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: oste...
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 disc protrusions are an important entity to recognise 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 tumour 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 tumours 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 a...
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, 20% to 25% loss of height
grade 2: moderate fracture, 25% to 40% los...
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 tumour (e.g. spinal schwannoma).
It is seen on axial post contrast T1 imaging, with ...
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 ...
Haematomyelia refers to the presence of intramedullary haemorrhage or haematoma within the spinal cord. This is distinct from extramedullary haemorrhage such as that seen in epidural haematoma.
Although haematomyelia can occur in the setting of trauma, the term is generally used to s...
The haemosiderin cap sign refers to an MR imaging feature in some spinal tumours where a cap of T2 hypointense haemosiderin is above and/or below the tumour due to previous haemorrhage.
It is most often associated with spinal cord ependymomas (20-33% of cases) 1. It may also be seen in haemang...
Hanging and strangulation are injuries involving constricting pressure applied to the neck.
In America hangings are the second most common form of suicide after firearm use. In other parts of the world due to the relative difficulty in accessing firearms, hangings are the most com...
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 characterised 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 vacuolar 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, gait disorders, sensory abnormalities in the lo...
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 tumour, or by a combination of both. It merely den...
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...
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 anaemia, and results from microvascular endplate infarction (figure 1) 3.
It may occasionall...
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...
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 disc, and are thought to be degenerative in aetiology.
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 fibres 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 disc height is lost.
The upper thoracic discs are the thinn...
Intervertebral disc calcification is seen with numerous conditions.
It may be observed in paediatric 5 as well as adult populations.
degenerative: relatively common and may occur in up to 6% in routine abdominal radiographs in adults
Vacuum phenomena involving the intervertebral discs is usually a result of 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 and...
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 disc 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 disc 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 disc herniations (IDH) occur when disc material related to an intervertebral disc 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 disc 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 tumour 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 (...
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...
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 tumours are rare, representing 4-10% of all CNS tumours and less than 10% of all paediatric CNS neoplasms 5. They account for 20% of all intraspinal tumours in adults and 35% of all intraspinal tumours in children 8.
A long duration of symptoms prior to diagnosis is typica...
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...
Iodophenylundecylic acid (brand name = Myodil (Glaxo)) is an oily organic iodinated contrast material which was used for myelography. It is no longer used. Residual contrast remains for years. Has been implicated in development of arachnoiditis, perhapse of the order of 1%.
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 o...
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 ischaemia and non-union of anterior vertebral body wedge fractures after major trauma.
Laminectomy refers to unilateral or bilateral surgical removal of the lamina of a vertebra body. It is performed to decompress the spinal canal in spinal canal stenosis. This is typically caused by degenerative changes.
The most common site of the procedure is the lumbar spine.
The lateral corticospinal tract is formed at the level of the of the medullary pyramids when the majority (90%) of descending corticospinal tract fibres decussate – the majority of the remaining non-decussating 10% of fibres 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 centre 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...
The 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 an...
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 meningocoele.
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 be originated both in primary CNS tumours (e.g. drop-metastases), as well as from distant tumours that have metastasised via haematogenous spread.
Leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) is a rare inherited autosomal recessive leukodystrophy characterised 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...
The ligamentum flava 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 base of skull and C1) and the posterior ...
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...
Limbus vertebra is a well-corticated unfused secondary ossification centre, 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...
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 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.
Affected individuals are usually asymptomatic at birth, but many (~ 50%)...
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...
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 medullar is. It contains cerebrospinal fluid and the nerve roots of the cauda equina. As the conus (usually) termin...
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 present of spinal nerve anterior rami which contribute to the lumbar and sacral plexuses.
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 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 abduction movements. Rotation is ...
The lumbar spine AP view images the lumbar spine which consists of five vertebrae. It is utilised in many imaging contexts including trauma, postoperatively, and for chronic conditions.
the patient is erect or supine, depending on clinical history
ideally, spinal imaging sho...
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 tumours) or epidural compartment, intramedullary lymphoma may rarely occur.
Apparent intramedullary spinal cord lymphoma may often, in fact, repres...
The Magerl classification of thoracolumbar spinal fractures is based on the three column concept by Denis, and the McAfee classification. It relies exclusively on CT findings.
A: compression injuries
A1: impaction fractures
A1.1: endplate impaction
A1.2: wedge impaction
Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral spinal 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
The Matterhorn sign is named after one of the most iconic mountains in the Alps: the Matterhorn.
McAfee classification of acute traumatic spinal injuries is based on the three column concept of the spine. CT is needed for accurate assessment.
wedge compression: isolated anterior column compression
stable burst: anterior and middle column compression but posterior column i...