The Spine - Clinical Tree

Spinal Dysraphism

Definition

This is also known as a neural tube defect (NTD), and are a group of congenital spine abnormalities that may cause progressive neurological damage (affecting 1 : 1000 live births)

The common feature is an anomaly of the midline structures of the back
It results from incomplete midline closure of the bony and neural spinal tissues following defective primary neural tube closure and persistence of the neural placode ▸ it is also associated with anomalous development of the caudal cell mass
Neural placode: a flat segment of un-neurulated nervous tissue
It can occur in closed (spina bifida occulta) and open (spina bifida aperta) forms
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  Spina bifida occulta: this is due to a failure of fusion of the posterior spinal bony elements ▸ the defect is covered by skin
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    Without a tethered cord: this is commonest at L5 or S1 ▸ it occurs in approximately 20% of the general population with no neurological problems (± back pain)
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    With a tethered cord: neurologic defects are uncommon ▸ a cutaneous lesion such as a dimple, sinus, hairy naevus or haemangioma may be a marker of an underlying defect and is seen in 50% of cases
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      Associations: meningocele ▸ lipomyelomeningodysplasia ▸ diastematomyelia ▸ neurenteric cyst ▸ dermoid and epidermoid cysts ▸ dorsal dermal sinus ▸ caudal agenesis ▸ myelocystocele ▸ spinal or filum terminale lipoma
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  Spina bifida aperta : the nervous tissue is exposed and neurologic defects are common
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    Most are myelomeningoceles and are virtually always associated with a Chiari II malformation ▸ they are usually found within the lumbosacral region
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    Usually the neural placode protrudes beyond the skin level with an expanded CSF containing sac lined by meninges ▸ occasionally it is a myelocele where the placode is flush with the surface and no meningocele component is present
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    Nerve roots (from the everted ventral placode) cross the widely dilated meningocele subarachnoid spaces to enter the neural exit foraminae ▸ the posterior elements of the vertebral column and the other mesenchymal derivatives (e.g. paravertebral muscles) remain everted
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    It is surgically repaired soon after birth, as untreated and exposed neural tissue is prone to ulceration and infection

Meningoceles

Definition

Herniation of the spinal meninges through the intervertebral foramina or a vertebral body defect ▸ varying degrees of dural ectasia usually accompany spinal dysraphisms

Generalized or focal dural ectasia may also be seen in: neurofibromatosis ▸ Ehlers–Danlos and Marfan's syndromes ▸ erosive arthropathies (e.g. ankylosing spondylitis)
Types of meningocele
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  Anterior thoracic meningocele with ventral herniation of the spinal cord : this is most easily recognized with a midsagittal MRI of the thoracic spine where the spinal cord is displaced anteriorly and is in contact with a vertebral body near an intervertebral disc (commonly T6)
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  Lateral thoracic meningocele: this commonly presents as a paravertebral mass (CXR) ▸ it is usually solitary and located on the right ▸ there is an angular kyphoscoliosis towards the side of the meningocele with pressure erosion of the relevant intervertebral foraminal margins
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    Neurofibromatosis is present in up to 85% of cases
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  Posterior meningocele: herniation of the CSF sac (which is lined by dura and arachnoid) through a spinal defect results in a clinically apparent mass covered by skin ▸ it occurs mainly within the lumbosacral region
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  Anterior sacral meningocele: these are typically presacral and appear as a unilocular, complex lobular or multilocular cystic mass (the mass contains CSF which communicates with the intraspinal subarachnoid space) ▸ there is usually a large eccentric anterior lower sacral defect (with a pathognomonic scimitar appearance on XR) and an expanded sacral canal ▸ there can be varying degrees of sacral or coccygeal agenesis
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    It presents in older children and adults with low-back pain and bladder or bowel disturbance
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  Terminal myelocystocele : the central canal is dilated by a large hydromyelic cavity herniating into a posterior meningocele (through a posterior spinal bony defect) ▸ it is rare, and associated with syndromes such as VACTERL
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  Myelomeningocele: herniation of the spinal meninges and spinal neural tissue through a vertebral canal defect
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  Myelocele: the neural placode is flush with the skin surface but there is no skin covering

