Basal encephalocele | Figure 1

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Basal encephalocele

Sagittal (image 1) and coronal (image 2) fetal MRI show a basal encephalocele (arrow) containing cerebrospinal fluid that is herniated into the posterior pharynx and a midline cleft lip and palate (arrowhead). Basal encephalocele accounts for 10% of encephaloceles. Basal encephaloceles are not visible externally. Because of this, they may remain undetected at birth. Occasionally, patients will present with a soft tissue mass in the nasal cavity. At direct visualization, that these have been previously misdiagnosed as nasal polyps.

Similar cases

Anterior flow (image 1) and static (image 2) images from a technetium 99m Neurolite brain study show absence of radiopharmaceutical within the brain (arrow) and significant radiotracer uptake within the nasopharyngeal region (arrowhead) in the scalp consistent with brain death. Brain death occurs when brain function ceases to exist. On imaging, this is shown with the absence of cerebral blood flow. The presence of flow to the scalp and nasopharynx is related to shunting of blood to the external carotid system.

Sagittal noncontrast CT (image 1), coronal T2-weighted (image 2), and axial T2 (image 3) images show a sphenoethmoidal encephalocele (arrow). Sphenoethmoidal encephaloceles are a rare type of basal encephaloceles. They occur less frequently than occipital encephaloceles and can be associated with other midline anomalies including abnormalities of the hypothalamic-pituitary axis, midface anomalies, and agenesis of the corpus callosum.

Coronal ultrasound images of the brain obtained 1 day apart (image 1 was obtained one day after image 2) in an infant with congenital heart disease shows a considerable difference in the appearance of the brain, ventricular size, extra-axial spaces, and corticomedullary differentiation (arrow). CT (image 3) performed shortly after the ultrasound shows diffuse edema, loss of corticomedullary differentiation, and lack of visible cortical sulcation. Neonatal hypoxic ischemic encephalopathy occurs as a result of global decreased oxygenation. It can occur during pregnancy, during labor and delivery, or postnatally. In the postnatal setting, hypoxic ischemic encephalopathy is most commonly associated with severe lung or heart disease or infection.

Axial (image 1) and sagittal (image 2) T2-weighted MRI images show a large frontonasal encephalocele. Frontonasal encephaloceles are distinguished from nasoethmoidal encephaloceles due to the location relative to the nasal bone. If above the nasal bone, it should be considered a frontonasal encephalocele, below the nasal bone is a nasoethmoidal encephalocele.