Although rare, pilocytic astrocytomas are the most common spinal cord tumours in the paediatric population.
This article specifically relates to spinal pilocytic astrocytomas. For a discussion on intracranial pilocytic astrocytomas refer to pilocytic astrocytoma. For a general discussion on spi...
Spinal primitive neuroectodermal tumours (PNETs) are rare. Most cases are secondary to metastatic spread through the subarachnoid space from a primary intracranial tumour although rare cases of primary spinal PNETs have been reported.
This article specifically relates to spinal PNETs. For a dis...
Spinal schwannomas are schwannomas arising from nerves within the spinal canal. They are the most common intradural extramedullary spinal tumours, representing 30% of such lesions. They are most frequently seen in the cervical and lumbar regions, far more frequently than in the thoracic spine.
The spinal subarachnoid space is the space between the arachnoid mater and pia mater in the spine and is continuous with the intracranial subarachnoid space.
It communicates with the intracranial subarachnoid space via the foramen magnum and ends at the level of the S2 vertebra. It is a relat...
Synovial cysts of the spine are cystic formations connected to the facet joint and containing synovial fluid lined by a cuboid or pseudostratified columnar epithelium. They may be result in lumbar radiculopathy in a significant number of cases.
They may be asymptomatic an...
Spinal vascular malformations (SVM) are rare but knowledge of them is important as if undiagnosed and untreated they can lead to serious complications.
There are two main types of SVMs 1,2:
spinal arteriovenous fistula (AVF): 70% of SVMs
pial: small, large, or giant
dural AVF (DA...
The spinocerebellar tracts are afferent neurons that convey proprioceptive data from the spinal cord to the cerebellum. There are anterior and posterior spinocerebellar tracts, the latter also referred to as Flechsig's tract. Both the anterior and posterior spinocerebellar tracts lie in the peri...
The spinothalamic tracts are ascending pathways primarily concerned with sensory function. They are responsible for transmitting pain, temperature, coarse (non-discriminative) touch and pressure sensations 1.
The spinothalamic tract is divided into lateral and anterior tracts, which are discuss...
The splenius capitis is a strap-like muscles that, along with the splenius cervicis, comprise the superficial layer of intrinsic back muscles.
origin: ligamentum nuchae, and the tips of the spinous processes and associated supraspinous ligaments of C7 and the upper t...
The splenius cervicis is part of the superficial layer of the intrinsic back muscles. It is one of the two muscles in this group, the other being the splenius capitis.
origin: spinous processes of T3-T6
insertion: transverse processes of C1-C3
innervation: dorsalrami of the lower cer...
The split fat sign is feature that can be seen typically on MRI images with peripheral nerve sheath tumours. It is seen as a fine rind of fat around the lesion. It is best appreciated on T1 weighted images 1. On coronal or sagittal images (i.e.images along the direction of the nerve) a tapered r...
Spondylodiscitis is characterised by infection involving the intervertebral disc and adjacent vertebrae.
Spondylodiscitis has a bimodal age distribution, which many authors consider essentially as separate entities:
older population ~50 years
Spondylolisthesis is a denotes the slippage of one vertebra relative to the one below. Spondylolisthesis can occur anywhere but is most frequent, particularly when due to spondylolysis, at L5/S1 and to a lesser degree L4/5.
Although etymologically it is directionless (see below) a...
A commonly adopted method of grading the severity of spondylolisthesis is the Meyerding classification. It divides the superior endplate of the vertebra below into 4 quarters. The grade depends on the location of the posteroinferior corner of the vertebra above.
grade I: 0-25%
grade II: 26-50...
Spondylolisthesis can be classified according to broad aetiology as described by Wiltse in 1981 1. Typically when reporting studies with spondylolisthesis the Wiltse type is merely stated without referring to it's number, whereas the grade of spondylolisthesis is explicitly stated: e.g. "Grade 1...
Spondylolysis is a defect in the pars interarticularis of the neural arch, the portion of the neural arch that connects the superior and inferior articular facets. It is commonly known as pars interarticularis defect or more simply as pars defect.
Spondylolysis is present in ~5% ...
Spondyloptosis is a term to denote grade V spondylolisthesis - a vertebra having slipped so far with respect to the vertebra below that the two endplates are no longer congruent. It is usually anterolisthesis of L5 on S1 but can be seen elsewhere rarely 1,2.
Spondylosis refers to a broad descriptive term referring to degeneration of the spinal column from any cause.
History and etymology
It derives from the the Greek term σπόνδυλος spóndylos, meaning "a vertebra",
Straight back syndrome refers to loss of the normal thoracic kyphosis. Individuals with this condition can present with a cardiac murmur due to compression of the right ventricular outflow tract (RVOT) 2.
There is questionable association with mitral valve prolapse 1.
