The inverted V sign has been described in several different pathologies:
inverted V sign (pneumoperitoneum)
inverted V sign (spinal cord)
The inverted "V" sign, also known as the inverted rabbit ears sign, is a radiological sign described in subacute combined degeneration of the spinal cord.
It refers to the appearance of the spinal cord on axial MRI slices 1-3. On these slices in a patient with subacute combined degeneration of...
Iophendylate (generic name is iodophenylundecylic acid) and sold under the tradename Myodil (except the USA where it was marketed as Pantopaque) was an oil-based contrast medium that was previously used for myelography. It was first used in 1944, but officially discontinued in 1988 6.
The ivory vertebra (also known as ivory vertebra sign) sign refers to the diffuse and homogeneous increase in opacity of a vertebral body that otherwise retains its size and contours, and with no change in the opacity and size of adjacent intervertebral discs.
The cause for...
The Jarcho-Levin syndrome (JLS) or spondylothoracic dysostosis is a rare autosomal recessive heterogeneous disorder that can occur with variable severity. Previously the condition spondylocostal dysostosis was also considered as part of the JLS spectrum but is now considered a distinct pathologi...
Jefferson fracture is the eponymous name given to a burst fracture of the atlas. It was originally described as a four-part fracture with double fractures through the anterior and posterior arches, but three-part and two-part fractures have also been described.
A typical m...
Klaus height index is the distance between tip of the dens and the tuberculum torcula line (Twining's line) 1,2. A normal height is 40-41 mm.
A decreased Klaus height index is seen in basilar invagination.
Klippel-Feil syndrome is a complex heterogeneous entity that results in cervical vertebral fusion. Two or more non-segmented cervical vertebrae are usually sufficient for diagnosis.
There is a recognized female predilection 1. Klippel-Feil syndrome has an incidence of 1:40,000-42,...
Kümmell disease is an eponymous name for osteonecrosis and collapse of a vertebral body.
Kümmell disease represents delayed (usually two weeks) vertebral body collapse due to ischemia and non-union of anterior vertebral body wedge fractures after major trauma.
Kyphosis (plural: kyphoses), much less commonly kyphus, is a term used to describe the sagittal curvature of the thoracic spine.
An increased kyphotic angle is seen in the following conditions:
vertebral body fracture
This article lists a series of labeled imaging anatomy cases by system and modality.
CT head: non-contrast axial
CT head: non-contrast coronal
CT head: non-contrast sagittal
CT head: angiogram axial
CT head: angiogram coronal
CT head: angiogram sagittal
CT head: venogram axial
Laminectomy (whether unilateral or bilateral) refers to the surgical removal of the lamina of a vertebral body. By removing the lamina, we are able to decompress the spinal canal, and thus reduce the pressure on the spinal cord.
Spinal stenosis may be caused by:
arthritis of the spine (in olde...
The lateral corticospinal tract is formed at the level of the of the medullary pyramids when the majority (90%) of descending corticospinal tract fibers decussate. The remaining 10% do not decussate and form the much smaller anterior corticospinal tract. A few non-decussated fibers may enter the...
A lateral hemivertebra is a form of hemivertebra which occurs when one of the two chondrification centers fails to develop. They can be single or multiple and usually associated in the formation of scoliosis.
Various subtypes have been descrbied
The lateral horn of the spinal cord is the small lateral projection of grey matter located between the dorsal horn and ventral horn and contain the neuronal cell bodies of the sympathetic nervous system.
On transverse section of the spinal cord, the spinal grey matter is describe...
Lateral meningocele syndrome is an extremely rare hereditary connective tissue disorder characterized by multiple lateral lumbar meningoceles, distinctive facial features, joint hypermobility, hypotonia, skeletal abnormalities, congenital cardiovascular malformations, urogenital anomalies and ne...
The lateral spinothalamic tract, also known as the lateral spinothalamic fasciculus, is an ascending pathway located anterolaterally within the peripheral white matter of the spinal cord. It is primarily responsible for transmitting pain and temperature as well as coarse touch.
The anterior sp...
Lateral thoracic meningoceles are a type of spinal meningocele.
As with any meningocele, it results from herniation of the meninges through a foramen or a defect in the vertebral column.
They are typically associated with neurofibromatosis type I but can rarely occur ...
Leptomeningeal drop-metastases correspond to a CNS primary neoplasm spread inferiorly along the cerebrospinal spaces. It is usually presented as diffuse enhancing nodules along the spine and cauda equina.
Please refer on leptomeningeal metastases to a broad discussion on this entity.