Pearl

Hemimyelomeningoceles and hemimyeloceles may occur with diastematomyelia

Meningocele. (A) A huge CSF collection spills out through a defect in the spinal canal. (B) T2WI through the lumbosacral region shows no solid material within the fluid herniating through the dysraphic spine. +

Cervical spinal cord diastematomyelia type II with associated craniocervical meningocele. (A) The meningocele is seen herniating through a bony defect in the vertebral posterior elements. (B) Axial T2WI shows that the cord has split into two hemicords. The apparent signal abnormality is in fact normal cerebrospinal fluid interspersed between the two hemicords. These reunite inferiorly. (C) Sagittal T2WI appears to show signal abnormality and thinning of the spinal cord, and is the clue to the diastematomyelia seen on the axial images. *

Myelomeningocele. Note the neural placode, enlarged spinal canal and spinal dysraphism. There is also a distal syrinx. +

Repaired myelomeningocele in a child with Chiari II malformation. Sagittal T1WI (A) and T2WI (B) showing that the neural placode terminates inferiorly in the meningeal sac (arrow). The lumbosacral posterior vertebral elements have not formed. *

Closed spinal dysraphism. The spinal cord is too low and the neural placode terminates at the lumbosacral junction in a lipomyelocele (black arrows). There is an associated spinal cord syringomyelic cavity (white arrows). The posterior elements are deficient and everted. *

Congenital Spinal Anomalies

Tethered Cord Syndrome

Definition

A low-lying conus medullaris tethered by a short thick filum terminale ▸ it is commonly a component of other spinal malformations (e.g. a spinal lipoma)

The spinal cord reaches the adult position by term – the majority lie between T11/12 and L1/2 (it is abnormal if it is seen at or below the level of L3)

Clinical presentation

Progressive neurological deterioration due to traction damage on the tethered cord

MRI

A low-lying conus ▸ an enlarged thecal sac ▸ a thickened (>1.5 mm) filum terminale

It may be associated with a spinal cord syrinx

Spinal Lipoma

Intramedullary/intradural lipomas: a mass of adipose tissue located mainly between the posterior spinal cord columns (a tongue-like extension along the central canal can often be seen) ▸ the overlying dura mater is usually intact and the lipoma entirely intradural – however, there may be a dural defect to which the cord and lipoma become adherent
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  Its usual location is near the thoracocervical or craniovertebral junctions
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  CT and MR will demonstrate the fatty nature of the tumour
Filum terminale lipoma: an asymptomatic fatty thickening of the filum terminale as a result of a disturbance of caudal regression ▸ it is considered a normal variant in the absence of a clinical tethered cord syndrome (and is seen in up to 5% of the normal population)

Lipomyelomeningodysplasias

Definition

These represent a spectrum of abnormalities ranging from an abnormally low conus medullaris (with minimal or even absent lipoma) to massive lipomatous formations involving all elements of the spinal and adjacent subcutaneous tissues

Lipomyelocele: a lumbosacral neural lipomatous lesion continuous with the subcutaneous fat via a dysraphic spinal defect (tethering the spinal cord)
Lipomyelomeningocele: a lipomyelocele + a meningocele

Clinical presentation

These frequently present in adult life (sometimes with only back pain or minimal neurological signs)

XR

There is non-fusion of ≥1 neural arches (± variable spinal canal expansion)

MRI

T1WI/T2WI: a high SI lipoma continuous with the subcutaneous fat (± spinal canal extension) ▸ the spinal cord terminates at or below the level of L3 (in 80% of cases), and is usually tethered to the dorsal dura where it fuses with the lipoma ▸ nerve roots issuing from an apparently thickened filum terminale indicate it contains significant nervous tissue and should not be surgically divided

