Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

587 results found
Article

Laminectomy

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...
Article

Lateral corticospinal tract

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...
Article

Lateral hemivertebra

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.  Pathology Subtypes Various subtypes have been descrbied incarcerated hemivertebra ...
Article

Lateral horn

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. Gross anatomy On transverse section of the spinal cord, the spinal grey matter is describe...
Article

Lateral meningocele syndrome

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...
Article

Lateral spinothalamic tract

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...
Article

Lateral thoracic meningocele

Lateral thoracic meningoceles are a type of spinal meningocele. Pathology As with any meningocele, it results from herniation of the meninges through a foramen or a defect in the vertebral column.  Associations They are typically associated with neurofibromatosis type I but can rarely occur ...
Article

Leptomeningeal drop-metastases

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. 
Article

Leptomeningeal metastases

Leptomeningeal metastases, also know 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 haematogenous spread. This article...
Article

Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation

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. Epidemiology Although considered rare, the exact prevalen...
Article

Levine and Edwards classification

Levine and Edwards classification is used to classify hangman fractures of C2 (also known as traumatic spondylolisthesis of axis). Classification type I: fracture with <3 mm antero-posterior deviation no angular deviation type II: fracture with >3 mm antero-posterior deviation significant a...
Article

Lhermitte sign (spinal cord)

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. Pathology It is typically seen with multiple sclerosis but is also associated wit...
Article

Ligamentum flavum

The 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 and C1 and between C1 and C2...
Article

Ligamentum flavum hypertrophy

Ligamentum flavum hypertrophy refers to abnormal thickening of the ligamentum flavum. If severe, it can be associated with central canal stenosis. Pathology It is thought to be mostly from fibrosis caused by the accumulation of mechanical stress with the aging process, especially along the dor...
Article

Ligamentum nuchae

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...
Article

Limbus vertebra

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 a...
Article

Lipiodol

Lipiodol® (also known as ethiodized oil) is an oil-based iodinated contrast medium that was historically used for myelography and hysterosalpingography. It was later superseded by newer, less hazardous, agents, and now is used primarily as a therapeutic agent. Guerbet is now the sole manufacture...
Article

Lipoma of the filum terminale

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...
Article

Lipomyelocele

Lipomyelocele, also known as lipomyeloschisis, is one of the most common closed spinal dysraphism. It is seen in thoracolumbar region and usually presents as a fatty subcutaneous mass. It is twice as common as lipomyelomeningocele. Clinical presentation Affected individuals are usually asympt...
Article

Lipomyelomeningocele

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. Clinical presentation Lipomyelomeningoceles may ...
Article

Locked facet joint

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. Radiographic features Plain radiograph The tip ...
Article

Longitudinally extensive spinal cord lesion

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. Differential diagnosis They are typi...
Article

Lordosis

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...
Article

Loss of intervertebral disc space (differential)

Loss of intervertebral disc space can be due to a variety of causes: degenerative disc disease of the spine: most common cause trauma diskitis neuropathic spondyloarthropathy dialysis related spondyloarthropathy ankylosing spondylitis ochronosis crystal deposition diseases sarcoidosis ...
Article

Low endplate signal on T1

Several conditions may give vertebral endplate T1 low signal on MRI. They include:   ankylosing spondylitis vertebral metastases disc infection haemodialysis
Article

Lumbar cistern

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...
Article

Lumbar disc disease

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...
Article

Lumbar enlargement

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.
Article

Lumbar epidural gas

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...
Article

Lumbar interlaminar epidural injection

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.  Indications Typically, epidural injections are performed in patients with rad...
Article

Lumbar plexus

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. Summary origin: ventral rami of T12 to L5 course: formed within the substance of the psoas ma...
Article

Lumbar plexus roots (mnemonic)

A handy mnemonic to recall the roots of the lumbar plexus is: 2 from 1, 2 from 2, 2 from 3 Mnemonic 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...
Article

Lumbar rib

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...
Article

Lumbar spine

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...
Article

Lumbar spine (AP/PA view)

The lumbar spine AP view images the lumbar spine which consists of five vertebrae. It is utilized in many imaging contexts including trauma, postoperatively, and for chronic conditions.  Patient position the patient is erect or supine, depending on clinical history ideally, spinal imaging sho...
Article

Lumbar spine series

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 x...
Article

Lumbosacral transitional vertebra

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 ...
Article

Lymphoma of the spinal cord

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...
Article

Magerl classification of thoracolumbar spinal fractures

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. Usage Although the Magerl classification is based ...
Article

