Spinal Epidermoid cyst MRI

Clinically: A 30 y o male with neurogenic bladder. 

Findings:

This MRI lumbar spine show a spinal intra dural cystic signal intensity well defined lesion hypo intense on T1, hyper intense on T2 with restricted diffusion on Dw images. 

An associated expansion and scalloping of bony spinal canal. 

Lesion is confined to spinal canal and not extending out of neural foramen. 

Lesion is non enhancing on post contrast, except thin rim of enhancement on post contrast T1. 

Imaging diagnosis : Spinal Epidermoid Cyst.

Urinary bladder show diffuse wall thickening, irregularity with trabeculations attributed to associated Neurogenic bladder. 

Spinal Epidermoid Cyst

They are usually extra medullary but rarely can be intra medullary. They may be congenital or acquired.
Spinal epidermoid cysts are uncommon.

Unlike intracranial epidermoid cysts, which are almost always congenital in origin, most of spinal epidermoid cysts are acquired. Although present since birth, congenital epidermoid tumours often do not present until the second to fourth decade of life.
Males are more commonly affected than females.

Spinal epidermoid cysts may asymptomatic and discovered incidentally. If symptomatic, motor disturbances, pain, sensory disturbances, and bowel or bladder dysfunction may be present.
Congenital spinal epidermoids result from anomalous implantation of ectodermal cells during closure of the neural tube between the third and fifth week of embryonic life.
Acquired spinal epidermoids are a late complication of lumbar puncture, resulting from implanted epidermal elements into the spinal canal. The time interval between lumbar puncture and tumour diagnosis ranges from 1 to more than 20 years. Acquired spinal epidermoids are generally extramedullary and situated near a vertebral interspace.

Congenital epidermoids usually occur at the conus or cauda equina. Acquired cysts are found in the lower lumbar region.
Epidermoid cysts are commonly associated with spinal malformations such as spina bifida and hemivertebrae.

On CT, a well circumscribed mass, hypodense (similar to CSF),  minimal to no enhancement on post contrast, calcification is rare. Associated osseous changes include an expanded spinal canal, laminar thinning and vertebral body scalloping. 

On MRI typical signal characteristics include hypointense (similar to CSF) on T1, hyperintense (similar to CSF) on T2 and slightly hyperintense compared to CSF on FLAIR due to incomplete signal suppression. On T1 C+ (Gd) no enhancement or a thin rim of capsular enhancement. Characteristic bright signal on Diffusion with corresponding low intensity on ADC map. Signal intensity may be homogeneous or heterogeneous according to the variable water, lipid and protein composition of the cyst.

Spinal epidermoid cysts are slow growing.
Surgery is the treatment of choice, complete excision.
If the cyst wall is tightly adherent to the cord parenchyma, the wall should be left in place, however this leads to a risk of recurrence.

Differential diagnosis include spinal arachnoid cyst which lacks brightness of restricted diffusion on DWI, complete signal suppression on FLAIR. Vertebral anomalies uncommon.
Spinal dermoid cyst usually contains fatty elements, less likely to demonstrate diffusion restriction on DWI, patients are usually younger than 20 years of age.
Spinal neurenteric cyst common in thoracic and cervical regions, ventral to spinal cord with associated vertebral anomalies. 

AVM with bleed and ischemic complications on MRI

Clinical Details  : Two months ago suffered from a left basal ganglionic bleed. Had to have decompression done. PResently has a power of grade 0 on the right arm and right leg but speech is fairly well preserved. 

Presently on Ecosprin gold, Omnacortil. Pantocard.

Advised MRI for better evaluation

MRI Brain with MR Angiography of Brain Report

Sequences planned are FLAIR, T2w*GRE and DW images.

Non Contrast Enhanced intracranial Angio performed with 3D TOF and Neck Angio performed with 2D TOF sequence. The study viewed in row as well as 3D reconstructed images.

A focal Gliosis  with hemosiderin staining on GRE involving left thalamus, adjacent basal ganglia, insula and temporal lobe_ Chronic resolved hematoma with areas of chronic ischemic infarcts in left MCA cortical branches territory. 

An associated changes of distal wallerian degeneration on left side. 

An obvious high flow vascular malformation _ AVM noted, left pcom appears to be the feeder. 

Sparisty of cortical branches of left MCA. 

Rest of the both intra cranial as well as extra cranial vessels show normal flow related signals on 3D reconstructed images of Non Enhanced 3D TOF and 2D TOF sequences.

Impression: 

Chronic resolved hematoma with chronic infarcts in left MCA cortical branches territory.

An obvious high flow vascular malformation / AVM noted, left pcom appears to be the feeder. 

Sparisty of cortical branches of left MCA compared to right.

Needs DSA for better evaluation / confirmation. 

Atypical Trigeminal Neuralgia MRI

Clinical details: right side trigeminal neuralgia.

MRI BRAIN FOR TRIGEMINAL NERVES

Multi planner multi echo MRI study of brain has been performed. Sequences planned are FSE T1W, FSE T2W, FLAIR, T2w *GRE and DW images. FIESTA for cranial nerves.
Pc t1

This MRI Brain shows:
Abnormal T2 hyper intensity in right half of Pons at the entry point of right side trigemninal nerve, and adjacent right side trigeminal nerve_ significant for patients clinical complaints.
There is faint high signal on DW images in corresponding region.
No abnormal enhancement on post contrast T1.

