Sunday 29 August 2021

Leukoencephalopathy, Calcifications and Cysts MRI

Clinically middle age male with history of progressive headache for last 5months.
CT brain shows multiple dense bilateral basal ganglia calcification. 
DDs thought were like Fahrs disease, hypo thyroidism, hypo, pseudo hypo para thyroidism.
However patients thyroid and para thyroid profile was normal and the posterior cranial fossa cyst could not be explained even by Fahrs. With a possibility of a concurrent posterior fossa tumor, patient was referred for MRI brain with contrast.
MRI brain with contrast showed dense calcification in bilateral basal ganglia. The posterior fossa cyst with debris level. No abnormal enhancement along wall of cyst or enhancing eccentric solid nodule depicted on post contrast MRI which ruled out tumor nodule. 
The bilateral symmetric confluent T2 white matter hyper intensity which represents an associated leukoencephalopathy.

Imaging wise primary diagnosis given was LCC. 

Due to mass effect, fourth ventricle compression by the posterior fossa cyst leading to obstructive hydrocephalus, patient underwent posterior fossa craniotomy and excision of posterior fossa cyst was done. Histopathology revealed nonspecific cyst without any tumor cells keeping with MRI diagnosis of LCC. 

LCC or  Labrune syndrome syndrome MRI

Leukoencephalopathy, brain calcifications, and cysts (LCC) also known as Labrune syndrome, an extremely rare with only near  10 cases reported so far in the medical literature.

The condition is caused by homozygous or compound heterozygous mutations in the SNORD118 gene on chromosome 17p13. Clinical presentation varies from spasticity, dystonia, seizures, and cognitive decline.

Etiopathogenesis of LCC is still a matter of debate. Obliterative microangiopathy has been found on histopathological examination as the basic abnormality, the cyst formation is due to necrotic process secondary to obliterative microangiopathy and calcifications is dystrophic in nature. White matter changes result from changes in water content rather than abnormality of myelination.

Another entity which deserves a special mention is cerebro retinal microangiopathy with calcifications and cysts is a distinct genetic disorder due to CTC1 gene problem. Similar leukoencephalopathy, cysts, and calcification have been reported in few cases in association with Coat's disease, described as “Coat's plus. Coat's disease is unilateral retinal telangiectasia with exudation commonly occurring in boys sporadically without systemic features. However, in Coat's plus, there is bilateral retinal telangiectasia with exudation along with systemic features in the form of LCC. 

In my case patient did not have any visual issues so that rules out retinal abnormality and the possibility of cerebro retinal microangiopathy. 

Ears of the lynx sign MRI Brain

Ears of the lynx sign

The ears of the lynx sign refers to an abnormal bilateral symmetric cone-shaped hyperintensity on FLAIR and T2w images at the tip of the frontal horns of lateral ventricles. The abnormality corresponds to the region of forceps minor which resembles the tufts of hair crowning the ears of a lynx. Sagittal T1w images show an associated thin stripe of corpus callosum. 

The sign is typically seen in hereditary spastic paraplegia with thin corpus callosum (HSP-TCC), a form of hereditary spastic paraplegia associated with mutations of the spastic paraparesis gene 11 (SPG11) on chromosome 15. The spatacsin vesicle trafficking associated (SPG11) gene, codes spatacsin. 

The sign may also be seen in SPG15, another of the hereditary spastic paraplegias, which is caused by a mutation in the zinc finger fyve domain-containing protein 26 (ZFYVE26) gene, encoding spastizin. 

This sign has also been described in chronic cases of Marchiafava-Bignami disease.

Isolated Superficial Sylvian Vein Thrombosis MRI

Clinical Details: middle-aged female, altered sensorium after convulsions.

MRI study of brain shows:
Abnormal T2 hyperintensity with marked focal parenchymal swelling due to vasogenic oedema involving left temporal, insular cortex and adjacent opercular parietal white matter. 
Diffusion restriction in corresponding region confined to cortical grey matter of left temporal lobe and adjacent insular cortex on diffusion weighted images. Sub cortical white matter is spared.
 An abnormal leptomeningeal enhancement depicted along left sylvian fissure and in left medial temporal region near cavernous sinus on post contrast MRI. 
Multifocal low signal intensity clustered nodularity demonstrated along left sylvian fissure extending towards cavernous sinus on GRE, which is hyper dense on CT. No abnormal calcification on CT. Normal MR angiography of brain. No obvious aneurysm or high flow vascular malformation on MR angio.
Mass effect, mid brain compression.

Left side Decompressive hemicraniectomy done.
Intraoperative findings revealed thrombosed superficial cortical veins in left sylvian fissure region and at the floor of left middle cranial fossa. 

Final diagnosis: Isolated superficial middle cerebral or Sylvian vein thrombosis.

Superficial middle cerebral vein also known as the Sylvian vein, is one of the superficial cerebral veins. It usually courses along the Sylvian fissure posteroanteriorly and drains numerous small tributaries from the opercular areas around the lateral sulcus. It curves anteriorly around the tip of the temporal lobe and drains into the sphenoparietal sinus or directly into the cavernous sinus. 

Suzuki classification of the superficial Sylvian venous drainage pathways:
1. sphenoparietal type: (54%) drains into the sphenoparietal sinus.
2. emissary type: (12%) courses along the lesser wing of sphenoid, turns inferiorly to reach the floor of the middle cranial fossa, joins the sphenoidal emissary veins, and passes through the floor to reach the pterygoid plexus.
3. cavernous type: (7%) directly drains into the anterior end of the cavernous sinus.
4. superior petrosal type: (2%) runs along the lesser wing and just before reaching the cavernous sinus, turns downward along the anterior inner wall of the middle cranial fossa, then runs along its floor medially to the foramen ovale to join the superior petrosal sinus.
5. basal type: (2%) runs along the lesser wing, turns downward along the anterior wall of the middle cranial fossa, then runs along its floor laterally to the foramen ovale over the petrous pyramid, presumably to join the transverse sinus through the lateral tentorial sinus or superior petrosal sinus.
6. squamosal type: (2%) turns directly backward along the inner aspect of the temporal squama and runs posteriorly to join the transverse sinus or lateral tentorial sinus.