Brain and Spinal Cord

Ventriculus terminalis

5th ventricle Dilatation of terminal spinal cord canal

L2 hydroxyglutaric aciduria

hyperintensity of subcortical white matter normal periventricular white matter hyperintense basal ganglia putamina bilateral cerebellar nuceli hyperintensity

Alexander disease

hyperintensity in subcortica, deep and periventricular white matter hyperintense basal ganglia

Vanishing white matter disease

hyperintensity of deep white matter normal subcortical white matter areas of cavitation

GM2 gangliosidosis

hypomyelination of white matter T1 thalmic hyperintensity, T2 hypointensity

Glutaric aciduria type I

hypoplasia of frontal and temporal insulae open sylvian fissures hyperintensity of posterior putamina

Late infantile neuronal ceroid lipofuscinosis LI-NCL

Diffuse cortical atrophy, sulcal, lateral ventricle enlarged, marked cerebellar atrophy, enlarged 4th ventricle

Schizencephaly

Clefts in brain that extende from cortex to ventricle lined by dysplastic gray matter

Lissencephaly

arrested neuronal migration thick 4 layer cortex hourglass or figure of 8 cerebral hemisphere shape posterior > anterior involvement

Colpocephaly

dilated atrium/occipital horns of lateral ventricle absent corpus callosum vertical posterior course of anterior cerebral artery

Cavum septum pellucidum

80% of babies Disappears after 6 months No communication with CSF No ependymal lining If it extends posteriorly, it is called cavum septum pellucidum et vergae

Virchow Robin spaces

Perivascular space Transmit small arteries and veins Radially oriented Seen as radiating lines in white matter CSF signal in all sequences Asymmetrically large perivascular spaces often misdiagnosed as lacunar infarcts In basal ganglia, they are ovoid in shape, obliquely oriented in direction of lenticulostriate vessels. Related to outer fibers of anterior commissure More evident as…

Mega cisterna magna

Normal fourth ventricle Normal cerebellum Dilatation of CSF posterior to cerebellum Simplest form of Dandy-Walker complex Read more Kollias, Spyros S., William S. Ball Jr, and Erin C. Prenger. “Cystic malformations of the posterior fossa: differential diagnosis clarified through embryologic analysis.” Radiographics 13.6 (1993): 1211-1231.

Dandy-Walker variant

Vermian hypoplasia Cerebellar hemispheres fairly preserved Large posterior fossa Large CSF cyst in posterior fossa without any brain stem compression Fourth ventricle is present Mild lifting of torcula Read more Estroff, J. A., M. R. Scott, and B. R. Benacerraf. “Dandy-Walker variant: prenatal sonographic features and clinical outcome.” Radiology 185.3 (1992): 755-758. Wilson, Murray E.,…

Dandy-Walker complex

Absent cerebellum and vermis Large posterior fossa Large CSF cyst in posterior fossa that compresses brainstem Absent fourth ventricle Lifting of torcula Absent falx cerebelli Elevated tentorium cerebelli  Associated with usually severe cerebral malformations Has poor prognosis Read more Chang, Miles C., et al. “Sonographic detection of inferior vermian agenesis in Dandy-Walker malformations: prognostic implications.”…

Chiari 2 malformation

Protrusion of tonsils > 5 mm below foramen magnum Herniation of fourth ventricle and cerebellar vermis below foramen magnum Small posterior fossa Cerebellar hemisphere can herniate superiorly through tectorial incisor Hypoplastic corpus callosum Tectal plate is beaked Brain stem is flattened and compressed Low torcula Read more Wolpert, Samuel M., et al. “Chiari II malformation:…

Chiari 1 malformation

Protrusion of tonsils > 5 mm below foramen magnum Tonsils are sharp and pointed inferiorly Fourth ventricle is slightly low in position Tonsil descent may cause mild medullary compression Cervical cord syrinx may be seen Tectal plate is normal Corpus callosum is normal Read more Elster, Allen D., and M. Y. Chen. “Chiari I malformations:…