Possibilities given were Demyelination, Ischemia.

He was prescribed
Amytryptiline 25 mg HS
Wyselon 20mg daily for 5 days, 10 mg for next 5 day and then stop
Gabapentine 300mg BD

During follow up after 2 weeks
He was clinically improved by 75 % which goes in favor of Demyelination.
During this follow up, MRI imaging shows lesion is same in size without any significant change on T2w images. The faint hyper intensity which was seen in previous MRI was reduced.
Advised further follow up imaging.

Current clinical status after 2 months, 100% improved.

There are persuasive evidences that trigeminal neuralgia is usually caused by demyelination of trigeminal sensory fibres within either the nerve root or, less commonly, the brainstem at the entry point of nerve. However in most cases, the trigeminal nerve root demyelination involves the proximal, CNS part of the root and results from compression by an overlying artery or vein.

Unilateral Optic Nerve Aplasia

Clinically a premature baby, Ophthamological evaluation revealed abnormally small Optic disc on right side. Advised MRI for further evaluation. 

MRI brain shows absent right side optic nerve, its intra cranial as well as intra orbital portion.
Left side optic nerve normal in caliber and signals, left half of optic chiasm and bilateral optic tracts normal. No associated anomalies of corpus callosum or septum pellucidum. Pituitary gland normal, no posterior lobe ectopia.

Impression: Congenital Unilateral Optic Nerve Aplasia.

Optic Nerve Aplasia 

A rare developmental anomaly characterized by the congenital absence of the optic nerve, central retinal vessels and retinal ganglion cells.
Aplasia is often unilateral, generally associated with otherwise normal brain development while bilateral optic nerve aplasia is usually accompanied by severe and widespread CNS malformations.
The pathogenesis of optic nerve aplasia may be due to defective formation of the embryonal fissure, failure of the mesenchymal anlage of the hyaloid system to enter the embryonal fissure, or primary agenesis of the retinal ganglion cells.

Optic nerve hypoplasia is seen ophthalmoscopically as an abnormally small optic nerve head. A peripapillary ring around a small optic disc is the hallmark, but is not always present. ONH may be associated with tortuosity of the retinal vasculature. A relative afferent pupil defect adds weight to the diagnosis.

ONH is commonly asymptomatic and may first be detected by identification of visual field loss or observation of the optic nerve head.

Associations,
1. Isolated ONH.
2. Absent septum pellucidum.
3. Posterior pituitary ectopia (commonly associated with endocrine dysfunction).
4. Migrational anomalies in the cerebral hemispheres (for example, thinning of the corpus callosum, which is predictive of neurodevelopmental problems). Other associated brain abnormalities include porencephaly, schizencephaly, intracranial arachnoid cyst, and intracranial epidermoid cyst.

Septo-optic dysplasia comprise any combination of ONH, pituitary gland hypoplasia, and midline abnormalities of the brain. Recent studies have shown that in SOD, key mutations have been identified in Hesx-1, a protein that is involved in the mediation of normal development of the forebrain and the eyes during embryogenesis.

Brain Stem Lesion MRI

MRI BRAIN WITH CONTRAST, WHOLE SPINE SCREENING REPORT

Multi planner multi echo MRI study of brain has been performed. Sequences planned are FSE T1W, FSE T2W, FLAIR, T2w *GRE and DW images. Pc T1 

This MRI study of Brain with whole spine shows:

1. An ~ 25x27mm intral axial cystic lesion with an avidly enhancing eccentric nodule, lesion causing marked expansion of medulla, marked peri lesional odema extending in adjacent Pons. Obstruction at the level of outlet foramen of fourth ventricle causing mild communicating hydrocephalus. 

2. An associated severe cervico dorsal cord syrinx.

3. Avidly enhancing nodule of spinal drop metastasis at D7-8 and D11.

Imaging wise Possible DDs given were Neoplastic_ like Medullary Pilocystic Astrocytoma, Hemangioblastoma. 

FOLLOW UP

Posterior fossa craniotomy with excision of lesion.

Histopathology report

Gross : The specimen consist of single nodular piece of gray white tissue, measuring 2x2x2cm. 

Microscopy: 

Sections shows moderately vascular neoplasm of both cellular and reticular areas comprising numerus proliferating vascular channels of varying caliber few of them appear to congested. The interstitium shows scattered round to oval cells having modestly hyperchromatic nuclei with coarse chromatin and abundant eosiophillic to vacuolated cytoplasm. These cells have indinct cytoplasmic margins. No atypical mitosis nor tumor necrosis seen. 

Impression :

Histopathological diagnosis : Hemangioblastoma. 

Posterior Fossa Mass MRI

Clinical Details  : About four to five months history of headaches over the vertex and the occipito-nuchal region, constant, not associated with any vomiting or blurring of vision. She has also been complaining of some blurring of vision. Examination shows papilloedema in the right eye. No other signs. 

Previous CT shows mild ventriculomegaly and an enhancing posterior fossa lesion behind right cerebellum with some degree of compression over 4th ventricle.

Advised MRI for better evaluation.

MRI BRAIN REPORT

Multi planner multi echo MRI study of brain has been performed. Sequences planned are FSE T1W, FSE T2W, FLAIR, and DW images. PC T1. 

Single voxel MR Spectroscopy. 

