I. What is sacral cyst?
Sacral duct cyst is generally considered to be a congenital disease, but some of them are acquired and belong to intradural cysts, with long-term chronic lower back, sacrococcygeal and perineal pain as the main manifestation
Second, what is the cause of sacral cyst? Why do you get sacral cyst?
Most believe that sacral duct cyst is a congenital disease, while some are acquired, the latter often secondary to trauma, infection and tumor followed by adhesive arachnoiditis. The common pathogenesis of both is congenital or acquired weakness of the dura mater and/or arachnoid membrane, combined with factors such as hydrostatic pressure of cerebrospinal fluid, which forms a cystic cavity communicating with the subarachnoid space, where cerebrospinal fluid enters the cyst with arterial pulsation, and eventually gradually expands due to poor outflow, fluid hydrostatic pressure and pulsatile impact of cerebrospinal fluid, forming a confined cyst.
What are the types of sacral cysts?
Sacral duct cyst is a type of spinal cyst, and spinal cyst can be divided into IA, IB, II and III according to Nabors typing, and sacral duct cyst mainly belongs to type IB and type II.
1. Nabors type IB, also known as sacral spinal bulge and occult sacral spinal bulge, is an epidural spinal cyst that does not contain spinal nerve root fibers, mostly located at the level of S1-3 of the sacral canal, and is often multiple.
Nabors type II, also called Tarlov’s nerve bundle membrane cyst or spinal nerve root diverticulum, is an epidural spinal cyst containing spinal nerve root fibers, which is an abnormal expansion of the distal end of the spinal nerve root sleeve to form a cyst, usually located at the level of S2-3 spinal nerve ganglion or its distal end, mostly seen in adults.
Fourth, what will be the manifestation of sacral canal cysts?
Intraspinal spinal cysts usually do not cause obvious discomfort and are sometimes found only incidentally during imaging.
Nabors type IB, mostly located at the level of S1-3 of sacral canal, often multiple, mostly seen in adults, no significant difference between men and women, usually asymptomatic, not associated with neurological dysfunction, possible associated diseases include juvenile kyphosis, rheumatoid spinal ankylosis and neurofibromatosis.
2. Nabors type II, usually located in the spinal ganglion at the level of S2-3 or its distal end, is mostly seen in adults, and about 1/4 have clinical symptoms, which may manifest as neurogenic claudication, lower back pain, sciatica and chronic perineal pain, sometimes with sensorimotor dysfunction and reflex changes.
V. How to diagnose sacral cyst? What are the characteristics?
1. Long duration of disease with intermediate remission period of symptoms.
2. Typical symptoms are lumbosacral pain, perineal hyperalgesia, dysfunction, limb weakness and numbness, etc.
Queckenstedt test indicates no or incomplete obstruction of the subarachnoid space.
4.X-ray sacral canal enlargement, fan-like lace-like changes of bone erosion at the posterior edge of the vertebral body, congenital deformities of the lumbosacral region such as occult spina bifida, spondylolisthesis and kyphosis may be seen at the same time.
5. CT lumbosacral bone destruction and low-density intracanalicular occupancy, type II is characterized by delayed visualization on CT scan after myelography.
6. MRI is the most reliable method of examination, which shows pouch-shaped, ovoid and irregular shaped cysts in the spinal canal, with low signal in TlWI and high signal in T2WI, similar to the signal of cerebrospinal fluid; enhanced scan shows no enhancement of the cyst wall. type IB is located in the sacral canal and separated from the dural sac by fat. Type II is located lateral to the dural sac with the presence of nerve roots within the sac.
VI. What diseases may be similar to sacral canal cysts?
1. Lumbar disc herniation can be differentiated according to the above clinical features and imaging examinations, especially MRI.
2. Intrasacral nerve sheath tumor Intrasacral multiple nerve sheath tumor is mostly the local manifestation of neurofibromatosis in the sacral canal, except for the combination of intracranial tumor and subcutaneous neurofibromatosis, MRI manifestation is often solid tumor or cystic solidity, MRI enhancement scan can see the solid part of tumor and tumor cystic wall enhancement.
How to treat sacral duct cysts?
1. Sacral duct cysts are common and most of them are asymptomatic. For asymptomatic patients and those with MRI showing cysts but with no obvious clinical symptoms, they usually do not need to be treated and can be observed first.
2. For those with obvious symptoms and consistent with MRI findings, surgery can be considered, such as: low back and leg pain or intermittent claudication with ineffective conservative treatment, affecting normal life or work; low back and leg pain with lower limb muscle strength and sensory loss; perineal pain or sensory loss, urinary and faecal or sexual dysfunction.
The main treatment strategy is to remove the cyst wall under the microscope and tightly suture the cyst and subarachnoid channel, and the so-called “minimally invasive” methods such as cyst aspiration and drug injection should not be used.