Eosinophilic Granuloma Skull

A 14 y o male with left parietal swelling. Slightly tender, non progressive.

MRI brain FLAIR screening shows left parietal expansile lesion centred to bony calvarium. Lesion is lytic on limited axial CT sections (images not available)
Whole body screening within normal limits.
X ray chest within normal limits.

Here is the histopathology report of the lesion.

Gross specimen: multiple irregular soft to bony pieces of dull greyish tan tissue, together measuring 3x3x1.6cm. The entire tissue submitted for processing after de calcification of the bony spicules.

Microscopy: Fragmented bits of fibrotic connective tissue amidst which are seen scattered sheets and aggregates of mixed inflammatory cells consisting of numerous eosinophils few polymorphs and moderate number of lymphocytes and plasma cells. Amidst this cellular infiltrates are seen interspersed occasional histioyctic cells with smudged characteristic ? langerhan’s histiocytic cells. The cells have indistinct cytoplasmic margins. No epithelioid granulomas seen. There is no evidence of tuberculosis or parasitis aetiology. Section b shows osseous component with minimal inter trabercular areas showing similar infiltrates as described above under section A.

Diagnosis: histo pathological features are compatible with solitary Eosinophilic Granuloma.

Medulla compression by kissing vertebrals

A case of medulla compression from bilateral tortuous vertebral arteries in a 55-year-old man with pyramidal tract signs and lower cranial nerve palsy.
This patient developed dysarthria, dysphagia, and unsteady gait over the previous 2 years.

MRI Brain shows medulla compression by bilateral tortuous and medially deviated vertebrals at foramen magnum clinically corresponds to patients clinical complaints.
Vascular decompression with Gore-tex sling creation around the vertebral artery was suggested to patient.
Brain stem compression by “kissing vertebral arteries” is extremely rare. Only a few case reports documenting the clinical condition of patients, diagnostic features and therapeutic options are available in literature. Out of these reports the observed symptoms comprise hypertension, hemiparesis, tetraparesis, hemihypaesthesia, pyramidal tract signs, central sleep apnea and vertigo.

Infarct in territory of bilateral medial branches of PICA

A 55 y o male with sudden onset of vertigo, followed by loss of consciousness. 

MRI Brain Diffusion shows an acute infarct involving bilateral cerebellar hemispheres confined to the territory of the medial branches of the posterior inferior cerebellar arteries. 

Three days later follow up CT showed increase in odema and mass effect, brain stem and fourth ventricle compression leading to mild to moderate hydrocephalus. Clinically patient showed mild dysarthria, dysequilibrium with retropulsion, symmetrical bilateral horizontal gaze-evoked nystagmus on lateral gaze, and marked gait ataxia. 

MRI Angiography of brain and neck shows narrowing of intra cranial portion of right vertebral. Normal cervical vertebral and rest of the neck vessels. 

MRI brain FLAIR shows, intra cranial portion of right vertebral with abnormal high signal implies to occlusion. 

So we speculate that our patient has occlusion of the origin of the right posterior inferior cerebellar artery, which probably gave rise to the bilateral medial branches of posterior inferior cerebellar arteries. This caused infarction in the territory of the medial branches on both sides without remaining brain stem signs. Such an unusual pattern of cerebellar infarction often accompanied by acute hydrocephalus. 

Ventriculus Terminalis of the Conus Medullaris

Terminal ventricle

Syn : Ventriculus terminalis, or fifth ventricle is widest part of the central canal of the spinal cord that is located at or near the conus medullaris.
It was described by Stilling in 1859 and Krause in 1875.
Krause introduced the term fifth ventricle after observation of normal ependymal cells.
The central canal expands as a fusiform terminal ventricle, and approximately 8-10 mm in length in the conus medullaris.
Although the terminal ventricle may be visible in the fetus and children, but is usually absent in adults.

Typically asymptomatic.
In some cases, the terminal ventricle may cause clinical symptoms due to its expansion.

Associations:
• Spina bifida.
• Arnold-Chiari syndrome.
• Tumors of the conus medullaris.
• Tethered cord.
• Myelomeningocele.
• Syringomyelia.
• Hydromyelia. In hydromyelia, a dilation of the central canal of the spinal cord is caused by an increase of cerebrospinal fluid.
• Syringohydromyelia (i.e., both Syringomyelia and Hydromyelia)

Multiple Sclerosis MRI

A 30 y o female with recent sudden onset double vision referred for MRI Brain and Orbit screening.
Neurological notes mentions left 6th CN palsy.

This MRI brain, sagittal FLAIR shows multiple linear T2 hyper intense foci involving corpus callosum and peri ventricular white matter aligned at right angle to lateral ventricle.
Optic nerve evaluation within normal limits.

Imaging diagnosis : Multiple sclerosis.


