Circumferential Thecal Sac Indentation

Circumferential thecal sac indentation refers to a condition in which the protective membrane surrounding the spinal cord—the thecal sac—is pressed inward all the way around its circumference. This indentation can occur at one or more levels of the spine and often results from factors such as bulging discs, thickened ligaments, or bony overgrowths. By narrowing the space available for the spinal cord and nerve roots, circumferential indentation can lead to pain, numbness, weakness, and, in severe cases, loss of function below the level of compression.

Circumferential Thecal Sac Indentation is an imaging finding—most often seen on MRI—where the dura mater (the outermost layer of the thecal sac) is indented from all sides. Unlike focal indentations, which occur at a single spot, circumferential indentation wraps around the spinal canal, reducing its overall diameter. This can cause diffuse pressure on neural structures, leading to widespread symptoms.

---

Anatomy of the Thecal Sac Region

1. Structure & Location

   • The thecal sac is a cylindrical sheath of dura mater that begins at the foramen magnum (base of skull) and extends down to the second sacral vertebra.

   • It encloses the spinal cord (or cauda equina below L1–L2), cerebrospinal fluid (CSF), and nerve roots.

2. Origin & Insertion

   • Origin: The dura at the foramen magnum where the cranial dura continues into the spine.

   • Insertion: Anchored inferiorly at S2 by the filum terminale, a fibrous extension of pia mater.

3. Blood Supply

   • Receives small branches from the vertebral arteries in the cervical region and radicular arteries (segmental medullary arteries) in the thoracic and lumbar regions.

   • Venous drainage occurs via the internal vertebral (epidural) venous plexus.

4. Nerve Supply

   • Innervated by recurrent meningeal (sinuvertebral) nerves arising from the ventral rami of spinal nerves; these carry pain signals from the dura.

