Appearance Walls of<unk> s are thin and fibrous; they are prone to rupture if touched, making surgery difficult. The nerve fibers embedded in the walls of the<unk> s have the appearance and size of dental floss; these nerve fibers are usually not arranged in any specific alignment. Histologic examination reveals the<unk>  outer wall is composed of vascular connective tissue, and the inner wall is lined with flattened arachnoid tissue. In addition, part of the lining containing nerve fibers also occasionally contains ganglion cells. The<unk> s can contain anywhere from a couple of milliliters of CSF to over of CSF. Location<unk> s are most commonly located in the S1 to S4/S5 region of the spinal canal, but can be found along any region of the spine. They usually form on the extradural components of sacrococcygeal nerve roots at the junction of dorsal root ganglion and posterior nerve roots and arise between the endoneurium and perineurium. Occasionally, these<unk> s are observed in the lumbar and thoracic spine. However, these<unk> s most commonly arise at the S2 or S3 junction of the dorsal nerve root ganglion. The<unk> s are often multiple, extending around the circumference of the nerve, and can enlarge over time to compress neighboring nerve roots, to cause bone erosion. The<unk> s may be found anterior to the sacral area and have been known to extend into the abdominal cavity. These<unk> s, though rare, can be found to grow large - over in size, often causing severe abdominal pain from compression on the<unk>  itself as well as adjoining nerves. Difference between<unk> s and other spinal meningeal<unk> s The following table is compilation of some key differences between<unk> s, meningeal<unk> s, and arachnoid diverticula<unk> s. Although the definitions for each entity are still controversial, the following items are generally accepted.<unk>  Meningeal Diverticula & Arachnoid Diverticula Potential communication with spinal subarachnoid space Communicates freely with spinal subarachnoid space Delayed filling in myelograms Rapid filling in myelograms Found distal to the junction of posterior nerve root and dorsal root ganglion in sacral region Found proximal to dorsal root ganglion throughout vertebral column Walls contain nerve fibers Walls lined by arachnoid mater with no signs of neural element Often multiple, extending around the circumference of nerve root No pattern of formation in regards to multiplicity Symptoms<unk> s are likely highly underdiagnosed as it was Isadore<unk> 's later research that led him to the understanding of their symptomology. Symptoms are based on the locations of the<unk> s along the spine, and follow general pathology of spinal injury: * Pain * Paresthesia * Spasticity, Hypertonia * Muscular Dysfunction or Weakness * Radiculopathy Although they are most frequently reported along sacral regions, they are rarely seen in other locations along the spine. Women are more likely to exhibit symptoms They can also appear in clusters or bilaterally along the spine, thus symptoms can be unilateral, bilateral, or with symptoms more dominant on one side. The cases of reported symptomatic<unk> s ranges from 15% to 30% of the overall reported<unk>  case, depending on the source of literature. Nevertheless, these<unk> s are important clinical entities because of their tendency to increase in size over time, potentially causing complications and eroding the surrounding bone tissue. Patients with symptomatic<unk> s near the sacrum (and not other locations of the spine) can be divided into 4 categories, according to their experienced symptoms: * Group 1 - Pain on tailbones that radiates to the legs with potential weakness; * Group 2 - Pain on bones, legs, groin area, sexual dysfunctions, and dysfunctional bladder; * Group 3 - Pain that radiate from the<unk>  site across hips to the lower abdomen; * Group 4 - No pain, just sexual dysfunction and dysfunctional bladder. Common symptoms specific to sacral<unk> s Below are a list of commonly reported symptoms associated with sacral<unk> s: Back pain, perineal pain, secondary Sciatica, secondary piriformis muscle dysfunction with tertiary sciatica, Cauda equina syndrome, neurogenic claudication (pain caused by walking), neurogenic bladder, dysuria, urinary incontinence, coccygodynia, sacral radiculopathy, radicular pain, headaches, retrograde ejaculation, paresthesia, hypesthesia, secondary pelvic floor dysfunction, vaginismus, motor disorders in lower limbs and the genital, perineal, or lumbosacral areas, sacral or buttocks pain, vaginal or penile paraesthesia, Persistent Genital Arousal Disorder (PGAD) characterized by unwanted, unrelenting genital sensory awareness, itch or pain that can persist for days, months, even years), sensory changes over buttocks, perineal area, and lower extremity; difficulty walking; severe lower abdominal pain, bowel dysfunction, intestinal motility disorders like constipation or bowel incontinence.
Tarlov cyst
Tornwaldt cyst
Dentigerous cyst
Colloid cyst
Epidermoid cyst
Choristoma
Ganglion cyst
Gartner's duct cyst