Multiple sclerosis (MS)

Probable autoimmune-mediated demyelination in genetically susceptible individuals.
The diagnostic clue is multiple perpendicular calloso septal T2 hyperintensities.

Characteristic locations are periventricular white matter, along deep medullary veins in more than 85%.
50-90% calloso septal interface.
Infra tentorial in 10% adults, more common in children.
Often bilateral and asymmetric. The T2 hyper intensities become confluent with severity.

Size, linear to small, ~ 5-10 mm, linear, round, or ovoid; "beveled", "target", "Dawson finger", "lesion-in-a-lesion" appearance. Tumefactive lesions can be large up to several cms can mimic neoplasm.
T2w images are more sensitive than FLAIR for posterior fossa lesions.
"Tumefactive" MS can mimic neoplasm.

On DWI, Acute lesions may show restricted diffusion, concentric ring pattern on diffusion-weighted
images with hyperintense rim.

Post contrast T1w, transient enhancement during active demyelination. More than 90% disappear within 6 months, may be nodular (68%) , ring (23%), Semilunar, incomplete, or "horseshoe-shaped"

MRS : Reduced NAA (NAA/Cr), increased Choline (Cho/Cr). MRS may allow early distinction between relapsing-remitting and secondary progressive disease.

Perfusion MRI (contrast-enhanced T2*) : Low rCBV


MR diagnostic criteria: 

1. More than 3 discrete lesions more than 5 mm.
2. Lesions in characteristic location.
3. Compatible clinical history.

Nuclear Medicine PET: increased Glucose utilization correlates with I NAA in lesions.

Differential diagnosis: 

ADEM
Viral prodrome, monophasic illness.
Autoimmune-mediated vasculitis
Enhancing lesions spare callososeptal interface
"Beaded" angiogram appearance.

Lyme disease
Can be identical to MS (skin rash common)

Susac syndrome
Clinical presentation, course different from MS
Classic triad :
1. Eephalopathy, memory loss, confusion.
2. Branch retinal artery occlusions
3. Hearing loss
Self-limited (2-4 y duration, then stabilizes), monophasic,
Multifocal supratentorial WM lesions, always involves CC.

General Features
Genetics
o Unknown; increase incidence in first-order relatives.
o Gene transcripts present/increased in MS lesions
Etiology
o Unknown; probably virus and/or autoimmune-mediated in genetically susceptible individuals
o Activated T-cells attack myelinated axons
o Cox-2, iNOS may cause excitotoxic death of oligodendrocytes
Epidemiology
Estimated 2,500,000 people in world have MS
Most common disabling CNS disease of young adults; 1:1000 in Western world

Staging, Grading or Classification Criteria
Major clinical subtypes
1. Relapsing-remitting (RR) (85% initial presentation)
2. Secondary-progressive (SP) aka relapsing progressive
• By 10 years 50%, and by 25 years 90% of RR patients enter SP progressive phase.
3. Primary-progressive (PP) aka chronic progressive
• 5-10% of MS population progressive from start
4. Progressive-relapsing (PR)
• Rare, defined as progressive disease with clear acute relapses, with/without full recovery
• Periods between relapses characterized by continuing disease progression

MS variants/subtypes
1. Marburg type: Younger patients, febrile prodrome, clinically fulminant, death in months
2. Devic type ("neuromyelitis optica"): Simultaneous optic/spinal demyelination
3. Schilder type ("diffuse sclerosis"): Extensive, confluent, asymmetric demyelination bilateral supra-/infratentorial parenchyma.
4. Balo type ("concentric sclerosis"): Large lesions with alternating zones of demyelinated/myelinated white matter.

Clinical Presentation
Most common signs/symptoms
Variable; initially impaired/double vision of acute optic neuritis (50% with positive MR develop MS)
Weakness, numbness, tingling, gait disturbances
Decrease Sphincter control, blindness, paralysis, dementia
Cranial nerve palsy; usually multiple, 1-5% isolated (CNs 5, 6 most common)
Spinal cord symptoms in 80%

CSF positive for oligoclonal bands.

Age: 20-40; peak onset = 30; 3-5% < 15, 9% > 50
Adults: M:F = 1 : 1.7 to 2
Children/adolescents: M:F = 1 : 5 to 10
Ethnicity
All groups but Caucasian most common
Most often occurs in temperate zones

Natural History & Prognosis: 
45% patients not severely affected, nearly normal
More than 80% with "probable" MS, positive MR progress to clinically definite MS
In early RR, recovery often complete
Majority: Protracted course with progression of deficits
Late: Severe disability, cognitive impairment.

Treatment:
Immunomodulators and /or immunosuppressant.

Insensitivity of FLAIR for infratentorial lesions

Transverse Myelitis MRI

TRANSVERSE MYELITIS

Syn: Idiopathic acute transverse myelitis (IATM)

Inflammatory disorder, demylination involving both halves of spinal cord resulting in bilateral motor, sensory, and autonomic dysfunction.