Magnetic resonance neurography

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. Dedicated high-resolution...
Article

Matterhorn sign

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.
Article

McAfee classification of thoracolumbar spinal fractures

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. Usage The McAfee classification uses terminology that is...
Article

McRae line

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). Significance indicates the presence of basilar invagination (atlantoaxial impaction): the...
Article

Meningeal melanocytoma

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,...
Article

Meninges

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: cranial meninges spinal meninges History and etymology The word meninges arises from the Ancient Greek meninx meaning "membrane" 1.
Article

Meningocele

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...
Article

Meningocele manqué

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. Epidemiology It has been reported in neonates, but median age...
Article

Modic type endplate changes

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...
Article

Modic type I endplate change

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...
Article

Modified Memphis criteria for blunt cerebrovascular injury

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...
Article

Movements of the spine

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...
Article

MRI classification system for lumbar disc degeneration

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 ...
Article

Myelitis

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: leukomyelitis multiple sclerosis ADEM transverse myelitis ideopathic transverse myelitis secondary transverse myelitis: viral, neurosyphilis...
Article

Myelography

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 ...
Article

Myelomeningocele

Myelomeningocele, also known as spina bifida cystica, is a complex congenital spinal anomaly that results in spinal cord malformation (myelodysplasia).  Epidemiology 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...
Article

Myxopapillary ependymoma

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. Epidemiology They tend to have an earlier clinical presen...
Article

Naked facet sign (vertebral column)

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...
Article

Neoplasms of the cauda equina (differential)

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 myxopapillary ependymoma by...
Article

Neoplasms of the spinal canal

Neoplasms of the spinal canal encompass a range of tumors which arise from or involve the spinal cord, theca, and spinal nerves. Pathology These can be divided according to the tissue/structure of origin within the spinal canal. Tumors of vertebral bodies are discussed separately: see vertebra...
Article

Nerve root enhancement

Nerve root enhancement is phenomenon described on post contrast MRI scans that can be observed in a number of situations. Common causes post-operative states post-operative nerve root enhancement arachnoiditis leptomeningeal metastases disseminated spinal leptomeningeal metastases HIV vac...
Article

Neurenteric canal of Kovalevsky

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.
Article

Neuroanatomy

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. 
Article

Neurogenic bladder

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...
Article

Neurolymphomatosis

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...
Article

Neuromyelitis optica spectrum disorder

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...
Article

Nitrous oxide toxicity

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...
Article

Normal spine imaging examples

This article lists examples of normal imaging of the spine and surrounding structures, divided by region and modality. Cervical spine plain films example 1: AP, lat, obliques only example 2: PEG view example 3: flexion and extension views only example 4: pediatric - 12 years old example 5...
Article

Notochord

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...
Article

Nucleus pulposus

The nucleus pulposus (plural: nuclei pulposi) is the central part of each intervertebral disc. Gross anatomy 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...
Article

Nude nerve root

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. 
Article

Occipital condyle fracture

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...
Article

Occipital vertebrae

Occipital vertebrae is a very rare anatomical variant and results 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) basilar process paracondy...
Article

Occult intrasacral meningocele

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...
Article

Ochronosis

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.  Terminology The term ochronosis usually refers to the bluish-black discolourat...
Article

Odontoid fracture

Odontoid process fracture, also known as the peg or dens fracture, occurs where there is a fracture through the odontoid process of C2. Pathology The mechanism of injury is variable, and can occur both during flexion or extension with or without compression 5. Classification There are two cl...
Article

Olisthesis

Olisthesis, also known as the etymologically less correct listhesis, means slipping or sliding. Pathology Types include: anterolisthesis spondylolisthesis spondylolisthesis grading retrolisthesis
Article

Oppenheimer ossicle

Oppenheimer ossicles are accessory ossicles associated with the facet joints found in ~4% (range 1-7%) 1 of lumbar spines.  Oppenheimer ossicles are thought to arise as a result of non-union of a secondary ossification center of the articular process. They predominantly occur as a single, unila...
Article

Opticospinal multiple sclerosis

Opticospinal multiple sclerosis (OSMS) is a demyelinating disease and has been considered a variant of multiple sclerosis (MS) encountered in Asian populations, who are generally rarely affected by normal multiple sclerosis. It has similar clinical and imaging features to neuromyelitis optica (N...
Article