Low cerebellar tonsils

Protrusion of tonsils < 5 mm below foramen magnum Tonsils are rounded inferiorly Fourth ventricle is in normal position Twining’s line –  horizontal line  from tuberculum sella to internal occipital protuberance. This line should traverse midway through the fourth ventricle Read more Elster, Allen D., and M. Y. Chen. “Chiari I malformations: clinical and radiologic…

Myxopapillary ependymoma

WHO grade I lesion Intradural neoplasm of conus medullaris and filum terminale  Children and young adults Slightly M>F Chronic low back ache worsening in night Slow-growing Usually large when diagnosis is made Mass effect causes scalloping of vertebral body, scoliosis and enlargement of neural foramina  When hemorrhage occurs within lesion, sudden worsening of clinical symptoms…

Polymicrogyria

Disorder of neuronal organization Occurs after neuronal migration Extent of involvement varies from small, isolated, unilateral areas to large bilateral areas Overconvoluted and fused cortex of normal thickness Sometimes associated with CMV or underlying neurometabolic disorder Imaging Broad thickened gyra (mimicking pachygyria) to overconvoluted multiple gyri with irregular outer and inner cortical surfaces May show…

Agenesis of septum pellucidum

Not a severe malformation Often an indicator of other malformations – septo-optic dysplasia, holoprosencephaly, Chiari II malformation, schizencephaly, other migration disorders  <1% associated with HESX1 gene mutation Imaging Absence of septum pellucidum Box-like configuration of frontal horns Small optic nerves and chiasm Small anterior pituitary gland Ectopic bright spot of posterior pituitary Look for associated…

Holoprosencephaly

1 in 10,000 births Disturbance in separation of embryonic prosencephalon into two separate cerebral hemispheres Associated with chromosomal abnormalities, maternal diabetes 3 types based on severity: alobar, semilobar, interhemispheric variant (syntelencephaly) Alobar holoprosencephaly Complete or near complete failure of separation of cerebral hemispheres Often seen in stillborn Infants that survive show abnormal reflexes, tone and…

Bickerstaff encephalitis

Rare acute syndrome Subgroup of ADEM Subtype of anti-GQ1b IgG antibody syndrome Inflammation confined to brainstem Preceded by febrile illness Benign prognosis Ataxia, ocular paresis, impaired reflexes Pathogenesis uncertain No CSF oligoclonal bands Imaging Extensive high T2 signal in midbrain and pons, sometimes in basal ganglia and thalamus Lesions resolve with time, good prognosis Read…

Balo concentric sclerosis

Variant of multiple sclerosis Large demyelinated lesions with peculiar alternating layers of preserved and destroyed myelin Isolated, multiple or mixed with normal MS type lesions Similar lesions seen in cocaine abuse, an autoimmune reaction to levamisole – common cocaine adulterant Imaging Thick concentric T2 hyperintense bands corresponding to demyelination and gliosis Isointense bands represent normal…

Schilder disease

Acute or subacute disorder Specific clinicoradiological presentation of multiple sclerosis Affects children, young adults Psychiatric predominance, acute intracranial hypertension, intermittent exacerbations, progressive deterioration Well demarcated demyelination, reactive gliosis, relative sparing of axons Microcystic changes, frank cavitation Dramatic response to steroids Imaging Ring enhancing lesions in both hemispheres Symmetric, in parieto-occipital regions Minimal mass effect Restricted…

Marburg disease

Rare acute variant of multiple sclerosis Seen in young adults Rapidly progressive course Frequent severe relapses Death or severe disability within weeks to months of onset Preceded by febrile illness Monophasic course Also considered fulminant form of ADEM Massive macrophage infiltration, demyelination, hypertrophic astrocytes, severe axonal injury Imaging More destructive lesions than in MS or…

Frontotemporal lobar degeneration

Tau protein or progranulin mutation Language and behavioral symptoms 5-10% of all dementia Autosomal dominant, Chr. 17 Lund-Manchester criteria (3 main subtypes) Behavioral variant frontotemporal dementia Progressive non-fluent aphasia Semantic dementia Imaging Asymmetrical atrophy of frontal and temporal lobes Semantic dementia: marked left temporal lobe atrophy (temporal pole > hippocampus) Behavioral variant: frontal lobe atrophy…

