Sunday 29 December 2013

Lhermitte Duclos disease MRI

MRI Brain T2w images show a well demarcated hyper intense lesion in right cerebellum with striations ("corduroy" sign). Despite of its size results in little mass effect.

Lhermitte-Duclos disease (Dysplastic cerebellar gangliocytoma)

• Cowden syndrome (CS) ~ multiple hamartoma syndrome, multiple hamartoma-neoplasia syndrome.
o Hamartoma of cerebellum.
o Hamartoblastoma.
o Granule cell hypertrophy, granulomolecular hypertrophy.
o Diffuse ganglioneuroma of cerebellar cortex.
o Neurocytic blastoma.
o Myelinated neurocytoma.
o Purkingeoma.

Dysplastic cerebellar gangliocytoma (LD) is a rare tumour of cerebellum.
Grading WHO grade 1 tumor.
Varies in size and extent, always occur in cerebellum.

Imaging findings: 
Generally affects one hemisphere but commonly extends to vermis, as a well demarcated area of abnormal low density on CT / T2 hyper intensity on MRI with striations ("corduroy" or "tiger-striped" pattern).
No edema.
Usually little mass effect.
No restricted diffusion on MRI Diffusion.
No enhancement on post contrast. Very rarely mild enhancement.
MRS Reduced NAA, decreased to normal Choline, raised Lactate.

Histopathological findings: 
Gross pathologic and surgical features includes markedly enlarged cerebellar hemisphere/vermis with thick folia, Pale appearing mass.
Microscopic features includes widening of molecular cell layer ~ occupied by abnormal ganglion cells, Absence of Purkinje cell layer, Hypertrophy of granule cell layer, decreased volume of white matter.
Histologically may be confused with ganglion cell tumor

Clinical Presentation: 

Signs/symptom are often vague related to raised intracranial pressure, brainstem and cerebellar findings (cranial nerve palsies, ataxia), hydrocephalus.
Onset of symptoms most common during 3rd-4th decades of life
Age and Gender:
Any age, birth-60 years, more common between 30-40 years.
M = F / M >  F

LD is very rare, all patients must be screened for CS.
Cowden syndrome is a hereditary hamartoma-tumor syndrome ("phakomatosis") characterized by
1. LD in brain,
2. Mucocutaneous lesions,
3. Multiple hamartomas/neoplasias in breast/thyroid,
4. Gastrointestinal tract polyps,
5. Genitourinary malignancies,

Clinically CS include:
Benign breast, skin lesions
Oral papillomas,
Benign thyroid lesions (adenomas),
Gastrointestinal tract polyps/hamartomas,
Genitourinary neoplasias.

Surgical resection in symptomatic patients
Borders of lesion blend into normal surrounding cerebellum may cause total resection difficult.

Saturday 28 December 2013

Focal Adhesive Arachnoiditis of Spinal Cord

A 35 y o male with both lower limb weakness.
History of meningitis in the past ~10 years back.
History of major trauma ~7 years back. 

MRI whole spine with contrast
This MRI study of whole spine with contrast shows:
Multiple loculation in the the Csf space anterior to cord in dorsal region iso intense to Csf. 
Changes of myelomalacia with cavitations.
No abnormal cord or lepto meningeal enhancement on post contrast. 
Lower cord and conus spared, Conus pulled up owing to upward traction. 
Multiple rib fractures on either side. 
Cauda equina normal. 

Imaging diagnosis: Focal Adhesive Arachnoiditis of the Spinal Cord with Myelomalacia. 

Focal Adhesive Arachnoiditis of the Spinal Cord

Adhesive arachnoiditis may result in the formation of syringomyelia or myelomalacia, causing neurological deterioration such as sensory disturbances in the extremities, urinary disturbance, or sexual dysfunction.
Basic studies suggest that spinal tissue scarring at the injury site may cause a tethering effect on the spinal cord, which may lead to significant alterations in CSF dynamics. It is speculated that the rostro caudal CSF pulse wave is misdirected into the spinal cord parenchyma. The resulting high intramural pressure and decreased compliance of the subarachnoid space favor the flow of fluid into the spinal cord, possibly through perivascular spaces, resulting in a destructive cavitation process and eventually the formation of a syrinx cavity.
Causes of Adhesive arachnoiditis include hemorrhage, infection, trauma, radiation necrosis, ischemic infarction, or surgery.

Adhesive Arachnoiditis and Foix-Alajouanine Syndrome 

Modern understanding of the non-infectious neuropathologic entity "adhesive arachnoiditis" began in 1926 with the publication "La Myélite nécrotique subaiguë (Myélite central angiohypertrophique évolution progressive) Paraplégie amyotrophique lentement ascendan d'abord spasmodique, puis flasque"  by authors C. Foix and T. Alajounanine in the French Revue Neurologique (Paris), 2: 1-42).

What these authors described were cases which, in all probability, represented primary spinal cord Arterio Venous malformations producing recurrent subarachnoid hemorrhage.  A-V malformations represent congenital abnormalities of blood vessel development.  They are collections of abnormal and flimsy blood vessels which shunt blood directly from arteries to veins. Because these blood vessels are so fragile they are likely to spontaneously bleed on an intermittent basis.