Best diagnostic clue is a long segment contiguous intra medullary T2 hyper intensity with mild cord swelling.

Thoracic region is more common. Cervical region cord involvement in 10%.
Characteristically involve central cord on axial imaging, more than two-thirds of cross-sectional area of cord.
Variable post-gadolinium enhancement, no to subtle diffuse, patchy or peripheral enhancement and is more frequent in subacute than in acute or chronic stage.

DDs:

Multiple sclerosis
• Eccentric or Peripheral location of lesion.
• Small or short segment lesions, less than two vertebral segments in length.
• Less than half cross-sectional area of cord.
• 90% with associated intracranial lesions.
• Relapsing and remitting clinical course.

Acute Disseminated Encephalomyelitis
• Associated Brain lesions.

Always include brain MRI FSE T2 axial and sagittal images through corpus callosum to exclude associated intracranial lesions of multiple sclerosis or acute disseminated encephalomyelitis.


General Features
• Genetics: No familial predisposition
• Etiology
o Possible association with previous viral infection or vaccination in some cases.
o Autoimmune phenomenon with formation of antigen-antibody complexes
o Small vessel vasculopathy resulting in cord ischemia
o Associated demyelinating process

Epidemiology
o 4.6 new cases of transverse myelitis per million people per year in US
• 1,400 new cases per year
o Majority of cases occurred in late winter through spring in one series
• Life time risk> 50%

Microscopic Features
• Necrosis of gray and white matter
• Destruction of neurons, axons, and myelin
• Astrocytic gliosis
• Perivascular lymphocytic infiltrate

Presentation
• Most common signs/symptom is sensory deficit_ Loss of pain and temperature sensation.
Clearly defined upper level
Ascending paresthesia in bilateral lower extremities
Band-like dysesthesia
Other signs/symptoms are Paraplegia or quadriplegia, back ± radicular pain, bladder and bowl dysfunction, urgency, incontinence, retention; hypotonia and hyporeflexia initially, spasticity and hyperreflexia over time

An associated preceding viral-like illness.
Rapid progression to maximal neurologic deficits within days.

All ages can be affected with two peaks, 10-19 and 30-39 years old.
No gender predilection
No racial predilection

Prognosis
One third of patients experience good to complete recovery. Symptomatic improvement starting 2-12 weeks after onset. Children with slightly better prognosis than adults.
One third fair recovery, residual spasticity and urinary dysfunction.
One third poor recovery, persistent complete deficits requiring assistance in activities of daily living.

Factors portending poor prognosis: 
o Rapid clinical deterioration
o Back pain
o Spinal shock: Loss of motor, sensation, sphincter
control, and areflexia
o MRI signal alteration> 10 spinal segments
o Significant denervation on electromyogram
o Abnormal somatosensory evoked potential

• Typically monophasic. 
If recurrent, must consider Multiple sclerosis (progression to multiple sclerosis in 2-8% of cases of transverse myelitis), SLE, Antiphospholipid syndrome, Vascular malformation.

Treatment
• High dose intravenous steroid pulse therapy
• Physio therapy.

Progressive Supranuclear Palsy MRI

Progressive Supranuclear Palsy (PSP)

Also known as the Steele-Richardson-Olszewski syndrome, a neuro degenerative disease with no treatment.

PSP typically becomes clinically apparent in the 6th decade of life, and progresses to death usually within next 2 decades from diagnosis.

Clinically characterized by decreased cognition, abnormal eye movements, vertical gaze palsy, postural instability and falls. Parkinsonian features and speech disturbances.

Investigation of choice is MRI.
Imaging features
Mid brain atrophy is must.
Hummingbird sign also known as the penguin sign on mid sagittal sections as in our case. The key is a flattening or concave outline to the superior aspect of the midbrain which should be upwardly convex.
Reduction of antero posterior mid line mid brain diameter, at the level of the superior colliculi on axial imaging (from interpeduncular fossa, to the inter colicular groove: < 12mm, give a mickey mouse appearance.
Reduced area of the midbrain on midline sagittal and  reduced midbrain to pons area ratio: approx 0.12  (normal approx 0.24) on midline sagittal.
Loss of the lateral convex margin of the tegmentum of midbrain has been described as the morning glory sign.
T2w images may show diffuse high-signal lesions in pontine tegmentum,tectum of the midbrain, inferior olivary nucleus.

Differential diagnosis especially when features are not typical.
1. Parkinson disease, spares the midbrain and superior cerebellar peduncles.
2. Multiple system atrophy (MSA), predominantly affects middle cerebellar peduncles and pons with a hot cross bun sign click here on T2w images.
3. Corticobasal degeneration (CBD), cortical atrophy is prominent.

