DDs of Owl's Eye _ Spinal cord T2 hyper intensities on MRI

There is not much mentioned about this sign but whatever is available in literatures and case reports where they have described this finding and in view of clinical scenario they have tried to attribute this finding to one particular condition or cause. Most of them have associated this finding with spinal cord infarction, however this finding is not specific or pathognomonic for spinal cord infarction.

I have tried to elaborate list of other remote conditions and causes which can present with such finding on MRI or follow up MRI irrespective of clinical settings. Most of them are with reference and few of them are through my personal experience.

What is Owl's Eye Sign? 
An abnormal intra medullary T2 hyper intensity in the region of anterior horn cells of spinal cord, as two white dots, one in each half of cord on axial T2w MRI images in the background of normal gray coloured spinal cord.

This is totally different from ‘Winking  Owl’  sign
Winking owl sign  is related to vertebral metastases, a reliable sign of osteolytic spinal metastases on AP radiographs corresponds to loss of the normal pedicle contour. The appearance of unilateral pedicle absence has been likened to that of a winking owl with the missing pedicle being the closed eye, the contralateral pedicle being the open eye and the spinous process being the beak.

DDs of Owl's Eye in spinal cord. 

1. Spinal cord Infarction 
The vascular supply to the spinal cord is primarily composed of one anterior and two posterior spinal arteries, which extend along the length of the spinal cord in a variable manner. The anterior and posterior spinal arteries are connected by a pial plexus that extends around the circumference of the spinal cord. At many levels, the anterior and posterior spinal arteries receive vascular contributions from the radicular arteries, which course along the nerve roots and enter the spinal canal. Thirty-one pairs of radicular arteries exist. The anterior spinal artery gives rise to central arteries at multiple levels; these arteries supply the anterior horn cells and the anterior aspect of the lateral columns on both sides of the spinal cord.
Two major forms of spinal cord infarcts are recognized. The first involves the interruption of supply by the radicular arteries or artery of Adamkiewicz and is characterized by unilateral or bilateral infarcts of the anterior or posterior spinal arteries. The second one is caused by diffuse hypoperfusion and is manifested by central or transverse infarcts.
Recognized causes include spinal and aortic surgery, hypotension, vertebral artery dissection, embolism, vasculitis, and cocaine abuse. In about half of cases, infarction occurs immediately after a movement, such as back extension, an arm movement or a Valsalva maneuver, possibly causing mechanical stress on a radicular artery.

2. Fibrocartilaginous emboli
Rapid onset of spinal cord symptoms from retrograde flow of emboli from a herniated nucleus pulposus into the anterior spinal artery or spinal veins during straining, causing an anterior spinal artery syndrome (Wilmshurst et al 1999). There is back or neck pain but often no history of trauma, followed by sudden (minutes to hours) onset of weakness and incontinence. This is more common in women than men and is associated with anterior cord lesions on MRI and anterior horn cell fallout on electrophysiologic testing. Cord swelling on MRI is associated with a collapsed disc at the level of the cord deficit, usually in the cervical region (Tosi et al 1996). The CSF is normal. There is no associated viral syndrome. Recovery is unlikely.

3. Resolved Cord Contusion
A resolved spinal cord contusion on follow up imaging can have similar appearance due to Gliosis. History of trauma particularly hyper flexion injury needs to ruled out clinically. Vertebral collapses may be an associated finding on MRI.

4. Poliomyelitis and Motor Neuron Diseases 
A disease of the lower motor neurons that affects the gray matter of the spinal cord, specifically the central horns. In a retrospective study, spinal cord segments from all patients who had had poliomyelitis showed loss or atrophy of motor neurons, severe reactive gliosis, and a perivascular and intraparenchymal inflammation even in the chronic phase, up to 20 years after infection. In acute to subacute phase (up to 8 weeks after acute illness), the ventral horn cells are characterized by a severe inflammation, neuronophagia, active gliosis, and destruction of the anterior horn cells. This correlates with the T2 signal hyperintensity in the region of the ventral horns on MRI and should be fairly specific for poliomyelitis.
(Reference : Poliomyelitis: Hyperintensity of the Anterior Horn Cells on MR Images of the Spinal Cord; Mark S. 1 Jeffrey M, Charlene A. Tate, Vladislav Zayas, and J. Donald Easton)