Description: 

An extra axial dural based ~ 60x30mm well-demarcated mass at the floor of posterior cranial fossa extending beyond foramen magnum in spinal canal, compressing cerebellar hemispheres , medulla and vertebrals at foramen magnum. Obstructive hydrocephalus due to fourth ventricle compression, peri ventricular ooze of Csf. 

No marked perilesional odema. Lesion is homogenously iso intense on cortical gray matter on T1 and iso intense on T2 images with homogeneous enhancement on post contrast T1.

On MRS, No NAA peak, significantly reduced Creatinine. High choline and choline -creatinine ratio. 

Impression: Imaging wise diagnosis given was Meningioma.

FOLLOW UP

Posterior fossa craniotomy done with complete excision of lesion.

Histopathology report

Microscopy: 
A high grade extra medullary myeloid cell tumor without any lineage differentiation.
The tumor cells express LCA, Mic 2 Weak , CD 3, TdT few cells and CD10 and are CD 33, 7, 68, 61 and Glycophorin C.
The Mib 1 labeling index is approximately 50%

Impression : High grade extra medullary myeloid cell tumor without any lineage differentiation - LYMPHOMA.

" This is second time that Lymphoma has surprised me". 

Ulegyria MRI

Ulegyria refers to shrunken cortical gyri due to ischaemic damage in the neonatal period.
The main method of detecting ulegyria is MRI will reveal a focal gliosis of affected gyri. In addition, unaffected gyri are also present especially in watershed regions indicating delayed effects of perinatal hypoxic damage.
There are three main criteria for diagnosing ulegyria using MRI. The presence of a poorly demarcated lesion, atrophy and thinning of the cortex resulting in the characteristic “mushroom” like shape of ulegyria and presence of white matter signal abnormalities on FLAIR.
Ulegyria must be differentiated from polymicrogyria, which is a neuronal migration disorder, characterized by excessive folding of the surface gyri and a thickening of the cerebral cortex, rather than the sulcal scarring that is typical of ulegyria.
The period in which polmicrogyria and ulegyria emerge is also different. Polymicrogyria typically forms while the embryo's central nervous system is maturing. Ulegyria is acquired later in development during the perinatal period after neuronal migration has already occurred. It is also suspected that polymicrogyra is genetically linked, whereas ulegyria is caused by environmental factors like ischemia.
Polymicrogyria can lead to similar conditions that are linked to ulegyria such as mental retardation, cerebral palsy, and epilepsy. It has been observed that patients with polymicrogyria are not receptive to epilepsy surgery. However, responses of patients with ulegyria to similar surgeries are still not fully known, which makes distinction of these two disorders significant. 

Role of MR Csf flow study in NPH

By definition NPH is Ventriculomegaly on MRI with normal CSF pressure, altered CSF dynamics.

Of course NPH is a clinical diagnosis.
The classical clinical triad of NPH is
1) urinary incontinence
2 ) deterioration in cognition (dementia) and
3 ) Ataxia i.e. Gait disturbances.
As the name suggests mean CSF opening pressure in patients with NPH is within the normal range with a classic neurological sign is magnetic gait.

Best diagnostic clue on MRI is ventricles and Sylvian fissures symmetrically dilated out of proportion to sulcal enlargement, with normal hippocampus which distinguishes NPH from atrophy.
Ventriculomegaly is prominent in all 3 horns of lateral ventricles and 3rd ventricle, with relative sparing of 4th ventricle.

Role of MRI is now not confined only to support the clinical diagnosis of NPH but is to identify shunt-responsive NPH pts from non responsive by calculating aqueductal stroke volume non invasively.
This is because studies have shown that aqueductal stroke volume in patients of NPH decreases later in the disease process despite clinical progression and classifcal findings on MRI this has been theorized to be caused by cerebral atrophy, which indicates that the patient is unlikely to respond to shunt surgery.


Normal CSF flow and its dynamics

The stroke volume across aqueduct is the average CSF volume flowing through the aqueduct in one cardiac cycle, craniocaudad during systole OR caudocraniad during diastole.
Normal values of stroke volume is < .04 ml/cycle
It is assumed that the net flow over 1 cardiac cycle is [negligible enough to be considered as] zero
Aqueductal velocity (caudal): 3-8mm/s
The peak velocity was determined from the maximum value of the measured velocities of each cardiac phase.


CSF flow study findings in NPH
In NPH actually there is lack of flow from the cisternal and subarachnoid spaces with significant increase in amount of ventricular csf flow.
There increased flow void across aqueduct with increase stroke volume.
1) Increased aqueductal stroke volume is the average volume of CSF moving through the cerebral aqueduct calculated by summing the absolute values of stroke volume in systole and diastole and dividing by 2
i.e   Forward stroke volume +  Reverse stroke volume   /   2
2) Increased aqueductal peak velocity.

Various publications have set various normal and abnormal ranges.
Flow rate of > 24.5mL/min 95% specific for NPH.
Stroke volume of > 42 microL shown on one paper to predict good response from shunting was statistically significant (P < .05).Studies have shown that aqueductal stroke volume decreases later in the disease process despite clinical progression.
Sroke volume upper limit is now suggested to be variable between institutions due to intrinsic scanner differences, thus each centre should obtain their own "normal values", with the upper limit being suggested as two times the normal value.
There was no statistically significant relationship between aqueductal CSF flow void score and responsiveness to shunting.

