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Michael Kerin Morgan, Nirav J. Patel, Mary Simons, Elizabeth Anne Ritson and Gillian Z. Heller

Object

Case reports suggest that young age is a critical factor in determining recurrence of brain arteriovenous malformations (AVMs) after surgery. However, other factors that may contribute to the increased risk of recurrence have not been considered. In this study, the authors' goal was to ascertain the risk and risk factors of recurrence after resection of AVMs of the brain.

Methods

A consecutive case series (prospectively collected data) of 600 cases of resection of brain AVMs was retrospectively analyzed. Radiological evidence of recurrence or nonrecurrence, as well as clinical evidence of recurrence, could be established in 427 of these cases that underwent follow-up for more than 350 days after initial surgery. These cases were analyzed using Kaplan-Meier curves and Cox regression with respect to age and the presence of deep venous drainage.

Results

Nine recurrent AVMs were found in 8 patients. By analysis of the Kaplan-Meier curves, the 10-year recurrence rate was 14% for those with deep venous drainage, compared with 4% for those without deep venous drainage. Stratifying by age, in the 0- to 20-year age group, the 10-year recurrence rates were 63% and 13% for those with and without deep venous drainage, respectively. In the 20- to 39-year age group, the rates were 5% and 0% respectively, and in the 40-year and older age group they were 0% and 3%, respectively. The hazard ratio for deep venous drainage, adjusted for age, was 5.97 (95% CI 1.20–29.69, p = 0.029).

Conclusions

The risk of recurrence after AVM resection is significant for young patients with deep venous drainage.

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David Bervini, Michael Kerin Morgan, Elizabeth Anne Ritson and Gillian Heller

Object

The aim of this study was to identify patients who are likely to benefit from surgery for unruptured brain arteriovenous malformations (ubAVMs).

Methods

The authors' database was interrogated for the risk and outcome of hemorrhage after referral and the outcome from surgery. Furthermore, the outcome from surgery incorporated those cases excluded from surgery because of perceived greater risk (sensitivity analysis). Finally, a comparison was made for the authors' patients between the natural history and surgery. Data were collected for 427 consecutively enrolled patients with ubAVMs in a database that included patients who were conservatively managed. Kaplan-Meier analysis was performed on patients observed for more than 1 day to determine the risk of hemorrhage. Variables that may influence the risk of first hemorrhage were assessed using Cox proportional hazard regression models and Kaplan-Meier life table analyses from referral until the first occurrence of the following: hemorrhage, treatment, or last review. The outcome from surgery (leading to a new permanent neurological deficit with last review modified Rankin Scale [mRS] score > 1) was determined. Further sensitivity analysis was made to predict risk from surgery for the total ubAVM cohort by incorporating outcomes of surgical cases as well as cases excluded from surgery because of perceived risk, and assuming an adverse outcome for these excluded cases.

Results

A total of 377 patients with a ubAVM were included in the analysis of the risk of hemorrhage. The 5-year risk of hemorrhage for ubAVM was 11.5%. Hemorrhage resulted in an mRS score > 1 in 14 cases (88% [95% CI 63%–98%]). Patients with Spetzler-Ponce Class A ubAVMs treated by surgery (n = 190) had a risk from surgery of 1.6% (95% CI 0.3%–4.8%) for a permanent neurological deficit leading to an mRS score > 1 and 0.5% (95% CI < 0.1%–3.2%) for a permanent neurological deficit leading to an mRS score > 2. Patients with Spetzler-Ponce Class B ubAVMs treated by surgery (n = 107) had a risk from surgery of 14.0% (95% CI 8.6%–22.0%) for a permanent neurological deficit leading to an mRS score > 1. Sensitivity analysis of Spetzler-Ponce Class B ubAVMs, including those in patients excluded from surgery, showed that the true risk for surgically eligible patients may have been as high as 15.6% (95% CI 9.9%–23.7%) for mRS score > 1, had all patients who were perceived to have a greater risk experienced an adverse outcome. Patients with Spetzler-Ponce Class C ubAVMs treated by surgery (n = 44) had a risk from surgery of 38.6% (95% CI 25.7%–53.4%) for a permanent neurological deficit leading to an mRS score > 1. Sensitivity analysis of Class C ubAVMs, including those harbored by patients excluded from surgery, showed that the true risk for surgically eligible patients may have been as high as 60.9% (95% CI 49.2%–71.5%) for mRS score > 1, had all patients who were perceived to have a greater risk experienced an adverse outcome.

Conclusions

Surgical outcomes for Spetzler-Ponce Class A ubAVMs are better than those for conservative management.

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Michael Kerin Morgan, Andrew Stewart Davidson, Stavros Koustais, Mary Simons and Elizabeth Anne Ritson

Object

Ethylene-vinyl alcohol copolymer embolization is increasingly used preoperatively in the resection of brain arteriovenous malformations (AVMs). However, the case for embolization improving the outcome of resection has not been evaluated. In this paper the authors set out to compare outcomes after surgery for brain AVMs in 2 consecutive periods of practice. In the first period, selective embolization was used without the use of ethylene-vinyl alcohol copolymer. In the second period, selective embolization with ethylene-vinyl alcohol copolymer was performed.

Methods

A consecutive case series (prospectively collected data) was retrospectively analyzed. Adverse outcomes were considered to be an outcome modified Rankin Scale score greater than 2 due to embolization or surgery.

Results

A total of 538 surgical cases were included. The percentages of adverse outcomes were as follows: 0.34% for Spetzler-Martin AVMs less than Grade III (1 of 297 cases); 5.23% (95% CI 2.64%–9.78%) for Grade III AVMs (9 of 172 cases); and 17% (95% CI 10%–28%) for AVMs greater than Grade III (12 of 69 cases). There was no improvement in outcomes from the first period to the second period. The adverse outcome for Grade III brain AVMs in the first period was 5.2% (7 of 135 cases) and in the second period (after ethylene-vinyl alcohol copolymer was introduced) it was 5.4% (2 of 37 cases). For AVMs greater than Grade III, the adverse outcome was 12% (6 of 49 cases) in the first period and 30% (6 of 20 cases) in the second period.

Conclusions

Outcomes for brain AVM surgery were not improved by ethylene-vinyl alcohol copolymer embolization. Preoperative embolization of high-grade AVMs with an ethylene-vinyl alcohol copolymer did not prevent those hemorrhagic complications which embolization is hypothesized to prevent based on theoretical speculations but not demonstrated in practice.