Neuro -- Phakomatoses

Front 1

1. What are the imaging findings in NF2?
2. What is the most common locations of schwannomas associated with NF2?
3. What is the most common tumor to occur in the spinal canal in NF2?

Back 1

- Multiple schwannomas.
- Multiple meningiomas
(including optic nerve)
- Ependymoma (usually arise w/n the spinal cord)
2. In NF2, schwannomas arise from the vestibular nerves (most common) and trigeminal nerves (2nd most common).
3. Schwannomas

Front 2

1. What are the imaging findings of NF1?
2. What is the prognosis of brainstem gliomas associated with NF1?

Back 2

SKIN
- Cafe au lait spots
- Cutaneous neurofibromas
- Axillary and inguinal freckling
- Plexiform neurofibromas

BONES:
- Dysplasia of greater and lesser wings of the sphenoid
- Thinning and bowing of long bones
- Pseudoarthrosis
- Scoliosis
- Dural ectasia resulting in posterior vertebral body scalloping
- Enlargement of neuroforamina from plexiform neurofibromas
- Lateral thoracic meningocele

EYE AND ORBIT:
- Flat or domelike hamartoma of the iris (Lisch nodule)
- Buphthalmos (enlarged globe)
- Optic glioma arising from optic nerve, optic chiasm, or optic tracts. Increased T2SI and moderate contrast enhancement.

BRAIN:
- Nonenhancing foci of increased T2SI in the white and deep gray matter due to myelin vacuolization. Typically resolves by adulthood.
- Astrocytomas (thalami, basal ganglia, and brainstem gliomas). Demonstrate post contrast enhancement differentiating from regions of myelin vacuolization.
- Macrocephaly

VASCULATURE:
- Moyamoya type appearance

2. Brainstem gliomas in pts w/ NF1 have a more indolent course and better prognosis than isolated brainstem gliomas and may not require aggressive therapy.

Front 3

1. What is the classic triad of Tuberous Sclerosis (TS)?
2. What are the findings of TS?
3. What are the imaging findings in the CNS?
4. Describe the pitfalls with subependymal nodules.

Back 3

1. Mental retardation, seizures, and adenoma sebaceum.
2.
CNS:
- Subependymal and cortical hamartomas
- White matter lesions
- Giant cell astrocytomas of the foramen of Monro
- Retinal hamartomas
KIDNEYS:
- Renal AML and cyst
LUNGS:
- Interstitial lung disease (mimics LAM)
CARDIAC:
- Rhabdomyomas (may lead to heart failure in infants)
SKIN:
- Facial angiofibromas (aka adenoma sebaceum)
- Shagreen patches
- Ash leaf spot
- Subungual fibromas
3.
- Subependymal nodules: line the ventricular surface, calcify around 1-2 years of age, +/- enhancement.
- "Radial bands" hyperintense bands in the white matter radiating from the ventricular margin to the subcortical region.
- Cortical and subcortical tubers: expand the gyri, hyperintense on FLAIR.
- Subependymal giant cell astrocytomas: located at the level of foramen of Monro and demonstrate growth on serial imaging studies. Intense enhancement is typical. May result in obstructive hydrocephalus.
4.
- Subependymal nodules should not be mistaken for periventricular nodular heterotopia. Subependymal nodules are isointense to mature white matter on T1WI, while nodular heterotopia are isointense to gray matter on all sequences.
- Subependymal nodules are rarely calcified in the newborn.
- Subependymal nodules may appear bright on T1WI compared to unmyelinated WM in the neonate. These should not be mistaken for subependymal hemorrhages.
- Gyral pattern of cortical calcification, which can mimic Sturge-Weber, may sometimes be seen with TS.

Front 4

1. What are the imaging findings in VHL?
2. Describe the CNS findings.

Back 4

1.
- Hemangioblastomas of the cerebellum (75%), spinal cord (13%), and medulla (5%). It is rare in the supratentorial brain.
- Retinal angiomas
- RCC
- Pheochromocytoma
- Cysts of the pancreas, kidney, and liver.
- Papillary cystadenoma of the epididymis
- Endolymphatic sac tumors

2.
- Cystic mass with an intensely enhancing nodule which usually abuts the pial surface.
- Flow voids
- May be entirely solid in 20-30%
3. Hemangioblastomas may produce EPO resulting in elevated hematocrit.

Front 5

1. What is the underlying abnormality in Sturge Weber disease?
2. What are the imaging findings?
3. What is Dyke-Davidoff-Masson syndrome (DDMS)?

Back 5

1. Lack of superficial cortical veins leads to impaired venous drainage, resulting in hemostasis and ischemic injury to brain.
2.
- Usually affects one side of the brain (hemiatrophy).
- "Tram-track" cortical calcifications due to ischemia and necrosis with calcification in apposing gyri.
- Ischemia leads to cortical atrophy with prominent sulci and subarachnoid spaces.
- Vaccuum created by cortical atrophy is filled by calvarial thickening, enlarging diploic space, and increase in pneumatization of the mastoid air cells.
- Intense leptomeningeal enhancement 2/2 leptomeningeal angiomatosis.
- Deep venous structures dilate secondary to the abnormal venous outflow.
- Enlargement of ipsilateral choroid plexus 2/2 angiomatous involvement.
- Abnormal increased T2SI in the white matter due to ischemia.
3. Changes in the skull in patients with cerebral hemiatrophy:
- thickening of the skull vault (compensatory)
- enlargement of the frontal sinus (also ethmoidal and mastoid air-cells)
- elevation of the petrous ridge
- ipsilateral falcine displacement
- Facial port wine stain in the distribution of the first and second divisions of the trigeminal nerve.

Front 6

1. What is neurocutaneous melanosis and what is its etiology?
2. What is the imaging appearance?
3. What is the dreaded complication of neurocutaneous melanosis?
4. What are associated malformations?

Back 6

1.
- Large melanocytic nevi on the skin.
- Benign/malignant melanotic lesions in the CNS.
Possibly due to disorder of migration of melanocyte precursors or abnormal expression of melanin producing genes within the skin and leptomeninges.
2. On MRI, T1 hyperintensity within the pia mater and parenchyma -- most commonly in the medial temporal lobes, pons, and cerebellum.
4. Vermian hypoplasia and Dandy-Walker malformation.

3. Degeneration of focal accumulation of melanocytes into melanoma can occur. Look for growth of the lesion with associated edema and mass effect.