A new supportive approach in the diagnosis of Chiari malformation type 1 in pediatric patients

PURPOSE

Chiari malformation type 1 (CM-1) is a posterior fossa anomaly characterized by herniation of the cerebellar tonsils from the foramen magnum (FM). This study compares FM, medulla spinalis (MS), and herniated cerebellar tonsils ratios by making area measurements from axial plane MRI in CM-1 patients and the control group.

METHODS

Our study evaluated 30 pediatric patients with CM-1 and 30 people in the control group. The lengths of the McRae line, twining line, and clivus line were measured on the posterior cranial fossa evaluation. The areas of FM (A_FM), MS (A_MS), and herniated cerebellar tonsils (A_TONSILS) were measured by axial images.

RESULTS

As a result of area measurements obtained from axial cross-sectional MRI, a statistically significant difference was found between CM-1 patients and the control group. According to the results of the ROC analysis, if an individual's A_MS/A_FM value is above 17.9% or the A_TONSILS/A_FM value is above 18.4%, it can be interpreted as a CM-1 patient.

CONCLUSION

It will be easier to diagnose the patient with the new approach we obtained from axial MR images in addition to sagittal MR images. This method can be a guide in some cases when the surgeons are undecided.

Chiari malformasyonu Tip-I’de fossa cranii posterior morfometrisinin radyolojik olarak değerlendirilmesi

Amaç:. Bu çalışmada, Chiari Malformasyonu Tip-I hastaları ve kontrol grubuna ait Manyetik Rezonans (MR) görüntülerinde fossa cranii posterior (FCP) ve cranium’ a ait morfometrik ölçümler yapılarak oluşan morfolojik değişiklikleri değerlendirmek amaçlandı. Gereç ve Yöntem: Çalışmamız retrospektif nitelikte olup çalışmaya 21 ve 47 yaş aralığında 32 kişilik kontrol grubu (16 kadın, 16 erkek) ve 12 kişilik CMI’ lı hasta grubu (6 erkek, 6 kadın) dahil edildi. CMI’ lı hasta ve kontrol grubuna ait T2 ağırlıklı MR görüntüleri üzerinde ölçümler yapıldı. Bulgular: Maksimum cranial uzunluk, maksimum cranial yükseklik, foramen magnum sagittal çapı, basis cranii uzunluğu, supraocciput uzunluğu, clivus uzunluğu, fossa cranii posterior’ un ön-arka çapı, occipital cord uzunluğu, cerebellum yüksekliği, herniasyon miktarı CMI’ lı hastalarda sırasıyla 164.13±10.67mm, 134.60 ±10.71 mm, 36.89±5.28 mm, 108.5±7.9 mm, 38.5±3.7 mm, 36.7±7.1 mm, 84.9±8.8 mm, 79.7±11.5 mm, 53.3±4.2 mm, 7.8±4.9 mm olarak ölçüldü. Sonuç: Sağlıklı bireylere ait değerlerle karşılaştırıldığında, CMI’lı hastalarda foramen magnum ön-arka çapında ve tonsiller herniasyonda artış; clivus uzunluğu, occipital cord uzunluğu ve supraocciput uzunluğunda azalma olduğu görüldü. CMI‘lı hastalara ait FCP morfometrisinin bilinmesinin hastaların takibine ve cerrahisine katkı sağlayacağı düşünüldü.

Correlation of a new hydrodynamic index with other effective indexes in Chiari I malformation patients with different associations

This study aimed to find a new CSF hydrodynamic index to assess Chiari type I malformation (CM-I) patients’ conditions and examine the relationship of this new index with morphometric and volumetric changes in these patients and their clinical symptoms. To this end, 58 CM-I patients in four groups and 20 healthy subjects underwent PC-MRI. Ten morphometric and three volumetric parameters were calculated. The CSF hydrodynamic parameters were also analyzed through computational fluid dynamic (CFD) simulation. The maximum CSF pressure was identified as a new hydrodynamic parameter to assess the CM-I patients’ conditions. This parameter was similar in patients with the same symptoms regardless of the group to which they belonged. The result showed a weak correlation between the maximum CSF pressure and the morphometric parameters in the patients. Among the volumetric parameters, PCF volume had the highest correlation with the maximum CSF pressure, which its value being higher in patients with CM-I/SM/scoliosis (R² = 65.6%, P = 0.0022) than in the other patients. PCF volume was the more relevant volumetric parameter to assess the patients’ symptoms. The values of PCF volume were greater in patients that headache symptom was more obvious than other symptoms, as compared to the other patients.