Case 1

With clinical diagnosis of NPH

MR brain reveals diffuse cerebral and cerebellar cortical atrophy.
The ventricular dilatation is disproportionate to the amount of cortical atrophy, scalloping of inferior margin of corpus callosum and prominent flow void in posterior portion of third ventricle, across cerebral aqueduct and superior portion of fourth ventricle consistant with clinical diagnosis of NPH.

Csf flow study report :
Gated cine phase contrast study was performed to evaluate the CSF flow.
The diastolic phases are equal in number to the systolic.
The stroke volume is 41 microliters per cycle consistent with shunt responsive status (Reference : Patients with stroke volume more than 40 microliters respond well to VP shunt _ Bradley et al)

Case 2 

Atrophy Vs NPH clinically

MRI brain reveals moderate cerebral and cerebellar atrophy. The ventricular dilatation is mildly disproportionate to the amount of cortical atrophy.

Csf flow study report :
Gated cine phase contrast study was performed to evaluate the CSF flow.
The diastolic phases are equal in number to the systolic. The stroke volume is 30 microliters per cycle consistent with non-shunt responsive status. ( Reference : Patients with stroke volume more than 40 microliters respond well to VP shunt _ Bradley et al).

Contributors:
Dr Deepak Patkar (HOD, Nanawati Superspeciality Hospital, Vile Parle, Mumbai)
Dr Balaji Anvekar (Short visiting Fellowship in Neuroradiology and Recent Advances in Neuroimaging)

Syntelencephaly MRI

A 14 yo male child, birth history uneventful.Complaints multiple episodes of seizures since 10 months with history of developmental delay and clinical impression of cerebral palsy with epilepsy

On MRI, 

The interhemispheric fissure not visualized in fronto parietal region with midline fusion of the cerebral hemispheres, single lateral ventricle cavity. 

The sylvian fissure extending across the midline. Body of corpus callosum is deficient. 

Normal 3rd and 4th ventricle.

The fused superior frontal cortex is thick , has a agyric / polymicrogyric  pattern.

Diagnosis : Syntelencephaly.

A varient of semilobar holoprosencephaly _ Congenital malformation of brain also known as Middle Interhemisheric variant.

A rare malformation in which the cerebral hemisphere fails to divide in the posterior frontal and parietal region.

Similar case : Semi-lobar-holoprosencephaly

Contributed by Dr Mitusha Verma SR DNB Radiology Nanavati. 

Haemorrhagic encephalitis - CNS Leptospirosis MRI

41 y o male patient admitted with c/o bilateral Lower limb Pain, Fever and Rapidly falling platelets.
Lab Investigations on admission Hb- 11.0, Platelets - 20,000 , Creatinine - 2.5, Bil(T)- 3.7, SGOT - 185, LDH- 1570

MRI Brain

Axial T1 and T2w images:

Axial GRE images:

DW images:

Sagittal T2wi for pituitary:

MRI shows multiple, patchy T2 hyperintense lesions of varying sizes on Flair and T2 W images in bilateral cerebral parenchyma involving the cortex and sub cortical white matter.
Some of the lesions show hyperintense foci on T1 weighted images, which appear hypointense on T2 weighted images and bloom on gradient echo images representing hemorrhage.
Restricted diffusion along the pyramidal tracts from the corona radiata upto the pons. These lesions are symmetric. Similar changes are seen in the corpus callosum, especially in the genu and splenium.
The pituitary gland appears hyperintense on T1 weighted images and hypointense on T2 weighted images and is probably also involved.

Findings are suggestive of haemorrhagic encephalitis. It involves cerebral hemispheres, corpus callosum and brain stem, as described.
The middle cerebellar peduncles and pituitary gland are also involved.

Follow up lab investigations shows raising Creatinine to 6.9,  Platelets on lower side.
Dengue NS1Ag -negative, Chikungunya IgM- Negetive, Leptospira IgM positive, Malaria -ve.

Final diagnosis : 

Haemorrhagic encephalitis - CNS Leptospirosis

Discussion: 

Hemorrhagic fevers are febrile illnesses with abnormal vascular regulation and vascular damage. Although the combination of fever and hemorrhage can be caused by a number of human pathogens: viruses, rickettsiae, bacteria, protozoa, and fungi, the term hemorrhagic fever usually refers
to a group of illnesses that are caused by 4 different families of
viruses: Arenaviridae, Filoviridae, Bunyaviridae, and Flaviviridae

Classic hemorrhagic fever with renal syndrome is a syndrome characterized by sequential periods of fever, hypotension, oliguria, and diuresis.

Headache may be associated with aseptic cerebral edema, or CNS hemorrhage .
Brainstem or posterior fossa subarachnoid hemorrhages are found.
May be associated with Pituitary dysfunction with pituitary apoplexy or panhypopituitarism

Leptospirosis

Infection caused by bacteria of the Leptospira type.
Symptoms - none to mild such as headaches, muscle pains, and fevers.
The disease presents with variable combinations of clinical syndromes, which cause diagnostic confusion.
In most cases hemorrhage in Leptospirosis occurs in the pulmonary and GI system and not in the Central Nervous system.
A small proportion of patients develop severe icteric illness with renal failure- Weils Disease.
Marked elevations of bilirubin with mildly elevated transaminases are some
characteristic features of leptospirosis.

