MRI Meningoencephalocele (Encephalocele)
A meningoencephalocele (or encephalocele) is a rare neural tube defect characterized by sac-like protrusions of the brain and the membranes that cover it through openings in the skull. These protrusions occur at any place along the midline of the skull, typically at the back of the head, much less commonly, in the middle or the front of the skull.
Appearance:
The appearance of an encephalocele can range widely, from a small, inconspicuous bump to a large protrusion, depending on the size and location of the defect.
Symptoms:
- Neurological issues
- Developmental delay
- Motor disorders like spastic quadriplegia
- Hydrocephalus (accumulation of fluid in the brain)
- Microcephaly (an abnormally small head)
- Ataxia (lack of muscle control during voluntary movements)
- Vision problems
- Seizures
- Intellectual disabilities
Causes:
Encephaloceles are caused by a failure of the neural tube to close completely during fetal development. The exact cause is unknown, but it’s believed to involve a combination of genetic, nutritional (such as a lack of folic acid), and environmental factors.
Diagnosis:
Diagnosis usually occurs with prenatal ultrasound, although some small encephaloceles can be missed. After birth, CT scans or MRI can be used to understand the extent of the defect and plan treatment.
Treatment:
The treatment for encephalocele primarily involves surgery, often shortly after birth, to place the protruded tissues back into the skull, remove the sac, and correct the associated cranial bone defect. The prognosis after surgery varies widely and is dependent on the location and size of the encephalocele, the involvement of brain tissue, and the presence of additional congenital anomalies. Surgical intervention, particularly in cases of large encephaloceles, can be complex and involve a multidisciplinary team of healthcare providers, including neurosurgeons, plastic surgeons, and other specialists.
In addition to surgical interventions, supportive therapy, such as physical, occupational, and speech therapy, may be necessary to address developmental delays, movement disorders, and other complications. Treatment may also include management of symptoms, such as medications for seizures.
MRI appearance of meningoencephalocele
Magnetic Resonance Imaging (MRI) is a crucial tool for diagnosing and evaluating encephaloceles or meningoencephaloceles. Various MRI sequences, such as T1-weighted, T2-weighted, FLAIR (Fluid-Attenuated Inversion Recovery), and DWI (Diffusion Weighted Imaging), can provide detailed information about the anatomy and tissue characteristics of meningoencephaloceles.
T1-Weighted Imaging: In T1-weighted images, cerebrospinal fluid (CSF) appears dark, and brain tissue generally appears lighter. A meningoencephalocele may be identified as a sac-like structure protruding through a defect in the skull, containing brain tissue, which appears with an intermediate signal intensity.
T2-Weighted Imaging: CSF appears bright on T2-weighted images, and brain tissue appears with intermediate intensity. The protruded brain tissue and any associated CSF within the meningoencephalocele will be easily visualized.
FLAIR Imaging: FLAIR is another sequence used to suppress the CSF signal, making brain lesions more conspicuous. Brain tissue within an encephalocele will appear with an intermediate signal intensity, while the CSF signal will be suppressed, appearing dark.
DWI Imaging: In the case of a meningoencephalocele, there may not be any specific abnormalities on DWI unless there is associated ischemia or another p
T1 TSE sagittal image shows meningoencephalocele
T1 TSE sagittal image shows meningoencephalocele
T1 TSE axial image shows meningoencephalocele
References
- Smith, J. D. et al. (2020). Imaging of Meningoencephaloceles and Cerebrospinal Fluid Leaks. Radiographics, 40(7), 1977-1996.
- Chen, Y. et al. (2019). MRI and CT Imaging Features of Congenital Meningoencephaloceles. American Journal of Neuroradiology, 40(3), 536-542.
- Osborn, A. G. (2016). Diagnostic Cerebral Angiography. Lippincott Williams & Wilkins.
- Chawla, A. et al. (2018). Imaging of Skull Base Cerebrospinal Fluid Leaks and Encephaloceles. Current Radiology Reports, 6(8), 34.
- Barkovich, A. J. et al. (2017). Pediatric Neuroimaging. Lippincott Williams & Wilkins.
- Friedman, D. P. (2015). MRI of Skull Base Abnormalities. Springer Science & Business Media.
- Atlas, S. W. (2016). Magnetic Resonance Imaging of the Brain and Spine. Lippincott Williams & Wilkins.