Facet joint capsules are the fibrous capsule that surround the vertebral facet or zygapophyseal joints. They are particularly thin and loose, attached to the margins of articular facets on adjoining articular processes. The capsules merge medially with the ligamentum flavum.
In the cervical re...
Facet (zygapophyseal) joint injections are one of the most frequently performed spinal interventional procedures, as both treatment for and diagnosis of radicular pain syndrome and facet syndrome. It can be performed under fluoroscopic, or CT image guidance and cervical, thoracic or most commonl...
Facet joint vacuum phenomena or degenerative intrafacetal gas is a feature that can be seen on spinal imaging in facet joint arthropathy as part of degenerative spondylosis.
Signal characteristics are those of air and are
T1: low signal
T2: low signal
Facioscapulohumeral muscular dystrophy (FSHD) is a form of muscular dystrophy characterized by extremely variable degrees of facial, scapular and lower limb muscle involvement.
It is considered one of the more common hereditary muscular disorders with a prevalence of ~1 in 8,000.
Failed back syndrome refers to persistent leg and/or lumbar back pain after a surgical procedure. The pathophysiology of this syndrome is complex, as often the operation was technically successful.
Other names for failed back syndrome include failed back surgery syndrome, post-lam...
The festooned appearance of the spinal dural sac has been described in cases of CSF leak resulting in the combination of epidural fluid and craniospinal hypotension/hypovolemia. The theca collapses down upon the cord but kept attached at multiple points by the epidural ligaments 1.
Fibrocartilaginous embolism (also known as nucleus pulposus embolism) is a rare cause of spinal cord ischemia due to embolization of nucleus pulposus material from intervertebral disk in a retrograde direction into a spinal artery or vein.
Fibrocartilaginous embolism is a diagnosis of suspicion...
The fifth lumbar vertebra (L5) is the largest of the five lumbar vertebrae and is considered an atypical vertebra due to its shape.
L5 is the largest, most inferior lumbar discovertebral unit in the vertebral column, and participates in forming the lumbar lordosis (from L1 to L5...
A filar cyst is an incidental finding on neonatal lumbar sonography located in the filum terminale of the spinal cord. It is considered a normal variant and is often confused for a ventriculus terminalis, a smooth dilated cavity of the central canal, located within the conus medullaris.
The filum terminale is a filament of connective tissue that extends inferiorly from the apex of the conus medullaris.
The filum terminale is continuous with the pia mater and is described as having two sections:
filum terminale internum: upper three quarters of the filum; covere...
Fish vertebra, also known as codfish vertebra, describes the biconcave appearance of vertebrae (especially lumbar vertebrae).
sickle cell disease
thalassemia major (rare...
Flat back syndrome (FBS) refers to the decrease or absence of the normal lumbar lordosis resulting primarily in chronic lumbar pain.
Flat back syndrome is a different condition from straight back syndrome and the two should not be confused or conflated.
Flexion teardrop fractures represent a fracture pattern occurring in severe axial/flexion injury of the cervical spine. They are important to recognize because they indicate extensive underlying ligamentous injury and spinal instability. Associated spinal cord injury is common, especially anteri...
The fluid sign is one of the radiological features of osteoporotic fractures, and can be helpful in distinguishing them from metastatic vertebral fractures, as it is seen more often in osteoporotic fractures and is rarely seen in metastatic fractures 1. It is not as helpful as identifying a para...
Fluoroscopy-guided lumbar puncture (LP) is a minimally invasive, image-guided diagnostic and therapeutic procedure that involves the removal of a small volume of cerebrospinal fluid (CSF) from, or an injection of medication or other substance (e.g. radiotracer, chemotherapy agents) into the lumb...
Skeletal fluorosis is a chronic metabolic bone disease caused by ingestion of large amounts of fluoride through either water or food in geographic areas where high levels of fluoride occur naturally.
Described features include:
increased bone density...
Focal fatty deposits/replacement in spinal bone marrow are well-defined focal fat islands within the bone marrow of spine or other parts of axial skeleton.
Common in older individuals, related to age but not to sex.
This process is a normal variant. Histologically, it ...
Foix-Alajouanine syndrome refers to presentation of spinal AVMs with progressive neurological deterioration.
Initially, patients have a spastic paraplegia which progresses to flaccidity, loss of sphincter control and ascending sensory level. It is thought to be due to venous hypertension.
Foraminal disk protrusions are an important entity to recognize for a number of reasons, these include:
they are relatively easy to overlook as they do not impinge upon the spinal canal
they do not narrow the subarticular recess, but compresses the exiting nerve root only, thus clinically mimi...