Os odontoideum

Os odontoideum (plural: ossa odontoidea) is an anatomic variant of the odontoid process of C2 and needs to be differentiated from persistent ossiculum terminale and from a type 2 odontoid fracture. It can be associated with atlantoaxial instability.  Although it was originally thought to be a c...
Article

Ossification centers of the vertebral column

Ossification of the vertebral column is complex but an overview of primary and secondary ossification centers is given below: Primary ossification centers The C3-L5 vertebrae typically have three primary ossification centers that start appearing at 9 weeks in utero and finish primary ossificat...
Article

Ossification of the ligamentum flavum

Ossification of the ligamentum flavum (OLF) is a phenomenon where there is a formation of ossific-calcific components in the ligamentum flavum. It is recognized causes of myelopathy (especially in the thoracic and to a lesser degree the cervical region). Epidemiology The condition as a whole i...
Article

Ossification of the posterior longitudinal ligament

Ossification of the posterior longitudinal ligament (OPLL) is typically an entity seen in patients of Asian descent, although it is seen in all ethnic groups. It is characterized by, as the name suggests, ossification of the posterior longitudinal ligament. Epidemiology There is a recognized g...
Article

Osteoarthritis of the vertebral column

Osteoarthritis of the vertebral column, also known as spondylosis deformans, is common and usually merely referred to as spinal "degenerative change". Complications such as spinal stenosis are important to recognize.  Radiographic features The hallmark of osteoarthritis in the spine, as is the...
Article

Osteophyte

Osteophytes are cartilage-capped bony proliferations (spurs) that most commonly develop at the margins of a synovial joint as a response to articular cartilage damage, as seen very commonly in degenerative joint disease. Central osteophytes can develop from cartilage lesions within a joint. They...
Article

Osteoporotic spinal compression fracture

Osteoporotic spinal compression fractures occur as a result of injury, commonly fall onto the buttock or pressure from normal activities, to the weakened vertebrae due to osteoporosis. Epidemiology They have a reported incidence of 1.2 per 1000 person-years after 85 years of age in the United ...
Article

Owl-eyes sign (spinal cord)

The owl-eyes sign, also referred to as snake-eyes sign or fried-eggs sign, represents bilaterally symmetric circular to ovoid foci of high T2-weighted signals in the anterior horn cells of the spinal cord and is seen on axial MR imaging. The sagittal corollary is a "pencil-like" vertical linear ...
Article

Paracondylar process

Paracondylar process is a rare anatomical variant of the occipital bone, where a bony exostosis extends caudally from the paracondylar region (lateral to the native occipital condyles), typically articulating with the superior surface of a transverse process of the atlas. This may be unilateral ...
Article

Parasyndesmophytes

Parasyndesmophytes or floating syndesmophytes are, as the name suggests, paravertebral dystrophic soft tissue calcifications or heterotopic ossifications. Pathology They are known to be seen in psoriatic arthritis and reactive arthritis 4. Radiographic features Initially they begin at a dist...
Article

Perched facet joint

Perched facet joint is a vertebral facet joint whose inferior articular process appears to sit 'perched' on the ipsilateral superior articular process of the vertebra below. Any further anterior subluxation will result in dislocation, with one facet "jumping" over the other and becoming locked ...
Article

Peripheral nerve sheath tumors

Peripheral nerve sheath tumors (PNSTs) are a group of primary neurogenic tumors that arise from nerve sheaths outside of the central nervous system. The vast majority are benign, however, malignant transformation is seen particularly in large tumors and those associated with neurofibromatosis ty...
Article

Perivertebral space

The perivertebral space is one of the deep compartments of the head and neck and includes the prevertebral space and paraspinal space. Gross anatomy The perivertebral space is a cylinder of soft tissue lying posterior to the retropharyngeal space and danger space surrounded by the prevertebral...
Article

Persistent ossiculum terminale

The ossiculum terminale appears as a secondary ossification center of the dens between 3-6 years and normally fuses by 12 years. Failure of fusion results in a persistent ossiculum terminale (also called Bergmann's ossicle or ossiculum terminale of Bergmann) and is considered a normal anatomical...
Article

Picture frame vertebral body

Picture frame vertebral body is a radiologic appearance in which the cortex of the vertebral body is thickened. This sign can be seen in patients with Paget disease.  It is a result of disorganized new cortical bone formation after excessive osteoclastic activity causes the resorption of normal...

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.