Subacute combined degeneration of the cord (SCD) is caused by a vitamin B12 deficiency.
Most common in patients older than 40 and especially older than 60 7.
The clinical presentation of SCD is usually with loss of vibration and proprioception in the hands...
Subluxed facet joint is the mildest form of facet dislocation in which the ligamentous injury leads to partial uncovering of facet joint (c.f. complete uncovering in perched facet). This results in mild anterior displacement of one vertebral body on another (anterolisthesis).
The suboccipital muscle group contains four paired muscles, three of which pairs belong to the suboccipital triangle. These muscles all lie below the occipital bone and are responsible for postural support of the head, as well as extension, lateral flexion and rotation. As these muscles are smal...
The so-called "sugar coating" or zuckerguss (German for sugar icing) is seen in post-contrast images of the brain and spinal cord in patients with leptomeningeal drop metastases or leptomeningeal carcinomatosis. It is seen both as a result of CNS involvement from distant primaries as well as dir...
Sulcal arteries are penetrating branches of the anterior spinal artery which arise from the anterior spinal artery and extend posteriorly through the anterior median fissure of the cord. The sulcal arteries supply the anterior two-thirds of the spinal cord at any cross-sectional level.
The supraspinous ligaments join the tips of adjacent spinous processes and are strong bands of white fibrous tissue.
The Swischuk line is helpful in differentiating pathological anterior displacement of the cervical spine from physiological displacement, termed pseudosubluxation.
the line is drawn from anterior aspect of posterior arch of C1 to anterior aspect of posterior arch of C3
Syndesmophytes are calcifications or heterotopic ossifications inside a spinal ligament or of the annulus fibrosus. They are seen in only a limited number of conditions including:
Appearance on plain radiographs comprises v...
Synovial cysts are para-articular fluid-filled sacs or pouch-like structures containing synovial fluid and lined by synovial membrane. They can occur around virtually every synovial joint in the body and also around tendon sheaths and bursae. Communication with the adjacent joint may or may not ...
There are specific terms used when describing a syrinx or other cystic lesions within the spinal cord 1:
hydromyelia: fluid accumulation/dilatation within the central canal, therefore, lined by ependyma
syringomyelia: cavitary lesion within cord parenchyma, of any cause (there are many); locat...
T11 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a single costal facet that articulates with the atypical eleventh rib. There are no facets on the transverse processes.
T12 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a single costal facet with no facets on transverse processes.
T1 is an atypical thoracic vertebra. In contrast to typical thoracic vertebrae, it contains a complete facet for the 1st rib and a demifacet for the 2nd rib. It contains lips on the upper surface of the body. T1 also has a spinous process more horizontal than other thoracic vertebrae.
Tabes dorsalis is a form of tertiary late neurosyphilis in which there is demyelination of the posterior columns of the spinal cord.
For a general discussion, and for links to other system specific manifestations, please refer to the article on syphilis.
Tailgut duplication cysts, also known as retrorectal cystic hamartomas, are rare congenital lesions that are thought to arise from vestiges of the embryonic hindgut.
There is a recognised strong female predilection. While it can present at any age presentation is usually at aroun...
Tarlov cysts, also called perineural cysts, are CSF filled dilatations of the nerve root sheath at the dorsal root ganglion (posterior nerve root sheath). These are type II spinal meningeal cysts that are, by definition, extradural but contain neural tissue.
They occur in ~5% of t...
The tectorial membrane is the thin superior continuation of the posterior longitudinal ligament from the body of the axis. It joins the axis body to the clivus on the anterior half of the foramen magnum, and ascends as high as the spheno-occipital synchondrosis and laterally extends to the hypog...
Terminal myelocystoceles are an uncommon form of spinal dysraphism representing marked dilatation of the central canal of the spinal cord, herniating posteriorly through a dorsal spinal defect. The result is a skin-covered mass in the lower lumbar region, consisting of an ependyma-lined sac.
The third condyle (also known as condylus tertius or median occipital condyle) is a rare anatomic variant of the occipital condyles. It is a small separate ossicle at the anteromedial margin of the occipital condyle formed by the failure of the embryonic proatlas (4th occipital sclerotome) to un...
The thoracic spine forms the middle part of the vertebral column. It extends from below C7 on the cervical spine to above L1 on the lumbar spine. There are 12 thoracic vertebra, termed T1-T12 (some older doctors and texts refer to the dorsal spine and D1-D12).
The thoracic spine is unique due ...
The thoracic spine AP view images the thoracic spine, which consists of twelve 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 imag...
The thoracic spine lateral view images the thoracic spine, which consists of twelve vertebrae. It is utilised in many imaging contexts including trauma, postoperatively, and for chronic conditions. It is used in conjunction with the thoracic spine AP view to complete a thoracic spine series.