Spectrum of CNS Leptospirosis

Aseptic Meningitis - most common
Rarely encephalitis , cerebellitis , myelitis.
Intracranial hemorrhage is a rare and serious presentation of leptospirosis.
Peripheral Nervous System - Polyneuritis.
Other associations- GBS , Stroke.

Contributed by Dr Mitusha Verma SR DNB Radiology Nanavati. 

Understanding Primary Dystonia with Advanced MRI Sequences

A 13 year old male patient resident of UK came with complaints of Dystonic hand movements on activity, right more than Left.
No history of seizures. No obvious cognitive impairment. No prior investigations were done.

Routine MRI brain imaging

Conventional MRI Brain normal 

Arterial Spin Labelled Perfusion MRI images of Brain

What is Arterial Spin Labelled Perfusion MRI ? 
• Uses magnetically labelled endogenous blood  water. 
• Ideal in  brain as the arterial supply is  well defined &  perfusion to brain tissue is high.
• Higher magnet strengths give improved ASL
• Gives an idea of tissue perfusion without using contrast
• Estimates cerebral blood flow in ml/gm/min






Diffusion Tensor Imaging and Fibre Tracking images of Brain

What is Diffusion Tensor Imaging ? 
• A form of diffusion-weighted imaging
• Analyzes the microstructural integrity of white matter
• Fractional anisotropy -The major index for this discrepant diffusion 
• Higher FA values correlate with more ordered tissue containing a larger number of aligned axons
• Higher FA values reflect tissue integrity and coherence


Fractional Anisotropy Maps

Average fractional Anisotropy ( FA) values:

Putamen                      (Right) 0.293             (Left) 0.328
Posterior limb of IC    (Right) 0.616             (Left) 0.709
Genu of IC                  (Right) 0.693             (Left) 0.637
Corpus callosum         (Right) 0.697             (Left) 0.880
Thalamus                    (Right) 0310              (Left) 0.321

Thalamo cortical tract fibers appear relatively sparse on right side compared to left.
Corpus callosal and cortico spinal tract fibres appears more ore less symmetrical on both sides.

Interpretation:

Average fractional Anisotropy values are more in putamen, Posterior limb of left internal capsule, Corpus callosum and left thalamus.
In the genu of internal capsules, the values are greater on right side.

Segmented Brain Volumes

Volumetry was performed using 3DSPGR acquisition.
Whole brain and segmented brain volumes were calculated.

Left putaminal volume is approximately 13 % more than right.

MR Spectroscopy

To summarize the findings in this case..
• Structural MRI is normal.
• MR spectroscopy is normal.
• Arterial Spin Labelled MR Perfusion (ASL) show increased cerebral blood flow in left parietal cortex and caudate nuclei.
• DTI and FA maps show Relatively dense Thalamo cortical tracts on left.
• Segmented Brain Volume show 13 % increased putamen volume on left.

Review of Literature:

Primary Dystonias is a hyperkinetic movement disorder characterized by involuntary, repetitive twisting movements.
Early onset - prior to 26 years of age.
Associated with a known gene carrier status (e.g., DYT1).
Symptoms more likely  begin in  one extremity and have a tendency to be generalized.

Conventional MRI does not typically reveal brain abnormalities.

Segmented Brain Volumes
• Putamen has been predominantly involved in focal hand dystonias.
• The involved side show > 10% increase in putaminal volume.

• Other areas which may be involved are thalami and caudate nucleus.

Summarization of Literature…
• Gray matter changes are not restricted to the basal ganglia.
• Sensorimotor cortices, thalamus, and cerebellum may also be involved
• White matter aberrations mainly involve cortico-striato-pallido-thalamic and cerebello-thalamo-cortical pathways.
• Whether these changes are causative or compensatory remains unknown.
• Newer MRI sequences may provide an insight in understanding disease pathophysiology and intricate brain networks involved.

To conclude…
• Advanced MRI sequences like ASL, DTI, Segmented brain volumes may provide more comprehensive insight into pathophysiology of dystonia.
• Further studies in this regard are needed to understand these findings and link them to disorder-specific clinico-behavioral characteristics.

References:
• Newer advances in the pathophysiology of focal dystonias  Brain (2006), 129, 6–7
• Thalamocortical Connectivity Correlates with Phenotypic Variability in Dystonia; May 2014 An Vo1,Wataru Sako1, Martin Niethammer1, Maren Carbon
• Primary Dystonia: Conceptualizing the Disorder Through a Structural Brain Imaging Lens  Ritesh A. Ramdhani & Kristina Simonyan
• Cortical somatosensory reorganization in children with spastic cerebral palsy: a multimodal neuroimaging study Front. Hum. Neurosci., 12 September 2014 Christos Papadelis1,2*†, Banu Ahtam1,2†, Maria Nazarova

Contributors:
Dr.Deepak Patkar (HOD Radiology) Nanavati Superspeciality Hospital, Mumbai
Dr.Mitusha Verma SR DNB Radiology Nanavati. 

MR Perfusion Imaging in Recurrence of Neoplasm with Subependymal spread : A Case Report

A fifty seven years old man, operated case of left parieto-temporal glioblastoma multiforme, post chemotherapy and post radiotherapy status.

