<%server.execute "isdev.asp"%> The relationship between obesity and symptomatic Chiari I malformation in the pediatric population Lam S, Auffinger B, Tormenti M, Bonfield C, Greene S - J Pediatr Neurosci
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Year : 2015  |  Volume : 10  |  Issue : 4  |  Page : 321-325

The relationship between obesity and symptomatic Chiari I malformation in the pediatric population

1 Section of Neurosurgery, The University of Chicago, Chicago, Illinois, USA
2 Department of Neurosurgery, Children’s Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, Pennsylvania, USA

Date of Web Publication20-Jan-2016

Correspondence Address:
Sandi Lam
Department of Neurosurgery, Baylor College of Medicine, Texas Children's Hospital,6701 Fannin Street, CCC 1230, Houston, TX 77030
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1817-1745.174443

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Background: Concomitant with the rise in childhood obesity in the United States is an increase in the diagnosis of Chiari I malformation (CM1). Objective: To discern a correlation between obesity and CM1, defined as >5 mm of cerebellar tonsillar descent on sagittal magnetic resonance imaging. Methods: Charts of CM1 patients aged 2–20 years were retrospectively reviewed. Chiari size, age, body mass index (BMI), and CM1 signs/symptoms were recorded. Patients were stratified by age: 2–9, 10–14, and 15–20 years. Mixed-effect linear models and linear regression analysis were applied to investigate the relationship between BMI-for-age percentiles and CM1 signs/symptoms. Results: One hundred sixty-seven patients were included (mean age 14.5 ± 2.97 years, BMI 22.98 ± 6.5, and Chiari size 12.27 mm ± 5.91). When adjusted for age, 42% were overweight or obese–higher than normative BMI for children in the studied area (29.6%). When stratified by age, patients between 2 and 9 years were most commonly obese and presented the highest mean BMI (25.66), largest Chiari size (13.58), and highest incidence of headache (75%) and syringomyelia (66.67%). Patients between 15 and 20 years were most commonly overweight and presented the smallest Chiari size (11.76 mm), but the highest incidence of cerebellar (50%) and brainstem (8.55%) compression symptoms. A significant positive correlation existed between BMI and headache in the first two age groups: (R2: 0.36, P = 0.03; R2: 0.39, P = 0.01, respectively). Obese patients had higher incidence of headache in the 10–14 group (R2: 0.37, P = 0.02) and the largest Chiari size in the 15–20 group (R2: 0.40, P = 0.03). Conclusions: The pediatric CM1 population is more likely to be overweight or obese. Younger obese patients presented the highest incidence of Chiari-related headache symptoms, and older obese patients, the highest incidence of findings other than headache. Thus, body weight and age should be considered when evaluating children with CM1.

Keywords: Body mass index, Chiari 1 malformation, idiopathic intracranial hypertension, obesity, pediatric, pseudotumor cerebri, tonsillar descent

How to cite this article:
Lam S, Auffinger B, Tormenti M, Bonfield C, Greene S. The relationship between obesity and symptomatic Chiari I malformation in the pediatric population. J Pediatr Neurosci 2015;10:321-5

How to cite this URL:
Lam S, Auffinger B, Tormenti M, Bonfield C, Greene S. The relationship between obesity and symptomatic Chiari I malformation in the pediatric population. J Pediatr Neurosci [serial online] 2015 [cited 2022 Jan 16];10:321-5. Available from: https://www.pediatricneurosciences.com/text.asp?2015/10/4/321/174443

   Introduction Top

Chiari I malformation (CM1) is characterized by the caudal displacement of the cerebellar tonsils through the foramen magnum, often referred to as tonsillar herniation or ectopia. Radiographically, CM1 is defined as displacement of the tonsils 5 mm or more below the level of the foramen magnum.[1],[2] Symptoms associated with the ectopic tonsils may result from one or multiple mechanisms such as compression of the medulla and upper cervical spinal cord (cranial nerve dysfunction and myelopathy), disruption of the flow of cerebrospinal fluid (CSF) through the foramen magnum (headache, neck pain, formation of syrinx, and subsequent spinal cord dysfunction symptoms), and compression of cerebellar tissue (ataxia, dysequilibrium, and other cerebellar symptoms).[3],[4] Patients are often clinically asymptomatic from this radiographic finding.

There is evidence suggesting a link between idiopathic intracranial hypertension (IIH), or pseudotumor cerebri/IIH, and CM1.[5],[6],[7],[8] IIH is a disorder associated with chronically elevated intracranial pressure (ICP) and has its highest incidence in obese women of childbearing age.[9],[10] Banik et al. reported that 24% of patients diagnosed with IIH also showed the presence of CM1 or “cerebellar ectopia,” with cerebellar tonsil displacement >2 mm but <5 mm below the foramen magnum.[11] They posited that the relationship between IIH and formation of CM1 was not purely coincidental.

