Synovial Spinal Cyst

Synovial Spinal Cyst

Synovial cyst of the spine is an interesting topic. Basically, you need to recognize that it is a synovial cyst, and you need to recognize the treatment is probably removal by some sort of decompression and you may need fusion if there is instability. It occurs due to arthritis of the facets. It occurs mostly in patients 60 years or older. It usually affects the level of L4-L5. This is one of the most active levels. There will be bulging of the lining of the covering of the facet joint. The synovial cyst is a cyst or a fluid filled cavity. When the fluid escapes from the arthritic facet joint, because it is under pressure, it dilates the capsule of the facet joint and creates a cyst. synThe connection between the synovial cyst and the facet joint becomes obvious. The synovial cyst is walled off from the spinal canal. The synovial cyst causes pressure on the nerve root as it tries to exit the foramen. Compare both sides. The synovial cyst acts like a herniated disc. The patient will have low back pain, numbness, and radiation of the pain down the leg. The synovial cyst is best diagnosed by an MRI. The MRI can also diagnose the compression on the nerve root by the cyst. The synovial cyst is bright in T2 MRI because it is a fluid filled mass (it’s not like an intervertebral disc) and the cyst is contiguous with the hypertrophied facet joint, which also has a high signal intensity. synoThe synovial cyst indicates a facet pathology. The patient will be initially treated conservatively. There is a high recurrence rate with nonsurgical treatment, and if there is no improvement, then you will need to do surgery. If the patient has radiculopathy alone, do decompression. If the patient has significant low back pain due to spinal instability, you will do decompression and fusion. To check for instability, look at the MRI or the x-rays. Get flexion/extension x-rays before you decide on surgical intervention. Basically, because you have the synovial cyst and when you go in and remove the cyst, you have hypertrophy of the facets and the ligamentum flavum, so you will do a hemilaminotomy and partial facetectomy with direct decompression of the neural elements. Do fusion if there is instability.

Differential Diagnosis of SI Joint Pain

Sacroiliac Joint pain can often be inappropriately treated or mistaken as lower back pain. There are several conditions that simulate sacroiliac joint pain.

1. Myofascial Painmyofacial pain

This is a chronic pain caused by multiple trigger points and fascial constrictions. This particular condition involves the muscles and fascial areas of the back. The patient may feel knots or hardening of the muscle with weakness and tenderness. Myofascial pain syndrome and fibromyalgia may present the same clinical picture but, they are different problems. The site location is close to the SI joint and can be confused with SI joint pain.

2. Trochanteric Bursitis

Inflammation of the greater trochanter bursa. This condition causes tenderness and pain bursapiriin the hip. Trochanteric bursitis occurs in middle aged women. The area of pain may overlap with the SI joint area of pain and can radiate close to the sacroiliac joint. The pain from this condition is sometimes severe and associated with iliotibial band syndrome. Trochanteric Bursitis is occasionally overlooked. This condition may present with arthritis of the hip and low back pain and other conditions.


3. Piriformis Syndrome

This condition occurs when the sciatic nerve is compressed by the piriformis muscle in the buttocks. Piriformis Syndrome may be associated with lower lumbar radiculopathy similar to spine pathology. It occasionally develops due to blunt trauma to the buttocks. Localized buttocks pain will increase with sitting or driving. Tenderness is commonly found in the sciatic notch.


4. Cluneal Nerve Entrapment

cluneal nerve entrapThe superior cluneal nerve has three branches. The medial branch of this nerve is confined within a tunnel which may cause impingement of the nerve producing pain close to the SI joint.

5. Lumbosacral Disc Herniation or Bulge

The disc may move out of place (herniate) or break open (rupture) from injury or strain. Disc herniation of the lumbosacral region could involve the nerve roots, creating lower back pain. The pain is usually found in the midline and can go down the leg.


6. Lumbosacral Facet Syndrome

facetThe facet provides stability for the spine and contain a joint. This joint may be affected by inflammations or degeneration which causes pain that can be mistaken for SI joint pain.


7. Lumbar Radiculopathy

Lumbar Radiculopathy is a major source of back pain. This condition occurs from inflammation, irritation, or impingement of the nerve root. It is commonly confused for SI joint pain.lumbarradi




Low Back Pain- Disc Herniation

The spine is comprised of bony vertebrae separated by discs. The neural structures of the spine include the spinal cord (T12-L1), The conus medullaris—which is the lower end of the spinal cord, and the Cauda Equina, which is the division of multiple nerve roots beginning at the level of L1. Conditions of the lumbar spine including disc herniation are a main cause of lower back pain.

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The lumbar spine (lower back) consists of five vertebrae numbered L1-L5. These vertebrae are attached to the sacrum at the lower end of the spine. The discs between the vertebrae are round cushioning pads which act as shock absorbers. In a normal disc, there are two layers—the inner disc layer, which is comprised of soft gelatinous tissue and known as the Nucleus Pulposus, and the outer disc layer—which is made up of thick strong tissue, which is known as the Annulus Fibrosis. Behind this disc lies the spinal nerve root and the cauda equina. A major disc herniation of the lumbosacral region could affect the nerve roots.



In about 95% of all disc herniation cases, the L4-L5 or L5-S1 disc levels are involved. Herniation of the L4-L5 disc will affect the L5 nerve root. Herniation of the L5-S1 disc will affect the S1 nerve root.


There are three types of disc herniation:

  1. Protrusion/ Bulge- A bulging disc with intact annular and posterior longitudinal ligament fibers
  2. Disc Herniation
    • Type A—Disruption of inner annular fibers with intact outer annular fibers
    • Type B—Disrupted annulus with tail of disc material extending into the disc space
  3. Sequestration
    • Free fragment without tail extending into disc space
    • Fragment may be reabsorbed spontaneously
    • May get better with the use of an epidural


There are three typical locations for disc herniation as well:

  1. Central
    • Involves multiple nerve roots
    • Predominantly causes low back pain more than leg pain
    • May cause incontinence of the bladder and bowel
    • Urgent surgical treatment if patient presents with neurological deficits
  2. Posterolateral—usual location, most commonly involving one nerve root (the lower one)
    • For example: L4-L5 posterolateral herniation will involve L5 nerve root
  3. Foraminal
    • Occurs in 8-10% of cases
    • Involves the exiting nerve
    • Example: L4-L5 foraminal herniation will involve the L4 nerve root

Discogenic Back Pain is an internal disc disruption with early disc degeneration. Pain gets worse with flexion and sitting but, gets slightly better with extension. Forward flexion is limited on the exam and there are no radicular symptoms.