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Ependymoma vs astrocytoma of the spinal cord

A number of factors are useful when differentiating between spinal cord ependymoma and spinal cord astrocytoma. Ependymoma child or adult more central in location bone remodeling is common low T1 signal well-defined enhancement syrinx is more common hemorrhage is more common Astrocytom...

Epidural angiolipoma

Epidural angiolipomas are rare benign tumors composed of mature adipocytes and abnormal vessels. Epidemiology Epidural angiolipomas are more frequently encountered in women, and typically in middle age (40-50 years of age) 1. Clinical presentation In keeping with the slow growth of these t...

Epidural blood patch

Epidural blood patch is a treatment option for patients with craniospinal hypotension or post-lumbar puncture headaches. The procedure can be done blind or under fluoroscopic or CT guidance, and is performed predominantly by radiologists and anesthesiologists. Indications craniospinal hypoten...

Epidural lipomatosis

Epidural lipomatosis refers to an excessive accumulation of fat within the spinal epidural space resulting in compression of the thecal sac. In severe cases, compression may be symptomatic. The lumbar region is most frequently affected. Epidemiology The demographics of affected individuals ref...

Epidural venous congestion

Epidural venous congestion represents the pathological dilatation of the spinal epidural venous plexus, and is typically a complication of other pathologies. Clinical presentation Radiculopathy caused by the dilated epidural veins is not uncommon 1. Pathology Several spinal and pelvic dise...

Epitransverse process of the atlas

Epitransverse process is a rare anatomical variant of the atlas, consisting of a bony exostosis which extends cephalad from the transverse process of the atlas to articulate with the occipital bone. This process sometimes meets with a paracondylar process from the occipital bone, forming a pseud...

Erector spinae group

The erector spinae group is the intermediate layer of the intrinsic muscles of the back. This group is made of three subgroups, with the group divisions occurring by location. iliocostalis subgroup is the most lateral longissimus subgroup is between iliocostalis and spinalis spinalis subgroup...

Erector spinae muscles (mnemonic)

There are multiple handy mnemonics to recall the erector spinae muscles. They usually describe the position from lateral to medial. I Like Standing I Love Sex I Long for Spinach I Like Siri Mnemonic I: iliocostalis L: longissimus S: spinalis

Erosion of the odontoid process (differential)

Erosion of the odontoid peg can result from a number of pathological entities: inflammatory arthropathy rheumatoid arthritis: classic 1,2 systemic lupus erythematosus crystal arthropathy calcium pyrophosphate arthropathy (CPPD): relatively common gout non-inflammatory arthropathy: osteoar...

Extension teardrop fracture

Extension teardrop fracture typically occurs due to forced extension of the neck with resulting avulsion of the anteroinferior corner of the vertebral body. Extension teardrop fractures are stable in flexion and unstable in extension as the anterior longitudinal ligament is disrupted. Extension ...

Extrapulmonary tuberculosis

Extrapulmonary tuberculosis (TB) refers to the hematogenous spread of Mycobacterium tuberculosis. Pathology Extrapulmonary tuberculosis can occur as a primary form of the disease, i.e. direct infection of an extrapulmonary organ without the presence of primary pulmonary tuberculosis or it can ...

Extreme lateral interbody fusion (XLIF)

Extreme lateral interbody fusion (XLIF) is a form of lumbar surgical spinal fusion developed in 2001 to be a safer alternative to the older anterior lumbar interbody fusion (ALIF) developed in the 1950s 1,2. Unlike an ALIF, an XLIF is performed from a lateral trans-psoas approach and does not r...

Facet dislocation

Facet dislocation refers to anterior displacement of one vertebral body on another. Without a fracture, the only way anterior displacement can occur is by dislocation of the facets. Facet dislocation can occur to varying degrees: subluxed facets perched facets locked facets The injury usua...

Facet joint

Facet joints, also known as apophyseal or zygapophyseal joints, are the articulations of the posterior arch of the vertebrae and form part of the posterior column. Gross anatomy They are symmetrical synovial-lined joints with a fibrous capsule that connect the articular facets of the vertebra...