The subarachnoid space represents the "salum sanctorum" of the human body.  It abhors all foreign body substances.  Even the presence of injected air is considered to be a "foreign body."  Blood is definitely considered a foreign body (particularly the breakdown products of blood ).  Repeat exposure to foreign body substances in the subarachnoid space can initiate auto-immune amnestic reactions which may potentiate and magnify the ongoing inflammatory process leading to severe local arachnoid fibrosis, associated thrombosis of local blood vessels, progressive destruction of the spinal cord producing myelomalacia and cystic degenerations in cord.

Initially the Foix-Alajouanine pathologic entity was only an autopsy phenomenon until the advent of high resolution MRI and associated modern spinal angiography.  This entity was mainly a medical curiosity until the midpart of the 20th century when some clinicians took a special interest in this entity. David B. Clark, neurologist at the Johns Hopkins Hospital was one of these pioneers.  With better neuropathologic definition combined with more astute clinical observation the Foix-Alajouanine Syndrome (FAS) became part of a patient's differential diagnosis.

FAS usually occur in the thoracic spinal cord in "watershed" zone of the thoracic spinal cord.  Because this spinal area has the most tenuous arterial blood supply it is most prone to injury when its vascular nourishment becomes impaired.  The remittent leakage of blood from the A-V malformation promotes slowly progressive local arachnoid fibrosis (adhesive arachnoiditis) which physically and physiologically "chokes" the spinal cord.

Because the changes are slow the patient may not experience any neurologic symptoms until some event produces a situation akin to "the straw that broke the camel's back."  most individual afflicted with adhesive arachnoiditis have few in the way of clinical symptoms.

Focal Adhesive Arachnoiditis and Lumbar Puncture

We live in a medical era still characterized by lumbar puncture routinely utilized for the following purposes like Initiation of spinal anesthesia, Diagnostic taps to obtain spinal fluid samples, i.e. to rule out meningitis. It is not unusual for patients to experience, as a complication of spinal tap, continued leakage of cerebro-spinal fluid producing postural headache, lightheadedness and inability to function due to these complaints.  The commonly employed treatment for this is a "blood patch."  Blood drawn from a vein is purposely injected into the supposed epidural space as a means of "patching" the leaking fluid. Appropriate blood patches routinely introduce some blood into the subarachnoid space and inappropriate ones may introduce as much as 10-12cc of blood directly into the subarachnoid space. How much blood, introduced how often, is necessary to create adhesive arachnoiditis?  This question has not yet been answered.  We only know at this point in time, that blood, and its breakdown products, can serve to create adhesive arachnoiditis and  the introduction of any foreign body substance (for any purpose) into the subarachnoid space is not a wonderful idea.

The diagnosis of the syndrome of Foix and Alajounanine (FAS) can occur only when the clinicians involved in the case know that this entity exists and also understand adhesive arachnoiditis as a pathologic entity.  Even at the start of the new millennium few radiologists or clinicians possess this awareness.


When the spinal cord is damaged as a result of trauma, there is often bruising or bleeding from the cord itself, either as a result of tearing of surface vessels by stretch, or by physical damage from bone fragments.  This bleeding then can lead to scar formation between the spinal cord and the inner surface of the canal, known as the dura.  When this scarring occurs, the deformity can cause further loss of neurological function or pain, often in a delayed fashion, sometimes 10-20 years later.  When this occurs, the tethering can be cut so that the cord no longer is being tugged on with every movement of the body, and this can relieve or improve the symptoms.


Various surgical procedures, including cerebrospinal fluid (CSF) shunting or subarachnoid reconstruction, are available.
Shunting of CSF from the syringomyelia to the subarachnoid, pleural, or peritoneal space has been proposed to resolve the propagation of the syringomyelia or myelomalacia, but the effect of the procedure is not long lasting and revision surgery is needed rather frequently.
Microsurgical dissection of the arachnoid adhesion, with decompression of the subarachnoid space, is another approach and may achieve better and more long-lasting outcomes in selected cases.

Thursday 5 December 2013

Posterior fossa cystic mass MRI

A 14 yo female with headache, vomiting.
Signs of raised ICT.

This MRI study shows:
A predominantly cystic lesion with thin wall in the region of cerebellar vermis with eccentric avidly enhancing solid nodule at its cranial portion extending in pineal region.
Mid brain Pons compressed. Fourth ventricle is seen anteriorly and separately compressed leading to mild obstructive hydrocephalus.

Imaging diagnosis given was Pilocytic Astrocytoma.

Operated with sub occipital craniotomy.


