# Surgical outcomes in Chiari malformation type I: A quality review from a Scandinavian medium-volume neurosurgical center

## TL;DR

This study examines the surgical outcomes of Chiari malformation type I at a Scandinavian neurosurgery center, finding clinical improvement in most patients but higher-than-expected complication rates.

## Contribution

The study provides outcome data from a medium-volume neurosurgical center, highlighting complication rates and potential quality improvement strategies for Chiari malformation surgery.

## Key findings

- Clinical improvement (CCOS ≥13) was observed in 78% of patients.
- New-onset hydrocephalus was the most frequent complication, occurring in 10% of patients.

## Abstract

Chiari malformation type 1 (CM-I) is characterized by caudal herniation of the cerebellar tonsils through the foramen magnum. Surgical decompression is generally indicated in patients with significant or progressive symptoms, or in clinically relevant or progressing syringomyelia. As CM-I surgery is relatively infrequent in medium-volume neurosurgical centers, outcome data from such settings remain limited. This study evaluates surgical outcomes following CM-I decompression at a Scandinavian medium-sized neurosurgical center.

What are the outcomes of CM-I surgery at the Department of Neurosurgery, Haukeland University Hospital?

We performed a retrospective case series of patients with CM-I treated at our department between 2014 and 2023. The primary outcome was the Chicago Chiari Outcome Scale (CCOS) at the last follow-up. Secondary outcomes were 30-day surgical quality indicators.

Forty patients comprised of 29 (72.5 %) adults and 11 (27.5 %) pediatric patients. Clinical improvement (CCOS ≥13) was observed in 78 %. The observed 30-day quality indicators were reoperations in three patients (7.5 %), infections in two patients (5.0 %), and readmission in seven patients (18 %). Complications within 30 days occurred in six patients (15 %). The most frequent complication was new-onset hydrocephalus, which occurred in four patients (10 %). The median hospital length of stay was 5.5 days. There was no mortality.

Most patients demonstrated clinical improvement, but complication rates exceeded benchmarks. Hydrocephalus was the most frequent issue. We discuss possible interventions to further strengthen CM-I care in our department, with an emphasis on hydrocephalus management.

•Clinical Improvement in Majority of Patients•Radiological Success Despite Variable Clinical Response•Hydrocephalus as Predominant Complication•Proposal for Preoperative ICP Monitoring•Quality Improvement Initiatives Introduced

Clinical Improvement in Majority of Patients

Radiological Success Despite Variable Clinical Response

Hydrocephalus as Predominant Complication

Proposal for Preoperative ICP Monitoring

Quality Improvement Initiatives Introduced