5. Compressive myelopathy 
A bulging disc causing mechanical compression over redicular artery leading to a chronic ischemic changes and Gliosis in the region of anterior horn cell. Disc herniation and degree of canal stenosis may be not be severe as here main culprit is radicular artery compression which is lying anterior to cord and not the direct cord compression by disc.

6. Hopkins syndrome
Flaccid paralysis of one or more limbs, 4 to 7 days after an asthma attack. Anterior cord lesions in 2 to 12 year-old children with onset over 1 to 2 days are followed by permanent paralysis. CSF typically contains 20 lymphocytes and 20 polymorphonuclear neutrophils (Hopkins 1974).

7. Radiation myelopathy
Possible with an exposure over 50 Gy. Damage is delayed up to 15 years after exposure but is typically 10 to 16 weeks later (Yamada et al 1987). Radiation myelopathy causes vasculopathic and sometimes anterior horn cell changes with high MRI T2 signal owing to Gliosis in corresponding region on follow up studies. 

Purely Intracanalicular Acoustic Schwannoma MRI

MRI Brain FIESTA (3D CISS) sequence shows an intra canalicular nodular low signal intensity of a 8th CN Schwannoma confined to Internal Auditory Canal on left side.

Comparison of FIESTA and Contrast enhanced study in MRI screening for Acoustic Schwannoma

Acoustic schwannomas are a treatable cause of sensorineural hearing loss.
Currently, MRI is the gold standard examination and screening test for exclusion of acoustic schwannoma particularly those confined to internal auditory canal.

In MRI we have two main options  in addition to the routine MRI sequences, one is Contrast Enhanced study and second is FIESTA (fast imaging employing steady-state acquisition) sequence.
Contrast Enhanced study consist of plain T1 and Gadolinium-enhanced T1-weighted images, both in multiple planes, adds extra time and cost to the examination, and possibility of contrast reaction exists.
Whereas FIESTA is a single sequence, a true-FISP (free induction steady-state precession) sequence that provides high-resolution fluid-bright images of the CPAs and basal cisterns.

In a study of 50 patients, results of contrast enhanced study and FIESTA images were compared. The hypothesis was that the FIESTA sequence can replace contrast enhanced study for screening and diagnosis of AS confined to internal auditory canal. The results showed that in 98% of cases, this was possible. So the FIESTA sequence can be employed in isolation for screening of AS. Same can be equally beneficial in cases where gadolinium is contraindicated such as pregnancy. However, Contrast enhanced study should be employed when pathology is seen and to follow-up post-surgical patients.

Conclusion: Use of the FIESTA (CISS) is sufficient to exclude AS confined to internal auditory canal without the need for gadolinium-enhanced sequences. 

Reference : Comparison of FIESTA and gadolinium-enhanced T1-weighted sequences in magnetic resonance of acoustic schwannoma; Paul J. Rigby

Measles Encephalitis MRI

 A 12 years old patient with characteristic morbiliform rash.

Admitted in our neuro institute with symptoms of encephalitis occurred 10 days after appearance of the rash, altered sensorial with lower limb flaccid paralysis now.

Csf report positive for specific IgM and IgG antibodies.  

Clinical diagnosis was measles encephalitis.

Here is her on admission MRI Brain Axial FLAIR, T2w and Diffusion. 

MRI Brain Axial FLAIR shows confluent bilateral cerebral white matter hyper intensity extending along external capsules with faint restricted diffusion. T2 w images show bilateral basal ganglionic  symmetric T2 hyper intensity with focal parenchymal swelling consistent with clinical diagnosis of measles encephalitis.