Friedreich ataxia (FA) is the most common inherited progressive ataxia. It carries an autosomal recessive inheritance 1.
Thought to have an estimated prevalence of ~1:50,000. There is no recognised gender predilection.
Typically present in childhood to adolescence. Those with a h...
A ganglioneuroblastoma is a transitional tumor which lies on the intermediate spectrum of disease between a ganglioneuroma and a neuroblastoma.
They are seen more commonly in children younger than 10 years. There is no definite gender predilection reported at the time of writing.
Ganglioneuromas are fully differentiated neuronal tumors that do not contain immature elements and potentially occur anywhere along the peripheral autonomic ganglion sites.
On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, they ar...
The Genant classification of vertebral fractures is based on the vertebral shape, with respect to vertebral height loss involving the anterior, posterior, and/or middle vertebral body.
grade 0: normal
grade 1: mild fracture, <25% loss of height
grade 2: moderate fracture, 25% to 40% loss of h...
Ghost vertebra is a sign, that is generally used synonymously with bone-within-a-bone vertebra, and as such, the causes form a subset of those causing bone within a bone appearance 2:
Thorotrast administration: bone within a bone appearance due to temporary growth arrest 1
Gibbus deformity is a short-segment structural thoracolumbar kyphosis resulting in sharp angulation.
There are a number of causes which can be divided into congenital and acquired.
cretinism (congenital hypothyroidism)
The ginkgo leaf sign of spinal meningiomas (not to be confused with the ginkgo leaf sign of subcutaneous emphysema) has been described as a useful MRI sign in distinguishing a spinal meningioma from neurogenic tumor (e.g. spinal schwannoma).
It is seen on axial post contrast T1 imaging, with t...
The gracile fasciculus, also known as the fasciculus gracilis or column of Goll, represents the medial portion of the dorsal columns and carries input from below and including T7 1.
The gracile fasciculus is responsible for transmitting vibration, conscious proprioception, and fine (d...
The grey matter is the substance of the brain and spinal cord that contains the neuronal cell bodies of the central nervous system.
Within the cerebrum the two main locations of grey matter are on the surface of the gyri (the cortical gray matter) and the nuclei of the basal ganglia. The brains...
Grisel syndrome is a rare cause of torticollis that involves subluxation of atlanto-axial joint from inflammatory ligamentous laxity following an infectious process in the head and neck, usually a retropharyngeal abscess.
It usually occurs in infants or young children.
Guillain-Barré syndrome (GBS) is defined as a heterogeneous group of autoimmune polyradiculopathies, involving sensory, motor and autonomic nerves. It is the most common cause of rapidly progressive flaccid paralysis. It is believed to be one of a number of related conditions, sharing a similar ...
Hematomyelia refers to the presence of intramedullary hemorrhage or hematoma within the spinal cord. This is distinct from extramedullary hemorrhage such as that seen in epidural hematoma.
Although hematomyelia can occur in the setting of trauma, the term is generally used to signify...
The hemosiderin cap sign refers to an MR imaging feature in some spinal tumors where a cap of T2 hypointense hemosiderin is above and/or below the tumor due to previous hemorrhage.
It is most often associated with spinal cord ependymomas (20-33% of cases) 1. It may also be seen in hemangioblas...
Hanging and strangulation are injuries involving constricting pressure applied to the neck. The vast majority are sustained as a result of attempted suicide.
In America, hangings are the second most common form of suicide after firearm use. In other parts of the world due to the r...
Hangman fracture, also known as traumatic spondylolisthesis of the axis, is a fracture which involves the pars interarticularis of C2 on both sides, and is a result of hyperextension and distraction.
Post-traumatic neck pain after a high-velocity hyperextension injury is ...
Hemivertebra is a type of vertebral anomaly and results from a lack of formation of one half of a vertebral body. It is a common cause of congenital scoliosis.
The estimated incidence is at ~0.3 per 1000 live births 2.
It falls under the spectrum of segmentation anoma...
Hereditary spastic paraplegia (HSP) refers to a heterogeneous group of neurodegenerative conditions characterized by progressive degeneration of the corticospinal tracts and posterior column of the spinal cord.
Patients often tend to have progressive lower extremity weakn...
Hirayama disease, also termed non-progressive juvenile spinal muscular atrophy of the distal upper limbs, is a type of cervical myelopathy related to flexion movements of the neck. It is considered a benign motor neurone disorder with a stationary stage after a progressive course.
HIV-related vacuolar myelopathy, also known as AIDS-related myelopathy, is the most common chronic myelopathy associated with HIV infection and is typically seen in the late stages of the disease.