Neurenteric Cyst

Definition

This results from incomplete separation of the notochord from the endoderm, or from herniation of the endoderm into the dorsal ectoderm ▸ the cyst attachment to the notochord can prevent vertebral body fusion (leading to spinal anomalies)

It forms part of the ‘split notochord’ syndrome : this is a persistent connection between the endoderm and ectoderm resulting in splitting or deviation of the notochord:
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  Dorsal enteric fistula: the most severe form, representing a fistula connecting the intestinal cavity with the midline dorsal skin surface (therefore travelling through soft tissues and spine)
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  Dorsal enteric (dermal) sinus: this is a remnant of the posterior portion of the fistula with a blind ending tube opening onto the skin surface
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  Dorsal enteric cyst (neurenteric cyst): this is a trapped remnant of the middle portion of the fistula and is found within the intraspinal or paraspinal compartments
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  Dorsal enteric diverticulum: this is a remnant of the anterior portion of the fistula with a tubular diverticulum originating from the dorsal bowel mesentery
Intraspinal neurenteric cysts : intradural (usually unilocular) cysts are lined by gastrointestinal or bronchial epithelium and are usually anterior to the spinal cord ▸ they occur within the cervical or lower thoracic regions and can compress the spinal cord (usually the anterior aspect)

XR

A focal expansion of the spinal canal (butterfly or hemivertebrae are associated with thoracic lesions)

MRI

T1WI / T2WI: the cyst contents are usually of high SI (relative to CSF)

Tethered cord (long arrow), thick filum and lipoma (short arrows) and sacral extradural arachnoid cyst (A) on sagittal T1WI. §

Lipomyelomeningodysplasia. Sagittal (A) T1WI and (B) T2WI and coronal (C) T2WI showing the lipoma, low position of the spinal cord and a cavity in the distal spinal cord. *

Neuroenteric cyst. (A) Chest radiograph and (B) coronal multiplanar reformat of CT thorax in same patient. There is a complex segmentation anomaly within the mid-thoracic region associated with kyphoscoliosis, consisting of congenital fusion and butterfly vertebrae. There is an associated right paraspinal mass. (C) Axial CT through the lesion shows that it is in direct continuation with the spinal canal through a large ventral bony defect. (D) Axial T2 and (E) axial T1 at the level of the lesion demonstrating that the lesion is cystic. (F) Axial T2 through the bony defect demonstrates the direct continuity of the cyst with the spinal canal. The appearances are in keeping with a neuroenteric cyst. The thoracic cord is also seen to extend through the bony defect. The neural tissue is seen to lie to the left of the neuroenteric cyst. (G) Sagittal T2 in the right paramidline demonstrating the direct communication with the spinal canal. **

Diastematomyelia

Definition

This forms part of the ‘split notochord’ syndrome: the spinal cord is split into two (usually unequal) hemicords ▸ each hemicord has a central canal and an anterior spinal artery but only gives off the ipsilateral spinal roots from one anterior and one posterior grey matter horn ▸ the hemicords nearly always re-unite caudally

They are usually found within the thoracic cord, extending over several vertebral segments

XR

A focal expansion of the spinal canal with narrowed intervertebral disc spaces ▸ there are varying degrees of laminar dysplasia and fusion

CT myelography/MRI

The hemicords are enclosed within a common dural tube in 50% of cases but in the remainder each is enclosed within its own dural tube ▸ they are usually located within the cervical region ▸ a bony or cartilaginous midline extradural spur may arise from the malformed lamina which often lies between each hemicord

Vertebral segmentation abnormalities are usually present (e.g. a hemivertebrae or bifid/fused vertebrae)
Syringohydromyelia (50% of cases) ▸ a tethered cord (75% of cases)

Spinal Dermoid/Epidermoid Cyst

Definition

A benign tumour arising from cells that can produce skin and its appendages ▸ it can be congenital or acquired (e.g. following a lumbar puncture)

