is a classification system used in neurosurgery to describe the location and extent of ruptured cerebral aneurysms. It was developed by Dr. Toshio Matsushima, a Japanese neurosurgeon, and is based on the location of the aneurysm in relation to the major blood vessels of the brain.

There are five different Matsushima types, each of which is based on the location of the aneurysm in relation to the major blood vessels of the brain. These types include:

Type I: An aneurysm located on the anterior communicating artery, which connects the two anterior cerebral arteries.

Type II: An aneurysm located on the internal carotid artery, which is one of the major arteries that supply blood to the brain.

Type III: An aneurysm located on the middle cerebral artery, which supplies blood to the lateral surface of the brain.

Type IV: An aneurysm located on the posterior circulation, which includes the vertebral and basilar arteries.

Type V: An aneurysm located on multiple arteries.

The Matsushima type classification system is important because it can help guide treatment decisions in patients with ruptured cerebral aneurysms. For example, aneurysms located in certain areas may require different surgical approaches or have different risks associated with treatment. By using a standardized system to classify aneurysms, neurosurgeons can better predict outcomes and tailor treatment plans to individual patients.