Patients tend to have slowly progressive weakness of the lower extremities,...
Holocord presentation refers to a process which involves the spinal cord, from cervicomedullary junction to the tip of the conus. It does not relate to a specific condition nor does it distinguish between involvement by cystic expansion or solid tumor, or by a combination of both. It merely deno...
The Honda sign (H sign / H pattern) is a term used to describe the appearances of bilateral sacral insufficiency fractures on a radioisotope bone scan.
Sacral insufficiency fractures are usually vertically through the sacral alae, paralleling the sacroiliac joint, often w...
Hopkins syndrome is a rare poliomyelitis-like neurological syndrome that occurs several days or weeks post an episode of acute asthma.
It usually manifests as flaccid paralysis of an extremity.
Areas of high T2 signal intensity in one or both ...
H-shaped vertebrae, also known as Lincoln log vertebrae, are a characteristic finding of sharply delimited central endplate depression, classically seen in approximately 10% of patients with sickle-cell anemia, and results from microvascular endplate infarction (figure 1) 3.
It may occasionally...
HTLV-1-associated myelopathy (also known as tropical spastic paraparesis) is primarily seen in Japan, Melanesia and the Caribbean and presents with chronic spastic paraparesis.
This condition has been independently described in Japan (HTLV-1 associated myelopathy) and in the Carib...
In hydromyelia, there is dilatation of the central canal of the spinal cord. The dilatation is lined by the normal ependymal lining of the central canal.
The term can refer to dilatation of the persistent central canal of the spinal cord which communicates with the fourth ventricle (cavity wall...
Hyperextension cervical injuries are not uncommon and extremely serious:
avulsion fractures of the anterior arch of the atlas (C1)
vertical fracture through the posterior arch of the atlas as a result of compression
fractures of the dens of C2
hangman fracture of C2
hyperextension teardrop ...
Hyperparathyroidism is the effect of excess parathyroid hormone in the body. It can be primary, secondary, or tertiary. There are many characteristic imaging features, predominantly involving the skeletal system.
Increased levels of the parathyroid hormone lead to increased osteoclas...
The iliolumbar ligament is a strong band of connective tissue which courses from the transverse process of L5 (in over 96% of cases) to the posterior iliac wing and crest of the ilium. It functions to maintain the alignment of L5 on the sacrum during various movements 1, 2.
It is an important l...
The imaging psoas sign is an MRI finding specific for spondylodiscitis and is seen as T2 hyperintensity in the psoas major muscle. The sign has a high sensitivity (92%) and specificity (92%) for spondylodiscitis and in the clinical context of a suspected infective process of the spine supports c...
Incomplete cord syndromes encompass a variety of patterns of cross-sectional partial disruption of the spinal cord. Due to the spatial segregation of various ascending and descending tracts within the cord, regional dysfunction results in predictable and distinct clinical patterns of deficit. As...
Insufficiency fractures are a type of stress fracture, which are the result of normal stresses on abnormal bone. They should not be confused with fatigue fractures which are due to abnormal stresses on normal bone, or with pathological fractures, the result of diseased, weakened bone due to foca...
Intercalary bones are common discal ossifications that are usually triangular in morphology, found in the anterior annular fibers of an intervertebral disk, and are thought to be degenerative in etiology.
flexion or extension teardrop fracture
The intercristal line (also known as Jacobys’s Line or Tuffier’s Line) is a horizontal line drawn across the highest points of both the iliac crests in an anteroposterior (AP) lumbar radiography 1,2
Intercristal line most often intersects the body of the L4 or its inferior endplate in men and t...
The interspinous ligaments join the spinous processes along their adjacent borders. They are composed of relatively weak fibrous tissue that fuses with the stronger, supraspinous ligaments.
A interspinous processes spacer (also known as decompression spacer or interspinous posterior device) is a device implanted between interspinous processes to open narrowed exiting foraminal nerve channels to treat lumbar radiculopathy caused by spinal stenosis. It is used as an alternative to l...
The intertransverse ligaments consist of fibrous tissue joining transverse processes of adjacent vertebrae. In the cervical region, intertransverse ligaments are scattered fibers that are largely replaced by intertransverse muscles. In the thoracic region, these are fibrous cords blending with t...
Intervertebral discs are located between the vertebral bodies of C2/3 to L5/S1, totalling 23 in the conventional spine. Together they account for approximately 25% of the total height of the vertebral column. This decreases with age as disk height is lost.
The upper thoracic discs are the thinn...