Radionecrosis

In white matter adjacent to irradiated cerebral tumor Adjacent brain tissue in field of head and neck tumor radiation therapy Radiation causes cerebral small vessel alterations, wall thickening and direct glial and lesser extent neuronal injury Imaging MRI Ring-enhancing lesion, areas of hemorrhage, surrounded by edema Difficult to distinguish from tumor recurrence Increased diffusivity on…

Methotrexate neurotoxicity

Usually seen in intrathecal administration of high doses in children Imaging MRI bilateral T2 hyperintense centrum semiovale lesions with diffusion restriction partial or totally reversible also causes delayed leukoencephalopathy – confluent T2/FLAIR white matter hyperintensities Read more de Oliveira, Arthur M., et al. “Imaging patterns of toxic and metabolic brain disorders.” Radiographics 39.6 (2019): 1672-1695. Vázquez, Elida,…

Posterior reversible encephalopathy syndrome

Due to severe hypertension (eclampsia), chemotherapy, transplantation, immunosuppressive therapy (ciclosporin), autoimmune diseases Dysfunction of posterior cerebral arterial circulation Secondary cerebral vasogenic edema and/or vascular endothelial damage Headache, seizures, confusion, cortical blindness, cerebellar syndrome, consciousness disorders Imaging MRI bilateral cortico-subcortical T2 confluent hyperintensities, mainly in watershed parietal and occipital lobes brainstem and deep cerebral nuclei may…

Carbon monoxide poisoning

Affinity of carbon monoxide for Hb is 250 times for than oxygen Carboxyhemoglobin reduces oxygen carrying capacity of Hb Headache, tinnitus, dizziness, nausea Survivors have severe extrapyramidal disorder or dementia Bilateral globus pallidus necrosis, sometimes involved lenticular nuclei and caudate. Thalami and hippocampi rarely involved. Sometimes distal frontal matter involved Imaging MRI Bilateral basal ganglia…

Osmotic demyelination

Occurs if hyponatremia is rapidly corrected This destroys blood-brain barrier, causes hypertonic fluid accumulation in extracellular space, causes non-inflammatory demyelination, affecting mainly pons Paralysis, dysphagia, dysarthria, pseudobulbar palsy Death frequent Imaging MRI High T2 signal in central pons, with symmetrical trident pattern sparing periphery and corticospinal tracts Hypointense on T1 Peripheral contrast enhancement Restricted diffusivity…

MELAS

Acronym: mitochondrial encephalopathy, lactic acidosis, stroke-like episodes Due to mitochondrial DNA mutation Stroke like symptoms, encephalopathy, seizures, myopathy Lactic acid in CSF Ragged red fibres on muscle biopsy Imaging MRI Cortico-subcortical T2 hyperintensities in parietal, temporal and occipital lobes Topography does not correspond to single vascular territory Cortical and leptomeningeal contrast enhancement DWI – restriction…

Fabry disease

Diagnosed after 20 years of age Neurological involvement common Cerebrovascular events – transient ischemic attacks, strokes, chronic cerebral vasculopathy, vessel ectasia in posterior circulation Imaging MRI Periventricular and subcortical white matter hyperintensities, microbleeds, lacunar infarcts Increased basilar artery diameter Pulvinar sign – exclusive involvement of lateral pulvinar with symmetrical T1 hyperintensity on plain MRI. Rare…

Hydatid disease of the brain

Two main types – cystic and alveolar. Cystic more common Definitive host – dog Intermediate host – sheep and cattle Accidental host – man Infected via feco-oral transmission CNS involvement in 4% of cases Hematogenous spread of embryos from gastrointestinal tract  Imaging Large, isolated, unilocular, well-defined and thin-walled cysts Small daughter cysts arranged peripherally within…

