Billy Joel has called off all his upcoming concerts because of a health issue that has been recently identified, as announced by the iconic musician on Instagram.

On Friday, a statement shared on his Instagram revealed he was recently diagnosed with normal pressure hydrocephalus.

Normal pressure hydrocephalus is a type of hydrocephalus, characterized by an “unusual collection of cerebrospinal fluid deep within the brain,” according to the U.S. National Institute of Neurological Disorders and Stroke.

Cerebrospinal fluid, or CSF, occupies the ventricles, the spaces in the brain, providing cushioning for both the brain and the spinal cord. When CSF flow is hindered and accumulates in the ventricles, it results in normal pressure hydrocephalus, as per NINDS.

The extra fluid in the brain can cause pressure and lead to brain damage, as well as issues with walking, bladder control and thinking and reasoning, according to the NINDS.

Though it can happen at any age, normal pressure hydrocephalus is most common in older adults. It is most often diagnosed through a combination of neurological testing and brain imaging.

The best chance of recovery from normal pressure hydrocephalus comes if it is diagnosed early and treated properly.

The most common treatment for normal pressure hydrocephalus, according to the NINDS, is surgery.

In one option, doctors insert a shunt into the brain, which connects to another tube under the skin to help drain the excess fluid from the brain. With this option, regular monitoring of the shunt is required, and additional surgeries and repairs may be needed.

A second surgical option for normal pressure hydrocephalus is endoscopic third ventriculostomy, or EVT, where a doctor makes a hole at the bottom of the third ventricle in the brain, which allows fluid to flow to relieve the pressure, according to the NINDS.