Original ArticlePredictive Factors of Headache Resolution After Chiari Type 1 Malformation Surgery
Introduction
Chiari type 1 malformation (CM1) is characterized by ectopia of cerebellar tonsils through the foramen magnum into the spinal canal. A syrinx can be associated at the time of diagnosis or may appear secondarily and manifest with medullary symptoms. The exact prevalence of CM1 in the general population is unknown but is estimated to be 0.5%–0.9% in adults and 1% in children.1, 2 The onset of CM1 symptoms usually occurs in the second or third decade. Headache is the most common symptom, occurring in 30%–90% of patients.3, 4, 5 Headaches are typically posterior, exacerbated by cough or Valsalva maneuvers or induced by cervical motion. Headaches attributed to Chiari criteria were established by the International Classification of Headache Disorders, third edition.6 Headaches can be isolated or associated with other symptoms, such as vertigo, ataxia, and limb weakness or numbness. Several theories have been advanced to explain the physiopathologic mechanisms of CM1. At the present time, these mechanisms are thought to involve obstruction to the flow of cerebrospinal fluid (CSF) in the craniocervical junction and lower intracranial compliance.7, 8, 9, 10 Management is primarily surgical, and the goal is to restore normal CSF flow and normal intracranial compliance as well, decompressing the posterior fossa. To date, evidence-based guidelines for surgical intervention are undefined. There is wide agreement for a nonoperative approach in asymptomatic patients, unless there is a multilevel syrinx.11 In contrast, faced with isolated clinical manifestations, the difficulty lies in establishing the imputability of CM1, which would then justify a decompressive procedure. In the absence of objective neurologic signs, the neurosurgeon mainly relies on headache symptoms. However, headaches are often polymorphous and poorly characterized. The whole pattern of CM1 headache is not well established in the literature.12, 13, 14 Given the high prevalence of primary headaches, such as migraine or tension headache,15, 16, 17 the challenge is to distinguish headaches actually related to CM1 from headaches that coexist in independently with CM1. Standardized prognostic tools are needed to stratify the probability of postoperative improvement of these headaches. To date, several studies have attempted to identify predictive factors of favorable outcomes in patients with CM1, but none of them focused on the headache itself.18, 19 More recently, researchers at the University of Washington have developed a preoperative grading system, the Chiari Severity Index (CSI), which takes into account headache as well as syrinx characteristics.20, 21 In this study, we sought to better characterize headache patterns and to determine clinical and radiologic predictive factors of headache resolution after surgery. To determine if this score is reproducible, we then applied the CSI to our cohort.
Section snippets
Study Design and Subjects
This retrospective clinical study was conducted between May 2011 and May 2016 at Rouen University Hospital. The study protocol was approved by the Ethics Committee of Rouen University Hospital. All patients were referred to the Department of Neurosurgery for surgical decompression of the posterior fossa in the context of CM1. We included all patients with CM1 and preoperative headaches not attributed to another evident cause and who had a postoperative follow-up of at least 6 months.
The
Clinical and Surgical Characteristics
In our cohort of 49 patients, mean age at diagnosis was 37.4 years (IQR, 18–60 years) with a male-to-female sex ratio of 3:1. Headache was the main symptom in 37 patients (75.5%). The mean headache duration before surgery was 3.4 years (IQR, 0.5–10 years). Headaches were associated with other symptoms in 41 patients (83.6%) and were isolated in 8 patients (16.3%). Main headache characteristics are presented in Figure 2. Of 49 patients, 28 (57.2%) had improved headache and 21 (42.8%) had
Discussion
The aim of this retrospective study was to investigate the predictive factors of headache resolution after surgery in patients with CM1. An improvement in headache, regardless of type, was observed in 57% of our cohort. In the literature, this rate is approximately 70%–80%, but most studies considered patients with classic cough headache only and not headaches with atypical features.26, 27, 28 Symptoms other than headache improved in 76% of our patients, which is consistent with data in the
Conclusions
This study emphasizes the relevance of IHS criteria for the identification of headaches related to CM1. Each of these criteria seems to be an individual predictive factor of headache resolution after surgery. The systematic use of a preoperative questionnaire that incorporates these IHS criteria could be helpful. Finally, no predictive factor could be identified on conventional MRI, emphasizing the role of lower compliance and CSF flux disturbances as responsible for headache rather than a
Acknowledgments
The authors thank all the patients who were involved in this study Nikki Sabourin-Gibbs, Rouen University Hospital, for her help in editing the manuscript.
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2021, Pediatric Clinics of North AmericaCitation Excerpt :Approximately 80% of patients meeting IHS criteria for CM1-related headache will have headache resolution after Chiari decompression. Only half of patients with other headache types had improved after Chiari decompression.15,29 Care should be taken when recommending surgery for CM1 when headache is the only symptom.
Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.