Cerebral toxoplasmosis

Toxoplasma gondii – intracellular protozoan.  Infects humans via cat feces, ingestion of raw or undercooked meat, shellfish, unwashed fruits and vegetables Healthy patients – asymptomatic, becomes latent in neuroparenchyma Latent infection reactivated when immunocompromised, like HIV when CD4 count drops bellow 100 cells per cu.mm.  Pyrimethamine-sulfadiazine and folic acid reduces size of lesions within a…

Idiopathic intracranial hypertension

Earlier called pseudotumor cerebri Unknown etiology Affects young obese women Papilledema  Raised intracranial pressure without intracranial cause, meningeal problem or any cerebral venous thrombosis Tortuosity and ectasia of optic nerve sheaths Flattening of posterior globes Empty sella turcica Narrowing of distal transverse venous sinuses Read more Friedman, Deborah I., and Daniel M. Jacobson. “Diagnostic criteria…

Alcohol and the brain

Central nervous system depressant primary interfering with GABA receptors Pleasure comes from release of endorphins and dopamine Acute phase usually CT is done Quite often CT is normal Sometimes mild cerebral edema is seen in the form of effacement of sulci and reduced size of ventricles Chronic phase Non specific atrophy: atrophy disproportionate for age…

Multiple sclerosis

Introduction 40-50 years age Relapsing-remitting type 85% Primary-progressive type 15% Characteristic abnormality – demyelinating plaques Location of plaques – middle cerebellar peduncle, callososeptal interface, periventricular white matter, juxtacortical Callososeptal interface involvement – pathognomonic Imaging Plaque character Initial stages: acute, with surrounding edema Remyelination may occur: resulting in target lesions in pathology Eventually, chronic stage: axon…

Progressive supranuclear palsy

Introduction Parkinsonism Supranuclear ophthalmoplegia Pseudobulbar palsy dementia Imaging Humming bird sign: concave upper mid brain border in sagittal image Mickey mouse sign: reduced anteroposterior mid brain diameter < 14 mm with deepening of interpeduncular cistern

Multiple system atrophy

Introduction Sporadic progressive neurodegenerative disorder Adulthood onset Glial cytoplasmic inclusions containing alpha synuclein Combination of cerebellar, autonomic, extra-pyramidal and pyramidal signs MSA-P: predominant parkinsonian features MSA-C: predominant cerebellar dysfunction Imaging MSA-C: reduced pontine volume. Cerebellar atrophy. Cruciform T2 pontine hyperintensity (hot cross bun sign) MSA-P: also shows excess mineralization of bilateral putamina and substantia nigra

Parkinson’s disease

Introduction Progressive neurodegenerative movement disorder Involves basal ganglia Hypokinetic disorder Impaired initiation of movement Reduction in amplitude and velocity of movement 1.5 times more common in men Usually after 60 years age Degeneration of cells in pars compacta of substantia nigra Symptoms appear after 50% of dopaminergic neurons and 80% of striatal dopamine is depleted…

Normal pressure hydrocephalus

gait disturbance dementia urinary incontinence communicating hydrocephalus normal measured pressure mostly idiopathic only some patients improve with shunting

Chance fracture

horizontal splitting of vertebral body little compression associated intra abdominal and neurological injuries mechanism anterior hyperflexion over an object (seatbelt) that acts as a fulcrum posterior ligaments intact if any ligament injury is present, epidural fat will be dirty soft tissue chance injury: posterior ligament injury without bony injury radiograph transverse/horizontal fracture of spinous process…

Clay shoveller’s fracture

C6-T1 spinous process avulsion mechanism rotation of upper trunk with a fixed cervical spine occasionally due to a direct blow stable injury

Flexion teardrop fracture

fracture-dislocation with spinal cord injury mechanism hyperflexion and axial compression unstable injury radiograph triangular fragment at anteroinferior aspect of involved vertebral body (teardrop) anterior vertebral body height reduction with soft tissue swelling posterior displacement of fractured vertebra diastasic of interfacetal joints longitudinal ligament, intervertebral disc and posterior ligament complex disruption

