Neurosurgery Coding Alert

Hydrocephalus is a condition caused by disturbance of formation, flow, or absorption of cerebrospinal fluid (CSF). This leads to the fluid in the central nervous system (CNS) to buildup.

“This can cause somnolence and brain injury from increased intracranial pressure,” says Gregory Przybylski, MD, director of neurosurgery at the New Jersey Neuroscience Institute, JFK Medical Center, Edison. “Historically, hydrocephalus has been treated with CSF diversion, typically by catheter shunting.  However, endoscopic third ventriculostomy offers an alternative for some patients to allow CSF to exit through a surgically created route, thereby avoiding the need for shunting.”

What are the types of hydrocephalus? Hydrocephalus can be communicating or obstructive depending upon the presence of obstruction in the flow of CSF. Sometimes, there may be a buildup of CSF without any rise in intracranial pressure. This condition is called an idiopathic normal pressure hydrocephalus. Hydrocephalus is also caused by an acquired deformity of the head. The ICD-9 and the corresponding ICD-10 codes for these conditions are listed in table 1.

Congenital hydrocephalus: In ICD-9, you report code 742.3 (Congenital hydrocephalus) for congenital hydrocephalus. When reporting the same in ICD-10, you will need to make sure that your surgeon documents the underlying congenital lesion that lead to the congenital hydrocephalus. A common cause of the congenital hydrocephalus is an obstruction of the aqueduct or foramina through which the cerebrospinal fluid drains. There can be other reasons too.

“Aqueductal stenosis is a common cause of congenital hydrocephalus, preventing CSF made in the lateral ventricles from traveling between the 3^rd and 4^th ventricles,” Przybylski says. “This prevents the natural flow of CSF, leading to obstructive hydrocephalus.”

Bear in mind that the ICD-9 code 742.3 actually expands to three codes in ICD-10. Below are the codes in ICD-10 that you may appropriately select, depending upon the site of the obstruction, when reporting congenital hydrocephalus:

• Q03.0 - Malformations of aqueduct of Sylvius

• Q03.1 - Atresia of foramina of Magendie and Luschka

• Q03.8 - Other congenital hydrocephalus