Cavernous Malformation Surgery in the United States: Validation of a Novel International Classification of Disease, 10th Edition, Clinical Modification Code Search Algorithm and Volume-Driven Surgical Outcomes

Approach Selection Strategies for Repeat Resection of Brain Cavernous Malformations: Cohort Study

BACKGROUND

Neurosurgical management of cerebral cavernous malformations (CMs) often benefits from using skull base approaches. Although many CMs are cured by resection, residual or recurrent disease may require repeat resection.

OBJECTIVE

To review approach selection strategies for reoperation of CMs to aid decision-making for repeat procedures.

METHODS

In this retrospective cohort study, a prospectively maintained single-surgeon registry was queried for patients with CMs who underwent repeat resection from January 1, 1997, to April 30, 2021.

RESULTS

Of 854 consecutive patients, 68 (8%) underwent 2 operations; 40 had accessible data on both. In most reoperations (33/40 [83%]), the index approach was repeated. In most reoperations using the index approach (29/33 [88%]), that approach was deemed ideal (no equivalent or superior alternative), whereas in some (4/33 [12%]), the alternative approach was deemed unsafe because of conformation of the tract. Among patients with reoperations using an alternative approach (7/40 [18%]), 2 with index transsylvian approaches underwent bifrontal transcallosal approaches, 2 with index presigmoid approaches underwent extended retrosigmoid revisions, and 3 with index supracerebellar-infratentorial approaches underwent alternative supracerebellar-infratentorial trajectory revisions. Among patients with reoperations with an alternative approach considered or selected (11/40 [28%]), 8 of 11 patients had a different surgeon for the index resection than for the repeat resection. The extended retrosigmoid-based approaches were used most often for reoperations.

CONCLUSION

Repeat resection of recurrent or residual CMs is a challenging neurosurgical niche at the intersection of cerebrovascular and skull base disciplines. Suboptimal index approaches may limit surgical options for repeat resection.

Long-term outcomes after surgery for brainstem cavernous malformations: analysis of 46 consecutive cases

OBJECTIVE

The objective of this study was to evaluate the long-term outcomes after resection of brainstem cavernous malformations (BSCMs) and to assess the usefulness of the Lawton grading system in these cases.

METHODS

This retrospective study analyzed 46 consecutive patients with BSCMs operated on between July 1990 and December 2020. Outcomes at the last follow-up were defined as favorable (modified Rankin Scale [mRS] score 0-2) or unfavorable (mRS score > 2).

RESULTS

The study cohort comprised 24 men (52%) and 22 women (48%), ranging in age from 8 to 78 years old (median 37 years). In 19 patients (41%), the preoperative mRS score was > 2. All patients had hemorrhagic BSCM. There were 12 (26%) mesencephalic, 19 (41%) pontine, 7 (15%) medullary, and 8 (17%) cerebellar peduncle lesions, with a maximal diameter ranging from 5 to 40 mm (median 15 mm). In total, 24 BSCMs (52%) had bilateral extension crossing the brainstem midline. Lawton grades of 0, I, II, III, IV, V, and VI were defined in 3 (7%), 2 (4%), 10 (22%), 11 (24%), 8 (17%), 7 (15%), and 5 (11%) cases, respectively. Total resection of BSCMs was attained in 43 patients (93%). There were no perioperative deaths. Excluding the 3 most recent cases, the length of follow-up ranged from 56 to 365 months. The majority of patients demonstrated good functional recovery, but regress of the preexisting oculomotor nerve deficit was usually incomplete. No new hemorrhagic events were noted after total resection of BSCMs. In 42 patients (91%), the mRS score at the time of last follow-up was ≤ 2 (favorable outcome), and in 18 (39%), it was 0 (absence of neurological symptoms). Forty-four patients (96%) demonstrated clinical improvement and 2 (4%) had no changes compared with the preoperative period. Multivariate analysis revealed that only lower Lawton grade had a statistically significant independent association (p = 0.0280) with favorable long-term outcome. The area under the receiver operating characteristic curve for prediction of favorable outcome with 7 available Lawton grades of BSCM was 0.93.