Hangman’s fracture

traumatic spondylolisthesis of C2 with fracture through both pedicles posterior elements separated from vertebral body fracture lines oblique and symmetrical anteroinferior C2 margin may be avulsed C2 body subluxes anteriorly to C3 but posterior elements remain aligned mechanism hyperextension injury unstable injury

Jefferson fracture

disrupted anterior and posterior arches of atlas mechanism axial compression injury to top of skull stable injury radiograph bilateral offset of lateral masses of C1 relative to lateral margin of C2 vertebral body widened space between dens and medial border of C1 lateral masses

Extension tear drop fracture

fracture of anteroinferior corner of body of C2 avulsed by an intact anterior longitudinal ligament no associated neurological deficit occurs in isolation or with hangman’s fracture occasionally involves lower cervical vertebral bodies an unstable extension injury

Wilson disease

hepatolenticular degeneration autosomal recessive excess copper retention chromosome 13 alteration – liver unable to excrete copper into bile 7-50 years hepatic findings in children neuropsychiatric findings in adults stages Stage 1 asymptomatic copper accumulation in liver cytosol Stage 2 redistribution of copper from hepatic lysosomes. when gradual it is asymptomatic, if rapid redistribution, presents with…

Ethanol intoxication

characteristic neuroparenchymal volume loss initial infratentorial predominance with vermian and cerebellar atrophy followed by frontal and temporal atrophy finally diffuse brain atrophy

Commercially available gadolinium-based contrast agents

ACR, FDA and EMA have classified Gadolinium-based contrast agents into three groups Group Type US Trade Name Chemical Name I linear, non-ionic Omniscan gadodiamide linear, non-ionic OptiMARK gadoversetamide linear, ionic Magnevist gadopentate dimeglumine II linear, ionic MultiHance gadobenate dimeglumine macrocyclic, non-ionic ProHance gadoteridol macrocyclic, non-ionic Gadavist gadobutrol macrocyclic, ionic Dotarem gadoterate meglumine III linear, ionic…

Communicating discs to clinicians

The Combined Task Forces classification based on anatomical boundaries used by surgeons transverse / axial plane central (posterior midline) paracentral (right/left central) right/left subarticular (lateral recess) right/left foraminal (neural foramen) right/left extraforaminal (outside neural foramen) anterior zone (anterior and anterolateral) vertical / sagittal plane pedicle level infrapedicle level disc level suprapedicle level

Disc herniation

displacement of disc material beyond limits of intervertebral disc space what is disc material? cartilage, nucleus, fragmented annular tissue and apophyseal bone break in vertebral end plates or disruption in annulus fibrosus needed for herniation to occur TYPES extrusion base against the disc is smaller than diameter of displaced disc material (measured in same plane…

Disc bulge

circumferential or generalized disc displacement >50% of disc circumference etiology physiological at L5-S1 advanced degenerative changes pseudo image due to partial volume effect related to bone remodeling or ligament laxity types symmetrical – uniform in all directions asymmetrical – seen in scoliosis

Limbus vertebra

in young individuals herniation of nucleus pulposus through ring apophysis before bony fusion as a result small segment of vertebral rim gets isolated more common in lumbar region, less common in mid cervical level defect in anterior wall of vertebra usually in anterior superior margin lumbar spine and anterior inferior margin in cervical spine

Schmorl’s nodes

also called intervertebral herniations disc displacement through one or both vertebral end plates break in vertebral end plates or disruption of annulus fibrosus surrounded by reactive bone marrow changes hypothesis: regression of nutrient vascular canals in the end plate causes a weak spot resulting in herniation

Modic vertebral degeneration

degenerative changes in vertebral end plates and bodies described by Modic in 1988 type I decreased signal intensity on T1 increased signal intensity on T2 inflammatory stage shows bone marrow edema type II increases signal intensity on T1 increased or intermediate signal intensity on T2 fatty stage local fatty replacement of bone marrow type III…

Orbital surface of frontal lobe