The thoracic spine series is comprised of two standard projections along with a range of additional projections depending on clinical indications. The series is often utilised in the context of trauma, postoperative imaging and for chronic conditions.
Radiographs of the thoracic spine are consi...
The thoracolumbar injury classification and severity score (TLICS) has been developed by the Spine Trauma Group to overcome some of the perceived difficulties regarding the use of other thoracolumbar spinal fracture classification systems for determining treatment 1.
There are several thoracolumbar spinal fracture classification systems:
three column concept of thoracolumbar spinal fractures (Denis classification)
thoracolumbar injury classification and severity score (TLICS)
The three column concept of thoracolumbar spinal fractures was initially devised by Francis Denis and presently CT is mandatory for an accurate classification.
While initially developed for classification of thoracolumbar spinal fractures, it can also be applied to the lower cervical spine 3 as...
Tight filum terminale syndrome is caused by incomplete involution of the distal spinal cord during embryogenesis. This leads to development of an abnormally thickened filum terminale, which may be associated with lipomas or cysts within the filum.
Tight filum terminale syndrome is always associ...
The toothpaste sign in spinal imaging represents an extrusion of an intervertebral disc into the epidural space. It is called after the shape of extruded material relatively to the parent disc in a sagittal plane.
Torticollis (wryneck) is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the paediatric age group.
Torticollis can be acute (<1 week) or chronic ...
Transforaminal nerve root injfection is performed for radicular pain treatment and diagnosis.
See spinal interventional procedures for complications and equipment.
The desired needle tip position is just lateral to the pedicle immediately below the...
Transitional vertebra is one that has indeterminate characteristic and features of vertebrae from adjacent vertebral segments. They occur at the junction between spinal morphological segments:
atlanto-occipital assimilation: complete or partial fusion of C1 and the o...
The transpyloric plane, also known as Addison's plane, is an imaginary axial plane located midway between the jugular notch and superior border of pubic symphysis, at approximately the level of L1 vertebral body. It an important landmark as many key structures are visualised at this level, altho...
Acute transverse myelitis (ATM) is an inflammatory condition affecting both halves of the spinal cord and associated with rapidly progressive motor, sensory, and autonomic dysfunction.
It is mostly imaged with MRI, which generally shows a long segment (3-4 segments or more) of T2 increased sign...
Transverse process fractures are a common sequelae of trauma, although they are considered a minor and stable lumbar spine fracture. There is strong association between transverse process fractures and other traumatic injuries.
Transverse process fracture most commonly occur in the ...
The transversospinalis group is the deep layer of the intrinsic back muscles. These muscles lie between the transverse and spinous processes and are grouped by length of the fascicles, as well as region covered. The groups are rotatores, multifidus, and semispinalis.
Traumatic spinal cord injury can manifest as a wide variety of clinical syndromes resulting from damage to the spinal cord or its surrounding structures. It can result from minor injury if the spine is weakened from disease such as ankylosing spondylitis or if there is pre-existing spinal stenos...
Musculoskeletal tuberculosis is always secondary to a primary lesion in the lung.
The prevalence of the disease is around 30 million globally and 1-3% of the 30 million have involvement of their bones and/or joints. Mycobacterium tuberculosis is responsible for almost all of the c...
Of the seven cervical vertebrae, C3 through C6 have typical anatomy, while C7 looks very similar. C1 (atlas) and C2 (axis) have very distinct anatomical features. For a basic anatomic description of the structure a generic vertebra, see vertebrae.
small, oval-sized vertebral bodi...
Given the twelve thoracic vertebrae are largely similar, most are considered typical thoracic vertebrae with the exceptions T1 and T9 to T12. For a basic anatomic description of the structure of typical vertebrae, see vertebrae.
Relative to cervical and lumbar vertebrae, thoracic...
Unfused spinous process, which is really failure of fusion of the neural arch, is a relatively common anatomical variant and is part of the spectrum of spina bifida occulta.
This should be differentiated from accessory ossicles of the spinous process, which appear after non-fusion of the secon...
Unilateral facet dislocation is a relatively stable type of facet dislocation.
Flexion/distraction associated with rotation. The inferior articular facet of vertebral above moves over the superior facet of the vertebral below and becomes locked. It usually affects C4-C5 or...
Vanishing vertebrae is a rare ischaemic manifestation of sickle cell disease, in which a completely infarcted vertebral body literally disappears or vanishes, as a result of infarction. In the few reported cases, the posterior elements remain intact.
codfish or h-shaped vertebrae
Ventral cord herniation, also known by a variety of other terms such as spontaneous thoracic cord herniation or idiopathic spinal cord herniation, is a rare cause of focal myelopathy due to herniation of the thoracic cord through a dural defect.