Leptomeningeal metastases, also known as carcinomatous meningitis, refers to the spread of malignant cells through the CSF space. These cells can originate from primary CNS tumors (e.g. drop metastases), as well as from distant tumors that have metastasized via hematogenous spread.
Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is a rare inherited autosomal recessive leukodystrophy characterized by slowly-progressive pyramidal, cerebellar, and dorsal column dysfunction.
Although considered rare, the exact prevalen...
Levine and Edwards classification is used to classify hangman fractures of the C2, which is also known as traumatic spondylolisthesis of the axis. Upper neck hyperextension causes bilateral pars interarticularis fractures and the amount and direction of displacement will guide treatment.
Lhermitte sign or the barber chair phenomenon is an electrical shock sensation running down the spine and into the limb on neck flexion. It suggests compression of the upper cervical spinal cord and/or brainstem.
It is typically seen with multiple sclerosis but is also associated wit...
The ligamenta flava (singular: ligamentum flavum) are paired ligaments which run between adjacent laminae of the vertebral bodies and are present from C2/3 to the sacrum. Above the C2/3 level, the equivalent structures are known as the posterior atlanto-occipital membrane between the skull base ...
Ligamentum flavum hypertrophy refers to abnormal thickening of the ligamentum flavum. If severe, it can be associated with central canal stenosis.
It is thought to be mostly from fibrosis caused by the accumulation of mechanical stress with the aging process, especially along the dor...
The ligamentum nuchae is a large median ligament composed of tendons and fascia located between the posterior muscles of the neck. It covers the spines of C1 to C6 vertebrae. It is a superior and posterior extension of the supraspinous ligament. It rises from the spinous process of C7 to the ini...
A limbus vertebra is a well-corticated unfused secondary ossification center, usually of the anterosuperior vertebral body corner, that occurs secondary to herniation of the nucleus pulposus through the vertebral body endplate beneath the ring apophysis (see ossification of the vertebrae). These...
Lipiodol® (also known as ethiodized oil) is an oil-based iodinated contrast medium that was historically used for myelography and hysterosalpingography 1. It was later superseded by newer, less hazardous, agents, and now is used primarily as a therapeutic agent. Guerbet is now the sole manufactu...
Fatty filum terminale, also known as lipoma of the filum terminale or filar lipoma, is a relatively common finding on imaging of the lumbar spine, and in most cases is an incidental finding of no clinical concern. However, in some patients it may be associated with signs and symptoms of tethered...
Lipomyelocele, also known as lipomyeloschisis, is one of the most common closed spinal dysraphism. It is seen in the thoracolumbar region and usually presents as a fatty subcutaneous mass.
It is twice as common as lipomyelomeningocele.
Affected individuals are usually as...
Lipomyelomeningoceles are one of the forms of closed spinal dysraphism. They usually present as a subcutaneous fatty mass just above the intergluteal cleft. However, some lipomyelomeningoceles may occur at other locations along the spinal canal.
Lipomyelomeningoceles may ...
Locked facet joint is a type of facet joint dislocation that results from jumping of the inferior articular process over the superior articular process of the vertebra below and becomes locked in the position.
It can be unilateral or bilateral.
The tip ...
Longitudinally extensive spinal cord lesions (LESCL), also known as longitudinally extensive transverse myelitis (LETM), represent extensive involvement of the spinal cord, with abnormal T2 signal traversing at least three vertebral body segments in length.
They are typi...
Lordosis (plural: lordoses) is the term used to refer to the normal anterior curvature of the cervical and lumbar spines when viewed from the side (concavity at the posterior aspect of the spine (cf kyphosis). Lordosis cervicis and lordosis lumbalis are the respective Terminologia Anatomica term...
Loss of intervertebral disc space can be due to a variety of causes:
degenerative disc disease of the spine: most common cause
dialysis related spondyloarthropathy
crystal deposition diseases
Several conditions may give vertebral endplate T1 low signal on MRI. They include:
The lumbar cistern refers to the subarachnoid space in the lower lumbar spinal canal.
The cistern is an enlargement of the subarachnoid space in the dural sac, distal to the conus medullaris. It contains cerebrospinal fluid and the nerve roots of the cauda equina. As the conus (usually) termina...
Lumbar disc disease is a very common entity with a high asymptomatic prevalence. Intervertebral disc abnormalities are found in 25% of individuals below the age of 60, and over 50% in those over the age of 60. It is therefore not enough to demonstrate a disc lesion in someone with non-specific b...