It is commonly located within the lumbosacral or cauda equina regions

CT/MRI

A rounded intradural (occasionally intramedullary) lesion demonstrating fat (± calcification) ▸ in 20% a dorsal dermal sinus can be traced to a skin dimple on the lower back (this is a possible source of intradural sepsis)

Dorsal Dermal Sinus

Definition

An epithelial-lined skin opening with a variable fistulous extension to the dural surface ▸ it typically affects the lumbosacral region ▸ it is often associated with cutaneous stigmata (e.g. a hairy naevus or capillary haemangioma)

MRI

A thin linear strip of tissue hypointense to the adjacent fat

Dermal openings at the sacrococcygeal level: these are directed inferiorly below the thecal sac (sacrococcygeal pits) ▸ they do not require further imaging
Dermal openings above the intergluteal cleft: these pass superiorly and may form a fistulous connection with the dural sac ▸ these warrant further investigation

Caudal Agenesis

Definition

This follows the abnormal development of the caudal cell mass as a result of apoptosis of notochordal cells which have not formed at the correct craniocaudal position

Caudal agenesis: absence of the vertebral column at the affected level (as well as a truncated spinal cord, an imperforate anus and genital anomalies)
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  Type I: there is a high (often T12) abrupt spinal cord termination ▸ there is a characteristic wedge-shaped configuration with variable coccygeal to lower thoracic vertebral aplasia
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  Type II: the true notochord is not affected and only the caudal cell mass is involved ▸ the vertebral aplasia is less extensive (with up to S4 present as the last vertebra)
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  Associations:
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    OEIS: o mphalocele/ e xstrophy/ i mperforate anus/ s pinal defects
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    VACTERL: v ertebral anomalies/ a nal atresia/ c ardiovascular anomalies/ t racheoesophageal fistula/ o esophageal atresia/ r enal or r adial abnormalities/ l imb anomalies
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    Currarino triad: Partial sacral agenesis + an anorectal malformation + a presacral mass (either a teratoma or anterior meningocele)
Segmental spinal dysgenesis: a rare segmental abnormality affecting the spinal cord, segmental nerve roots and vertebrae
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  Associations: congenital paraparesis ▸ lower limb deformities

MRI

An acute angle kyphus ▸ the spine and spinal cord may appear severed (the most severe cases) or focally hypoplastic (less severe cases)

Diastematomyelia. (A) Sagittal T1 of the lumbar spine demonstrating an ill-defined low-lying conus at the L4–L5 level. The nerve roots are tethered caudally and herniate through a bony defect in the posterior elements. There is agenesis of the lower sacrum and of the coccyx. (B) Axial T2 through the lower thoracic spine clearly demonstrates the split cord. (C) Axial T1 through the lower dural sac demonstrates an intradural extramedullary left-sided high signal-intensity lesion. This suppresses on (D) fat-suppressed axial T2 at the same level. The appearances are in keeping with a lipoma. **

Thoracic dermal sinus (posterior black and white arrows in (A) and (B)) and a cyst with an enhancing abscess (anterior white arrows in (B)) with cord oedema on the sagittal T1WI + Gad (A) and T2WI (B). §

Intradural extramedullary dermoid in a 52-year-old man with backache, leg paresthesia, and anal incontinence. A, Sagittal T2W MR image depicts a large cystic intradural mass (thin black arrow) in the region of the conus medullaris and cauda equina. Note displacement of the dura mater (thin white arrow) posteriorly and the conus medullaris (thick black arrow) anteriorly. B, Sagittal T1W MR image shows an isointense solid component (thin black arrow) and a hyperintense fatty component (thick black arrow). A small fatty droplet is also visible in the subarachnoidal space (thin white arrow). C, Sagittal T1W MR image with fat suppression and administration of gadolinium affi rms the presence of fat (arrow) that is suppressed with this sequence. D, The sagittal CT image shows an additional small calcifi cation (arrow). E, The axial CT with bone window depicts a spinal canal widening in the region of the hypodense fatty component (at the level of L2) (arrow). In F, the spinal canal above it (at the level of L1) looks normal. This is a sign of a slowgrowing pathologic process with remodeling of the subjacent bony structures. ■