Semi lobar holoprosencephaly MRI

MRI BRAIN

This MRI study shows:
Frontal lobes and thalami fused.
Absence of septum pellucidum.
Agenesis / hypoplasia of the corpus callosum
Mono ventricle with partially developed occipital and temporal horns.
Incompletely formed interhemispheric fissure, rudimentary falx cerebri is absent anteriorly
Absent olfactory tracts and bulbs.
Absence of normal hippocampal formation and orientation.
Hypotelorism.
Cleft lip.
Microcephaly.

IMPRESSION:

Semi lobar holoprosencephaly.

Holoprosencephaly

Types:
Alobar
Semi lobar
Lobar

Similar Case : Syntelencephaly MRI

Tuberculoma with associated Subdural Meningeal Cyst

Tuberculomas can take several unusual forms representing the spectrum of inflammatory reaction. 

1. single tuberculoma or a grape like clusters of tuberculoma.

2. Tubercular abscess. 

3. Sub dural cyst overlying an intra cerebral tuberculoma.

4. Cystic tuberculoma.

5. Extensive odematous encephalopathy without tuberculoma.

6. Severe cerebral odema with tuberculoma.

7. Rarely tuberculoma with transdural spread to bony calvarium. 

MRI post contrast T1w images of this patient showing a right parietal grape like clusters of tuberculoma with an associated sub dural cyst overlying the intra cerebral tuberculoma.

Germinal matrix hemorrhage MRI Brain

A 8 month baby with seizures. 

Birth history is significant, discharge summary mentions pre term cesarean section delivery for meconium staining. 

MRI Brain shows a faint low signal intensity focal hemosiderin staining on GRE in right parietal peri ventricular white matter is a resolved Germinal Matrix Bleed consistent with history of pre maturity and a possible Birth Asphyxia. Rest of the MRI Brain is within normal limits.

Germinal matrix hemorrhage

The germinal matrix is a layer of cells near the Csf containing ventricles of the brain, formed early during embryogenesis and is the site of glial and neuronal differentiation. Activity in the germinal matrix peaks between 8 and 28 weeks during embryonic development. From here cells migrate peripherally to form the brain. It is densely cellular and vascular. The blood vessels of the germinal matrix are weak walled and predisposed to hemorrhage. By 35-36 weeks gestation the germinal matrix essentially disappears and thus the risk of hemorrhage is markedly reduced.

The brain of a premature infant lacks the ability to autoregulate cerebral blood pressure; thus, fluctuations in cerebral blood pressure and flow can rupture the primitive germinal matrix vessels or lead to infarction of the metabolically active germinal matrix. It may occur before birth, or within several hours following birth. A hemorrhage can extend into the periventricular white matter, resulting in significant neurologic sequelae like cerebral palsy, mental retardation, and seizures. Blood may rupture the ventricles, increasing the damage to the brain.

On CT and MRI of brain of infant, the appearance of the hemorrhage will vary according to the age of the bleed and time of scanning. With time bleed resolves, follow up CT and MRI may show post haemorrhagic hydrocephalus secondary to blockage of villi, periventricular leukomalacia, cavitations as subependymal cyst or Porencephalic cyst with or without hemosiderin staining. MRI GRE sequence is sensitive for hemosiderin, a blood degradation product.

Prevention of premature delivery is ideal. Antenatal dexamethasone administered to the mother, or indomethacin administered to the infant also decrease the incidence, although the exact mechanism by which this occurs is uncertain . If hydrocephalus is present, CSF drainage may be necessary.Prognosis depends on the extent of haemorrhage and presence of hydrocephalus.

Intraocular silicon gel CT

Axial CT study of a 50 yr old male with history of minor trauma.
CT Brain within normal limits.
Orbital sections show hyper dense right side vitreous.

Retrograde inquiry revealed history of previous silicone injection into the right globe to treat retinal detachment. The increased opacification in the right globe which could easily be mistaken for blood in the acute traumatic setting.
References: Radiology, Bart's and The Royal London Hospitals - London/UK

Tamponade for retinal detachment 

The mechanism of action of tamponade agents is twofold. They close the retinal breaks, and the buoyancy force helps appose the retina to the eye wall while the retinopexy matures or heals. The former is considered by far the more important mechanism of action. The existing subretinal fluid is absorbed, leading to retinal reattachment.

Intraocular gas tamponade agents include air and mixtures of air and long-acting gases (sulfur hexafluoride [SF6] and perfluoropropane [C3F8]). The main difference in these agents is their duration of action. An air bubble will resorb in 3–5 days after injection, a mixture of SF6 in 10–14 days, and a mixture of C3F8 in 6–8 weeks. Gases may be injected in their pure form, after which they will expand into larger bubbles, driven by the difference in the partial pressure of nitrogen in the gas bubble versus in the body. Intraocular gas tamponade results in air attenuation and fluid levels within the nondependent portion of the vitreous cavity. There are no attenuation differences between air and the longer-acting gases at CT. The presence of air within the globe following retinal reattachment should not be misinterpreted as evidence of a postoperative complication such as intraocular infection.