Imaging findings of Measles Encephalitis mentioned in literatures are 1. Multifocal high signal in bilateral cerebral hemispheres, swelling of the cortex, 2.  Bilateral, symmetrical involvement of the putamen and caudate nucleus, lesions showing low apparent diffusion coefficients. 3. Sub acute gyriform hemorrhage, asymmetrical gyriform contrast enhancement mentioned in severe cases. 4 Diffuse cerebral cortical atrophy, gliosis and encephalomalacic changes on follow up MRI studies. 

Histopathological findings of Measles Encephalitis mentioned in literatures are perivascular mononuclear cell infiltration, white matter demyelination, gliosis and intranuclear and intracytoplasmic eosinophilic inclusions in neuronal and glial cells in the temporal, parietal and occipital cortex as well as in the thalamus. 

Slit Ventricle Syndrome

• Slit ventricle syndrome occurs in minority of patients who have been shunted.
• "Slit ventricle" refers to finding of very small ("slit-like") ventricles on CT or MRI indicating excessive drainage.

Diagnostic criteria: 
An association of  clinical signs of headache, vomiting with signs of  slit like ventricles on CT or MRI. 

• Headache may be intermittent, often postural occurring when standing up and resolving when the patient lies down. Vomiting can be related to visual or auditory disturbance, drowsiness.
• Symptoms usually present years after shunt placement or shunt revision.
• Severe form of slit ventricle syndrome occurs in children. The absence of cerebrospinal fluid (CSF) within the ventricles combined with a growing brain leads to situation in which "the brain is too big for the skull." The intracranial pressure (brain pressure) can be very high. Adults can develop a milder form of slit ventricle syndrome. 
• The diagnosis of slit ventricle syndrome can be difficult and the condition is often misdiagnosed or the diagnosis delayed. The finding of small ventricles in a shunted patient can be misinterpreted as a properly working shunt. Most patients with small ventricles on CT or MRI may not have the slit ventricle syndrome clinically. Patients must be symptomatic to call Slit ventricle Syndrome. 
• Typically, the shunt is nearly blocked but still barely flowing.

A case of  Vp shunt done for Post TB Meningitis Hydrocephalus. Now came for follow up with new onset of headache and nausea. CT Brain plain shows right parietal Vp shunt with collapsed lateral ventricles. Possibility of "Slit Ventricle Syndrome" considered clinically and patient re admitted for further management.  

Treatment: 
The management of slit ventricle syndrome is difficult and challenging.
In general, a neurosurgeon with expertise in the management of hydrocephalus is optimal.
Various treatment options have been proposed, and include:
1. Observation.
Usually limited to minimally symptomatic patients
2. Anti-migraine medicines.
3. Shunt revision.
 Change the ventricular catheter.
 Change the shunt valve.
 Add siphon controlling device (SCD).
 Programmable valve with or without SCD.
 Converting to a lumboperitoneal shunt.
4. Temporarily blocking the flow of the shunt (via "externalization" of the shunt) in order to expand the ventricles.
This should be done with ICP monitoring due to the risk of coma.
Many patients have aqueductal stenosis, and therefore are candidates for endoscopic third ventriculostomy (ETV).
In some cases, a special shunt configuration draining both the ventricles and the cisterns (space around the brain) can equalize the inner and outer brain pressures, thus reducing the chance of producing slit ventricles again. This type of shunt is called a ventriculocisternoperitoneal shunt.
5. Subtemporal decompression.
This procedure is rarely performed because improvements, if any, are typically short-lived.

HELLP Syndrome with Spontaneous subdural haematoma and intracerebral haemorrhage

A 32-year old primigravida,with prolonged labour and fetal distress, fell unconscious during labour.

Refereed to our neuro institute for further investigation and management. 

No history of trauma. 

On admission MRI Brain shows:

Left fronto parietal subdural haematoma with max with 13mm, T1 bright signals of hematoma attributed to Meth Hb – a sub acute stage blood degradation product.

An associated left frontal intracerebral hematoma. 

