focuses on motor and sensory functions, while a large proportion of individuals in this series had symptoms related to visceral dysfunction. Although not being the purpose of this study, a better description of the outcome in terms of sphincter continence and pain scores would be interesting as SCCM are rare and reports in the literature are limited.
In their series, all patients had a gross total resection, with some experiencing a transient neurological decline after surgery. By the last follow-up, 19 patients (65.5%) had an objective improvement of neurological function and 6 cases (20.7%) declined in performance. Unfavorable outcomes occurred in patients with recurrent hemorrhages, whereas older age and lower preoperative MMCS scores correlated with better functional results [3]. Interestingly, chronic presentation and longer duration of symptoms were consistent with better outcome, conflicting with the conclusion of a recent systematic review that reported duration of symptoms less than 3 months prior to surgery to lead a better functional status [5]. Arguments favoring early intervention include that chronic damage to the perilesional neural tissue produces gliosis that can interfere with microsurgical dissection, increasing the chances of postoperative neurological deficits and early surgery is recommended after an acute hemorrhage, when the blood has created a dissection plane and adherences were not formed [4,6]. Nevertheless, the current study demonstrate that functional improvement can be achieved when appropriate and careful microdissection is performed by an experienced surgeon, even in complex cases of SCCM presenting along a chronic timeline.
The annual hemorrhage rate found in this study was 2.1%. Eighteen cases (62.0%) had symptoms related to acute hemorrhage, with half of these patients presenting recurrent events. Smaller lesions had higher risk of bleeding and acute presentations had worse preoperative MMCS [3]. Thoracic location and recurrent bleeding were found to predict poor outcome and the authors advocate early surgical intervention in such cases.
In conclusion, this study brings valuable information as it shows that surgery may have better results in patients with chronic presentation and provide evidence that thoracic location and recurrent hemorrhage associate with poorer functional outcome. The discrepancies in demographical and clinical presentation to previous reports suggest the occurrence of heterogeneity in this population. Identifying subsets of patients who are more likely to benefit from early surgery is of great importance in clinical practice. The contrary is also relevant, as surgical risks may overcome benefits in patients at low risk of bleeding, especially when the SCCM is deep seated not in contact with the dorsal pial surface.
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