CONCLUSIONS

Resection of hemorrhagic BSCMs by an experienced neurosurgeon may be performed safely and effectively, even in severely disabled patients. In the authors' experience, preexisting oculomotor nerve palsy represents the main cause of permanent postoperative neurological morbidity. The Lawton grading system effectively predicts long-term outcome after surgery.

Earlier Age at Surgery for Brain Cavernous Angioma-Related Epilepsy May Achieve Complete Seizure Freedom without Aid of Anti-Seizure Medication

Background: The present study hypothesized that some factors may distinguish between patients with a brain cavernous angioma (BCA), who were free from anti-seizure medication (ASM), and patients who still required ASMs postoperatively. The purpose of the study was thus to identify factors associated with ceasing ASMs for patients with drug-resistant epilepsy secondary to BCA, who underwent BCA removal surgery. Methods: We divided patients into those with drug-resistant epilepsy secondary to BCA who achieved complete seizure freedom without ASMs a year after surgery (No-ASM group) (International League Against Epilepsy (ILAE) classification class I with no epileptiform discharges), and others (ASM group) (ILAE classification ≤ II and/or epileptiform discharges). We statistically compared groups in terms of: (1) age at operation; (2) history of epilepsy; (3) size of BCA; and (4) location of BCA. Results: Overall, a year after the surgery, the No-ASM group comprised 12 patients (48%), and the ASM group comprised 13 patients (52%). In both multi- and univariate logistic regression analyses, age at BCA removal surgery correlated significantly with the No-ASM group (p = 0.043, p = 0.019), but history of epilepsy did not (p = 0.581, p = 0.585). Conclusions: Earlier age at surgery for patients with drug-resistant epilepsy is encouraged to achieve complete seizure freedom without the need for ASMs when the cause of epilepsy is BCA.

The National Inpatient Sample: A Primer for Neurosurgical Big Data Research and Systematic Review

OBJECTIVE

The National Inpatient Sample - the largest all-payer inpatient database in the United States - is an important instrument for big data analysis of neurosurgical inquiries. However, earlier research has determined that many NIS studies are limited by common methodological pitfalls. In this study, we provide the first primer of NIS methodological procedures in the setting of neurosurgical research and review all published neurosurgical studies utilizing the NIS.

METHODS

We designed a protocol for neurosurgical big data research using the NIS, based on the authors' subject matter expertise, NIS documentation, and input and verification from the Healthcare Cost and Utilization Project. We subsequently used a comprehensive search strategy to identify all neurosurgical studies utilizing the NIS in the PubMed and MEDLINE, Embase, and Web of Science databases from inception to August 2021. Studies underwent qualitative categorization (years of the NIS studied, neurosurgical subspecialty, age group, and thematic focus of study objective) and analysis of longitudinal trends.

RESULTS

We identified a canonical, four-step protocol for NIS analysis: study population selection, defining additional clinical variables, identification and coding of outcomes, and statistical analysis. Methodological nuances discussed include identifying neurosurgery-specific admissions, addressing missing data, calculating additional severity and hospital-specific metrics, coding perioperative complications, and applying survey weights to make nationwide estimates. Inherent database limitations and common pitfalls of NIS studies discussed include lack of disease process-specific variables and data following the index admission, inability to calculate certain hospital-specific variables after 2011, performing state-level analyses, conflating hospitalization charges and costs, and not following proper statistical methodology for performing survey-weighted regression. In a systematic review, we identified 647 neurosurgical studies utilizing the NIS. While almost 60% of studies were published after 2015, <10% of studies analyzed NIS data after 2015. The average sample size of studies was 507,352 patients (standard deviation=2,739,900). Most studies analyzed cranial procedures (58.1%) and adults (68.1%). The most prevalent topic areas analyzed were surgical outcome trends (35.7%) and health policy and economics (17.8%), while patient disparities (9.4%) and surgeon or hospital volume (6.6%) were the least studied.

CONCLUSIONS

We present a standardized methodology to analyze the NIS, systematically review the state of the NIS neurosurgical literature, suggest potential future directions for neurosurgical big data inquiries, and outline recommendations to improve the design of future neurosurgical data instruments.