Silicone oil (polydimethylsiloxane) is different chemically from silicone rubber and has a lower specific gravity than vitreous fluid. This natural buoyancy, together with surface tension differences, makes it a useful agent for intraocular tamponade. Silicone oil provides several distinct advantages over air tamponade. Head positioning is less critical with silicone oil, making it a preferred agent for treatment of children with retinal detachment. Unlike the gas-filled eye, which temporarily leaves the patient with no useful vision, silicone oil is transparent (it does not mix with intraocular fluids or blood) and permits the patient to see after proper refraction. It is left in for at least 8 weeks, after which it is usually removed, although it can be left permanently at the discretion of the surgeon. The retina surgeon may choose to leave the silicone oil indefinitely if there is evidence of residual traction on the retina or recurrent detachment is noted in a patient with acceptable vision. Oil may also be left in cases of ocular hypotony to prevent development of phthisis bulbi.

On CT Silicone oil is hyper attenuating to normal vitreous fluid and should not be mistaken for intra ocular blood. Density of silicone gel is more than 100 HU vs blood less than 90 HU.

Mamillary body compression by Basilar Presenting as Parkinson's Clinically

A 50 y o male comes for MRI Brain.

In history technician mentions recent onset impaired memory and confusion. Clinical diagnosis of Parkinson disease noted in the accompanying referring letter.

MRI Brain sagittal and axial T2 w images show flow void of abnormally high riding basilar tip_ a normal anatomical variation but significant in this case as it is causing obvious compression over mamillary bodies explains patients problem with memory and may explain Parkinson’s presentation.

Discussion: 

Mammillary body anatomy 
The mammillary bodies are a pair of small round bodies, located on the under surface of the brain as a part of the diencephalon and form part of the limbic system. They consist of two groups of nuclei, the medial mammillary nuclei and the lateral mammillary nuclei.
Neuroanatomists have often categorized the mammillary bodies as part of the hypothalamus.

Role of mammillary bodies in memory
Mammillary bodies, and their projections to the anterior thalamus via the mammillothalamic tract, are important for recollective memory. The medial mammillary nucleus is mainly responsible for the spatial memory deficits that are seen in rats with mammillary body lesions. They are believed to add the element of smell to memories.
Damage to the mammillary bodies due to thiamine deficiency is implied in pathogenesis of Wernicke-Korsakoff syndrome. Symptoms include impaired memory, also called anterograde amnesia, suggesting that the mammillary bodies may be important for memory. Mammillary body atrophy is present in a number of other conditions, such as colloid cysts in the third ventricle, Alzheimer’s disease, schizophrenia, heart failure, and sleep apnea. In spite of this the exact function of the mammillary bodies is still not clear.

Role of hypothalamus in Parkinson disease.
Sandyk R, Iacono RP, Bamford CR.

It is currently believed that Parkinson disease (PD) is due to a degenerative process that independently damages multiple areas of the central and peripheral nervous system. Loss of nigrostriatal dopamine is now widely recognized as being directly related to the motor symptoms in Parkinson's disease. Parkinsonian patients also exhibit symptoms and signs suggestive of hypothalamic dysfunction (e.g. dysautonomia, impaired heat tolerance). The latter clinical features are supported by pathological, biochemical and endocrinological findings. Lewy body formation has been demonstrated in every nucleus of the hypothalamus, specifically the tuberomamillary and posterior hypothalamic. Preferential involvement of the hypothalamus was also noted in patients after post-encephalitic parkinsonism. Loss of dopamine (30-40%) in the hypothalamus of affected patients has been shown in recent studies, and is compatible with the reported abnormalities of growth hormone release in response to L-dopa administration, elevated plasma levels of MSH, and reduced CSF levels of somatostatin and beta-endorphins in these patients. Deranged immunological mechanisms have been found in PD patients including the presence of autoantibodies against sympathetic ganglia neurons, adrenal medulla and caudate nucleus. On the evidence of on pathological studies demonstrating the early vulnerability of the hypothalamus in aging and PD, and the known role of the hypothalamus in immune modulation, we expect that it will be shown that primary damage of the hypothalamus leads to subsequent secondary degeneration of structures receiving direct projections from the hypothalamus.

Hypothalamic Hamartoma presenting with precocious puberty

A 11 month old female child with bleeding per vagina.

Precocious puberty as per endocrinologist, advised MRI Brain for Pituitary.

MRI brain shows a supra sellar solid well defined lesion.

Pituitary seen separately in hypophyseal fossa. Normal enhancing pituitaty stalk seen separately and immediately anterior to lesion.