5. Functions (Six)

   1. Protection: Shields the spinal cord and nerve roots.

   2. Support: Maintains CSF within a closed system.

   3. Shock Absorption: CSF cushions neural tissue against mechanical forces.

   4. Nutrient Transport: Circulates nutrients and removes waste via CSF flow.

   5. Homeostasis: Helps regulate intracranial and spinal pressure.

   6. Pathway for Immune Cells: Allows immune surveillance of the central nervous system.

---

Types of Circumferential Indentation

1. Mild: Slight uniform inward bowing without cord compression.

2. Moderate: Noticeable narrowing with early signs of cord deformation.

3. Severe: Marked indentation causing visible cord flattening or signal changes.

4. Acute vs. Chronic: Acute results from sudden events (e.g., trauma), chronic from progressive degenerative changes.

5. Single-Level vs. Multilevel: Involvement of one vertebral level or multiple consecutive levels.

---

Causes

1. Degenerative disc bulge

2. Disc herniation (annular tear)

3. Ligamentum flavum hypertrophy

4. Facet joint osteoarthritis

5. Spondylolisthesis (vertebral slippage)

6. Spinal stenosis (general narrowing)

7. Epidural fibrosis (scar tissue)

8. Tumors (e.g., meningioma)

9. Spinal infections (e.g., epidural abscess)

10. Trauma (fracture fragments)

11. Congenital canal stenosis

12. Ossification of the posterior longitudinal ligament (OPLL)

13. Calcified disc

14. Rheumatoid arthritis affecting spine

15. Paget’s disease of bone

16. Diffuse idiopathic skeletal hyperostosis (DISH)

17. Metastatic cancer

18. Hemorrhage into epidural space

19. Intrathecal cysts (e.g., arachnoid cyst)

20. Iatrogenic changes (post-surgical scarring)

---

Symptoms

1. Neck/back pain (axial)

2. Radicular pain (radiating down limbs)

3. Numbness in arms or legs

4. Tingling (“pins and needles”)

5. Muscle weakness in affected myotomes

6. Gait instability or difficulty walking

7. Balance problems

8. Loss of fine motor skills (hands)

9. Bladder dysfunction (urgency, retention)

10. Bowel dysfunction

11. Sexual dysfunction

12. Spasticity (increased muscle tone)

13. Hyperreflexia (exaggerated reflexes)

14. Clonus (rhythmic muscle contractions)

15. Lhermitte’s sign (electric shock sensation on neck flexion)

16. Atrophy of muscles over time

17. Fatigue from chronic pain

18. Headaches (if cervical spine involved)

19. Sensory level (band of altered sensation)

20. Unsteady posture

---

Diagnostic Tests

1. Magnetic Resonance Imaging (MRI) – gold standard for soft tissue detail

2. Computed Tomography (CT) – bone and calcification evaluation

3. X-ray – alignment, congenital stenosis

4. Myelography – contrast in CSF to show indentations

5. CT Myelogram – combines CT detail with myelographic contrast

6. Electromyography (EMG) – nerve root function

7. Nerve Conduction Studies (NCS)

8. Somatosensory Evoked Potentials (SSEPs) – spinal cord pathway integrity

9. Motor Evoked Potentials (MEPs)

10. Ultrasound (for superficial regions)

11. Bone scan (for infection or tumor)

12. Laboratory tests (CRP, ESR for infection/inflammation)

13. CSF analysis (via lumbar puncture)

14. Dynamic flexion–extension X-rays

15. Dual-energy CT (for gouty tophi)

16. Discography (discogenic pain)

17. Facet joint injections (diagnostic block)

18. Selective nerve root block

19. Intraoperative neurophysiology (if surgery planned)

20. Psychosocial assessments (pain questionnaires)

Non-Pharmacological Treatments

1. Physical therapy (strengthening, stretching)

2. Traction therapy

3. Manual therapy (chiropractic, osteopathic manipulation)

4. Postural education

5. Ergonomic adjustments (workstation setup)

6. Heat therapy

7. Cold therapy

8. Ultrasound therapy

9. Electrical stimulation (TENS)

10. Acupuncture

11. Massage therapy

12. Yoga

13. Pilates

14. Tai Chi

15. Cervical/lumbar supports (braces)

16. Traction devices (home neck traction)

17. Hydrotherapy

18. Mindfulness meditation

19. Cognitive-behavioral therapy (CBT)

20. Biofeedback

21. Weight management

22. Aquatic exercise

23. Postural taping (KT tape)

24. Inversion tables

25. Ergonomic mattresses/pillows

26. Walking programs

27. Stationary cycling

28. Core stabilization training

29. Education on body mechanics

30. Complementary therapies (e.g., herbal compress)

---

Drug Treatments

1. Non-steroidal anti-inflammatory drugs (NSAIDs) – ibuprofen, naproxen

2. Acetaminophen

3. Muscle relaxants – cyclobenzaprine, tizanidine

4. Oral corticosteroids – prednisone taper

5. Gabapentinoids – gabapentin, pregabalin

6. Tricyclic antidepressants – amitriptyline

7. Serotonin-norepinephrine reuptake inhibitors (SNRIs) – duloxetine

8. Opioids (short-term) – tramadol, oxycodone

9. Topical NSAIDs – diclofenac gel

10. Topical lidocaine patches

11. Capsaicin cream

12. Bisphosphonates (if bone involvement)

13. Calcitonin (for pain modulation)

14. Anti-TNF agents (in rheumatoid cases)

15. Antibiotics (for infection)

16. Anticonvulsants – carbamazepine (for neuropathic pain)

17. Steroid injections – epidural corticosteroid

18. Facet joint steroid injections

19. Botulinum toxin (experimental for spasm)

20. Duloxetine (for chronic musculoskeletal pain)

---

Surgical Options

1. Laminectomy – remove lamina to decompress canal

2. Laminotomy – partial lamina removal

3. Laminoplasty – reshape lamina to enlarge canal

4. Discectomy – remove herniated disc fragment

5. Foraminotomy – enlarge neural foramen

6. Posterior cervical fusion – stabilize levels

7. Anterior cervical discectomy and fusion (ACDF)

8. Corpectomy – remove vertebral body for decompression

9. Spinal instrumentation (rods, screws)

10. Endoscopic decompression (minimally invasive)

---

Preventive Measures

1. Maintain proper posture when sitting, standing

2. Regular core strengthening exercises

3. Use ergonomic furniture

4. Avoid repetitive strain (take breaks)

5. Lift objects correctly (bend knees)

6. Maintain healthy weight

7. Stay active (daily moderate exercise)

8. Quit smoking (improves disc health)

9. Stay hydrated (disc nutrition)

10. Regular medical check-ups for early detection

---

When to See a Doctor

• Persistent pain lasting more than 6 weeks despite home care

• Progressive weakness in arms or legs

• Loss of bladder or bowel control

• Severe, unrelenting pain that wakes you at night

• Signs of infection (fever, chills) with back pain

• Neurological deficits on self-exam (e.g., foot drop)

• Trauma followed by new or worsening symptoms

---

Frequently Asked Questions

1. What exactly is circumferential thecal sac indentation?
   Circumferential thecal sac indentation occurs when structures around the spinal canal push inward from all sides, narrowing the space for the spinal cord.

2. How is it different from focal indentation?
   Focal indentation is a pinpoint area of compression, while circumferential indentation wraps evenly around the dura, reducing the canal’s overall diameter.

3. What tests confirm this condition?
   MRI is best for identifying the extent and cause; CT myelogram can help if MRI isn’t possible.

4. Can mild cases improve on their own?
   Yes, with physical therapy, posture correction, and anti-inflammatory measures, mild indentations may stabilize or improve.

5. When is surgery necessary?
   Surgery is considered for moderate to severe cases causing neurological deficits or unmanageable pain after conservative care.

6. Are there lifestyle changes that help?
   Regular exercise, weight control, ergonomic adjustments, and avoiding heavy lifting can slow progression.

7. What medications are first-line?
   NSAIDs and acetaminophen are usually tried first; neuropathic agents like gabapentin may be added for nerve pain.

8. Is this condition common?
   It’s relatively common in older adults with degenerative spine disease but less so in younger people.

9. What are the risks of surgery?
   Potential risks include infection, bleeding, nerve injury, and incomplete relief of symptoms.

10. How long is recovery from surgery?
    Most patients use a brace for 4–6 weeks; full recovery can take 3–6 months depending on procedure.

11. Can physical therapy worsen indentation?
    Improper technique can aggravate symptoms; always work with a qualified therapist.

12. Is chiropractic safe?
    Gentle, experienced care can help—but high-force adjustments in severe stenosis may be risky.

13. What role does MRI signal change play?
    Signal changes in the cord indicate cord damage; these cases need prompt attention.

14. Are steroids useful?
    Oral or injected steroids can reduce inflammation and pain temporarily but don’t reverse structural narrowing.

15. Can children get this condition?
    Rarely; when it occurs in children, it’s usually due to congenital stenosis or tumors.\

Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical  history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.

The article is written by Team Rxharun and reviewed by the Rx Editorial Board Members

Last Updated: May 02, 2025.

PDF Document For This Disease Conditions

References