Tuberous Sclerosis

 

This CT and MRI study of brain shows:
Multiple dense nodular calcifications along enpendymal lining of bilateral lateral ventricle best seen on CT. Cortical tubers seen as small multi focal cortical and sub cortical white matter patchy hypodensities on CT and T2 hyper intensities on MRI. No obvious obstructive hydrocephalus.

The lesion at right caudo thalamic groove not calcified on CT but shows avid enhancement on post contrast, needs follow up imaging as it may turn out to be a sub ependymal giant cell astrocytoma leading to obstructive hydrocephalus. However as of now there is not obvious obstructive hydrocephalus.

Imaging diagnosis : Tuberous Sclerosis.

TUBEROUS SCLEROSIS

Syn: Tuberous sclerosis complex (TSC), Bourneville-Pringle Syndrome.
A inherited tumor disorder with multi-organ Hamartomas.

In CNS characterized by Subependymal nodules, Subependymal giant cell astrocytoma, Cortical/subcortical tubers.
Abnormal differentiation/proliferation of germinal matrix cells, Migrational arrest of dysgenetic neurons appears to be the pathogenesis behind the lesions.
Histopathology and microscopic features are Balloon cells, Myelin loss, vacuolation and gliosis, Ectopic neurons.

Imaging 

CT and MRI both are equally sensitive but MRI often shows more number of lesions.
Subependymal nodules
Seen in ~ 98%. Commonest and specific site is caudothalamic groove followed by atrial and temporal lobe white matter.
~ 50% them shows an associated calcification best depicted on CT. calcification is often progressive after 1 yr.
30-80% of SEN shows mild enhancement on post contrast study, appreciated better on MRI than CT.
SEN at foramen of Monro needs close follow. If its enlarging it is equivalent to Subependymal giant cell astrocytoma (SGCA) and can cause obstructive hydrocephalus.
Subependymal giant cell astrocytoma (SGCA)
Seen in ~15%.
Cortical/subcortical tubers, WM lesions
Seen in ~ 70-95% common in Fronto parietal followed by temporo occipital regions and Cerebellum.
Ill defined patchy hypodensites on CT +/- calcification.
Hypo intense on T1 hyper intense on T2 and FLAIR on MRI. No restricted diffusion. May show low signal intensity on T2*GRE if an associated calcification.
~12% cortical/subependymal tubers show faint enhancement on post contrast T1.
Cyst-like white matter lesions as focal lacune best seen on MRI T2w images, common in corona radiata.
An associated thickened cortex, enlarged gyri.
MRS: decreased NAA/Cr, increased ml/Cr in subcortical tubers, SENs.

Associated abnormalities

o Renal: Angiomyolipoma and cysts 40-80%
o Cardiac: Rhabdomyomas 50-65%; majority involute over time
o Lung: Cystic lymphangiomyomatosis/fibrosis
o Solid organs: Adenomas; leiomyomas
o Skin: Ash-leaf spots (majority) including scalp/hair; facial angiofibromas; shagreen patches 20-35% post pubertal
o Extremities: Subungual fibromas 15-20%; cystic bone lesions; undulating periosteal newbone formation
o Ocular: "Giant drusen" (50%)
o Dental pitting permanent teeth in most adults with TSC

DDs: 

Subependymal heterotopia : Isointense to GM, don't enhance or Ca++.
TORCH : Periventricular Ca++ , White matter lesions, Cortical dysplasia common with Cytomegalovirus (CMV).
Taylors dysplasia

Genetics

De novo = spontaneous mutation/germ-line mosaicism
Autosomal dominant, high but variable penetrance. Approximately 50% of TSC cases are inherited.

Clinical presentation

Classic clinical triad
1. Facial angiofibromas 90%;
2. Mental retardation 50-80%;
3. Seizures /  Epilepsy 80-90%

All three ("epiloia") seen in ~ 30% of cases.

More the number lesion ~ high the neurologic symptoms.
Diagnosed at any age.

First year of life commonly present with seizures, Infantile spasms like episodes.
Child present with Autistic-like behavior, mental retardation, seizures, or skin lesions.
Adult may present for first time due to a symptomatic SGCA.

Treatment

Treat seizures.
Resect isolated tubers if seizure focus or if able to identify seizure focus among many tubers.
SGCAs resected if obstructing foramen of Monro.

Reference :

Diagnostic imaging Osborn.

Hyperammonemia MRI

Clinically:  young female patient with short history of drowsiness, brought unconscious.

MRI brain shows bilateral fronto parietal, temporo parietal cortical T2 hyperintensity with restricted diffusion. Lab report mentions Patient’s serum ammonia was high.

Imaging diagnosis: 

Hyperammonaemia.

DDs:

Differential diagnosis considered were Posterior reversible encephalopathy, CJD (Creutzfeldt-Jakob disease). Possibility of posterior reversible encephalopathy, PRES was ruled out as blood pressure was normal and there was no intra or postpartum history of seizures, eclampsia.

Absence of dementia, very short clinical history and absence of cerebral cortical atrophy on MRI was against CJD.

Bilateral Facial Colliculus Syndrome MRI

Clinically: 35 year old female with sudden onset slurred speech since two days with associated giddiness, fever.

On neurological examination there was facial Palsy. No signs of internuclear ophthalmoplegia.

MRI BRAIN shows:
Bilateral symmetric abnormal T2 hyperintensity with mild focal parenchymal swelling involving dorsum of Pons at the floor of fourth ventricle.
Area of involvement corresponds to facial colliculus.

Imaging wise differential diagnosis:
Bilateral facial colliculus syndrome due to demyelinating lesion.
Viral infection, Rhombencephalitis.

Suggested CSF for oligoclonal band and serum immunoglobulin in view of Multiple sclerosis.
Antinuclear antibodies in view of autoimmune disease.
Routine CSF for viral infection.

Facial colliculus and facial follicle syndrome

Facial colliculus is an elevation on the floor of fourth ventricle in Pons under which there is a presence No nucleus is located with facial nerve axons traversing over it giving of bump like appearance.

Lesion involving facial colliculus present with Internuclear ophthalmoplegia, abducens nerve, lower motor neuron type of facial nerve palsy with an associated features of medial longitudinal fascicles involvement.
There is important to make note that not symptoms and signs will be present in each and every patient.

Causes of facial colliculus syndrome include demyelination for example multiple sclerosis, viral infection like Rhombencephalitis, tumour whereas it can be secondary to ischaemic infarct in old age patient.
Facial colliculus syndrome secondary to Stroke going to be uni lateral whereas demyelinating lesion will be more or less bilateral.