Significant mass effect, mid line shift with internal herniation. 

MR Angiography of Brain normal. No obvious aneurysm. 

No abnormal adjacent T2 flow voids to suggest any vascular malformation.

MR Venography of Brain normal, particularly superior sagittal sinus. 

No obvious cortical vein thrombosis on GRE. 

Patient underwent emergency decompressive craniotomy.

Follow up CT shows:

Left anterior craniotomy with evacuation of left fronto parietal subdural hematoma and left frontal intra parenchymal bleed.
Complete reversal of mass effect and mid line shift. No mid brain compression.
Bilateral frontal subdural pneumocephalus noted, which also regressed on subsequent follow studies. 

Patient is clinically improving, residual right hemiparesis. 

During this a diagnosis of HELLP syndrome with Disseminated Intravascular Coagulation (DIC) was made, as her Platelet count was 50,000/μL (low), e/o hemolysis on peripheral blood smear with Serum lactate dehydrogenase : 800 IU/L (Abnormal) and Serum aspartate aminotransferase : 80 IU/L (Abnormal)

HELLP (haemolysis, elevated liver enzymes, and low platelet count) syndrome can result in a fatal intracranial haemorrhage during the perinatal period. 

Patients with HELLP syndrome should be managed as high-risk, which requires an excellent working relationship of the physicians involved. Prompt recognition of intracranial haemorrhagic complications and neurosurgical intervention are particularly important.

CSF shunt imaging

CSF, Cerebrospinal fluid is an ultra-filtrate of plasma, produced by the choroid plexus of the lateral ventricle, fourth ventricle and ependymal lining of the ventricles.
CSF flows from the lateral ventricle through the foramen of Monro into the third ventricle and then into the fourth ventricle through aqueduct.
The CSF exits the ventricular system via the foramina of Luschka (lateral) and Magendie (medial) situated in the fourth ventricle. CSF then ascends into the basal cisterns and around the cerebral convexities where it is reabsorbed by the arachnoid villi which project into the dural venous sinuses.

Hydrocephalus is defined as excess of CSF, primarily caused by obstruction to the flow of CSF within the ventricular system.

Hydrocephalus is primarily classified into two types: communicating and noncommunicating.

Communicating or extraventricular hydrocephalus is caused by extraventricular obstruction at the level of the arachnoid villi and decreased absorption of the CSF mainly caused by prior hemorrhage, meningitis or obstruction of the dural venous sinuses. On imaging lateral ventricles, third ventricles as well as fourth ventricle are equally dilated as level of obstruction is after fourth ventricle.

Non communicating or intraventricular hydrocephalus is induced by obstructive lesions at various levels within the ventricular system due to various causes such as intra ventricular tumors or aqueductal stenosis. Here dilatation is confined to ventricular system proximal to the level of obstruction.

An intra ventricular mass in third ventricle causing non communicating hydrocephalus.
Fourth ventricle is not dilated. 

Csf Diversionary shunts

CSF diversionary procedures like shunt placement are one of the most common pediatric neurosurgical procedures.

Types of shunt include:
ventriculoperitoneal (VP),
ventriculopleural (VPL),
ventriculoatrial (VA),
ventriculolumbar (VL),
ventriculovenous and
Ventriculo-gallbladder.

TheVP shunt is by far the commonest type of shunt used in the pediatric population.
The ventriculolumbar shunts are mainly reserved for adults with normal pressure hydrocephalus and patients with small slit ventricles or recurrent VP shunt malfunction.
Ventriculoatrial shunts have the distal tip in the right atrium. Complications like sepsis, thromboembolic events, shunt nephritis and pulmonary hypertension have led to the decline of their use except as a last resort. Ventriculopleural shunts are also not favored due to inadvertent life-threatening complications like pneumothorax, pleural effusion and infection.
Other proposed shunts have also failed due to various complications and are rarely used in clinical practice.