Protocol:

Scan done on GE DISCOVERY 750 W 3 T scanner after injecting 10 ml of Dotarem.
Pre and post contrast MRI of the brain was performed using T1 and T2 weighted sequences in multiple planes, using a quadrature head coil. Perfusion studies of the brain were performed after intravenous injection of Dotarem using EPI sequences. Negative enhancement integral was evaluated. ROIs were placed within different parts of the lesion and normal appearing contralateral parenchyma and time intensity curves were plotted.
Single and multi voxel spectroscopy and chemical shift imaging were performed through the lesion using short TE (35 ms) PRESS sequences. Post processing was performed using FUNCTOOL on ADVANTAGE GE workstation.

Findings :

There is a large ill-defined, mixed signal intensity lesion in left parietotemproal region.  Multiple areas of blooming are seen within, suggestive of hemorrhagic changes.  Areas of restricted diffusion are also seen within the lesion which correspond to infarcts, likely treatment induced. Heterogeneous post-contrast enhancement is detected with non-enhancing areas representing necrosis.

These findings are suggestive of post-treatment changes admixed with residual neoplasm in left temporo-parietal region. Diffuse subependymal enhancement is detected along both lateral and third ventricles, suggestive of subependymal spread of neoplasm.

Single voxel spectroscopy from the enhancing component of the lesion showed . elevated choline and reduced NAA peak, along with elevated lactate levels. Cho / Cr ratio is 1.531 and Cho / NAA ratio is 4.529.

Multivoxel spectroscopy of necrotic areas reveal elevated lactate peak and diminished choline and NAA peaks suggestive of post radiation change.

The enhancing areas show increased perfusion with maximum rCBV ratio (calculated from signal intensity value) of 2.8.  The right subependymal areas of enhancement also demonstrate hyper perfusion with rCBV ratio calculated from signal intensity value) of 3 suggestive of high grade neoplastic infiltration.
The necrotic areas are hypoperfused.

Diagnosis:

Post treatment recurrence of neoplasm with sub ependymal spread.

CE - MRI, Dynamic susceptibility contrast MRI and MRS increase the diagnostic confidence of detecting tumor recurrence in a treated case of glioblastoma multiforme.

Contributors:

Dr. Deepak P. Patkar (HOD) Nanawati Superspeciality Hospital, Mumbai
Dr. Amit J. Choudhari Consultant Radiologist, Nanawati Superspeciality Hospital, Mumbai
Dr Balaji Anvekar

Frontal subcortical white matter cystic lesions MRI

A 30 y o male with headache.
MRI Brain with contrast shows:

Multiple T2 hyper intense well defined cystic foci in right frontal sub cortical white matter.
Lesions are iso intense to Csf on all pulse sequences.
No abnormal enhancement on post contrast T1.
No obvious restricted diffusion or hemosiderin staining on GRE in corresponding region.
No significant mass effect.
No adjacent white matter Gliosis.
No obvious calcification on CT sections.
Rest of the MRI brain within normal limits.

These appears to be benign lesions, and incidental finding not related to patient's headache.
Possibility given was Enlarged peri vascular spaces ( ' V R Spaces') and advised EEG correlation.
EEG was unremarkable.

Follow up imaging after 6 month revealed no change which again favors imaging diagnosis of Enlarged peri vascular spaces.

Bilateral Hypertrophic Olivary Degeneration MRI

A 50 y o was admitted after acute onset of unconsciousness. On admission MRI brain reveled hypertensive Pontine bleed extending in adjacent mid brain. His clinical condition gradually improved.

On follow up after 6 month pt was alert, dysartric, bilateral dysmetria of the arms without paresis, bilateral horizzontal gaze paresis. No palatal myoclonus.

During this 6mth follow, MRI  shows;
A resolved chronic Pontine bleed with,

New bilateral and symmetric T2 hyper intense foci with mild swelling in the region of inferior olivary nuclei of medulla suggestive of bilateral hypertrophic inferior olivary degeneration. 

Hypertrophic olivary degeneration ( HOD)

Hypertrophic olivary degeneration is a rare finding secondary to focal lesions of the brain stem involving Guillain–Mollaret triangle.

The three corners of the triangle are:
1.             Red nucleus.
2.             Inferior olivary nucleus
3.             Contralateral dentate nucleus.

In CNS the degeneration of an anatomical structure is usually characterized by neuronal loss replaced by proliferation of glial elements.
Unique to the inferior olivary nucleus is transneuronal degeneration resulting in hypertrophy.
Clinical presentation is Palatal myoclonus, a classically described feature.
Interruption of either of the connections between the dentate nucleus and contralateral red nucleus (dentatorubral tract, superior cerebellar peduncle) or the connection between the red nucleus and ipsilateral inferior olivary nucleus (central tegmental tract) leads to changes in the olive.
In short hypertrophic olivary degeneration can be caused by any lesion involving the above mentioned structures, it is typically seen with focal lesions involving the ipsilateral central tegmental tract, the contralateral superior cerebellar peduncle, or the dentate nucleus.
Isolated lesions of the inferior cerebellar peduncle do not cause HOD, as anatommically there are no direct connections between the inferior olivary nucleus and the contralateral dentate nucleus.

Pathologically, cell body enlargement, vacuolation of the cytoplasm, astrocytic hyperplasia and proliferation, demyelination, and fibrillary gliosis have been described.

Hypertensive bleeding is a relatively common cause of pontine haemorrhages resulting in hypertrophic olivary degeneration.

Imaging wise the inferior olivary nucleus or nuclei gets larger and increases in T2 signal intensity. Typically, within a few months T2 signal increases and lasts 3-4 years, whereas hypertrophy occurs later (at about one year), and resolves by 3-4 years.
On imaging DDs include infarction, demyelination, Neoplastic, metastases, lymphoma, infection, including tuberculoma.