While IIH once had been considered a rare disorder, it since has become increasingly common. Among overweight or obese women aged 15–44, the incidence of IIH is estimated to be 13–19 cases/100,000.[12],[13],[14] The increasing incidence of obesity in the United States (U.S.) is hypothesized to be a contributing factor to the increasing incidence of IIH.[12],[13] The obesity epidemic involves children as well as adults. At present 20–25% of children in the U.S. are either overweight or obese, with an even higher prevalence in certain minority groups.[15] Several lines of evidence link obesity to IIH.[12],[13],[16],[17] Two recent studies reported that childhood obesity is strongly associated with an increased risk of IIH in children and adolescents.[18],[19]

With evidence linking the identification of CM1 in individuals diagnosed with IIH, and evidence that obesity is associated with an increased risk of IIH, the relationship between overweight and obese pediatric patients and CM1 warranted further investigation. The purpose of this study was to examine the impact of obesity on the development of symptoms in CM1 patients and to estimate the magnitude of the association between body mass index (BMI) and the likelihood of young patients presenting with symptomatic CM1.

   Methods Top

Patient sample

A retrospective chart review of 167 consecutive pediatric patients with a diagnosis of CM1 seen at Children's Hospital of Pittsburgh between 2007 and 2010 was conducted. Approval for this study was obtained from the University of Pittsburgh Institutional Review Board. Patients up to 20 years of age were evaluated. Data collected included height, weight, age, gender, Chiari size (mm), BMI, and signs (i.e., syrinx, cerebellar, or brainstem compression), and symptoms (i.e., headache) of CM1. For the purposes of this study, CM1 was defined as cerebellar tonsillar position of ≥5 mm below the foramen magnum. Cerebellar tonsillar position was assessed by drawing a line from basion to opisthion and measuring inferior tonsillar displacement in mm below the foramen magnum.[1],[2]

Body mass index calculation and patient stratification

BMI was calculated for each patient at the time of diagnosis based on year 2000 data from the Center for Disease Control BMI-for-age growth charts.[20] Underweight was defined as a BMI below the 5th percentile, normal weight was defined as a BMI between the 5th and 85th percentiles, overweight was defined as a BMI between the 85th and 95th percentiles, and obese was defined as a BMI greater than the 95th percentile. All patients were stratified by age into three main groups: 2–9, 10–14, and 15–20 years. The prepubertal age group had fewer patients.

Statistical analysis

All statistical analyses were carried out in Prism 5 for Mac OS X version 5.0c (GraphPad Software Inc., La Jolla, CA, USA) and STATA 11.1 (StataCorp, College Station, TX, USA). A P < 0.05 was regarded as statistically significant. Mixed-effects linear models and linear regression analysis were applied to investigate the relationship between different BMI-for-age percentiles and signs and symptoms of CM1. Analysis of variance between groups was used to compare variables between the three stratified age groups (2–9, 10–14, and 15–20 years).

   Results Top

The medical records of 167 patients diagnosed with CM1 and seen at Children's Hospital of Pittsburgh between 2007 and 2010 were retrospectively analyzed. No patient had prior surgical treatment for CM1. All patients had complete charts and original magnetic resonance imaging (MRI) scans revealing ≥5 mm of cerebellar tonsillar herniation. The average age at presentation was 14.5 ± 2.97, with a range of 2–20 years. Ninety-four patients (56.2%) were female. The average BMI for all patients was 22.98 ± 6.5, and the mean Chiari size was 12.27 ± 5.91 mm [Table 1]. Twelve patients (7.18%) were 2–9-years-old, 73 (43.71%) were 10–14, and 82 (49.10%) were 15–20. Overall, 42% of the patients were either overweight or obese. According to the BMI-per-age percentiles, two patients (1%) were underweight (BMI < 5th percentile), 96 patients (57%) were normal weight (BMI between the 5th and 85th percentiles), 38 (23%) were overweight (BMI between the 85th and 95th percentiles), and 31 (19%) were obese (BMI > 95th percentile) [Table 2].
Table 1: Patient characteristics

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Table 2: Patients divided by BMI category

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Many patients were symptomatic at presentation. Sixty-one patients (36.5%) had syringomyelia, 92 (55%) complained of headaches, 11 (6.5%) showed cerebellar symptoms, and 9 (5.3%) presented with brainstem symptoms [Table 3]. Thirty-nine patients (23.3%) had clinically asymptomatic tonsillar descent without other radiographic abnormalities. When stratified by age, important differences between age groups and significant correlations (P < 0.05) between the studied variables were identified [Table 4] and [Table 5].
Table 3: Signs and symptoms

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Table 4: Patient characteristics, signs and symptoms stratified by age

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Table 5: Significant correlations stratified by age

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Two to nine-year-old group

Twelve patients were included in this set. This group was comprised of the most obese patients (average BMI: 25.66), with the largest Chiari size (13.58 mm), the highest incidence of syrinx (66.67%), the highest incidence of headache (75%), a low rate of cerebellar symptoms (8.33%), and no brainstem symptoms. Patients from this group with higher weight presented with more symptoms, such as headache (R2: 0.36, P = 0.03), but no occurrence of brainstem dysfunction (R2: −0.41, P = 0.015).

