Sensitivity in the dermatomes | Deafness – Sensitivity disorder

Sensitivity in the dermatomes

However, the dermatomes are not separated on the body by clear lines, but there is a partial overlap. It is assumed that this overlapping is more pronounced when touch stimuli are felt than when pain or temperature is felt. Thus, it is often the case with patients that the failure of one spinal nerve goes unnoticed at first, since the adjacent spinal nerves continue to supply the affected dermatome. However, if two adjacent segments fail, the sensory disturbance is usually clearly perceptible. In addition to the dermatomes, there are also so-called autonomous areas on the skin.These are supply areas for certain nerves that are far from the body center and are not spinal nerves.

Transfer from internal organs

Just like the skin, the internal organs are also partially supplied by the spinal nerves. Thus, the brain is sometimes unable to assign received signals to a perception exactly to their place of origin. Thus, a heart attack also results in the typical painful radiation into the left arm (dermatome Th1-Th5).

In the case of a disease of the liver or the bile ducts, there is pain in the dermatomes Th6 – Th9 (right). In this way, almost every organ can be assigned a skin area. In some cases, the pain is not limited to just one dermatome, but spreads to adjacent areas or even affects an entire half of the body (generalization). This process is called transmitted pain and can be an important feature in the diagnosis.

Herniated disc as cause of deafness

Dermatoms are of particular importance in the diagnosis of herniated discs. Here, the jelly-like core of the intervertebral disc has slipped out and is pressing on a spinal nerve fiber, resulting in disorders and failures in the assigned segments and dermatomes. By localizing the exact sensitive failure in a specific dermatome, it can be assigned at what exact height the herniated disc occurred.

In most cases, the herniated disc is located in the area L4/5, resulting in a reduced sensation of touch on the inner side of the lower leg and the foot. If, on the other hand, the herniated disc is in the area L5/S1, this leads to sensory disturbances on the outside of the foot and on the sole of the foot.