T2 hyperintense non enhancing lesion that is accompanied by enlargement of the olivary nucleus, particularly if bilateral and symmetric, as our patient, can be explained only by hypertrophic olivary degeneration. Typically T 2  hyperintensity is evident on follow up imaging  the signal abnormality was absent in the on admission MR imaging. In the next few months the patient could complain palatal myoclonus which is not evident now.

Most commonly a lesion involving central tegmental tract causes unilateral olivary degeneration. Our patient is having bilateral hypertrophic degeneration from lesion located in the midbrain and Pons.

MELAS

A 15 y o male with altered sensorium. 

Here is CT Brain study. 

CT study of Brain shows bilateral symmetric chronic lacunes in bilateral caudate nuclei.
Rest of the CT brain normal.
No associated atrophy or cortical involvement.

I really got surprised when I noted the clinical history.
Patient was a known case of MELAS, laboratory Studies with abnormal reports of Serum lactic acid, serum pyruvic acid, cerebrospinal fluid (CSF) lactic acid, and CSF pyruvic acid noted.

Imaging findings are actually atypical for MELAS.

The typical radiographic features of MELAS includes multiple acute and chronic infarcts in multiple vascular territories, may be either symmetrical or asymmetrical. Parieto-occipital and parieto-temporal involvement is most common. Associated basal ganglial calcification and atrophy.

MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) is one of many mitochondrial disorders, only inherited from the mother, characterised by 'stroke-like' episodes, typically in childhood or early adulthood. 90% present before 40 years of age.
Clinical presentation usually has a relapsing remitting course with or without superimposed accretion of permanent deficits.
Clinical presentation is characterized by stroke like episodes, encephalopathy, seizures, dementia, lactic acidosis, muscle weakness, deafness. 

Astrocytoma vs Ependymoma

These common spinal cord neoplasms, differentiating Astrocytoma vs Ependymoma imaging wise is challenging, sure differentiation is out of imaging consensus however the combination of following set of findings can be used to give a more likely possibility of one over other.
Again it is one of favorite questions in FRCR 2A.

Astrocytomas are common in Children, Thoracic region, Eccentric lesion in spinal cord, Ill defined margins, Long segment involvement , No to faint enhancement on post contrast. 

Ependymomas are common in Adult, Cervical region, Central location in spinal cord, Well defined margins, Short segment involvement of cord, Avid enhancement on post contrast, Associated with cord syrinx, intralesional Bleed and Spinal canal remodeling.  

Cholesteatoma vs Cholesterol Granuloma

This is one of favorite questions in FRCR 2A exam. 

Appearances of Infarct on Diffusion and ADC with time

This is one of favorite questions in FRCR 2A exam. 

Toxoplasmosis Vs Lymphoma

It’s some times challenging to differentiate Toxoplasmosis Vs Lymphoma imagingwise as both of these are common in immune compromised patients, again its one of favorite questions in FRCR 2A.

Sure differentiation is out of imaging consensus however the combination of following set of findings can be used to give a more likely possibility of one over other.

Hypo dense to hyper dense lesion on CT, involvement of Basal ganglia, intra lesional bleed or hemosiderin staining on MRI GRE, Multiplicity of lesions, Rim enhancement on Contrast, an associated eccentric nodule goes in favor of Toxoplasmosis over Lymphoma.

Whereas hyper dense lesion on CT,  involvement of Peri ventricular white matter, an associated sub ependymal spread of lesion, Single lesion, Homogenous enhancement in immune component and rim enhancement in immune compromised goes in favor of Lymphoma over Toxoplasmosis.

Occipital Encephalocele MRI

Discal Cyst MRI Lumbar Spine

A 44-year-old male with low backache with left lower  limb radiating pain, straight leg raising test positive at 40 degrees in the left leg. Rest of the neurological examinations normal.

MRI revealed a well defined spherical extra dural cystic lesion with low signal intensity on T1 and high signal intensity on T2 antero lateral to thecal sac at L4-5 level. 

Imaging wise possibility of discal cyst was given compressing left traversing L5 nerve root in lateral recess.
Left partial hemilaminectomy at L4-5 revealed blue colored cyst compressing the left traversing L5 nerve root. The cyst contained serous fluid without blood. A connection between the cyst and the disc was identified, and the cyst was removed at the base of the connection by dissecting the annulus fibrosus.
Histopathological examination of the cyst revealed fibrous connective tissue with hemosiderin deposits without lining cell layers, no disc materials.
The patient's low back pain and radiating pain in the left leg improved remarkably immediately after surgery.

Discal Cyst

The discal cyst is a new clinical entity and it communicates with the intervertebral disc. More and more cases are now diagnosed with advent of MRI. Histologically, intraspinal cysts of the facet are referred to as synovial cysts. Although the difference between discal cysts and synovial cysts is based on the presence of lining cells.  The clinical symptoms of patients with discal cysts are indistinguishable from those of patients with a typical disc herniation manifesting as a unilateral single nerve root lesion. MRI and discography are useful for obtaining a presumptive diagnosis of this disease.