Ventriculoperitoneal (VP) shunt

Shunt tube has a proximal intracranial segment inserted through the frontal, parietal or temporal bone, so that the tip and the side holes of the catheter lie within the frontal horn of the lateral ventricle.
Care is taken by the neurosurgeons to avoid proximity of the shunt catheter tip to the choroid plexus, to prevent the occlusion of the catheter by the growth of choroid plexus into the tip and side holes of the shunt catheter. The distal tip of the catheter is tunneled through the skin of the neck, thorax and abdomen into the peritoneal cavity for the drainage of CSF.
Today neurosurgeons have a wide variety of shunts with programmable valves to choose from for a particular patient.
One of the commonly used valves is the Codman Hakim programmable valve which has 18 pressure settings ranging between 30 and 200mmH2O.
The neurosurgeon selects one of the settings at the time of shunt placement and is also able to make precise pressure adjustments to help control intracranial pressure and the ventricle size at any time in the future.

Shunt imaging 

Normal findings
In patients with previous ventricular shunt, the most common and normal finding is an area of Gliosis in the brain along the course of shunt tube (See image)
Diffuse and relatively thin pachymeningeal enhancement along the inner table of the skull and in the dural reflections is a normal finding on post shunt post contrast T1 w MRI images, due to the continued use of the ventricular shunt.
Post shunt Ventricular asymmetry is a known and common finding after ventricular shunting. Asymmetry result due to significantly greater decrease in ventricular size on the side of the ventricular shunt catheter and isolation of the contra lateral ventricle from adequate decompression. Studies have shown that contra lateral placement of tip catheter after perforation of the septum pellucidum that is transeptal placement of catheter would significantly decrease the incidence of post shunting ventricular asymmetry. A special cathter is used which consist of two sets of holes, such that holes are located in both the lateral ventricles. (See Image)

A linear area of Gliosis in right parietal region along the course of shunt tube.

Post shunt mild asymmetry of lateral ventricles, left lateral ventricle wider than right

Shunt malfunction
If a child with a shunt presents acutely with the classical clinical triad of raised ICP with headaches, vomiting and papilledema is need evaluation of shunt for any malfunction.

Causes of shunt malfunction
Mechanical causes leading to inadequate drainage:
○Kinking
○Discontinuity/disconnection
○Break/fracture
○Functional failure of the valve/shunt apparatus
○Migration
Overdrainage:
○Epidural, subdural and intracranial hematoma
○Slit ventricle syndrome
Infection:


INTRACRANIAL COMPLICATIONS

1. Shunt infection.The prevalence of shunt infection is reported in 2.6%-38% of cases. Most infections develop within 2 months from the shunt placement. The common microorganisms are Staphylococcus aureus, Staphylococcus epidermidis, or gram-negative enteric infections.
E/o Ventriculitis and meningitis on CT and MR imaging, are ventriculomegaly, an abnormal enhancement along ventricular ependymal lining and or cerebral cortical sulci. Shunt replacement is usually necessary.
Repeated infections can lead to cerebral venous sinus thrombosis.

2. Shunt obstruction can occur at any time after insertion, and all points along the shunt course. Presents with clinical evidence of raised intracranial pressure.
There two most common locations for obstruction, one is ventricular catheter tip, which can be blocked by ingrowth of choroid plexus, and second is shunt valve, where blood or debris can block the lumen of the valve.
If the ventricular catheter is obstructed by ingrowth of choroid plexus into the lumen of the ventricular catheter tip, its removal is complicated by the risk of bleeding caused by avulsion of choroid plexus if the catheter is forcefully removed.

