Välilevyjen

Intervertebral discs are fibrocartilaginous cushions that separate adjacent vertebral bodies along the spine, from the neck to the lower back. In Finnish medical terminology, these structures are called välilevyt, and the genitive form is välilevyjen. They function as shock absorbers and allow limited mobility while transmitting loads between vertebrae.

Anatomically, a disc consists of a central nucleus pulposus surrounded by a tough annulus fibrosus. The nucleus pulposus is a gel-like core rich in water and proteoglycans, providing viscoelastic properties. The annulus fibrosus comprises concentric lamellae of collagen fibers that confine the nucleus. The disc sits between endplates on the adjacent vertebral bodies. The outer annulus is innervated, whereas the nucleus is largely avascular, receiving nutrients via diffusion through the endplates.

The discs depend on diffusion through the endplates for nutrition and waste removal, and they lose water content with aging. This leads to reduced disc height and altered biomechanics, contributing to degeneration over time.

Common disorders include degenerative disc disease and disc herniation, where the nucleus protrudes through the annulus. Herniation can compress nerve roots, causing radicular pain, weakness, or numbness. In severe cases, cauda equina syndrome may occur and requires urgent attention.

Diagnosis typically relies on clinical evaluation and magnetic resonance imaging (MRI), which best visualizes soft tissues. Treatment ranges from conservative measures—physical therapy, analgesics, nonsteroidal anti-inflammatory drugs, and lifestyle modification—to injections such as epidural steroids. Surgical options include microdiscectomy, spinal fusion, or disc replacement, reserved for persistent symptoms or neurological deficits.

Prevention emphasizes core strengthening, good posture, weight management, smoking cessation, and avoidance of repetitive strain. Most patients experience improvement within weeks to months, though recurrence is possible.