The lumbar enlargement of the spinal cord corresponds to the mild increase in cross sectional area of the cord from the T11 level to the conus medullaris. It is enlarged due to the presence of the spinal nerve anterior rami which contribute to the lumbar and sacral plexuses.
Lumbar epidural gas is a rare phenomenon where gas locules are observed within the central canal of the lumbar spine. It can arise from a number of factors:
due to regional degenerative disc disease with or without dorsal epidural disc migration: thought to be from gas leaking from the disc spa...
Lumbar foraminal stenosis or lumbar neuroforaminal stenosis is a common cause of back pain and/or radiculopathy, and is assessed for as part of the routine evaluation of lumbar MRI studies to determine what impact, if any, the surrounding structures have on the exiting nerve root.
The lumbar gravity line is a measurement made on spinal / chiropractic imaging. It is usually drawn on an erect weight bearing radiograph as plumb line drawn downwards on a sagittal image from the L3 vertebra and usually should pass through the anterior 1/3 of the sacrum.
Lumbar interlaminar epidural injections are one of some possible spinal epidural injections. For an alternative approach for the same region, please refer to the article on lumbar transforaminal epidural injections.
Typically, epidural injections are performed in patients with rad...
The lumbar plexus is a complex neural network formed by the lower thoracic and lumbar ventral nerve roots (T12 to L5) which supplies motor and sensory innervation to the lower limb and pelvic girdle.
origin: ventral rami of T12 to L5
course: formed within the substance of the psoas ma...
A handy mnemonic to recall the roots of the lumbar plexus is:
2 from 1, 2 from 2, 2 from 3
2 nerves from 1 root: ilioinguinal (L1), iliohypogastric (L1)
2 nerves from 2 roots: genitofemoral (L1/L2), lateral femoral cutaneous (L2/L3)
2 nerves from 3 roots: obturator (L2/L3/L4), femo...
Lumbar (or 13th) ribs are a rare anatomical variant and represent transitional vertebrae at the thoracolumbar junction with a prevalence of ~1% 1. It presents as an additional rib coming off T13 or L1 (depending on numbering classification) and may be unilateral or bilateral. Lumbar ribs are mos...
The lumbar spine (often shortened to L-spine) consists of five adjacent vertebrae of the lower vertebral column. They participate in the lumbar lordosis, a natural curve in the spine, that is convex anteriorly.
Articulations of the facet (zygapophyseal) joints permit flexion/extension and abdu...
The lumbar spine anteroposterior or posteroanterior view images the lumbar spine in its anatomical position. The lumbar spine generally consists of five vertebrae (see: lumbosacral transitional vertebra).
This projection is utilized in many imaging contexts including trauma, postop...
The lumbar spine flexion and extension views images the lumbar spine which consists of five vertebrae.
These views are specialized projections to provide functional tests 1 of lumbar spine instability, often in the context of spondylolisthesis.
the patient is pos...
Lumbar spine fractures are often a result of significant blunt trauma such as motor vehicle accidents or a fall from height. Non-traumatic causes include osteoporotic and pathological fractures.
Traumatic fractures are more common in males. The risk of osteoporotic fractures incre...
The lumbar spine lateral view images the lumbar spine which generally consists of five vertebrae (see: lumbosacral transitional vertebra).
This projection shows an orthogonal view of the AP/PA view and is utilized in many imaging contexts including trauma, postoperatively, and for ...
The lumbar spine series is comprised of two standard projections along with a range of additional projections depending on clinical indications. The series is often utilized in the context of trauma, postoperative imaging and for chronic conditions such as ankylosing spondylosis.
Lumbar spine r...
Lumbosacral transitional vertebrae (LSTV) are a relatively common variant and can be seen in ~25% (range 15-35%) of the general population 1-3. Non-recognition of this variant and/or poor description in the report can lead to operations or procedures performed at the wrong level.
Depending on ...
Lymphoma of the spinal cord is an uncommon manifestation of lymphoma. Although lymphoma more commonly involves the vertebral body (vertebral body tumors) or epidural compartment, intramedullary lymphoma may rarely occur.
Apparent intramedullary spinal cord lymphoma may often, in fact, represe...
The Magerl classification, one of many thoracolumbar spinal fracture classification systems, was adopted as the original AO classification in 1994 but has since then been superseded: see the current AO classification of thoracolumbar injuries.
Although the Magerl classification is based ...
Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral nerves.
It is used to assess peripheral nerve entrapments and impingements as well as localization and grading of nerve injuries and lesions.