3. Overdrainage refers to when shunt removes more fluid than necessary for that particular patient. Early rapid reduction in ventricular size may result in collapse of the brain and accumulation of extra-axial fluid or results in mid brain compression.
* Slit ventricle syndrome, CT will reveal collapsed converging lateral ventricles (see image)
* Paradoxical herniation and sunken skin flap, very uncommon complication, seen in patients with a large craniectomy defect who then undergo CSF drainage by either lumbar puncture or ventriculoperitoneal shunt result in marked decrease in Csf pressure, which leads to reduction in intracranial pressure making intra cranial content vulnerable to atmospheric pressure. This pressure imbalance particularly the negative intara cranial pressure deforms brain and mid line.
On CT / MR Imaging a significant mid line shift away from the craniectomy side with subfalcine and or transtentorial herniations. Uncal herniation if severe may results in mid brain compression. (see image)
Clinically patient present with depressed level of consciousness, autonomic instability, signs of brainstem release, and focal neurologic deficits.
Management: Paradoxical herniation is a neurosurgical emergency and urgent treatment is necessary in order to increase intracranial pressure, to stop any CSF leakage, and restore the continuity of the calvaria.
Options include urgent placing the patient in Trendelenburg position and head inclined towards to craniectomy side, clamping ventricular shunts or drains, administering intravenous fluid. Cranioplasty as soon as possible. Paradoxical herniation also has been reported to be effectively and quickly reversed with a lumbar epidural blood patch or clamping ventricular shunt tube.

Slit ventricle syndrome

Sunken Skin flap with Paradoxical herniation

EXTRA CRANIAL COMPLICATIONS

1. Abdominal pseudocyst, a pseudocyst is a loculated intra-abdominal fluid collection that develops around the peritoneum and is more common than ascites.
Indicates the presence of a chronic low-grade infection; however, it is common to find sterile fluid within the pseudocyst cavity when it is aspirated.
Symptoms may be consistent with bowel obstruction if the pseudocyst is large.

2. Shunt misplacement can also occur at the distal end of the catheter, including the abdomen, atrium, or pleura. Patients present with abdominal discomfort and eventually may develop headache, nausea, or vomiting. CT scan may discloses, the distal end of the shunt located in the preperitoneal space, resulting in fluid collection under the abdominal incision.

3. Broken shunt. The typical presentation is usually many years after initial insertion and is related to both biomechanical stress as patient's height increases and the inherent degradation of indwelling components because of host reactions. The distal tubing should be free to slide in the subcutaneous tract; however, scar tissue may tether the tubing and produce shear forces that promote fractures as the children grows. The common presentation is that of mildly elevated raised intracranial pressure. It is also common for patients to present with pain, mild erythema, or swelling over the shunt tract often in a location over the shunt fracture.
Shunt series comprising of AP and lateral radiographs of the skull and neck, radiographs of the chest and abdomen are obtained to evaluate for obvious kinks, discontinuity or disconnection. The commonest site of disconnection is between the valve apparatus and the distal shunt tubing.
Most shunts have translucent areas that one should be aware of to avoid being mistaken for abnormal disconnection.
CT scan of the brain is mainly done to assess the size of the ventricles. Worsening hydrocephalus and overdrainage with epidural, subdural and intraventricular hematomas and slit ventricles are easily identified on a CT brain study.

As mentioned earlier, the programmable valves are susceptible to magnetic disturbances due to their ferromagnetic properties, and hence evaluation of valve pressure is necessary after a diagnostic MRI.

Anticancer drug induced Neurotoxicity - Drug induced Leukoencephalopathy

A known case of Ca Cervix, locally advanced cancer.
Offered first-Line Therapy with Radiotherapy
Cisplatin + 5-FU
Days 1 and 29: 4 hrs prior to external-beam radiotherapy: Cisplatin 50mg/m2 IV infusion at 1mg/min with standard hydration, plus
Days 2–5, and 30–33: 5-FU 1000mg/m2 IV continuous infusion over 24 hrs (total dose 4000mg/m2 each course).

Now patient presented with recent sudden onset altered sensorium.
Here is her on admission MRI brain diffusion

This MRI Diffusion shows:
Restricted diffusion involving splenium of corpus callosum and bilateral centrum semi ovale.
Imaging diagnosis : Drug induced Leukoencephalopathy.

Drug induced Leukoencephalopathy

Many chemotherapy drugs are known to cause significant clinical neurotoxicity. Neurotoxicity is a common and often dose-limiting complication of chemotherapy treatment.