Facet joint arthropathy

Facet joint arthropathy (also known as facet joint arthrosis) is one of the causes of lower back pain. It occurs from zygapophysial joint space reduction, osteophyte formation and hypertrophy of the articular processes that may cause spinal canal stenosis in severe cases. Epidemiology It is a ...

Facet joint capsule

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 joint injection

Facet (zygapophyseal) joint injections are performed primarily for the diagnosis and differentiation of facet syndrome and radicular pain syndrome, and are one of the spinal interventional procedures. They can be performed under fluoroscopic, or CT image guidance, and cervical, thoracic or most ...

Facet joint vacuum phenomenon

Facet joint vacuum phenomenon or degenerative intrafacetal gas is a feature that can be seen on spinal imaging in facet joint arthropathy as part of degenerative spondylosis. Radiographic features Signal characteristics are those of air and are T1: low signal T2: low signal Differential di...

Facioscapulohumeral muscular dystrophy

Facioscapulohumeral muscular dystrophy (FSHD) is a form of muscular dystrophy characterized by extremely variable degrees of facial, scapular and lower limb muscle involvement. Epidemiology It is considered one of the more common hereditary muscular disorders with a prevalence of ~1 in 8,000. ...

Failed back syndrome

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. Terminology Other names for failed back syndrome include failed back surgery syndrome, post-lam...

Festooned dura (CSF leak)

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

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 disc in a retrograde direction into a spinal artery or vein. Fibrocartilaginous embolism is a diagnosis of suspicion...

Fifth lumbar vertebra (L5)

The fifth lumbar vertebra (L5) is the largest of the five lumbar vertebrae and is considered an atypical vertebra due to its shape. Gross anatomy L5 is the largest, most inferior lumbar discovertebral unit in the vertebral column, and participates in forming the lumbar lordosis (from L1 to L5...

Filar cyst

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 inc...

Filum terminale

The filum terminale is a small thin filament of connective tissue that extends inferiorly from the apex of the conus medullaris to the sacrum. Gross anatomy The filum terminale is continuous with the pia mater and is described as having two sections: filum terminale internum: upper three quar...

Fish vertebra

Fish vertebra, also known as codfish vertebra, describes the biconcave appearance of vertebrae (especially lumbar vertebrae). Pathology Etiology osteoporosis sickle cell disease: caution required as more usually an H-shaped vertebra hereditary spherocytosis homocystinuria renal osteodyst...

Flame sign (spinal cord metastasis)

The flame sign has been described as a helpful MRI sign of spinal cord metastases, enabling them to be distinguished from other enhancing spinal cord lesions (e.g. ependymoma, astrocytoma and hemangioblastoma) 1. Radiographic features MRI The flame sign is seen on sagittal post contrast T1 w...

Flat back syndrome

Flat back syndrome (FBS) refers to the decrease or absence of the normal lumbar lordosis resulting primarily in chronic lumbar pain. Terminology Flat back syndrome is a different condition from straight back syndrome and the two should not be confused or conflated. Clinical presentation Mos...

Flexion teardrop fracture

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...

Fluid sign (vertebral collapse)

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

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...

Fluorosis

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. Voriconazole is a trifluorinated azole drug which has been purported to cause a diffuse asymmet...

Focal fatty deposits in spinal bone marrow

Focal fatty deposits/replacement in spinal bone marrow are well-defined focal fat islands within the bone marrow of the spine or other parts of the axial skeleton. Epidemiology Common in older individuals, related to age but not to sex. Pathology This process is a normal variant. Histologica...

Foix-Alajouanine syndrome

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 protrusion

Foraminal disc 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

Friedreich ataxia is the most common hereditary progressive ataxia. Epidemiology Thought to have an estimated prevalence of ~1:50,000. There is no recognized gender predilection. Typically present in childhood to adolescence 11. Those with a higher number of trinucleotide repeats (>500) are t...

Functional neuroanatomy

Functional neuroanatomy is the study of the functional connections in the brain and spinal cord, distinct but interconnected with the structural or "more conventional" anatomic descriptions of the central nervous system. It focuses on the relationship between structure and function and hence it ...