The Matterhorn sign is a descriptive sign for a calcified disc herniation that impales the dural sac and sometimes the cord, typically located in the thoracic spine.
History and etymology
This sign is named after one of the most iconic mountains in the Alps: the Matterhorn.
McAfee classification of acute traumatic spinal injuries is one of a number of thoracolumbar spinal fracture classification systems and based on the three-column concept of the spine (of Denis). It requires CT for an accurate assessment.
The McAfee classification uses terminology that is...
McRae line is a radiographic line drawn on a lateral skull radiograph or on a midsagittal section of CT or MRI that connects the anterior and posterior margins of the foramen magnum (basion to opisthion).
indicates the presence of basilar invagination (atlantoaxial impaction): the...
Meningeal melanocytomas are rare benign primary melanocytic tumors of the CNS that are derived from leptomeningeal melanocytes. They can occur anywhere along the neuraxis but are most commonly found in the spinal canal near the foramen magnum, as well as the posterior cranial fossa, Meckel cave,...
The meninges (singular: meninx) is a collective term for the three membranes that cover the brain and spinal cord and are covered in separate articles:
History and etymology
The word meninges arises from the Ancient Greek meninx meaning "membrane" 1.
Meningoceles are protrusions of the meninges through a defect or weak point in the skull or spine, usually involving the soft tissues beneath the surface of the skin. They are typically categorized into congenital, iatrogenic (e.g. following a craniotomy, sinus surgery, or as a laminectomy compl...
Meningocele manqué (from French, literally "missed meningocele") is a rare condition characterized by focal dorsal tethering of the spinal cord. The term is used to designate a meningocele which failed to develop and became atretic.
It has been reported in neonates, but median age...
The meniscus sign refers to the intradural filling defect which is outlined by the sharp meniscus of intrathecal contrast due to blockage of subarachnoid space by an intradural lesion. The CSF above the blocked segment remains unopacified.
Methotrexate-induced myelopathy is an uncommon toxic manifestation of intrathecal methotrexate administration that closely mimics subacute combined degeneration of the cord but with normal vitamin B12 and copper 1,2. It is far less common than methotrexate-related leukoencephalopathy.
Modic type endplate changes represent a classification for vertebral body endplate MRI signal, first described in 1988 1. It is widely recognized by radiologists and clinicians and is a useful shorthand for reporting MRIs of the spine.
Recently Modic type I has received renewed attention due to...
Modic type I endplate change is the most controversial and important of the three types described (see Modic endplate change). It is seen on MRI of the spine and represents the presence of low T1 and high T2 signal within the bone marrow of a vertebral body adjacent to a disk. Type 1 change can...
The modified Memphis criteria are a set of screening criteria for blunt cerebrovascular injury (BCVI) in trauma. The presence of one or more of these criteria makes necessary a complementary CTA or DSA study to exclude a BCVI.
The screening protocol criteria for BCVI are:
base of skull fractur...
Movements of the spine are possible due to intervertebral discs, and with the fulcrum of movement occurring primarily around the nucleus pulposus. Specialized motion occurs at the atlanto-occipital and atlantoaxial joints, which do not contain a disc.
The spine (vertebral column) forms the cent...
Disc degeneration can be graded on MRI T2 spin-echo weighted images using a grading system proposed by Pfirrmann 1. This classification is not used on routine spine reports, being more important for research purposes.
grade I: disc is homogeneous with bright hyperintense white signal intensity ...
Myelitis, is a collective term simply referring to any inflammation of the spinal cord. It is a form of myelopathy.
The two major sub types include:
ideopathic transverse myelitis
secondary transverse myelitis: viral, neurosyphilis...
Myelography is a form of imaging intended to evaluate the subarachnoid spaces within the spinal canal. It is now usually performed with either CT or MR imaging of the spine after injection of an intrathecal iodinated or gadolinium-based contrast agent. MR myelography may also provide evaluation ...
Myelomeningocele, also known as spina bifida cystica, is a complex congenital spinal anomaly that results in spinal cord malformation (myelodysplasia).
It is one of the commonest congenital CNS anomalies and thought to occur in approximately 1:500 of live births 5. There may be a...
Myxopapillary ependymomas are a variant type of ependymoma that occurs predominantly in the filum terminale and/or conus medullaris. They represent 13% of all spinal ependymomas and are the most common tumors of the cauda equina region.
They tend to have an earlier clinical presen...
The naked facet sign (also known as the hamburger sign or reverse hamburger bun sign) refers to the CT appearance of an uncovered vertebral articular facet when the facet joint is dislocated, most often in cases of locked facet.
