Neuroanatomie (Fach) / Alles (Lektion)
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- Disk protrusion terminology Bulge_ Broad-based disk bulge. Usually bulging annulus fibrosus. Protrusion_ Focal disk bulge. Usually herniated nucleus pulposus.
- Intervertebral disk high intensity zone (HIZ) High T2 signal of annulus indicating annular tear.
- Disk free fragment mimickers Conjoined root_ Normal variant of two roots exiting thecal sac together. Same density of thecal sac. Tarlov cyst_ Normal variant of dilated nerve root sleeve. Same density of thecal sac.
- Lateral Disks May cause nerve root impingement causing symptoms of a superior level. Nerve root has already exited central canal.
- Common causes of Central Canal Stenosis Facet joint degenerative change (most common). Lligamentum flavum hypertrophy.
- Most common cause of neuroforaminal stenosis Facet joint degenerative change with bony encroachment.
- Lateral recess Lumbar spine bony canals where nerve roots lie after exiting thecal sac and before entering neuroforamen. Hypertrophy of superior articular facet is most common cause of encroachment.
- Spondylolysis identified on axial images Break in bony ring of the lamina (pars interarticularis) at the mid vertebral body level.
- Spondylolisthesis occurs from either Bilateral spondylolysis. Facet joint degenerative change.
- Distinguishes postop scar from disk material Scar tissue enhances. Disk material has only minimal peripheral enhancement.
- Differentiates disk infection fromdegenerative disk ... Type 2 degenerative disk disease_ Low T1 disk and high T2 parallel endplate bands. Disk space infection_ High T2 disk.
- Myelopathy neurologic signs Ataxia. Bowel and bladder incontinence. Babinski sign.
- Radiculopathy neurologic signs Muscle weakness. Decreased reflexes. Dermatomal sensory deficits.
- Urgency for imaging acute myelopathy Poor prognosis if left untreated for greater than 24 hours.
- Common causes of myelopathy Extramedullary_ Epidural mass cord compression. Cervical spine stenosis. Intramedullary_ Tumor. Inflammation, Arteriovenous malformation (AVM). Spinal dural arteriovenous fistula (SPAVF).
- Definition of Intramedullary spinal canal lesion Usually confined to spinal cord. May be exophytic.
- Definition of extramedullary spinal canal lesion Outside of spinal cord. May be intradural or extradural.
- Intradural intramedullary lesions Ependymoma. Astrocytoma. Hemangioblastoma. Lipoma/(Epi)dermoid. Syringohydromyelia. Intramedullary AVM. Met/abscess (rare).
- Intradural extramedullary lesions (includes subarachnoid ... Meningioma. Schwannoma/neurinoma. Neurofibroma. Hemangiopericytoma. Lipoma/(Epi)dermoid. Arachnoid cyst/adhesion. Drop/leptomeningeal metastasis. Veins (extramedullary AVM).
- Extradural extramedullary lesions Degenerative_ Herniated disc. Synovial cyst. Osteophyte. Rheumatoid pannus. Nondegenerative_ Metastasis. Abscess. Hematoma. Primary tumor expansion or invasion. Epidural lipomatosis
- Most common intramedullary lesion at MRI Multiple sclerosis
- Lupus Erythematosus spinal cord involvement Areas of high T2 signal with cord swelling. May involve 4 or 5 vertebral segments. Have less well-defined margins than MS plaques.
- Atlantoaxial instability and rheumatoid arthritis Inflammatory changes (pannus) destroy transverse ligament of C1. Dens may slide posteriorly and intermittently compress cord causing myelomalacia. 5% of RA patients frank atlantoaxial instability.
- Vertebral body and disc infection findings Adjacent vertebral bodies and disc usually involved. Destruction greatest at endplates. Posterior elements usually spared. Low T1 and high T2 marrow signal with normal diffusion. If pyogenic disk enhances, ...
- Vertebral body neoplasm findings Isolated or noncontiguous involvement. Pedicles typically affected. Low T1 and high T2 signal with restricted diffusion. Disk typically spared (except prostate cancer). Enhancement may obscure metastases ...