Lesion is iso intense to cortical gray matter on T1 as well as T2 w images, no cystic component. No enhancement on post contrast T1.

Lesion is in mid line, in the region of tuber cinerium and appears to be protruding from hypothalamus.

Imaging wise diagnosis: Hypothalamic Hamartoma.

Discussion: Hypothalamic Hamartoma supports clinical finding of Precocious Puberty though age is unusual but presentation with Precocious Puberty at 1 year of age is known and is well mentioned in literatures.

CADASIL MRI Brain

A 40 years old male with recurrent headache.

Findings:
MRI Brain FLAIR shows multiple T2 hyper intense foci in bilateral fronto parietal peri ventricular white matter. Confluent T2 hyper intensity in bilateral temporal white matter at its pole.
No restricted diffusion on Dw images.
No microbleed on GRE.

Changes of Small vessel disease _ early for age of patient.
Pt is non hypertensive and non diabetic clinically.
Migraine is major and a well known problem in family.

Imaging diagnosis: CADASIL. 

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy 
(CADASIL)

A hereditary small-vessel disease due to mutations in Notch3 gene on chromosome 19, which causes stroke in young adults. The small vessel disease is non arteriosclerotic, amyloid-negative angiopathy primarily affecting leptomeningeal and long perforating arteries of brain.

Imaging wise diagnostic clue is characteristic sub cortical lacunar infarcts and leukoencephalopathy in young adults. Lesions hypo dense on CT and T2 hyper intense on MRI.
Frontal lobe has highest lesion load followed by temporal lobe and insula which is characteristic. Other frequent locations are periventricular regions and centrum semiovale. Internal and external capsule. Less frequent regions are basal ganglia and brain stem. Spares fronto-orbital and occipital subcortical areas. Cerebral cortex is generally spared.

DDs:

1. Sporadic subcortical arteriosclerotic encephalopathy (sSAE)
Associated with hypertension
Multiple lacunar infarcts in lenticular nuclei, pons, thalamus, internal capsule, and caudate nuclei.
Associated diffuse, confluent regions of periventricular WM involvement.

2. Chronic Hyper tensive Encephalopathy.
Associated with hyper tension.
Microbleeds on GRE.

3. Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes
(MELAS)
Bilateral multifocal cortical and subcortical infarcts, hyper intense lesions on FLAIR images.
Recent infarct show restricted diffusion on Dw images.

Clinical presentation 
Most common signs/symptoms
Recurrent ischemic episodes (TIA, stroke) (70-80%),
Cognitive deficits (30-50%),
Migraine (20-40%), mostly with aura,
Psychiatric disorders (20-30%): Major depression,
Seizures (6-10%), most often following strokes.

Young or middle-aged patient with recurrent transient ischemic attacks is typical. Complete or near complete recovery after individual strokes, particularly early in disease process.
No gender preference

Treatment 
No specific therapy.

Reference : Diagnostic imaging Osborn. 

Persistent Hyperplastic Primary Vitreous

A 1 y o baby with Left side Leukocoria clinically. Advised MRI orbit, with referring letter mentioning PHPV Vs Retinoblastoma by Ophthalmologist. 

MRI Brain T1w image show left side micro ophthalmos, hyper intense vitreous with a linear low signal intensity structure running antero posteriorly from lens to optic disc. 

Non contrast CT sections for orbit of same patient show no obvious evidence of dystrophic calcification rules out Retinoblastoma. Vitreous is hyper dense may be due to an associated retinal detachment. 

Impression: left side PHPV

Persistent Hyperplastic Primary Vitreous

Also known as persistent fetal vasculature, a rare congenital developmental malformation of the eye, due to a failure of normal regression of the embryonic hyaloid vascular system.
In the normal situation the primary vitreous forms around 7 th week of gestation life and starts involuting around 20 th week and nearly always disappears at the time of birth.
Persistent fetal vasculature in PHPV can lead to fibrosis, resulting in elongation of the ciliary processes, retinal detachment, and spontaneous cataracts.

Clinical presentation is usually unilateral or bilateral leucocoria, may also have poor vision, small eye (microphthalmia) and strabismus. PHPV is the second most common cause of leukocoria. (Retinoblastoma is most common cause of leukocoria in childhood) These patients also develop glaucoma and cataract.
It may be bilateral as a part of congenital syndromes such as Norrie disease.

What is Leukocoria ?
Normally when a light shines through the iris, the retina appears red to the observer.
In leukocoria (white pupil) the retina abnormally appears white.

Sub types of PHPV are Anterior (Ventral) or Posterior (Dorsal) types with most patients with PHPV having a combination of these.
Associations of PHPV are it can occur on its own or in association with various other conditions like Norrie disease,Warburg syndrome, retinal dysplasia particularly when bilateral.