This CT sign is characteristic of a flexion-distraction injury an...
The differential diagnosis for masses of the cauda equina region is often considered separately to the remainder of the spinal cord. It is often difficult to determine whether masses in this region are intramedullary or intradural-extramedullary.
Most common tumors
Neoplasms of the spinal canal encompass a range of tumors which arise from or involve the spinal cord, theca, and spinal nerves.
These can be divided according to the tissue/structure of origin within the spinal canal. Tumors of vertebral bodies are discussed separately: see vertebra...
Nerve root enhancement is phenomenon described on post contrast MRI scans that can be observed in a number of situations.
post-operative nerve root enhancement
disseminated spinal leptomeningeal metastases
The neurenteric canal or canal of Kovalevsky is the transient communication of the amnion through notochordal canal to the yolk sac during notochordal formation at day 16-17.
Abnormalities during this stage produce the neurenteric cyst spectrum.
Neuroanatomy encompasses the anatomy of all structures of the central nervous system, which includes the brain and the spinal cord, and their supporting structures.
This anatomy section promotes the use of the Terminologia Anatomica, the international standard of anatomical nomenclature.
Neurogenic bladder is a term applied to a dysfunctional urinary bladder that results from an injury to the central or peripheral nerves that control and regulate urination. Injury to the brain, brainstem, spinal cord or peripheral nerves from various causes including infection, trauma, malignanc...
Neurolymphomatosis is a rare condition characterized by the direct invasion of the cranial and peripheral nerves and roots by lymphoma, in the great majority B-cell non-Hodgkin lymphoma.
It should be differentiated from non-tumor conditions associated with lymphoma that also affect the peripher...
Neuromyelis optica (NMO) and neuromyelitis optica spectrum disorder (NMOSD) are closely related severe demyelinating diseases caused by an autoantibody to the aquaporin-4 water channel. The classic presentation of NMO is with the triad of optic neuritis, longitudinally extensive myelitis, and po...
Nitrous oxide (N2O) toxicity has serious medical sequelae affecting both the CNS and the bone marrow. Neurological effects include encephalopathy, myelopathy, and neuropathy. This results from demyelination and gliosis due to selective inhibition of vitamin B12 1. Bone marrow toxicity may lead t...
This article lists examples of normal imaging of the spine and surrounding structures, divided by region and modality.
example 1: AP, lat, obliques only
example 2: PEG view
example 3: flexion and extension views only
example 4: pediatric - 12 years old
The notochord represents the earliest fetal axial skeleton, extending from the Rathke pouch to the coccyx. It is a primitive cell line from which the skull base and vertebral column develop. The notochord is cylindrical and is replaced by sclerotomes that produce cartilage, and subsequently bone...
The nucleus pulposus (plural: nuclei pulposi) is the central part of each intervertebral disc.
It is located within the annulus fibrosus and between the vertebral body endplates. It is composed of a thin lattice of collagen fibers (type II) which traverse though hydrophilic glyco...
A nude nerve root is perhaps not as exciting as the name would suggest. It refers to an uncommon anatomical variant where nerve roots simply exit the theca without investing dural sleeves 1. These have been associated, at least in case reports, with spontaneous craniospinal hypotension 1.
Occipital condylar fractures are uncommon injuries usually resulting from high-energy blunt trauma. They are considered a specific type of basilar skull fracture, and importantly can be seen along with craniocervical dissociation.
Treatment of isolated injury is generally conservative, unless t...
Occipital vertebrae are very rare anatomical variants that result from incomplete or aberrant fusion of occipital bone ossification centers. There is a broad spectrum of occipital vertebrae variations and the four most common include:
third condyle (condylus tertius)
Occult intrasacral meningocele is a rare congenital lesion characterized by the presence of a cyst within the sacral thecal sac. It is an extradural sacral arachnoid cyst - Nabor type Ib meningeal cyst. It is not a true meningocele.
It is associated with spinal dysraphism, tethered cord syndrom...
Ochronosis, or alkaptonuria (AKU), is a rare multisystem autosomal recessive metabolic disorder.
On imaging, the most particular presentation is on the spine, with osteoporotic bones and dense disc calcifications.
The term ochronosis usually refers to the bluish-black discolourat...
Odontoid process fracture, also known as a peg or dens fracture, occurs where there is a fracture through the odontoid process of C2.
The mechanism of injury is variable, and can occur both during flexion or extension, and with or without compression 5.
There are two...