Syringomyelia

Definition

A longitudinal CSF filled cavity that is lined mainly by glial tissue ▸ it usually involves many segments (or the whole cord) ▸ it follows either cord damage (and subsequent cavitation) or CSF that has been abnormally driven into the cord (via the perivascular spaces) ▸ as a result of hydrodynamic forces the lesion is capable of propagating into normal cord tissue

Syringomyelia: the cystic cavity is not continuous with the central cord canal
Hydromyelia: cystic dilatation of the central cord canal
Syringohydromyelia: features common to both of the above

Location

It is commonly located within the cervical cord (only 10% extend cranial to C2)

Associations

Cerebellar ectopia (70–90%) with the cerebellar tonsils usually lying at the level of C1 or C2

XR

An expanded spinal canal (30–40%) ▸ scoliosis

MRI

An enlarged spinal cord (affecting 80% of cases) which varies with changes in posture or respiration ▸ a well circumscribed CSF cavity often demonstrating prominent transverse ridges within its wall (giving a beaded or loculated appearance) ▸ pulsatile cysts can show flow-related signal changes

There is a moderate correlation between the cavity location and the clinical features (but not between the clinical severity and the syrinx size relative to the remaining cord substance)
T1WI/T2WI: a similar uniform SI to CSF (with slightly more variable SI on T2WI)

Intraspinal Arachnoid Cyst

Definition

A loculated CSF fluid collection:

Extradural: these arise from defects within the dura mater (congenital or inflammatory)
Intradural: these arise from arachnoidal duplications or spinal arachnoiditis
Tarlov cyst: a perineural arachnoid cyst occurring commonly within the sacrum (especially on the 2 ^nd sacral root) ▸ can be large ▸ it is of doubtful clinical significance

Clinical presentation

Pain or neurological disability if the spinal cord or cauda equina is compressed ▸ aspiration of cysts compressing the cord can improve symptoms

XR

Spinal canal expansion (with extradural cysts)

MRI

A well-defined cystic structure that often demonstrates higher SI than CSF (due to its reduced mobility) ▸ they can be multiple and are rarely associated with myelomalacia or syringomyelia ▸ extradural lesions can be overdiagnosed within the thoracic region (the thoracic spine is commonly wide and partly loculated)

Cystic tumors usually show contrast enhancement (black arrows), whereas arachnoidal cysts (meningeal cyst type III) do not (white arrows). ■

Skeletal Abnormalities

Achondroplasia

Definition

An autosomal dominant dwarfism affecting the spine and extremities

XR

A decreasing lumbar spine interpedicular distance in the caudal direction ▸ bullet-shaped vertebral bodies ▸ short pedicles ▸ posterior vertebral body scalloping ▸ lumbar hyperlordosis ▸ a ‘champagne glass’ pelvis ▸ squared pelvic iliac wings

The Mucopolysaccharidoses

Definition

Inherited lysosomal storage disorders

Morquio–Brailsford type

Instability and subluxation at the atlantoaxial joint and thoracolumbar junction (due to ligamentous laxity) ▸ upper spinal cord compression (due to ligamentous thickening) ▸ dens hypoplasia ▸ posterior vertebral body scalloping

Central vertebral beaking

Hurler's type

Especially marked thickening of dural and extradural tissues ▸ dens hypoplasia ▸ posterior vertebral body scalloping

Inferior vertebral beaking

Spondyloepiphyseal Dysplasia

Definition

Flattened or enlarged vertebrae in an AP dimension (especially with a thoracic kyphosis) ▸ there may be a severe scoliosis
Neurological complications are uncommon

Neurofibromatosis

Definition

Neurofibromatosis type I is usually associated with a skeletal dysplasia:

Severe scoliosis (50%) ▸ dysplastic vertebrae (10%) – often consisting of ≥1 absent or hypoplastic pedicles ▸ dural ectasia (10%) ▸ C1/2 or C2/3 subluxation or spinal compression (16%)

