3.33
Degenerative Bandscheibenerkrankung II: Pathophysiologie
Die Symptome einer degenerativen Bandscheibenerkrankung entstehen durch eine Kombination aus mechanischer Kompression, vaskulärer Beeinträchtigung und…
Die Symptome der degenerativen Bandscheibenerkrankung und der damit verbundenen strukturellen Veränderungen entstehen durch einen miteinander verbundenen Mechanismus.
Die mechanische Kompression benachbarter neuronaler Strukturen entwickelt sich, wenn Scheiben an Höhe, Elastizität und struktureller Integrität verlieren. Dies kann dazu führen, dass der Nucleus pulposus anfälliger für einen Herniation kommt, wodurch nahegelegene Nervenwurzeln möglicherweise komprimiert werden und zu radikulären Schmerzen beiträgt.
Ein weiterer Mechanismus ist der beeinträchtigte Nährstofftransport. Da Bandscheiben avaskulär sind, diffundieren Nährstoffe von Kapillaren in benachbarten Wirbelkörpern über die Endplatten. Degenerative Veränderungen wie Endplatten-Sklerose reduzieren diesen Austausch, was zu Bandscheibenzelltod und -degeneration führt.
Außerdem verstärken entzündliche Kaskaden die Symptome. Bandscheibenvorfälle lösen eine Immunantwort aus, die Zytokine, Stickstoffmonoxid und matrixabbauende Enzyme freisetzt.
Diese rekrutieren Makrophagen und sensibilisieren Nervenwurzeln, wodurch chemische Radikulitis auch ohne nennenswerte Kompression entsteht.
Entzündungsmediatoren treiben auch abnormale Nerven- und Gefäßwachstum voran, ein Kennzeichen chronischer diskogener Schmerzen.
View the full transcript and gain access to JoVE Core videos
Q1: How does disc degeneration lead to mechanical compression of nerve roots?
As intervertebral discs lose height and elasticity during degeneration, the nucleus pulposus becomes more likely to herniate. This herniation can compress adjacent nerve roots, causing radicular pain. Additional factors like ligamentum flavum hypertrophy and facet joint osteoarthritis further narrow the spinal canal, contributing to spinal stenosis and nerve compression.
Q2: What role does impaired nutrient transport play in disc degeneration?
Intervertebral discs are avascular and rely on nutrient diffusion through endplates from adjacent vertebral bodies. Degenerative changes like endplate sclerosis reduce this nutrient exchange, leading to disc cell death and progressive degeneration. This vascular compromise appears as Modic changes on MRI and is associated with discogenic pain.
Q3: How do inflammatory mediators contribute to pain in degenerative disc disease?
Herniated disc material triggers an immune response that releases cytokines, nitric oxide, and matrix-degrading enzymes. These inflammatory mediators recruit macrophages and sensitize nerve roots, producing chemical radiculitis even without significant mechanical compression. Growth factors like nerve growth factor promote abnormal nerve ingrowth, contributing to chronic discogenic pain.
Q4: What is the difference between disc protrusion, extrusion, and sequestration?
Disc protrusion occurs when the nucleus pulposus bulges with the annulus remaining intact. Extrusion happens when the nucleus extends beyond the disc but stays connected. Sequestration involves a free fragment in the spinal canal that may regress through macrophage clearance. Each type produces different degrees of nerve compression and pain.
Q5: How does nerve root compression affect blood flow and cause ischemia?
Nerve root compression first impairs venous outflow, causing congestion and edema. Continued compression restricts arterial flow, leading to ischemia and nerve dysfunction. This vascular compromise can trigger increased intracranial pressure and secondary neural injury, similar to mechanisms seen in spinal cord injury pathophysiology.
Q6: Why do some people with degenerative disc changes remain asymptomatic?
Symptoms result from combined mechanical compression, ischemia, inflammation, and neural sensitization. Many individuals with radiographic disc degeneration remain asymptomatic because they lack sufficient inflammatory response or neural sensitization. Genetic polymorphisms in collagens, aggrecan, and enzymes like ADAMTS-4/5 influence degeneration severity and symptom development.
Q7: What systemic factors accelerate intervertebral disc degeneration?
Obesity and adipokines such as leptin, TNF-alpha, and IL-6 accelerate disc degeneration. Genetic polymorphisms affecting collagen, aggrecan, and matrix-degrading enzymes also increase susceptibility. These systemic factors combine with local mechanical and inflammatory processes to drive progressive degeneration and variable clinical presentations.