Definition
The S1 syndrome describes a complex of symptoms that is caused by irritation or damage to the S1 nerve root. The most common cause of S1 syndrome is a herniated disc in the area of the fifth lumbar vertebra and the first sacral vertebra. S1 syndrome is accompanied by pain, sensory disturbances and paralysis in the area supplied by the nerve root, which extends from the buttocks to the little toe. These complaints are generally known as the typical “sciatica pain“.
Cause
There are several causes that can trigger an S1 syndrome. In principle, a possible cause of S1 syndrome is any process in the spine that can lead to a reduction in space and narrowing of the nerve root. In principle, S1 syndrome occurs when the nerve root S1 in the spinal column is compressed.
In most cases, this is a herniated disc between the 5th lumbar vertebra (L5) and the beginning of the os sacrum (S1). Both a pure protrusion of the intervertebral disc and the emergence of the gelatinous core from the fibrous ring can exert pressure on the nerve root and cause discomfort. Other possible causes of an S1 syndrome are benign and malignant tumors and cysts in the area of the spinal column or fluid accumulations, so-called edema, as a result of inflammation.
Another possibility is a tightness in the area of the neuroforamina. This is a bony opening of the vertebral bodies through which the nerve fibers run. A narrowing of these structures can be congenital or degenerative. Often, constricted neuroforamina are a natural sign of wear and tear.
Slipped disc L5/S1
The intervertebral discs are located between the vertebral bodies and serve to buffer the spinal column under load and to increase its mobility. A herniated disc causes parts of the disc to shift, usually backwards and to the side. This leads to the entrapment of one or more nerve roots, which emerge from the spinal cord.
In a herniated disc at the level of L5/S1, the nerve root of S1 is usually affected. Depending on the amount of displaced tissue and the direction of displacement, the nerve root of L5 (L5 syndrome) or both nerve roots can also be affected. This then manifests itself in a specific pattern of symptoms.