Ten to fourteen-year-old group

This group consisted of 73 patients. When compared with the other two groups, patients from this set presented with the lowest average BMI (21.47), intermediate Chiari size (12.63 mm), the lowest incidence of syrinx (38.69%), the lowest incidence of headaches (51.39%), and a low rate of cerebellar (8.33%) and brainstem symptoms (2.77%). In this group, obese patients presented with significantly higher rates of headache (R2: 0.37, P = 0.02). However, there was no significant correlation between high BMI and the presence of syrinx, Chiari size, or brainstem dysfunction.

Fifteen to twenty-year-old group

Patients from this group (n = 82) were mostly overweight, with a mean BMI-per-age of 23.91, the smallest Chiari size (11.76 mm), high syrinx incidence (63.16%), and intermediate incidence of headache (59.34%). They had the highest rates of cerebellar dysfunction (50%) and the highest rates of brainstem symptoms (8.55%). Obese patients from this group presented a significantly higher Chiari size (R2: 0.40, P = 0.03). However, BMI was inversely correlated with headache (R2: −0.45, P = 0.008).

   Discussion Top

In this study, we retrospectively reviewed presenting characteristics of pediatric patients with CM1. We found a strong association between a BMI greater than the 85th percentile and the diagnosis of CM1 in children and adolescents. While several studies have assessed the link between obesity and IIH,[12],[13] as well as IIH and CM1,[8],[11],[21] to our knowledge, this is the first study to establish a relationship between childhood obesity and CM1 and to investigate the effects of obesity on CM1-related signs and symptoms.

In recent years, childhood obesity has risen to the forefront of health concerns affecting the U.S. For children and adolescents in the U.S., the prevalence of obesity is approximately 16.9%.[15] The morbidity and mortality associated with obesity is well documented, particularly with regard to cardiovascular disease and diabetes.[15],[22] With this trend of ever-increasing rates of obesity in recent decades, there has been a concomitant increase in incidence of IIH, indicating that there may be an association between obesity and IIH.[16],[17],[18] While the pathophysiologic link between obesity and IIH is not fully elucidated, a recent study using three-dimensional volumetric MRI of the brain in adults suggested that impaired CSF homeostasis and venous hemodynamics were present in IIH.[23]

It is reasonable to postulate that elevated ICP, as seen in IIH, contributes to the caudal displacement of the cerebellar tonsils seen in CM1. Banik et al. reported that 16 out of 68 patients (24%) with IIH also had tonsillar ectopia.[11] The majority of these 16 patients were overweight or obese female patients. This is significantly higher than the prevalence of CM1 in the general population, which is estimated to be 0.1–0.5%.[24]

With this study encompassing 167 pediatric patients over a 4-year period, we have attempted to establish a potential link between childhood obesity and diagnosis of CM1 based on existing data on the relationship between obesity, IIH, and CM1. This study demonstrated that pediatric patients presenting with CM1 are more likely to be overweight or obese (42%) when compared to normative BMI values from children for the state of Pennsylvania (29.6%).[25] Our results showed that patients with lower BMI have less CM1-related signs and symptoms than obese patients.

In the study population, BMI-per-age did not have a strict linear correlation with age. Younger patients (2–9 years) were the most obese (BMI: 25.66) and presented a higher incidence of CM1-related symptoms (headache) and signs (syrinx and Chiari size). Although obesity in these patients was significantly correlated with headache, high BMI patients presented less brainstem-related complaints. Patients from the other two stratified groups (10–14 and 15–20 years) were most likely to be overweight (BMI: 21.47 and 23.91, respectively). The analysis of these groups showed that lower BMI patients were less likely to present with headache (68.52% less) and syrinx (58% less) when compared to the most obese group (2–9 years).

Although older patients (15–20 years) presented with the smallest Chiari size, there was a significant correlation between BMI and Chiari size (R2: 0.40, P = 0.03). Patients from this group presented with the highest incidence of cerebellar symptoms (50%)—six times more than patients from the other two groups—and higher incidence of brainstem symptoms (8.55%). However, BMI in this group was inversely correlated with headaches. Further studies are necessary to investigate the mechanisms behind these disparate findings.

The mechanism of the potential link between BMI and CM1 symptoms is not yet understood. It is possible that increased venous pressure in the brain and decreased venous return cause a chronic state of increased ICP, leading to the caudal displacement of the cerebellar tonsils. It is also possible that the skull (and/or posterior fossa) develops to a smaller size due to the mechanical obstruction of increased body mass and neck tissue in obese children.

   Conclusion Top

In summary, the results of this study appear to suggest that the combination of patient age and BMI plays a significant role in the development of CM1 signs and symptoms. Older obese patients presented with significantly larger  Chiari malformation More Detailss, more cerebellar symptoms, and fewer headaches. Obese patients in the younger group presented with more headaches, but lesser cerebellar and brainstem dysfunction. Therefore, both BMI and age should be taken into consideration when evaluating children with CM1. Larger prospective studies would need to be undertaken to explore this association more fully, as well as to address the utility of weight-loss strategies in the prevention or treatment of overweight and obese children with a diagnosis of IIH or CM1.

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Conflicts of interest

There are no conflicts of interest.

   References Top

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]


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