Ganglioneuroblastoma

A ganglioneuroblastoma is a transitional tumor which lies on the intermediate spectrum of disease between a ganglioneuroma and a neuroblastoma. Epidemiology They are seen more commonly in children younger than 10 years. There is no definite gender predilection reported at the time of writing. ...

Ganglioneuroma

Ganglioneuromas are fully differentiated neuronal tumors that do not contain immature elements and potentially occur anywhere along with the peripheral autonomic ganglion sites. On imaging, usually, they present as well-defined solid masses and can be quite large at presentation. Generally, th...

Gehweiler classification of atlas fractures

The Gehweiler classification of atlas fractures described 5 types of fractures of the atlas. In addition, Dickman classified injuries of the transverse atlantal ligament (transverse band of the cruciform ligament) which has been incorporated into this classification system. type 1: fractures of...

Genant classification of vertebral fractures

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...

Gertzbein and Robbins classification

The Gertzbein and Robbins classification assesses the position of transpedicular screws. Classification Transpedicular screw position is graded from A to E based on the extent by which the screw breaches the cortex of the pedicle 1-3: A: fully intrapedicular position without breach of the ped...

Ghost vertebra

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 stress line rickets...

Gibbus deformity

A gibbus deformity is a short-segment structural thoracolumbar kyphosis resulting in sharp angulation. Pathology Etiology There are a number of causes which can be divided into congenital and acquired. Congenital achondroplasia cretinism (congenital hypothyroidism) Apert syndrome Coffin-...

Ginkgo leaf sign (spinal meningioma)

The ginkgo leaf sign of spinal meningiomas has been described as a useful MRI sign in distinguishing a spinal meningioma from a neurogenic tumor (e.g. spinal schwannoma). It is seen on axial post contrast T1 imaging, with the leaf representing the distorted spinal cord, pushed to one side of t...

Gracile fasciculus

The gracile fasciculus, also known as the fasciculus gracilis (plural: fasciculi graciles) or column of Goll, represents the medial portion of the dorsal columns and carries input from below and including T7 1. Function The gracile fasciculus is responsible for transmitting vibration, consciou...

Grey matter

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 grey matter) and the nuclei of the basal ganglia. The brains...

Grisel syndrome

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. Epidemiology It usually occurs in infants or young children. Clinical p...

Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is 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 underlying...

Hematomyelia

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. Pathology Although hematomyelia can occur in the setting of trauma, the term is generally used to signify...

Hemosiderin cap sign

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 (trauma)

Hanging and strangulation are injuries involving constricting pressure applied to the neck. The vast majority are sustained as a result of attempted suicide. Epidemiology 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

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. Epidemiology These injuries account for 4-7% of all cervical spine fractures and up to 22% of ...

Hemivertebra

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. Epidemiology The estimated incidence is at ~0.3 per 1000 live births 2. Pathology It falls under the spectrum of segmentation anoma...

Hereditary spastic paraplegia

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. Clinical presentation Patients often tend to have progressive lower extremity weakn...

Hernia (general)

Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening. The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...

Hirayama disease

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 neuron disorder with a stationary stage after a progressive course 1. Epidemiology...

HIV-related vacuolar myelopathy

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. Clinical presentation Patients tend to have slowly progressive weakness of the lower extremities,...

Holocord presentation

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...

Honda sign (sacrum)

The Honda sign (H sign / H pattern) is a term used to describe the appearance of bilateral sacral insufficiency fractures on a radioisotope bone scan. Radiographic features Sacral insufficiency fractures are usually vertically through the sacral alae, paralleling the sacroiliac joint, often wi...

Hopkins syndrome

Hopkins syndrome is a rare poliomyelitis-like neurological syndrome that occurs following an episode of acute asthma. Clinical presentation It usually manifests as flaccid paralysis of one or more limbs, several days or weeks following an episode of acute asthma. Pathology The pathogenesis i...

H-shaped vertebra

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 disease, and results from microvascular endplate infarction (figure 1) 3. It may occasionall...

