Brainstem cavernomas: a surgical challenge

Microsurgical anatomy of safe entry zones on the ventrolateral brainstem: a morphometric study

Surgery of the brainstem is challenging due to the complexity of the area with cranial nerve nuclei, reticular formation, and ascending and descending fibers. Safe entry zones are required to reach the intrinsic lesions of the brainstem. The aim of this study was to provide detailed measurements for anatomical landmark zones of the ventrolateral surface of the human brainstem related to previously described safe entry zones. In this study, 53 complete and 34 midsagittal brainstems were measured using a stainless caliper with an accuracy of 0.01 mm. The distance between the pontomesencephalic and bulbopontine sulci was measured as 26.94 mm. Basilar sulcus-lateral side of pons (origin of the fibers of the trigeminal nerve) distance was 17.23 mm, transverse length of the pyramid 5.42 mm, and vertical length of the pyramid 21.36 mm. Lateral mesencephalic sulcus was 12.73 mm, distance of the lateral mesencephalic sulcus to the oculomotor nerve 13.85 mm, and distance of trigeminal nerve to the upper tip of pyramid 17.58 mm. The transverse length for the inferior olive at midpoint and vertical length were measured as 5.21 mm and 14.77 mm, consequently. The thickness of the superior colliculus was 4.36 mm, and the inferior colliculus 5.06 mm; length of the tectum was 14.5 mm and interpeduncular fossa 11.26 mm. Profound anatomical knowledge and careful analysis of preoperative imaging are mandatory before surgery of the brainstem lesions. The results presented in this study will serve neurosurgeons operating in the brainstem region.

Mortality in Patients with Brainstem Cavernous Malformations

OBJECTIVE

Brainstem cavernous malformations (BSCM)-associated mortality has been reported up to 20% in patients managed conservatively, whereas postoperative mortality rates range from 0 to 1.9%. Our aim was to analyze the actual risk and causes of BSCM-associated mortality in patients managed conservatively and surgically based on our own patient cohort and a systematic literature review.

METHODS

Observational, retrospective single-center study encompassing all patients with BSCM that presented to our institution between 2006 and 2018. In addition, a systematic review was performed on all studies encompassing patients with BSCM managed conservatively and surgically.

RESULTS

Of 118 patients, 54 were treated conservatively (961.0 person years follow-up in total). No BSCM-associated mortality was observed in our conservatively as well as surgically managed patient cohort. Our systematic literature review and analysis revealed an overall BSCM-associated mortality rate of 2.3% (95% CI: 1.6-3.3) in 22 studies comprising 1,251 patients managed conservatively and of 1.3% (95% CI: 0.9-1.7) in 99 studies comprising 3,275 patients with BSCM treated surgically.

CONCLUSION

The BSCM-associated mortality rate in patients managed conservatively is almost as low as in patients treated surgically and much lower than in frequently cited reports, most probably due to the good selection nowadays in regard to surgery.

Risk Factors for Unfavorable Outcomes in Surgically Treated Brainstem Cavernous Malformations

OBJECTIVE

Brainstem cavernous malformations (BSCMs) account for up to 18% of all intracranial cavernous malformations. Due to their complex anatomic location, they represent a significant challenge for neurosurgeons. As such, the identification of risk factors associated with negative outcomes is of significant importance. We analyze a series of 50 cases of BSCMs treated surgically in order to identify risk factors for unfavorable outcomes.

METHODS

Patients who underwent surgical resection of BSCM at our institution between 2000 and 2015 were retrospectively reviewed. Univariate and multivariable logistic regression models were used to identify predictors of unfavorable outcomes, defined as those with a modified Rankin score (mRs) of >2.

RESULTS

Fifty Latin American patients, with a mean age of 35.85 ± 13.06 years, consisting of 29 females (58%) and 21 males (42%), underwent surgical resection. Mean modified Rankin Scale (mRs) score at admission was 2.6 ± 1.05, and the mean BCSM size was 18.00 ± 7.19 mm. The rate of gross total resection was 92%. Overall, 80% of patients showed improved or unchanged clinical status at the last follow-up period; however, only 58% of patients had a favorable outcome with a mean mRs of 2.33 ± 1.136. Multivariable logistic binary regression identified hemorrhagic recurrence (P = 0.040), lower cranial nerve deficit (P = 0.019), and BSCMs >15 mm in diameter (P = 0.006) as predictive factors for unfavorable surgical outcomes.