Vertebral Fusion Anomalies

Definition

Narrowed intervertebral discs which are partly bridged by regions where the disc material never formed early in development
The fused segments usually show varying degrees of hypoplasia ▸ marked dysplasias (e.g. hemivertebrae) can occur if multiple segments are involved

Klippel–Feil syndrome

The cervical region is predominantly involved

Spondylothoracic and spondylocostal dysplasia

The thoracic spine is predominantly involved

Transitional Vertebrae

Transitional lumbosacral vertebrae

Complete or partial fusion of L5 with the sacrum ▸ there are enlarged L5 transverse processes with a narrowed L5–S1 disc space

Its main significance lies in the fact that it may result in the wrong spinal level being identified preoperatively – a useful landmark is that the level of the iliac crests usually correlates with the L4/5 disc
Lumbarization of S1 is less frequently seen

Cervical ribs

Additional ribs arising from the 7 ^th cervical vertebra

Differentiating feature: the transverse processes of T1 tend to be directed superiorly (they are directed inferiorly with a cervical rib)

Spinal Instability – C2

Os odontoideum

Separation of the odontoid process from the body of the axis – this may represent a congenital failure of fusion, or a previous fracture of the odontoid synchondrosis before its closure

True hypoplasia of the dens

Associated with more complex fusion anomalies, especially those that restrict rotation at C1/2

Spondylolysis

Definition

A defect within the pars interarticularis of a vertebral body (not to be confused with spondylosis) ▸ they probably represent stress fractures through the pars interarticularis of the laminae (resulting in a hypertrophic pseudoarthrosis)

Spondylolytic defects are relatively common at the lumbosacral junction in young athletic adults

Oblique lumbar XR

The ‘Scottie dog’ appearance with the pars defect represented by a dark ‘collar’ along its ‘neck’ (the pars intrarticularis)

Congenital type

This is uncommon and is associated with absent pedicles, an absent superior articular facet, hypoplastic laminae with deviation of the spinous process and hypertrophy of the contralateral pedicle ▸ it is found within the cervical and lumbar regions

Bilateral spondylolysis

This may result in a true spondylolisthesis (i.e. anterior displacement of an affected vertebral body relative to the vertebral body below) ▸ it must be differentiated from a degenerative spondylolisthesis (a pseudospondylolisthesis)

Anterolisthesis: there is anterior displacement
Retrolisthesis: there is posterior displacement with subsequent narrowing of the intervertebral foramina
It is graded depending upon the degree of anterior displacement: Grade 1 (<25%) ▸ Grade 2 (25–50%) ▸ Grade 3 (50–75%) ▸ Grade 4 (75–100%)

Hurler syndrome. There is hypoplasia of the anterosuperior aspect of the vertebral body at the thoracolumbar junction resulting in an anteroinferior beaking appearance. The other vertebral bodies have a short anteroposterior dimension and are ovoid with concave anterior and posterior margins and convex superior and inferior end plates. Thoracolumbar gibbus deformity is typically present in Hurler syndrome. ©35

Morquio syndrome. There is universal vertebra plana, or flattened vertebral bodies. This can be distinguished from the ovoid vertebral bodies of Hurler syndrome and other mucopolysaccharidoses. The central anterior beaking of Morquio syndrome also differs from the anteroinferior beaking of Hurler syndrome and other mucopolysaccharidoses. ©35

Hurler syndrome. The ribs are oar-shaped and wider than the intercostal spaces but become narrower in the paravertebral region. The iliac wings of the pelvis are flared, and the iliac body is constricted inferiorly. ©35

Achondroplasia. (A) Lateral radiograph of spine. Note posterior scalloping, bullet-shaped vertebral bodies, short pedicles and horizontal orientation of the sacrum. (B) Anteroposterior radiograph of the spine. There is abnormal narrowing of the interpedicular distances from L1 to L5 (should get progressively wider). This narrowing is not seen in infants. (C) Anteroposterior radiograph of the pelvis. Typical changes include horizontal acetabular roofs, trident acetabula and square iliac wings. (D) Anteroposterior radiograph shows a trident hand and bullet-shaped phalanges. ©35