HTLV-1-associated myelopathy

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. Terminology This condition has been independently described in Japan (HTLV-1 associated myelopathy) and in the Carib...

Hydromyelia

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

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

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. Clinical presentation Hyperparathyroidism is supported biochemically by either an...

Iliolumbar ligament

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 la...

Imaging psoas sign (spondylodiskitis)

The imaging psoas sign is an MRI finding specific for spondylodiskitis and is seen as T2 hyperintensity in the psoas major muscle. The sign has a high sensitivity (92%) and specificity (92%) for spondylodiskitis and in the clinical context of a suspected infective process of the spine supports c...

Incomplete cord syndromes

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 fracture

Insufficiency fractures are a type of stress fracture, which are the result of normal stresses on abnormal bone. Looser zones are also a type of insufficiency fracture. They should not be confused with fatigue fractures which are due to abnormal stresses on normal bone, or with pathological frac...

Intercalary bone

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 etiology. Differential diagnosis limbus vertebra flexion or extension teardrop fracture

Intercristal line

The intercristal line (also known as Jacoby’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 radiograph 1,2. The intercristal line most often intersects the body of L4 or its inferior endplate in men and th...

Interspinous ligament

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.

Interspinous processes spacer

An interspinous processes spacer (also known as a decompression spacer or interspinous posterior device) is a device implanted between spinous processes to open narrowed exiting foraminal nerve channels to treat lumbar radiculopathy caused by spinal stenosis. It is used as an alternative to lam...

Intertransverse ligaments

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 disc

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. They represent the hydro-mechanical sy...

Intervertebral disc calcification

Intervertebral disc calcification is a non-specific finding seen in numerous conditions. Epidemiology It may be observed in pediatric 5 as well as adult populations. Pathology Etiology degenerative: relatively common and may occur in up to 6% of routine abdominal radiographs in adults post...

Intervertebral disc disease nomenclature

Intervertebral disc 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 disc disease is a common problem and a source of a great deal of imaging....

Intervertebral disc vacuum phenomenon

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. Epidemiology It is a relatively common occurrence which can be observed in 1-3% of spinal radiographs ...

Intervertebral foramen

The intervertebral foramina allow passage of structures out of and into the vertebral canal. Boundaries anterior - lower posterolateral aspect of a vertebral body and the intervertebral disc below, in the thoracic and lumbar regions. in the cervical region a portion of the vertebral body belo...

Intervertebral joint

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). Gross anatomy Movement flexion: the anterior interv...

Intervertebral osteochondrosis

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 herniation

Intradural disc herniations occur when disc material related to an intervertebral disc hernia penetrates the spinal dura and lies in an intradural extramedullary location. Epidemiology Intradural disc herniations correspond to a rare presentation of a common pathology, comprising ~0.28% of all...

Intradural extramedullary metastases

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. Epidemiology The age at presentation depends on tumor type....

Intradural extramedullary spinal tumors

Intradural extramedullary neoplasms are located outside the spinal cord but within the dural sheath. Epidemiology The majority (70-80%) of spinal canal tumors are intradural extramedullary 1. Clinical presentation Patients present with signs and symptoms of spinal cord or nerve root compres...

Intradural extramedullary spinal tumors (mnemonic)

Useful mnemonics to remember the differential diagnoses for intradural extramedullary spinal neoplasms include the following: No More Spinal Masses MNM Mnemonics No More Spinal Masses N: neurofibroma M: meningioma S: schwannoma M: metastasis MnM This simplified mnemonic, as in M&M cand...

Intradural spinal lipoma

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: lipomyelocele/...

Intradural spinal mass lesions (an approach)

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 masses (mnemonic)

A useful mnemonic to remember the differential diagnoses of intramedullary spinal masses is: I HEAL Mnemonic I: infarction H: hemangioblastoma E: ependymoma A: astrocytoma L: lipoma

Intramedullary spinal metastasis

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 hematogenous dissemination direct extension from leptomeninges Epidemio...

Intramedullary spinal tumors

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. P...

Inverted Mercedes-Benz sign

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...

Inverted Napoleon hat sign

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...

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