CONCLUSION

BSCM size, compromise of lower cranial nerves, and hemorrhagic recurrence before surgery were identified as risk factors associated with unfavorable outcomes of surgically treated BSCMs in this cohort.

A systematic review and meta-analysis of surgeries performed for treating deep-seated cerebral cavernous malformations

OBJECTIVE

The clinical benefit of surgery for treatment of deep-seated cerebral cavernous malformations (CCMs) is still a matter of debate. Although the surgical removal of CCMs is widely accepted, the benefits of reducing the rate of haemorrhage must be balanced against the risk of peri-operative morbidity. Here, we provide a systematic review and meta-analysis of the clinical benefits of surgery for treating deeply localised CCMs.

METHODS

A comprehensive search of PubMed and Embase was conducted to identify relevant studies. The rate and a 95% confidence interval (CI) were used to measure the risk of haemorrhage and adverse outcomes.

RESULTS

A total of 34 cohort studies reporting surgeries on CCMs were included in our analysis. Overall, the average post-surgical haemorrhage rate was 1.0% (95% CI: 0.7-1.4%). Nine per cent (95% CI: 6.9-11.3%) of the patients developed adverse events at follow-up following the surgical resection of deep-seated CCMs. The percentage of transient neural defects following surgical resection was 34.6% (95% CI: 29.4-39.9%). The proportions of transient focal neurological defect before and after the year 2006 were 44.9% (95% CI: 34.1-55.8%) and 30.3% (95% CI: 25.1-35.9%), respectively.

CONCLUSIONS

Our meta-analysis demonstrates post-surgical haemorrhage rate and complications related to surgeries on deep-seated CCMs. The post-surgical haemorrhage rate was low with a relatively high rate of post-surgical complications.

Hemorrhage risk, surgical management, and functional outcome of brainstem cavernous malformations

OBJECT

The aim of this study was to evaluate the pre- and postoperative rehemorrhage risk, neurological function outcome, and prognostic factors of surgically treated brainstem cavernous malformations (CMs) with long-term follow-up.

METHODS

The authors conducted a retrospective review of the clinical data from 242 patients with brainstem CMs that were surgically treated between 1999 and 2010. Patient charts, imaging findings, and outcomes were examined.

RESULTS

The study included 242 patients, with a male-to-female ratio of 1.3 and mean age of 32.6 years. The mean modified Rankin Scale scores on admission, at discharge, at 3 and 6 months after surgery, and at recent evaluation were 2.2, 2.6, 2.3, 1.8, and 1.5, respectively. The preoperative calculated annual hemorrhage and rehemorrhage rates were 5.0% and 60.9%, respectively. The complete resection rate was 95%. Surgical morbidity occurred in 112 patients (46.3%). Eighty-five patients (35.1%) demonstrated worsened condition immediately after surgery; 34 (41.0%) and 51 (61.4%) of these patients recovered to their baseline level within 3 and 6 months after surgery, respectively. At a mean follow-up of 89.4 months, the patients' condition had improved in 147 cases (60.7%), was unchanged in 70 cases (28.9%), and had worsened in 25 cases (10.3%). A total of 8 hemorrhages occurred in 6 patients, and the postoperative annual hemorrhage rate was 0.4%. Permanent morbidity remained in 65 patients (26.9%). The adverse factors for preoperative rehemorrhage were age ≥ 50 years, size ≥ 2 cm, and perilesional edema. The risk factors for postoperative hemorrhage were developmental venous anomaly and incomplete resection. The independent adverse factors for long-term outcome were increased age, multiple hemorrhages, ventral-seated lesions, and poor preoperative status. Favorable, complete improvement in the postoperative deficits over time was correlated with good preoperative neurological function and continuing improvement thereafter.

CONCLUSIONS

Favorable long-term outcomes and significantly low postoperative annual hemorrhage rates were achieved via surgery. Total resection should be attempted with an aim of minimal injury to neurological function; however, postoperative deficits can improve during the postoperative course. Close follow-up with radiological examination is proposed for patients with adverse factors predictive of rehemorrhage.