- Head circumference: Head circumference is measured to look for signs of macrocrania.
- Ophthalmological examination: A funduscopic examination is performed to look for signs of increased ICP.
- Neurocutaneous markings: 8–10% of patients with neurocutaneous melanosis, characterized by the presence of multiple congenital melanocytic nevi and benign or malignant pigment cell tumors of the leptomeninges, also harbor an associated Dandy-Walker malformation. Such neurocutaneous lesions are notable as they can often be recognized at birth, whereas neurological manifestations develop later (11, 12, 13).
- Cerebellar examination: Balance and coordination are tested to look for signs of cerebellar dysfunction.
- Routine: No abnormal laboratory test results are expected.
Dandy-Walker cysts are differentiated from other cystic abnormalities and from hydrocephalus by the following characteristic abnormalities that are evidenced on ultrasonography, CT scan, or MRI:
- Vermis: There is a spectrum of vermian abnormalities ranging from hypoplasia to complete absence of the cerebellar vermis. These are the hallmark of the Dandy-Walker malformation.
- Tentorium: Imaging can demonstrate upward displacement of the tentorium and vascular sinuses.
- Hydrocephalus: There is variable occurrence of hydrocephalus and other associated intracranial anomalies.
- Fetal diagnosis: The above findings can be imaged with either ultrasound or MRI in the fetus with Dandy-Walker syndrome.
- Reveals hydrocephalus: Ultrasound will show hydrocephalus and is thus useful as an initial step. It may or may not show the posterior fossa abnormalities.
- Shows hydrocephalus and posterior fossa abnormalities: These can be variable.
- Shows anatomy and sequelae of hydrocephalus: T1- and T2-weighted sequences show the extent of the hydrocephalus, the posterior fossa fluid collection, and the vermian abnormalities. Transependymal edema can indicate the severity of the hydrocephalus. A contrast-enhanced scan should be obtained to evaluate for other abnormalities, including tumors.
- Screening to document cognitive level: Patients should be assessed for their cognitive level of functioning to direct further care.
Correlation of Tests
- Clinical examination and imaging: The degree of hydrocephalus and the concomitant degree of ICP elevation indicate the need for treatment and the urgency of treatment.