MRI features of discal cysts are a ventrolateral extradural cyst attached to a lumbar disc with or without rim enhancement on contrast enhanced MRI, occasional extension in lateral recess. These MRI features are the key to differentiating between a discal cyst and lumbar disc herniation. Discography and CT discography provide a connection between the cyst and the corresponding disc, and it is possible to differentiate discal cysts from lumbar disc herniation and other intraspinal cysts. However, need of this differentiation is controversial because the line of management is same for both of them. Removal of the cyst leads to symptom improvement, regardless of its origin.

The pathogenesis of discal cysts is still unclear. Several pathogeneses, such as resorption of a preexisting herniation and hematoma associated with a disc prolapse, have been suggested. Kyo et al. reported a case of discal cyst with an annular defect of the corresponding disc. Jeong and Bendo argued that the underlying pathological mechanism of discal cysts is a subsequent change in a herniated disc material. Tokunaga et al. confirmed the presence of cartilaginous tissue in the cyst wall and thought that the discal cyst might have developed from the absorption process of an intervertebral disc herniation. Chiba et al. proposed that discal cysts arise first from an underlying intervertebral disc injury that causes an annulus fibrosis fissure in the posterior intervertebral disc. Hemorrhage from the epidural venous plexus with a rich blood flow then occurs in the space between the peridural membrane and the vertebral body.
Whatever the pathogenesis may be, a discal cyst is responsible for the development of the symptoms in patients. Most of the discal cysts have been treated surgically. Lee et al. reported a case of recurrence among nine patients of discal cysts who underwent surgery at one year follow-up after the operation. It is suggested that careful long-term follow-up is necessary after surgery.

In 2007, Chou et al. reported a case of spontaneous regression of a discal cyst, patient who was treated with a routine epidural injection and selective nerve root block, and the discal cyst regressed spontaneously after 5 months. However, it is unclear whether steroid injection contributed to the regression of a discal cyst. Nevertheless, it is important to consider that although steroids influence the regression of discal cysts, potential spontaneous regression may also occur in discal cysts.
Standard therapeutic guidelines for discal cysts have not been established because the natural history and the long-term prognosis of discal cysts treated by surgery or percutaneous CT-guided aspiration and steroid injection are still unknown.

Reference : Discal Cyst of the Lumbar Spine J Korean Neurosurg Soc. 2008 Oct; 44(4): 262–264. Jae Ha Hwang, M.D., In Sung Park, M.D.

Temporal Bone Fracture with Facial Nerve Palsy

A middle aged male with h.o. RTA.

Now present with right side Facial nerve palsy and Deafness.

Here is CT study of brain with Bone window images as the level of petrous temporal bone: 

CT study shows non depressed fracture involving occipital bone extending anteriorly to involve petrous bone. The fracture line is running transverse to petrous axis, involving internal auditory canal and vestibule appears to be the cause of patient's right side facial nerve palsy and sensory neural hearing loss. 

Petrous Temporal Bone Fractures

Temporal bone fracture is encountered in 75% of all skull base fractures.
There are 3 subtypes of temporal fractures are longitudinal, transverse, and mixed.

A. Longitudinal fractures occurs in the temporo parietal region and involves the squamous portion of temporal bone, superior wall of the external auditory canal, and the tegmen tympani. These fractures may run either anterior or posterior to the cochlea and labyrinthine capsule, ending in the middle cranial fossa near the foramen spinosum or in the mastoid air cells, respectively. Longitudinal fracture is the most common of the 3 subtypes (70-90%) and associated with conductive deafness due to ossicular chain disruption.

B. Transverse fractures begin at the foramen magnum and extend through the cochlea and labyrinth, involves internal auditory canal, ending in the middle cranial fossa (5-30%), are associated with sensory neural deafness and facial nerve palsy.

C. Mixed fractures have elements of both longitudinal and transverse fractures.

Another classification system of temporal bone fractures has been proposed. This system divides temporal bone fractures into petrous and non petrous fractures; the latter includes fractures that involve mastoid air cells. These fractures do not present with cranial nerve deficits. 

Radiation Induced Bone Necrosis MRI

A 60 y o male with known case of Naso pharyngeal Carcinoma under Radiotherapy.

Now presents with severe neck pain, reduced neck movements. 

Here is MRI study of Cervical spine, Sagittal T1, T2 and STIR sections, Post Contrast Sagittal T1w images. 

This MRI study of Cervical spine shows:
Radiation Induced fatty marrow signal noted as diffuse high marrow signal on T1 involving cervical vertebrae confined to Radiation field which is an expected finding.
But the altered marrow signal, marrow edema involving Odontoid process of C2 with adjacent abnormal enhancing soft tissue is suggestive of Radiation Induced Osteonecrosis.
No cord compression.

In this case the history of Naso Pharyngeal Carcinoma and Radiotherapy is vital otherwise the case is likely to get confused with Infective etiology.

Osteoradionecrosis

Osteoradionecrosis refers to a severe delayed radiation-induced injury and is characterised by bone tissue necrosis and failure in healing.
There is some overlap with the term radiation osteitis.

Pathology is thought to be alteration in blood supply to the bone from microvascular damage limits the ability of tissues to adjust to normal wear and turnover, resulting in tissue breakdown

Usually large radiation doses are required for osteoradionecrosis to occur.

While it can involve any bone which is in an irradiation field, there are specific sites in which osteoradionecrosis is more commonly seen. These include mandible during radiation required to radically treat naso-oro-pharyngeal tumours, chest wall-shoulder-humerus-scapula, Spine and Bony pelvis.