Hydrocephalus involves an accumulation of cerebrospinal fluid (CSF) within the brain’s ventricles, which are fluid-filled spaces. This excess fluid can lead to increased pressure within the skull, potentially affecting brain development and function. Ultrasound technology serves as a non-invasive imaging method for the initial detection of this condition. It provides a safe and effective way to visualize the brain’s structures, particularly in developing infants and fetuses.
The Ultrasound Procedure for Detecting Hydrocephalus
Ultrasound examinations for hydrocephalus vary by patient age. During pregnancy, prenatal ultrasounds are performed as part of routine anatomy scans, around 18 to 22 weeks of gestation. These scans are usually transabdominal, though a transvaginal approach may be used for detailed views.
For newborns and infants, a postnatal cranial ultrasound uses the open fontanelles, or soft spots. This procedure is portable and can be conducted at the bedside. A small transducer is placed on the anterior fontanelle, allowing sound waves to create images of the brain’s internal structures. This non-radiating method assesses brain anatomy in young children.
Identifying Hydrocephalus on an Ultrasound
When evaluating for hydrocephalus, sonographers and radiologists focus on identifying ventriculomegaly, the enlargement of the brain’s lateral ventricles. This is the primary sign observed during an ultrasound examination. Measurements quantify the extent and severity of this enlargement.
A key measurement is the width of the ventricular atrium (trigone) of the lateral ventricles. A measurement exceeding 10 millimeters (mm) is the threshold for ventriculomegaly. Measurements between 10 mm and 12 mm indicate mild ventriculomegaly; 13 mm to 15 mm suggests moderate enlargement; and measurements greater than 15 mm are classified as severe. Other visual cues include increased head circumference (macrocephaly) or thinning of the brain’s cortical tissue. A “dangling choroid plexus sign” can also indicate hydrocephalus. The ultrasound also assesses underlying causes or associated structural abnormalities, such as spina bifida or blockages within CSF pathways.
Follow-Up Diagnostic Imaging and Monitoring
Following an initial ultrasound suggesting hydrocephalus, further diagnostic steps confirm the finding and provide a comprehensive understanding. Serial ultrasounds monitor the progression of ventricular enlargement. These repeated scans help determine if the condition is stable, improving, or worsening, guiding management decisions.
For detailed assessment, a fetal Magnetic Resonance Imaging (MRI) scan may be recommended during pregnancy. Fetal MRI provides superior soft-tissue contrast and a broader field of view compared to ultrasound, enhancing visualization of fetal brain anatomy. This advanced imaging helps confirm diagnosis, identify potential underlying causes, and evaluate associated brain anomalies without ionizing radiation. After birth, a computed tomography (CT) scan or an MRI of the brain may be used for definitive imaging. These postnatal scans provide high-resolution images of the brain’s structure and the full extent of the hydrocephalus, important for planning interventions.
Overview of Management After Diagnosis
Once hydrocephalus is diagnosed, a multidisciplinary team of specialists collaborates to develop a management plan. This team includes pediatric neurosurgeons, neurologists, and developmental pediatricians. The primary goal of treatment is to relieve pressure on the brain caused by excess cerebrospinal fluid.
Management strategies involve surgical interventions to divert or drain accumulated CSF. One common approach is shunt placement: a thin tube implanted to divert CSF from the brain ventricles to another body part for absorption. Another option is Endoscopic Third Ventriculostomy (ETV), where a small hole is created in the floor of the third ventricle, allowing CSF to flow more freely. These interventions aim to normalize intracranial pressure and support healthy brain development.