It can involve acute alterations in consciousness, seizures, cerebral infarctions, paralysis, neuropathy, and ototoxicity. Sub acute and delayed toxicities also occur. Despite intensive efforts on the management of the neurologic side effects of chemotherapy in patients and the development of chemo protective agents, there is no generally accepted therapy at present.

In a study of effects of paclitaxel (taxol), cisplatin, and methotrexate on primary rat neurons including hippocampal, cortical, and dorsal horn/dorsal root ganglion neuronal cultures found that all of these anti-cancer drugs induce substantial neurotoxicity evidenced by neurite degeneration.
Taxol stabilizes microtubules and prevents cell division in cancer cells but its major side-effect in treatment is neurotoxicity. Cisplatin cross-links DNA which hampers DNA replication and has a long history of inducing peripheral neuropathy but also has been implicated in toxic leukoencephalopathy and ototoxicity. Methotrexate is a folic acid analog that has been shown to produce a number of cognitive deficits and other neurotoxicities in patients, including children.

Plexiform Neurofibroma MRI

A 20 y o female.
MRI Pelvis
Sequences: Cor STIR, T1WI. Axial STIR and T2WI.

This MRI study reveals T2 hyper intense multi lobulated / conglomerate masses along right sided exiting sacral nerve roots in pre sacral region, extending along sacral nerve at greater sciatic notch deep to Gluteal muscles.

Imaging wise possible diagnosis: Plexiform Neurofibroma.

Excisional biopsy done.

Histo pathology Report

Gross appearance : The specimen consist of multiple fusiform, globular yellowish white nodular tissue together measuring 6x4cm. The nodules appear encapsulated with overall rubbery consistency. The cut section shows dull yellowish white appearance. Representative sections are submitted for processing. Codes A and B.

Microscopy : Sections A and B both show benign encapsulated neoplasm of peripheral nerve sheath origin, comprising interlacing fascicles. whorls and bundles of slender - spindle shaped cells having wavy elongated nuclei and scanty eosinophilic cytoplasm. The interstitial stroma shows variable myxoid change along with fatty tissue, congested blood vessels and residual mononuclear inflammatory infiltrates. There is no evidence of malignancy.

Final diagnosis : Neural Plexiform lesion_ Plexiform Neurofibroma.

Sellar Suprasellar mass DDs

A 49 yo male.
Non contrast CT, MRI Brain with contrast

Non contrast CT

FLAIR

T2

Non contrast T1

Non contrast T1

Post contrast T1 MRI

MRI BRAIN

This MRI study shows:
A well-demarcated sellar supra sellar solid mass with right para sellar component.
Expansion of right half of Sella. No direct Sphenoid sinus extension.
Size of the mass 46mm width, 30mm AP, and height 48mm.
Mass is multi lobulated, Cysts around the lesion can be attributed to areas of cystic degeneration or an associated adjacent meningeal cysts. Signals are homogeneously isointense on T1w and T2w images. Homogeneous enhancement on post contrast T1.
A tissue resembling Pituitary is seen at the floor of left half of hypophyseal fossa on Sagittal T1 and Post contrast T1 sections.
Extension and mass effect _ Prepontine cistern extension causing Basilar compression and encasement. Mid brain and Pons compressed. Right para sellar component causing encasement of right ICA. Optic Chiasma, Optic nerve significantly compressed.
Low signal intensity hemosiderin staining along sub arachnoid space on T2* GRE attributed to superficial siderosis.
Moderate communicating hydrocephalus.

Imaging wise possible DDs: Meningioma more likely than Macro adenoma as pituitary seen separately.

Operated with right sub frontal approach.

Histopathology Report

Gross appearance : The Specimen consist of friable pieces of dull grey tan tissue. The entire tissue submitted for processing. 

