Which diagnostic tool is essential for evaluating hydrocephalus in children?

The diagnostic tool essential for evaluating hydrocephalus in children is MRI or CT scan. These imaging techniques provide detailed images of the brain's anatomy, allowing for the assessment of ventricular size and the presence of any associated structural abnormalities.

In cases of hydrocephalus, there is an accumulation of cerebrospinal fluid (CSF) in the ventricles, leading to increased intracranial pressure and potentially serious complications. MRI, with its superior soft tissue contrast, is particularly useful in visualizing brain structures and assessing the flow of CSF, along with identifying any obstructions that might be causing the hydrocephalus. CT scans, while less detailed than MRI, are more widely available in emergency situations and can quickly identify ventricular enlargement.

Other techniques like X-ray do not provide the necessary visualization of soft brain tissue and CSF flow, making them ineffective for diagnosing hydrocephalus. Ultrasound can be used, especially in infants through fontanelles, but it has limitations in defining the structure and extent of hydrocephalus compared to MRI or CT. An electroencephalogram is primarily used to evaluate electrical activity in the brain and is not directly useful for diagnosing structural abnormalities such as hydrocephalus.