Thecal Sac – Compression, Causes, Effects and Treatment

thecal sac

The spine is an important component of the human body. It supports the body and enables it to keep its structure. It also helps us perform different movements. The spinal cord is a build-up of many parts and components that offer it protection. One vital part is the thecal sac. But what exactly is this sac? We get into details of what you need to know about this crucial sac.

What is Thecal Sac

The thecal sac, also referred to as the dural sac, is a membrane-filled tube surrounding the spinal cord and nerves (the cauda equina). It is filled with the cerebrospinal fluid that offers the spinal cord nutrients, buoyancy, and protection and is separated from the inner surface of the spinal canal by the epidural space. It originates from the skull and extends down to the sacral vertebra. Females have a wider dural sac than men.

The cauda equina nerve root collection is found at the end or on the lower end of the spine. They leave the spinal cord between the vertebrae to connect to other body parts in the lower peripheries. These nerve roots offer the bladder and legs sensation and their ability to move.

Thecal Sac effacement

Thecal Sac compression

Thecal sac compression or flattening can occur with conditions that bring about pressure on the spinal cord or those that cause pinching of the spinal cord. Anything that puts pressure on the dural sac can cause compression. Spinal cord compression affects any part of the spine and can occur on the dural sac.


Symptoms are caused by nerve pressure and not the compression of the cerebrospinal fluid. They may include;

  • Pain and stiffness on the lumbar spine.
  • Radiated pain that can spread to other body parts like the legs.
  • Numbness between the inner thighs and legs.
  • Cramps and weakness.
  • Burning or a tingling sensation.
  • Radiculopathy.
  • Lost feet sensation.
  • Foot drop (foot weakness) that may be bilateral.


  • Medical procedure complications can disrupt the dural sac.
  • Trauma or injuries that cause leaking of the cerebrospinal can also disrupt the sac to cause immediate symptoms.
  • Spinal stenosis or the narrowing of the spinal canal- mainly occurs on the cervical or lumbar spines and can be an osteoarthritis complication.
  • Tumor or cancer that metastasizes and extends into the epidural space.
  • Calcified anterior or posterior spinal discs.


A compressed dural sac can cause metastatic epidural spinal cord compression, which is a cancer complication that causes back pain and possible loss of neurologic function. It can also cause cauda equina syndrome, which can cause issues with bladder and bowel control- bladder and rectal dysfunction or sphincter loss can occur.

If the entire dural sac is marked by compression, one may suffer or demonstrate issues of paralysis.

Suppose one’s spinal cord cannot move freely move within the sac as a result of abnormal tissue attachments, particularly during growth. In that case, it may result in a condition referred to as a tethered spinal syndrome.


A compressed dural sac is an objective sign that can be determined using radiology images. Mostly, CT and MRI scans are used and not X-rays. An MRI is the preferred imaging modality since it noninvasively allows specialists to study the entire dural sac. An image can reveal a compressed dural sac even when the person does not feel anything, meaning the nerve roots suffer no pressure.

If an MRI of the lumbar spine shows an empty dural sac, a patient is diagnosed with adhesive arachnoiditis (arachnoiditis that affects the cauda equina). Arachnoiditis refers to disorders that inflame the arachnoid (one of the membranes surrounding and offering spinal cord nerves protection).


Treatment and prevention

Treatment for dural sac compression is meant to relieve the symptoms and, more importantly, the pain. Simply put, pressure on the dural sac does not necessarily mean there is cause for concern or treatment. Symptoms that are experienced in a pattern consistent with nerve pressure are the main concern. Treatment and prevention options include;

  • The administration of anti-inflammatory medications to relieve pain.
  • Administration of steroidal injections (epidural or systemic), especially where there are radicular symptoms.
  • Physiotherapy and exercises- a patient can carry out exercises that can stabilize the back and offer relief. It is best whereby a physical therapist guides the exercises. Extension and core exercises and some yoga asanas for the back are best. Regular exercises will strengthen the back muscles.
  • Chiropractic manipulation of the lumbar spine.
  • Surgery can be done where other non-surgical solutions are ineffective or where the condition causes severe nerve damage. They can also be done in the presence of a tumor or cauda equina syndrome. Surgeries may include laminectomy, lumbar fusion, or microdiscectomy.
  • Avoidance of forward bending.
  • Always maintaining the correct posture. Using Lumbar Spine belts can help you add flexibility and stability to the spine.
  • Wearing protective gear to prevent spine injury.

Final Thoughts

The thecal sac is an important component of the spinal cord. When it is compressed, pain and other symptoms mentioned above come up. Whenever you face any of these symptoms, you must consult a doctor or spine specialist. They will provide you with an accurate diagnosis for the best treatment.

Compression of the dural sac can have severe outcomes, including nerve damage, neurologic problems and paralysis. Therefore, take preventative measures to avoid putting pressure on the dural sac.

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