Type 1 neurofibromatosis with a short angular thoracolumbar curve as seen on an anteroposterior radiograph (A), lateral radiograph (B) and coronal T2WI (C). There is scalloping of the posterior vertebral body wall and enlargement of the exit foramen. The MR image demonstrates dural ectasia with a widened spinal canal. ©35

Vascular Spinal Lesions

Spinal Dural Arteriovenous Fistula (SDAVF)

Definition

These represent >80% of all spinal arteriovenous malformations ▸ middle aged me leading to gait disturbance, paresthesia and incontinence

Location: located within the spinal dura mater close to a root sleeve ▸ they are commonly found within the thoracic region (although within the cervical spine they are only found around the foramen magnum)
Anatomy: usually supplied by 1–2 radiculomeningeal arterial branches with shunting via a single vein into an intradural vein ▸ symptomatic lesions demonstrate slow and anomalous venous drainage which remains intradural through a greater part of the spinal canal than normal (venous stagnation is an important cause of a clinical myelopathy)

Radiological features

MRI

T2WI: ill defined central intramedullary high SI extending over multiple levels (representing venous hypertensive oedema) ± cord expansion ± low SI rim ▸ engorged perimedullary veins seen as flow voids (dorsal > ventral surface)
T1WI + Gad: diffuse enhancement of the cord ▸ enhancing perimedullary veins ▸ this may demonstrate the site of the dural fistula

Digital subtraction angiography (DSA)

This is the gold standard investigation, also allowing access for interventional therapy (e.g. embolization)

Pearl

Embolization of arteries supplying a fistula may be feasible (if they can be shown not to supply the cord)

Spinal Arteriovenous Malformations (SAVMs)

Definition

In contrast to SDAVFs, these are fed by spinal arteries (radiculomedullary/radicullopial) and are more prone to haemorrhage (intramedullary or subarachnoid)

Glomerular AVMs (plexiform or nidus type): the most common, contains a cluster or nidus of abnormal vessels between the feeding artery and draining vein
Fistulous AVMs (intradural AV fistula): direct AV shunts commonly located superficially on the cord

Radiological features

MRI

T2WI: serpiginous flow voids (dilated veins) ▸ oedema (venous congestion) as ill defined high SI with cord expansion
T1WI + Gad: enhancement

Spinal Cord Cavernous Malformation (SCCM)

Definition

Rare vascular malformations composed of sinusoidal-type vessels in immediate apposition to each other without normal intervening parenchyma

Extradural/intradural–extramedullary/intramedullary (commonest)

Clinical presentation

Discrete episodes of neurological deterioration separated by variable time intervals ± recovery ▸ slowly progressive myelopathy ▸ acute neurological deficit with either gradual or rapid decline

Radiological features

MRI

T1WI + T2WI: heterogenous lesions displaying typical ‘popcorn’ appearances (blood products of differing ages) ▸ low SI T2WI rim and hypointense ‘blooming’ on GE sequences (haemosiderin deposition)

Spinal Cord Infarction

Definition

A rare complication of arteriosclerotic vascular disease (rich anastomotic blood supply) ▸ it may also complicate an aortic dissection or aortic aneurysm surgery

Thoracolumbar > cervical cord (arterial border zones) ▸ located in the central/anterior territories of the anterior spinal artery – resulting in classical sensory pattern loss of pain and temperature sensation with preservation of touch and proprioception
A venous infarction (due to extensive thrombosis of the local pial veins) is rare

MRI

T2WI: high SI within the central cord (‘owl's eyes’ or ‘snake's eyes’ appearance) ▸ mild cord swelling
T1WI + Gad: mild enhancement (breakdown of the blood–brain barrier)
DWI: very sensitive in the acute phase