- Vertebral body osteoporosis findings Several vertebral bodies with height loss. Anterior weding with posterior elements spared. Normal T1 and T2 unless fracture. Disk spared.
- TB of the spine, or Pott disease Causes slow collapse of one or more vertebral bodies. Gibbus deformity, acute kyphosis. Infection spreads underneath longitudinal ligaments. Can lead to cord compression. May spare disks.
- Most common neoplasm of the spine Metastases
- Two most common primary intramedullary tumors Astrocytoma. Ependymoma.
- Spinal cord astrocytoma and ependymoma shared features ... Expansile. Low T1 and high T2 signal with variable enhancement. Increased incidence in neurofibromatosis.
- Spinal cord Ependymoma features Most common spinal cord tumor in adults. Divided into cellular (intramedullary) and myxopapillary (filum terminale) types. Peak incidence inf ourth decade. Male predominance. These slow-growing neoplasms ...
- Spinal cord Astrocytoma features Most (75%) occur in cervical and upper to midthoracic cord. Fusiform cord widening. High T2 signal. Contrast enhancement over several vertebral body segments.
- Hemangioblastoma features Occur in spinal cord and posterior fossa. High association with Von Hippel-Lindau syndrome. Densely enhancing nidus with related cyst and or cord expansion. May be extramedullary and multiple. May be ...
- Syrinx Shorter term for syringohydromyelia. Hydromyelia, dilation of central canal and lined by ependyma. Syringomyelia, cavity outside central canal lined by glial cells. Suspect tumor as a cause of unexplained ...
- Most common intradural tumor in thoracic region Meningioma
- Spinal meningioma features Most (80%) occur in women. Average age of 45. Multiple meningiomas suspicious for neurofibromatosis. Usually extramedullary/intradural. Can have extradural component. Dense calcification can occur. Dense ...
- Most common intraspinal mass Schwannoma
- Spinal schwannoma features Neuroforaminal extension and expansion are common in cervical and thoracic spine with intra and extraspinal components, dumbbell shape. In lumbar spine, tend to remain within dural sac.
- Common intrathecal drop metastases Subarachnoid seeding of primary CNS tumors_ Posterior fossa medulloblastomas. Ependymomas. Pineal region neoplasms.
- Most common spine extradural neoplasm Metastatses_ Breast, Lung, Prostate carcinoma.
- Very low T1 and T2 marrow signal Myelofibrosis
- Spinal AVM features May be intramedullary or extramedullary. Intramedullary AVMs have a nidus of abnormal vessels that may cause hemorrhage or ischemia. Extramedullary AVMs generally are arteriovenous fistulas. Spinal dural ...
- Tethered Cord features Low-lying conus medullaris. In a newborn conus normally at L2. Typically ascends one to two vertebral segments as child grows. May form a taut mass in posterior lumbar canal, obscuring conus/cauda junction. ...
- Caudal Regression Syndrome Hypoplastic or absent distal spine and sacrum. Blunted conus.
- Spinal Arachnoid cysts and epidermoids Similar to brain arachnoid cysts and epidermoids. Arachnoid cysts follow CSFsignal. Epidermoids restrict diffusion, bright on DWIs.
- Spinal Epidural Hematoma Ventral epidural space contains plexus of veins. These can tear in trauma, resulting in epidural hematoma.
- Nerve Root Avulsion Most commonly occur in cervical spine. Typically involve roots of brachial plexus and upper extremities. Birth trauma from shoulder traction is common example.
- Acute versus chronic sinusitis findings Acute sinusitis_ Air-fluid levels and foamy secretions. Typically caused by viral URI. Chronic sinusitis_ Mucoperiosteal thickening. Thickening of bony sinus walls.
- Disease limited to the infundibulum of the maxillary ... Isolated obstruction of maxillary sinus.
- Lesion located at hiatus semilunaris (middle meatus) ... Obstruction of ipsilateral maxillary sinus, anterior and middle ethmoid air cells, and frontal sinus. Described as ostiomeatal pattern of obstruction.