Saturday, 4 October 2014

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.

Monday, 29 September 2014

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 Bran 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.

Sunday, 28 September 2014

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.

Saturday, 27 September 2014

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

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.

Sunday, 23 March 2014

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.