Imaging findings:
A persistent canal may be seen that goes from the optic nerve to the lens. Retinal detachment occurs in 30-55%.
Ocular ultrasound: An echogenic band may be seen in the posterior segment of the globe extending from posterior surface of the lens to the optic nerve head. On colour Doppler, arterial blood flow was may be seen within this band.
On CT Orbit, appearance can be quite variable and the described spectrum of CT findings includes soft-tissue replacement (infiltration) of the vitreous body, retrolental soft tissue along the Cloquet canal - fine linear structure extending from the head of the optic nerve to the posterior surface of the lens, absence of abnormal calcification within the orbit, microphthalmus, retro hyaloid layered blood, hypervascularity of the vitreous humor on post contrast, Recent onset Retinal detachments may be hyperdense on CT.
On MRI, the MRI findings of the anterior type of PHPV included a shallow or collapsed anterior chamber, an anterior segment anomaly, and a retrolental vascular membrane which demonstrated hyperintensity after contrast enhancement. MRI findings of the posterior type consisted of microphthalmos; a tubular image, representing the hyaloid vessel; a funnel-shaped retinal detachment, with the subretinal fluid hyperintense on both T1- and T2-weighted images; the fluid-fluid level, which was hypointense on both T1- and T2-weighted images and probably corresponded to the presence of hemorrhage in the subretinal space; a retrolental mass; and vitreous hemorrhage.

Differential diagnosis 
Clinically closely mimics a retinoblastoma.
On Ultrasound the main differential is retinal detachment.
MRI is the investigation of choice.

Imaging wise PHPV Vs Retinoblastoma
PHPV as associated with Micro ophthalmia and optic nerve atrophy where as in Retinoblastoma there may be Macro ophthalmia with Optic nerve enlargement due to tumor extension. Dystrophic calcification is not a feature of PHPV where as its common in Retinoblastoma. 

Hemichorea hemiballismus in non ketotic hyperglycaemia

Clinically : known diabetic patient, irregular with his anti diabetic treatment. Now presented with right side involuntary movement of body and face.

Imaging finding of non contrast CT brain is left side / unilateral basal ganglionic hyper density.
Diagnosis: Hyperglycaemic Hemichorea – Hemiballismus.

SIMILAR CASE : Unilateral-basal-ganglionic-t1 hyper intensity on MRI

Hyperglycemic Hemichorea-Hemiballismus

Syn: HCHB, Hemiballismus-hemichorea, Chorea-ballismus with nonketotic hyperglycemia, Nonketotic hyperglycemia,
Triple H of Hyperglycemic Hemichorea-Hemiballismus are 1. Unilateral basal ganglionic T1 Hyper intensity, 2. Hyper glycemia / Hyper glycemic coma and 3. Hemi chorea / Hemi ballismus.

It is a syndrome associated with nonketotic hyperglycemia in patients with poorly controlled diabetes mellitus, characterized by sudden onset hemiballismus or hemichorea.
The most common cause of hemichoreahemiballism in adults is a vascular lesion in the basal ganglia. Rarely, it can also be the first clinical manifestation of non-ketotic hyperglycemia, associated with unique radiological features.

Imaging findings of Hyperglycemic Hemichorea-Hemiballismus:
CT may be normal. May show faint contra lateral / unilateral basal ganglionic hyperdensity.
MRI is most sensitive. May show typical unilateral T1 hyperintensity in basal ganglia.

Elderly diabetic patients with non-ketotic hyperglycemia presenting with hemichorea-hemiballism, hyperdensity in contralateral basal ganglia on CT scan and high signal intensity in corresponding areas on T1 weighted MRI have been already reported.
But there was much controversy regarding the cause of these imaging changes.
Initially it was thought to be due to calcification.
Chang and colleagues postulated petechial hemorrhage to be the cause.
Stereotactic biopsy and histopathology from the striatum revealed gliotic brain tissue with abundant gemistocytes suggesting that the hyperintensities in T1 could be due to the protein hydration layer inside the cytoplasm of the swollen gemistocytes.
These gemistocytes abundantly present in the basal ganglia and cause excessive neuronal activity especially in the GABA-ergic projections and thus may be responsible for generating hemichorea-hemiballism.
The basal ganglia hyperintensity generally resolves within a few months rarely reported to remain for several years.
So it may be concluded that hemichorea -hemiballism occurring in diabetes mellitus owing to non-ketotic hyperglycemia is a rather benign condition with a good prognostic outcome provided the syndrome is recognized early and corrected.

