LHERMIETTE DUCLOS DISEASE

T2-AXIAL IMAGE

T1-AXIAL IMAGE

FLAIR-AXIAL IMAGE

CONTRAST ENHANCED T1 AXIAL IMAGE

A 7 year old child presented with ataxia and dizziness. MRI of brain shows increased volume and abnormal signal in right cerebellar hemisphere with a characteristic "striated" appearance on T2. There is mass effect on the 4th ventricle. It shows mild patchy enhancement.

SALIENT RADIOLOGICAL FEATURES:

• It is also called dysplastic cerebellar gangliocytoma
• Well defined cerebellar lesion involving usually unilateral hemisphere. 
• It may be large and involve the entire hemisphere as in this patient.
• Widened cerebellar folia with a characeteristic "layered" or "striated"appearance on T2
• It is hypointense on T1 and may show striated appearance with alternating layers of isointense and hypointense signal
• Calcification may be seen rarely
• These may show bright signal on DWI due to T2" shine through"
• There is no diffusion disturbance on ADC map.
• Rarely, some lesions may enhance
• MRS may show elevated lactate. There is diminished NAA, choline and myoinositol

REFERENCES:


Jones BV: Dysplastic Cerebellar Gangliocytoma. Diagnostic Imaging Brain: First Edition. Amirsys: I-6-70, 2005.  

IDIOPATHIC INTRACRANIAL HYPERTENSION

IDIOPATHIC INTRACRANIAL HYPERTENSION:

 Figure 1: showing increased fluid in sheaths surrounding optic nerves along with tortuosity of the sheaths

 Figure 2: showing flattening of posterior sclera

Figure 3: Sagittal T2 WI showing a partially empty sella

The above pictures are of a 35 year old female who presented with headache and progressive visual loss.

MRI of the brain and orbits showed a partially empty sella, dilated/ tortuous optic nerve sheaths along with posterior scleral flattening. 
There was no evidence of an intracranial mass/ space occupying lesion or dural sinus thrombosis.

IDIOPATHIC INTRACRANIAL HYPERTENSION( IIH):
Also called pseudotumor cerebri.
As the name implies,the intracranial pressure is raised with no obvious underlying pathology in the brain.
Most common clinical presentation is an obese female aged 20-40 years with headache( aggravated by Valsalva), papilledema, progressive visual loss, diplopia etc.
MRI reveals a partially empty sella, optic nerve sheath dilatation with vertical tortuosity, optic nerve head protrusion and scleral flattening.
The diagnosis is made after other potential causes of raised intracranial hypertension like dural sinus thrombosis, space occupying lesion are excluded.
Aim of treatment is to prevent visual loss which is a potential danger from chronic papilledema.

REFERENCES:

1.  Suzuki H, Takanashi J, Kobayashi K et al: MR Imaging of Idiopathic Intracranial Hypertension. AJNR 22:196-199, 2011
2. Hingwala DR, Kesavadas C, Thomas B et al: Imaging signs in idiopathic intracranial hypertension: Are these signs seen in secondary intracranial hypertension too? Ann Indian Acad Neurol 16(2):229-233, 2013
3. Castillo M: Idiopathic Intracranial Hypertension. Diagnostic Imaging Brain: First Edition. Amirsys: I-10-36, 2005.

DWI ABNORMALITIES IN STATUS EPILEPTICUS

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figures 1, 2, 3, 4 and 5 ( T2, T1, DWI, ADC, FLAIR) show cortical swelling with increased signal intensity in left parieto-occipital region( mainly cortical) on T2/ FLAIR, hypointense signal on T1, increased signal on DWI( suggestive of restricted diffusion) with corresponding low signal on ADC.

A 14 year old girl with history of seizures presented with ongoing generalized seizure activity for the last 3 days. MRI showed altered signal in left frontal( not shown here), parietal and occipital regions involving cortex and minimal subcortical white matter with cortical swelling and increased gyral volume of the affected areas. There was restricted diffusion in these areas suggestive of cytotoxic oedema. The area of abnormal signal did not conform to any vascular territory and was hence thought to be due to sustained seizure activity rather than cerebral ischaemia.

DIFFUSION WEIGHTED IMAGING IN STATUS EPILEPTICUS:

Diffusion weighted imaging( DWI) is an MR technique that allows characterization of tissues according to the degree of water mobility.

Its widest application is still in evaluation of cerebral ischemia where restricted water diffusion is seen early after onset of ischemia. Increased signal on DWI reflects the presence of cytotoxic edema.

DWI abnormalities are also reported in prolonged seizure activity.

DWI signal abnormalities are accompanied by abnormal signal on T2/ FLAIR if MRI is done 24 hours after onset of sustained seizure activity.
If however, MRI is done earlier, DWI may show restricted diffusion in the absence of signal changes on T2/ FLAIR ( as in early cerebral ischemia).

The areas of involvement do not correspond to any vascular territory. Morever, the changes are transient and return to normal after the seizure activity ceases.

Changes are seen as increased signal intensity and swelling of the cortical gray matter, subcortical white matter, or hippocampus on periictal T2/ FLAIR and diffusion-weighted images. These findings reflect transient cytotoxic and vasogenic edema induced by seizure, although this has not been proven pathologically. 

To conclude, it is  important to remember that abnormal processes other than cerebral ischemia can also cause acute diffusion-weighted imaging changes.

 REFERENCES:
1. Kassem-Moussa H, Provenzale JM, Petrella JR et al:Early Diffusion Weighted MR Imaging Abnormalities in Suatained Seizure Activity. AJR 174(5):1304-6, 2000
2.Kim JA, Chung JI, Yoon PH: Transient MR signal changes with Generalized Tonicoclonic Seizures or Status Epilepticus: Periictal Diffusion-weighted Imaging. AJNR 22:1149-60, 2001

RIGHT ACOUSTIC NEUROMA CAUSING TRIGEMINAL NEURALGIA

Axial T1C+ MR scan showing enhancing right acoustic schwannoma with ice cream on cone appearance

 Coronal T1C+ MR showing the enhancing right acoustic schwannoma

Sagittal CISS image showing compression of the right trigeminal nerve by the acoustic schwannoma

Sagittal CISS image showing normal left trigeminal nerve for comparison.

A 54 year old lady presented with right sided deafness, vertigo and right trigeminal neuralgia.
MRI revealed a right acoustic neuroma compressing the right trigeminal nerve.

DURAL SINUS THROMBOSIS IN A PATIENT OF ULCERATIVE COLITIS

Axial FLAIR MR images and MR venograms showing acute infarcts in left cerebellar / left occipital regions due to thrombosis involving left transverse, left sigmoid sinuses along with left IJV.

Case history: 55 years old female with a long history of ulcerative colitis presenting with venous infarction due to dural sinus thrombosis.

Cerebral sinus thrombosis is an uncommon complication of ulcerative colitis( UC) in approximately 7.5%patients. It is probably due to genetic predisposition in combination with hypercoagulable state during relapse of UC.
It often presents with headaches and focal/ diffuse neurological signs.
It is important to be aware of this condition as it is a serious complication of inflammatory bowel disease with the potential of being fatal.

REFERENCE:
Nudelman RJ, Rosen DG, Rouah E, Verstovsek G. Cerebral Sinus Thrombosis: A Fatal Neurological Complication of Ulcerative Colitis.Pathology Research International: Volume 2010.