Post surgical cord herniation can occur at any l...
The ventriculus terminalis, also known as the 5th ventricle, is an ependymal-lined, anatomical remnant, positioned at the transition from the tip of the conus medullaris to the origin of the filum terminale.
It represents the canalization and retrogressive differentiation of the caudal end of ...
The vertebra (plural: vertebrae) is the fundamental segmental unit of the vertebral column (also know as the spine).
Vertebrae, apart from those that are atypical, have a similar basic structure which can be described as an anterior vertebral body and a posterior neural (or verte...
The vertebral column is affected by a range of anatomical variants of the body and/or neural arch as well as accessory ossicles. Knowledge of basic vertebral anatomy and ossification is essential for describing and understanding the range of anomalies.
The vertebral arteries (VA) are paired arteries, each arising from the respective subclavian artery and ascending in the neck to supply the posterior fossa and occipital lobes, as well as provide segmental vertebral and spinal column blood supply.
origin: branches off the 1st part of t...
The differential diagnosis for a vertebral body mass is broad and may range from a completely benign, sclerotic enostosis (bone island) to a malignant primary bone tumour.
Broadly, these lesions can be separated into:
primary bone tumours
Vertebral body squaring refers to the loss of normal concavity of the anterior border. It is seen in a variety of conditions including:
Ankylosing spondylitis is the most common cause of vertebral body squaring. It usually involves multiple level...
Vertebral haemangiomas are the most common benign vertebral neoplasms. They are usually asymptomatic and incidentally detected due to their characteristic features on imaging for other reasons.
Please refer on the article on primary intraosseous haemangioma for a general discussion in this enti...
Differential diagnosis of vertebral lesions includes:
Lesion originating in vertebral body
vertebral body osteomyelitis
giant cell tumour
Langerhans cell histiocytosis
Many vertebral levels are associated with key anatomical landmarks. Below is a summary of vertebral levels and associated internal or surface anatomy.
bifurcation of common carotid artery
trachea begins (end of la...
Vertebral metastases represent the secondary involvement of the vertebral spine by haematogenously-disseminated metastatic cells. They must be included in any differential diagnosis of a bone lesion in a patient older 40 years.
This article will focus only on the metastasis involving the bony s...
Vertebral pneumatocysts refers to the presence of a gas-filled cavity within the vertebrae, more prevalent on the cervical spine. Intraosseous pneumatocysts are more common adjacent to the sacroiliac joint while it is rare in the vertebral column. Other causes of vertebral gas e.g. Kümmell disea...
Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring).
Vertebral vascular foramina are normal findings seen on cross-sectional imaging and should not be mistaken for a fracture, especially in the setting of trauma.
basivertebral veins (forms Hahn's canal): foramen is seen on the posterior surface of the vertebral body in the midline...
The vertebral venous plexus is a highly anastomotic network of valveless veins running along the entire length of the vertebral column from the foramen magnum to the sacral hiatus.
The vertebral venous plexus is comprised of three interconnected divisions:
internal vertebral ven...
Vertebra plana (a.k.a. pancake / silver dollar / coin-on-edge vertebra) is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture. Plural is vertebrae planae. It can occur in a variety of settings, incl...
C7, also called vertebra prominens, is the seventh cervical vertebra and looks like vertebrae C3-C6, but has some distinct features making it an atypical vertebrae. The name vertebra prominens arises from its long spinous process, which is easily palpable.
C7 possesses the stand...
Vertebroplasty is an imaging-guided procedure which entails percutaneous injection of surgical polymethylmethacrylate (PMMA) cement into a diseased vertebral body. Vertebroplasty provides pain relief and strengthening of the bone of vertebrae weakened by disease.
It can be used as ...
Wedge fractures are hyperflexion injuries to the vertebral body resulting from axial loading. Most commonly affecting the anterior aspect, wedge fractures are considered a single-column (i.e. stable) fracture.
Less commonly wedge fractures refer to a subtype of tibial plateau fractures. This a...
The spinal cord has numeorus white matter tracts that ascend and descend in the peripheral substance of the cord. They can be divided by their location and function:
anterior corticospinal tract
medial longitudinal fasiculus
lateral spinothalamic t...
The WHO classification of CNS tumours is the most widely accepted system for classifying CNS tumours and was based on the histological characteristics of the tumour. Although the most recent version of the 'blue book' is the 4th edition from 2007, an update has been released in 2016 3, which sho...
The (absent) pedicle sign, also called the winking owl sign, occurs on plain film when a pedicle is absent.
The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other open eye, and the spinous process to the beak of the animal on ...
The Y sign refers to a common appearance in lumbar epidural lipomatosis where excess fat in the extradural space compresses the dural sac into the shape of the letter "Y".