Thecal Sac

What is Thecal Sac?

Thecal sac is one of the most significant parts of the body. It is the cover of the Spinal Cord of the body. It has the very important Cerebrospinal Fluid (CSF). There are many nerve roots as well, at the Thecal Sac. This is the protective layer of the Spinal Cord.  The Thecal Sac is covered with the membrane called Dura Matter. This is the outer most layer and it encapsulates the Central Nervous System of the body. It also encapsulates the brain.

Thecal Sac image

Picture 1 – Thecal Sac Showing Spinal nerves.

Structure of Thecal Sac

Thecal Sac is quite wide in case which contains the CSF and nerve roots. However, if anatomy is considered than the Thecal Sac for women are wider than the men. If the Vertebrates are taken into consideration for the measurement or the location of the Thecal Sac then it is situated between S1 and S3 vibrates. The position of the Thecal Sac helps it to synchronize along with the Spinal Cord. Whenever the spinal cord is flexing (Bending) the thecal sac will elongate in order to accommodate the movement. Similarly, it will contract whenever the spinal cord is extending or it move downwards.

Thecal Sac Compression

thecal Sac impingement

Picture 2 – Impingement of thecal sac from intervertebral disc

Thecal Sac Compression is very common and often causes a bulge of the disk. The compression can lead to numbness and also to wear and tear in the Spinal Cord. However, the amount of seriousness depends upon the causes of the Thecal Sac Compression. The Thecal Sac is the membrane with the fluid of CSF. The disk can cause herniations. It can compress it or in other words impinge on it.

However, medical terms also say that effacing is also similar to compression in case of Thecal Sac. It causes high amount of back pain, however, if the nerve tissues are not affected by it then, it is not a matter of worry. The situation is also explained as Cauda  Equina and the Thecal Sac has a purpose of protecting the spinal cord from it. Muscle weakness, pain in the lower back is very common symptoms of the Thecal Sac. The MRI Technology has the capability to diagnose the Thecal Sac Compression and it is understood that Thecal Sac Compression can be  better understood by the MRI technology.

Causes of Thecal Sac Compression

There can many causes for the causes of compression and these can be listed down. However, the compression has a degree of severity in terms of pain and health issues. The pain should not be severe and neither should be very painful. However, if it hurts the nerves of the Thecal Sac then it could be a big matter of deal.

  • The prime reason for Thecal sac is the Neoplasms or in more common language tumors. It imparts pressure on the Thecal Sac and that in turn creates the nerve issues and ultimately Cauda Equina Syndrome reaches.
  • Spinal Canal Stenosis is another reason for the compression of the Thecal Sac.
  • Injury or fracture of the Spinal Cord may also result in the compression of the Thecal Sac.
  • Cysts can force the situation to be like this. Synovial Cysts can be a major reason for the Compression of the Thecal Sac.
  • There could be many more reasons for the Compression which are very common in this case. Disk delocation and movement is probably the most common reason for compression. On the other hand, the facet joints can also trigger the pain and ultimately cause the compression of Thecal sac. High fatigue and the Spinal Hematoma or the internal bleeding of the Spinal Cord may cause the same issue.

In all cases the primary reason for the compression of the Thecal Sac is the anatomical disorder. It can also be said that the due to the structure of the Thecal Sac, there are many sensitive structures present in surrounding and that become the cause of the compression.

Treatment of Thecal Sac Compression

As discussed earlier, that the pain cause due to the structure. So, in that case most of the time the suitable treatment for the compression is surgery. However, the must be given the analgesics for the immense lower back pain. In most of the cases it has been observed that the compression is treated with the surgery and that has solved the problems for the patients. With the advancement of technologies in medical science, the treatment might get diversified in coming times.


  1. I was involved in mva in 2009 and the vehicle over turned 3times I got unconscious had lower mandible fracture ORIF was done and p8 plates and 16 screw were fixed then 1yr later the 4 outer plates and screw were removed till to date im still having the inner plates

  2. There is severe neck pain and MRI shows C4-C5 and C5-C6 discs thecal impingement. Please suggest treatment alongwith physical exercise.

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