Microscopy : Section shows fragmented bits of hyper cellular neoplasm of probable meningothelial cell origin. Tumour consist largely of cohesive sheets of intermediate sized round to oval cells having modestly hyper chromatic nuclei with delicate - irregularly condensed chromatin and scantly eosinophillic to clear cytoplasm having indistinct cytoplasmic membranes. Many neoplastic cells display nucleoli. Overall the tissue reveals 1 to 2 mitosis per 10 HPF. The interstitial stroma shows numerous congested blood vessels. The adjacent stroma shows foci of hyalinised blood vessels. There is no e/o vascular space invasion. Couple of foci show areas of tumor hemorrhage with focal coagulative necrosis. There is no e/o brain invasion. 

Final Diagnosis : Atypical Meningioma Grade II of III (as per  WHO Classification)

Fourth ventricular mass MRI

A 7 y o female.

MRI BRAIN WITH MR SPECTROSCOPY
Sequences planned are FSE T1W, FSE T2W, FLAIR, T2w *GRE and DW images.
Post contrast T1w.
Axial T2w localizer taken and Single voxel MR Spectroscopy performed. The voxel of size 2x2cm placed over the lesion. Water suppression obtained was 99% with optimum spectral waveform obtained at short as well as long TE.
Non contrast CT.

Description of findings:

An ~50x40mm solid hyper dense well defined mass in the region of fourth ventricle on non contrast CT. Lesion is iso intense on T2 and FLAIR. High signal on Dw images. Avid enhancement on post contrast T1 marked at periphery.
Significant mass effect _ moderate obstructive hydrocephalus with mild peri ventricular ooze of Csf. Brain stem compressed.

MRI SPECTROSCOPY performed over lesion.
On short TE of 35ms and TR of 1500ms.
From right to left.
At 2.01ppm - short peak of NAA. NAA is reduced.
At 3.03ppm - short peak of Creatinine.
At 3.2ppm - sharp and long peak of Choline. High choline.
A peak of lactate at 1.4.
NAA/ Creatinine ratio is 1:1
Choline/ Creatinine ratio is 2:1

Imaging possible diagnosis: Medulloblastoma. 

Operated, posterior fossa craniotomy done.

Histopathology report 

Gross specimen : specimen consist of multiple irregular soft to friable pieces of dull – gray tan tissue. Representative sections submitted for processing. Codes : A and B.

Microscopy : sections A and B show a cellular neoplasm composed of medium sized cells with indistinct outlines and round oval or angular hyperchromatic nuclei varying in size. The larger nuclei show clumped chromatin. A fine fibrillary background is discerned between the cells at many places. Peri vascular arrangement of tumor cells with fibrillary processes arising from the cells and extending towards the blood vessels in the center are seen. The tumor is vascular and shows areas of hemorrhage.

Histopathological Diagnosis: Medulloblastoma. 

Similar cases of Medulloblastoma. 
Case 1 : Medulloblastoma MR Spectroscopy 
Case 2 : Medullobastoma lateral origin

MEDULLOBLASTOMA

Syn: MB, Posterior fossa PNET, PNET – MB,
A highly cellular embryonal cell tumor.
Age group : common in children, ~75% diagnosed by 10 years.
3 times more common in males.

Location:
Intraventricular – 4th ventricular roof is a typical and most common location. A most common posterior fossa tumour in children.
Lateral origin – Cerebellar hemisphere is an atypical location common in older children and adults.

Size vary, average size ranges between 3- 5cm at the time of presentation.
On Non contrast CT, solid 4th ventricle mass, hyperdense, calcifcaiton seen in ~20% cases, small intra tumoural cysts, necrosis in ~50% cases.
On MR signal on T1 iso - hypo intense to cortical grey matter on T1 , iso – hyperintense on T2w and FLAIR. High signal on diffusion attributed to its dense, highly cellular nature.
An associated Obstructive hydrocephalus is common seen in ~ 95% cases.
Usually mild to moderate and homogenous enhancement, may show patchy heterogeneous enhancement due to areas of necrosis.

On MR Spectroscopy, NAA reduced or absent as it’s a non neuronal tumour, raised choline.