Other causes of basal ganglioinic T1 hyperintensity:
There are many causes of basal ganglionic T1 hyperintensity, majority are related to deposition of T1 intense elements within the basal ganglia.
Methaemoglobin in intracranial hemorrhage or hemorrhagic transformation of infarct.
Idiopathic calcification.
Hepatic failure.
Hamartoma in neurofibromatosis type 1.
Hyperalimentation or long term parenteral nutrition, manganese toxicity.
Carbon monoxide.
Wilson's disease (copper),  acquired non-Wilson's hepatocerebral degeneration
Japanese encephalitis,
global hypoxia,
Hyperglycemia associated chorea-ballism /  non ketotic hyperglycaemic hemichorea,

Causes of unilateral basal ganglioinic T1 hyperintensity are very uncommon than bilateral and are unique. Unilateral basal ganglionic / putaminal CT or MR signal abnormality of nonketotic hyperglycemia to be recognized and distinguished from acute ischemic stroke in patients with acute neurologic symptoms. Although nonketotic hyperglycemia may mimic stroke in clinical presentation and imaging findings, the pathophysiologic mechanisms of this entity are not clearly ischemic, so recognisation of this syndrome is important as it can affect the treatment options. Physicians and radiologists needs to be aware of non-ketotic hyperglycemia and its imaging findings as a cause for a potentially reversible hemichoreahemiballism syndrome.

References:
Neurology Asia 2010; 15(1) : 89 – 91, Diabetic non-ketotic hyperglycemia and the hemichorea-hemiballism syndrome: B Shalini , W Salmah.
 Lai PH, Chen C, Liang HL et-al. Hyperintense basal ganglia on T1-weighted MR imaging. AJR Am J Roentgenol. 1999;172 (4): 1109-15. AJR Am J Roentgenol (citation)
 Lai PH, Tien RD, Chang MH et-al. Chorea-ballismus with nonketotic hyperglycemia in primary diabetes mellitus. AJNR Am J Neuroradiol. 17 (6): 1057-64.

Paranasal sinus osteoma CT

A 45 y o male presented clinically with right nasal watery discharge and recurrent meningitis.

 

CT Brain bone window images show an Osteoma in right frontal sinus and adjacent anterior ethmoid air cell.

 Same case showing an associated right frontal sub dural pneumo cephalus secondary to erosion of overlying cribriform plate of ethmoid. 

Paranasal Sinus Osteoma

An osteoma of the paranasal sinuses is a common benign tumour, usually found incidentally in patients undergoing imaging of the sinuses or CT head, account for up to 3% of CT examinations of the paranasal sinuses.
Common age group is middle age male predilection. 

Most osteomas are asymptomatic and are found incidentally, may become symptomatic either due to its direct mass effect or obstruction of normal sinus drainage. 
Presentation with pain is often a referred pain via the trigeminal nerve and a prostagladin E-2 mediated mechanism, there can be a significant inversely proportional discrepancy between the size of the lesion and the symptoms.
Some osteomas are large and exophytic present as hard subcutaneous palpable swelling or compress structures, such as content of the orbit.
Rarely an osteoma may encroach upon the brain, may even result in erosion of the dura with resultant CSF leak, pneumocephalus or intra cranial infection (meningitis, cerebral abscess) as in our case. 
More frequently they may impair normal drainage of one or more paranasal sinuses thereby resulting in acute or chronic sinusitis or even mucocoele formation.

Distribution, Osteomas are frequently seen elsewhere in the head and neck, particularly the mandible and outer table of the skull vault. Within the para nasal sinuses the distribution is frontal sinuses. (most common) ~ 80%, ethmoid air cells ~ 15%, maxillary sinuses  ~ 5% and sphenoid sinus is rare.
A well recognized association with the Gardner syndrome.

Osteomas are, as the name suggests, osteogenic tumours composed of mature bone. Three histological patterns are recognised.
1.    ivory osteoma : Most common. Also known as eburnated osteoma, most common, dense bone lacking haversian system
2.    mature osteoma : also known as osteoma spongiosum, resembles 'normal' bone, including trabecular bone often with marrow
3.    mixed osteoma : mixture of ivory and mature histology.

Imaging findings:
CT is the investigation of choice, demonstrates a well circumscribed mass of variable density, varying from very dense (similar in density to normal cortical bone) to less dense with a ground-glass appearance. They are seen either with a sinus or less commonly exophytically growing out of a sinus.
On MRI, ivory osteomas are low on all sequence. Mature osteomas may demonstrate some marrow signal, but are also predominantly low on all sequence.

Treatment and prognosis:
In asymptomatic cases excision is not necessarily indicated.
If sinonasal disease, where the osteoma is thought to be responsible for symptoms, resection is required performed either endoscopically or externally.

 Another case with two concurrent Osteomas, an inner table Osteoma at the floor of right middle cranial fossa and another is outer table Osteoma in right parietal region.

Superior sagittal sinus Duplication MR Venogram

This non contrast 2 D TOF MR Venogram of Brain shows duplication of posterior part of superior sagittal sinus near torcula _ a normal anatomical variation. Rest of the dural venous sinuses normal.
Vein of labbe noted on right side draining into right lateral sinus.