Dural Dysplasia

Neurofibroma

Myelomeningocele/Myelocele

Lipomyelomeningocele/Lipomyelocele

Terminal Myelocystocele

Bony remodeling: Dural dysplasia, neurofibroma, ependymoma

Bone destruction: Metastases, chordoma

Intrinsic weakness in dura

Transmission of chronic CSF pressures leads to bony remodeling and expansion of lumbosacral canal and neuroforamina

Contents follow CSF signal on MR and show no appreciable enhancement

Can be seen with neurofibromatosis type 1, Marfan disease, homocystinuria, Ehlers-Danlos, and ankylosing spondylitis

Fusiform enlargement of nerve root(s)

Heterogeneous enhancement

Multiple lesions typical of type 1 neurofibromatosis

Bony remodeling caused by intraspinal or transforaminal lesions can cause scalloping or the posterior lumbar vertebra and sacrum, neuroforaminal widening

Unilateral or bilateral vertical component through the sacral alae, possibly with a horizontal component through the body

Subtle fracture may be hard to identify even with high-quality CT

Associated marrow edema signal most conspicuous on fat-saturated T2WI (e.g., STIR)

Increased tracer uptake on bone scan

95% occur in conjunction with other pelvic fractures

Denis classification

Higher Denis zones associated with increasing probability of significant neurologic deficit

Renal, lung, breast, and prostate carcinomas are common primaries to develop osseous metastases

Sacral fracture can develop within bone weakened by tumor or by pelvic radiation therapy

Most common neoplasm of the conus and distal spinal canal

Marked enhancement typical

Can show signs of necrosis (heterogeneity, cyst formation) and hemorrhage: Subarachnoid hemorrhage, superficial siderosis

Bony remodeling when large: Scalloping of the margins of the spinal canal, foraminal enlargement

Common features: Everted elements of dorsal neural arch; tethered, dysraphic cord

Lipomyelomeningocele, lipomyelocele: Placode adherent to fatty mass contiguous with subcutaneous fat; intact skin

Myelomeningocele, myelocele: Placode exposed; no overlying skin

Lipomyelocele, myelocele: Placode lies within spinal canal

Lipomyelomeningocele, myelomeningocele: Placode and meninges protrude through spinal defect

Terminal myelocystocele: Meningeal sac containing tethered, hydromyelic cord extends through sacral defect; intact skin

CSF-containing meningeal cyst within the sacral canal; thin or imperceptible wall; no appreciable enhancement

Does not contain neural elements

Chronic CSF pulsation pressure leads to expansion and bony remodeling

Often asymptomatic, may be associated with low back pain, radicular symptoms, and bladder dysfunction

CSF-containing meningeal sac protruding into the pelvis through an enlarged sacral foramen or a defect in a dysplastic sacrum

Important to determine if nerve roots traverse the neck of the sac for surgical planning

Malignant tumor arising from notochord remnants; 50% sacrococcygeal in location

Hyperintense on T2WI; usually containing multiple septae; calcification common in sacral chordoma

Peak incidence in 5th and 6th decades, rare in children

Rare, congenital tumors arising from totipotential cells in the caudal cell mass

Most are large, encapsulated with mixed solid and cystic components

Sacral canal involved in 2%

Classified by location