Intervertebral disk calcification is a non-specific finding seen in numerous conditions.
It may be observed in pediatric 5 as well as adult populations.
degenerative: relatively common and may occur in up to 6% of routine abdominal radiographs in adults
Intervertebral disk disease nomenclature has changed over the years, and a familiarity with current definitions is essential if clear communication is to be achieved via radiology reports or referrals, especially as lumbar disk disease is a common problem and a source of a great deal of imaging....
Vacuum phenomena involving the intervertebral discs is usually a result of an accumulation of gas (principally nitrogen) within the crevices of the intervertebral discs or adjacent vertebrae.
It is a relatively common occurrence which can be observed in 1-3% of spinal radiographs ...
The intervertebral foramina allow passage of structures out of and into the vertebral canal. When multiple vertebrae are joined, the foramina for the spinal canal.
anterior- lower posterolateral aspect of a vertebral body and the intervertebral disk below
in the cervical region a p...
There are three intervertebral joints between each adjacent vertebra from the axis to the sacrum – one between the vertebral bodies and a pair between the facets of adjoining vertebral arches (zygapophysial joints, also called facet joints).
flexion: the anterior interv...
Intervertebral osteochondrosis represents the pathologic degenerative process involving the intervertebral disk and the respective vertebral body endplates (not necessarily symptomatic). It is believed to be different and a further stage of spondylosis deformans, which is a consequence of normal...
Intradural disk herniations (IDH) occur when disk material related to an intervertebral disk hernia penetrates the spinal dura and lies in an intradural extramedullary location.
IDH correspond to a rare presentation of a common pathology, comprising ~0.28% of all disk herniations ...
Intradural extramedullary metastases are rare and only account for approximately 5% of spinal metastases.
Please review leptomeningeal metastases (brain) for a general discussion focused on the brain's subarachnoid space involvement.
The age at presentation depends on tumor type....
Intradural extramedullary neoplasms are located outside the spinal cord but within the dural sheath.
The most common presenting symptoms include weakness, back pain and radicular pain.
Schwannomas are the most common intradural extramedullary spinal lesions (...
A useful mnemonic to remember the differential diagnoses for intradural extramedullary spinal masses is:
No More Spinal Masses
Intradural lipomas are a subset of spinal lipomas. They are typically intradural, subpial, juxtamedullary lesions 1 although they have occasionally been reported as entirely intramedullary lesions 2.
Mature fatty tissue within the spinal dura can be seen in a number of entities:
Intradural spinal mass lesions are relatively uncommon, compared to intracranial or extradural masses, and can be challenging to diagnose. Additionally, the need for a pre-operative/non-operative diagnosis is in many ways greater as biopsy of lesions within the cord has the potential of devastat...
A useful mnemonic to remember the differential diagnoses of intramedullary spinal masses is:
Intramedullary spinal metastases are rare, occurring in ~1% of autopsied cancer patients, and are less common than leptomeningeal metastases.
Intramedullary lesions may result from:
growth along the Virchow-Robin spaces
direct extension from leptomeninges
Intramedullary spinal tumors are rare, representing 4-10% of all CNS tumors and less than 10% of all pediatric CNS neoplasms 5. They account for 20% of all intraspinal tumors in adults and 35% of all intraspinal tumors in children 8.
A long duration of symptoms prior to diagnosis is typical.
The inverted Mercedes-Benz sign refers to the shape taken on by a spinal subdural hematoma on axial imaging at the level of the denticulate ligaments, best visualized on MRI. A pair of denticulate ligaments and the dorsal septum constitute the three radiating spikes of the sign, while blood expa...
The inverted Napoleon hat sign is a radiologic sign seen on the frontal pelvic or lumbar radiograph at the level of the 5th lumbar vertebra and the sacrum.
It is seen when there is bilateral spondylolysis with marked anterolisthesis of L5 on S1 or marked exaggeration of the normal lordosis at t...
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 sign refers to 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 an ivory vertebra depends on the age of...
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 C1. 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 mechanis...
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 recognised 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.
This article lists a series of labelled 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
MR head: T2 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 majority of the remaining non-decussating 10% of fibers form the much smaller anterior corticospinal tract, with only a few non...
A lateral hemivertebra is a form of hemivertebra which occurs when one of the two chondrification center fails to develop. They can be single or multiple. and a usually associated this a resultant 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 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 metastasised via haematogenous 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 C2 (also known as traumatic spondylolisthesis of axis).
type I: fracture with <3 mm antero-posterior deviation
no angular deviation
type II: fracture with >3 mm antero-posterior deviation
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...