What percentage of circumference spread indicates a Grade 4 disc herniation?

A Grade 4 disc herniation is characterized by a significant protrusion of the disc material beyond its normal confines. Specifically, this condition is assessed by measuring the extent of the herniated disc's spread in terms of percentage of the disc's circumference.

In the context of a Grade 4 herniation, a spread greater than 30% indicates a severe disc herniation, which suggests substantial displacement of the disc material. This degree of herniation often correlates with more pronounced symptoms and may impact neural structures such as the spinal cord or nerve roots, leading to more significant clinical manifestations in the patient.

The classification system for disc herniation helps clinicians communicate findings effectively and determine the appropriate management strategies. In this classification, the determination of the degree of herniation can guide interventions, whether conservative treatment or surgical options are warranted.

Thus, identifying Grade 4 specifically with a greater than 30% circumference spread is crucial for proper diagnosis and treatment planning in interventional radiology.