What is a thecal sac?

The thecal sac is a protective covering that surrounds the spinal cord and nerve roots. It is a membranous tube-like structure filled with cerebrospinal fluid (CSF) and is located within the spinal canal, which is formed by the vertebrae.

The thecal sac serves as a barrier and provides cushioning and protection for the delicate spinal cord and nerve roots from surrounding structures, such as the bone, ligaments, and discs. It helps prevent damage to the spinal cord and allows for the free movement of CSF around the spinal cord.

Measuring the dimensions of the thecal sac, particularly its diameter, can be useful in diagnosing certain spinal conditions and assessing nerve root compression. In several medical imaging techniques like magnetic resonance imaging (MRI) or computed tomography (CT) scans, thecal sac diameter can be evaluated to determine if there is enough space for the spinal cord and nerve roots to function properly.

When the thecal sac becomes compressed or narrowed due to various conditions like spinal stenosis, herniated discs, tumors, or trauma, it can put pressure on the spinal cord and nerve roots, resulting in pain, numbness, weakness, or other neurological symptoms. In such cases, treatment options may include medication, physical therapy, epidural injections, or surgical intervention depending on the underlying cause and severity of the compression.

Overall, the thecal sac is an essential component of the spinal anatomy, providing protection and support to the spinal cord and nerve roots. Understanding its role and monitoring its dimensions can aid in the diagnosis and management of certain spinal conditions.