Tissue damage in herniated brain parenchyma into giant arachnoid granulations: demonstration with high resolution MRI

Acta Radiol. 2021 Jun;62(6):799-806. doi: 10.1177/0284185120941829. Epub 2020 Jul 19.


Background: Brain herniation (BH) into arachnoid granulation has been remarkable in recent years.

Purpose: To evaluate the damage in herniated parenchyma into the giant arachnoid granulation (GAG) and to investigate the clinical-demographic importance of this damage.

Material and methods: Patients with BH into GAG were retrospectively included in the study. Each of the patients had at least one high-resolution 3D magnetic resonance imaging (MRI) sequence. The arachnoid granulation dimensions, locations, and origin of herniated parenchyma were evaluated by two experienced radiologists. The demographic and symptomatic features of the patients were recorded from the hospital database.

Results: A total of 27 patients (21 females, 6 males; age range 6-71 years; mean age 41.3 years) were found to contain BH into GAG. It was most commonly seen in the transverse sinus (67%); the origin was most common in the cerebellar parenchyma (56%). Abnormal signal and morphology were detected in herniated parenchyma in 11 (47%) patients, atrophy in six, and atrophy and gliosis in five. The most common complaints were headache (47%), while other frequent symptoms were vertigo (15%) and blurred vision (11%). There was a statistically significant positive correlation between frequency of damage in herniated brain parenchyma and the maximal size of GAG (P<0.05).

Conclusion: In patients with BH into GAG, parenchymal damage may be associated with various symptoms, such as headache and vertigo, although they have not been statistically proven. It is important to carefully evaluate hernia tissue, as the risk of tissue damage may increase in larger GAGs.

Keywords: Giant arachnoid granulation; brain herniation; high-resolution magnetic resonance imaging.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Arachnoid / diagnostic imaging*
  • Brain / diagnostic imaging
  • Brain / pathology*
  • Child
  • Encephalocele / complications*
  • Encephalocele / diagnostic imaging*
  • Female
  • Granulation Tissue / diagnostic imaging*
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Retrospective Studies
  • Young Adult