Clivus length distinguishes between asymptomatic healthy controls and symptomatic adult women with Chiari malformation type I

PURPOSE

While the presence of cerebellar tonsillar descent in radiological images has been used as evidence of Chiari malformation type I (CMI), tonsillar ectopia alone is insufficient to identify individuals with symptomatic CMI. This study sought to identify differences in brain morphology between symptomatic CMI and healthy controls in adult females.

METHODS

Two hundred and ten adult females with symptomatic CMI and 90 age- and body mass index-matched asymptomatic female controls were compared using seven brain morphometric measures visible on magnetic resonance images. The CMI and control groups were divided into four subgroups based on the tonsillar position (TP) relative to the foramen magnum: group 1 was made up of healthy controls with normal TP (TP < 0 mm); group 2 was comprised of control individuals with low-lying TP (1-5 mm); group 3 was comprised of symptomatic CMI patients with low-lying TP (1-5 mm); group 4 contained symptomatic CMI patients with severe tonsillar descent (6-13 mm).

RESULTS

All morphometrics for symptomatic CMI with severe tonsillar descent were significantly different than those for both control groups. The CMI group with low-lying TP was significantly different for four measures when compared to controls with normal TP. However, only clivus length was statistically different between the CMI and healthy control groups with low-lying TP.

CONCLUSION

This study demonstrates that clivus length distinguishes adult female healthy individuals with low-lying tonsils from those with symptomatic CMI. Further investigation is required to understand the importance of a shorter clivus length on CMI symptomatology and pathophysiology.

Quantification of changes in brain morphology following posterior fossa decompression surgery in women treated for Chiari malformation type 1

PURPOSE

While 84% of patients surgically treated for Chiari malformation type 1 (CM1) demonstrate improved quality of life after posterior fossa decompression surgery, there are many risks associated with this surgery. Surgical planning to identify candidates likely to improve postoperatively may benefit from an improved understanding of morphological changes after decompression surgery. To evaluate these changes, we quantified 59 morphological parameters on 42 CM1 adult female patients before and after CM1 decompression surgery.

METHODS

Fifty-nine morphological parameters in the posterior cranial fossa, cranio-cervical, and intracranial regions in the midsagittal plane were evaluated using 42 T1-weighted magnetic resonance images of female CM1 patients before and after surgery, and 42 healthy female controls. Morphological differences before and after surgery were compared through the development of a technique to establish the opisthion location, a key reference point not present after surgery.

RESULTS

In addition to the expected reduction of the cranio-caudal dimension of the cerebellum, objective analyses showed a significant increase in the area of the cerebrospinal fluid spaces, posterior (6×) and inferior (2.6×) to the cerebellum (+ 112 ± 102 and + 140 ± 127 mm2, respectively). This increased area was primarily impacted by an average reduction in the occipital bone length of 24.5 ± 7.3 mm following surgery. Based on multiple angles, results demonstrated a 2°-4° anterior rotation of the cerebellum after surgery.

CONCLUSION

Our results show that decompression surgery results in significant changes in the cerebellum and cerebrospinal fluid spaces. Further investigation should determine how these morphological changes impact clinical outcomes.

Quantification of Cerebellar Crowding in Type I Chiari Malformation

This study was focused on a semi-automated morphometric analysis of the cerebellum in the mid-sagittal plane as an alternative to tonsillar descent alone in the evaluation of Chiari malformation type 1 (CMI) patients. Morphometric analyses of posterior fossa structures were performed on mid-sagittal MRI images of 375 individuals (females, > 18 years, 235 CMI and 140 healthy controls). Twenty-six parameters including linear, angular and area measurements together with non-dimensional ratios were calculated. Eighteen parameters were found to be significantly different between CMI and control subjects. Smaller posterior cranial fossa (PCF) area in CMI subjects was attributed to a smaller PCF area anterior to the brainstem. The cerebellar area was found to be larger in CMI subjects as compared to controls (15.1%), even without inclusion of the tonsillar area below the foramen magnum (FM) (8.4%). The larger cerebellar area in CMI subjects was due to cranial-caudal elongation of the cerebellum, predominately below the fastigium. The cerebrospinal fluid spaces below the FM were smaller in CMI subjects as compared to controls. Overall, greater cerebellar crowding was identified in CMI subjects relative to healthy controls. These observations may improve our understanding of the pathophysiology of CMI in adult female patients.