Specimen : Excisional biopsy Vermian SOL.
Gross appearance : The specimen consists of multiple irregular soft to friable pieces of dull grey tan tissue together measuring 30x30x10mm The cut section through the larger pieces appear grey tan fieshy. The entire tissue submitted for processing.
Microscopy : Sections A and B shows Astrocytic neoplasm of probable pilocytic differentiation. The tumour comprises of cellular areas consisting of relatively monomorphic round oval to elongated fibrillated cells with scanty eosinophiillic cytoplasm seen to be arranged in sheets with intervening loose spongy tissue showing prominent microcysts and occasional macrocysts with numerous congested micro vascular proliferative vessels. In couple of foci the neoplastic tissue shows presence of ganglionic cells and few cells with Resenthal fibers. Overall the entire neoplasm shows scattered eosinophillic granular bodies, few mitosis and foci of tumour ischemic coagulative necrosis.

Histopathological diagnosis: Pilocystic Astrocytoma _ Pilomyxoid variant, Grade ii as per WHO grading. 


Synonym: Polar spongioblastoma.
Astrocytic precursor cell tumor.
Contributes 5-10% of all gliomas.
Most common primary brain tumor in children. More than 80% are under 20 y, Peak incidence: 5-15 years of age, Gender: M = F.

Has syndromic association with NF 1.
15% of NF 1 patients develop PAs, most commonly in optic pathway.
Up to 1/3 of patients with optic pathway PAs have NF 1.

Cystic cerebellar mass with enhancing mural nodule is diagnostic clue.
Overall morphology often determined by cystic Component.
Cerebellum is most common (60%) > optic nerve/chiasm (25-30%) > adjacent to 3rd ventricle > brainstem.

Imaging findings:
Discrete cystic /solid mass, may have little or no surrounding edema.
Solid component variable density on CT and signal intensity on MRI, enhance strongly as enhancing mural nodule in more than 95%.
Non enhancing cyst in ~ 50% cases. Cyst may accumulate contrast on delayed images.
Associated calcification in ~ 20%, hemorrhage rare.
Rarely tumor may spread through subarachnoid space (but is still WHO grade I)
MR Spectroscopy is aggressive appearing metabolite pattern, high choline, low NAA, high lactate

Frequently causes obstructive hydrocephalus, may be a greater clinical management problem than tumor itself.
Most common signs/symptoms are Headache, nausea and vomiting, Ataxia, Cerebellar signs.

Adjuvant chemotherapy or radiation only if residual, progressive, unresectable tumor.

Medulloblastoma (PNET-MB)
• Hyperdense enhancing midline mass fills 4th ventricle
• Younger patient age (2-6 y)
• "Plastic" tumor, extends out 4th ventricle foramina

• Ca++, cysts, hemorrhage common; heterogeneous enhancement.

Similar Case :

Sunday 1 December 2013

Joubert Syndrome CT Brain

Molar tooth shape of mid brain with bat wing shape of fourth ventricle 

First identified by Dr Marie Joubert, Montreal, Canada, Pediatric neurologist.
A rare genetic disorder that involves areas of the brain that controls balance and coordination.

Characterized by absence or underdevelopment of cerebellar vermis and a malformed brain stem
'Molar tooth' sign - molar tooth shape of mid brain on axial sections and bat wing shape of fourth ventricle.

Clinical features:
Ataxia Most common, hyperpnea, sleep apnea, abnormal eye and tongue movements and hypotonia.
May be associated with other malformations like polydactaly, cleft lip or palate, anomaly of tongue.
Mental retardation.
Joubert is one of the many other genetic syndromes which are associated with syndromic retinitis pigmentosa.

Treatment is symptomatic and supportive like Infant stimulation, physical, occupational, and speech therapy.Infants with abnormal breathing patterns may need respiratory support and monitoring.

Similar Case : Joubert-syndrome MRI

Spinal epidural lesion causing cord compression MRI

A 15 yo female with bilateral lower limb weakness.
Compressive myelopathy clinically.
MRI Dorsal spine performed with contrast.
Non contrast T1
Post contrast T1
Axial T2
Axial Post contrast T1
D7 vertebral body and adjacent posterior elements show an abnormal altered marrow signals, heterogeneously hyper intense on T2 and STIR with low signal intensity vertical striations on sagittal sections, multiple punctate low signal intensity dots on Axial T2w sections so called as 'Polka dot' appearance corresponds to coarse, thickened vertical trabeculae characteristic of Spinal Osseous Hemangioma.
An associated posterior epidural lentiform shaped soft tissue with intense homogeneous enhancement on post contrast T1 causing canal stenosis, anterior displacement of cord with significant cord compression.

Imaging wise possible diagnosis : Aggressive vertebral Hemangioma with significant cord compression. 

Patient operated, cord decompressed by complete excision of posterior epidural soft tissue by Laminectomy. Tissue subjected for histopathology.


Specimen: D7 vertebral lamina and spinous process with epidural soft tissue.

Gross Appearance : The specimen consists of grey brown soft and largely bony fragments together measuring ~ 25x14mm. Representative sections are submitted for processing after de calcifying bone.

Microscopy : A benign neoplasm composed of vascular tubes or spaces lined by endothelium and many containing blood. The interstitial tissue contains a couple of spicules or trabeculae of bone.

Histopathological Diagnosis : Spinal Intraosseous Hemangioma. 

Vertebral body hemangioma are usually benign looking and asymptomatic.
Rarely aggressive and pt may present with cord compression due to an associated epidural soft tissue as in this case.