Download WD - Rackcdn.com

Wallerian Degeneration
Beyond the ‘Corticospinal Tracts’
Conventional & Advanced MRI Findings
S. Ali Nabavizadeh1, Arastoo Vossough2
Yin Jie Chen1, Sunil Kumar 3
Laurie A Loevner 1, Suyash Mohan1
PENN RADIOLOGY
THE ROOTS OF
1 Neuroradiology
RADIOLOGICAL
EXCELLENCE
Division, Department of Radiology
Perelman School of Medicine at University of Pennsylvania,
2Children’s Hospital of Philadelphia, Philadelphia, PA
3Sanjay Gandhi Postgraduate Institute of Medical Sciences,
Lucknow, India
Presentation Title: eEdE-13
Disclosure statement
Neither the authors nor their immediate family members have a financial
relationship with a commercial organization that may have a direct or indirect
interest in the content.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Wallerian degeneration: Overview
• First described in peripheral nerves by ‘Waller’ in 1850.
• Process of progressive demyelination and disintegration of the distal
axonal segment following axonal transection or damage to the neuron.
• Imaging findings of Wallerian degeneration (WD) can be challenging,
especially outside the corticospinal tracts.
• In this exhibit, we will elaborate imaging findings of different types of
Wallerian degeneration secondary to various pathologies.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Content Organization
A. Anatomy & pathophysiology of different types of WD
1. Corticospinal tract
2. Hypertrophic olivary degeneration
3. Pontocerebellar tract
4. Posterior column of the spinal cord
5. Corpus callosum
6. Mammillary body/fornix
B. Imaging modalities reviewed
1. Conventional MRI
2. Diffusion weighted & diffusion tensor imaging
3. Susceptibility weighted imaging
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Wallerian degeneration: Stages
The following temporal relationships between the MRI findings & the stages of WD
are usually recognized.
I.
First stage: Characterized by the physical disintegration of the axons & myelin
sheaths with little chemical changes. Usually no signal abnormality on
conventional MR sequences.
II. Second stage: Characterized by the rapid destruction of the myelin fragments
observed in the first stage. Usually takes about 2-4 months.
III. Third stage: Characterized by almost entire disappearance of myelin sheath,
with gliosis occupying the area of the degenerated axons & myelin sheaths.
Imaging findings of T2 hyperintensity develop in late stage 2 & stage 3
I.
Fourth stage: Characterized by volume loss from atrophy in the brain stem as
unilateral shrinkage following WD of the corticospinal tract. Generally happens
after several years.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Corticospinal tract
Illustration of the corticospinal tract
with fibers that project from the
upper motor neurons in the cerebral
cortex through the internal capsule &
the cerebral peduncles before
reaching the medulla, where the
fibers mainly decussate to the
contralateral side to form the lateral
corticospinal tract, with small amount
of fibers remaining on the ipsilateral
side as the anterior corticospinal
tract. Fibers of the upper motor
neurons within the corticospinal tract
ultimately project onto lower motor
neurons within the anterior grey
column of the spinal cord.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
70 Y/F with slurred speech
MRI demonsrates T2
prolongation & restricted
diffusion consistent with
acute infarction in left
corona radiata
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
5 month follow up MRI
demonstrates gliosis at the
site of infarction & T2
prolongartion in left cerebral
peduncle consistent with WD
Penn Radiology
WD: Diffusion weighted imaging
• DWI can identify acute white matter injury corresponding
to stage I WD, which is not detectable on conventional
sequences.
• DWI & DTI could serve as prognostic indicators in
patients with infarction & intracranial hemorrhage.
• DTI is also sensitive to detect WD in corpus callosum in
patients with brain tumors.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
WD: Diffusion weighted imaging
Axial DWI images
demonstrate acute
infarction in right
middle cerebral
artery territory in a
neonate
Notice: Acute WD
with restricted
diffusion in right
cerebral peduncle
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
WD: Diffusion tensor imaging
Axial T2 images demonstrate
encephalomalacia in left MCA
territory & atrophy of left cerebral
peduncle consistent with WD
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Color coded FA map & fiber
tractography demonstrate
marked attenuation of the
left corticospinal tract
Penn Radiology
DTI as an early predictor of WD
T
Axial T2 images in a 15 year
old with 3rd ventricular tumor
(T) (Path: WHO Grade 3
glioma)
Bilateral encephalomacia in
medial frontal lobes
FA Values
Right 0.658
Left 0.540
FA Values
Right 0.377
Left 0.223
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Axial color coded FA maps
demonstrates decreased FA
values in corticospinal tracts
at the level of internal
capsules & pons consistent
with WD
Penn Radiology
Cortico-ponto-cerebellar fiber tract
Illustration of cortico-ponto-cerebellar
fiber tract, which extends from the
cerebellar cortex to ipsilateral pontine
nucleus (corticopontine tract), with
second order neurons projecting to
contralateral cerebellar hemisphere
through middle cerebellar peduncle
(pontocerebellar tract).
SCP – superior cerebellar peduncle
MCP – middle cerebellar peduncle
ICP – inferior cerebellar peduncle
PN – pontine nucleus
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Axial FLAIR, axial trace diffusion & ADC
maps demonstrate acute left
paramedian pontine infarction
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
3 month follow-up MRI demonstrates faint
T2 hyperintensity without restricted
diffusion in bilateral middle cerebellar
peduncles ( ) without restricted diffusion
consistent with WD of pontocerebellar
tracts
Penn Radiology
Hypertrophic olivary degeneration (HOD)
• Unique neural degeneration caused by disruption of the dentato-rubroolivary pathway, also known as the triangle of Guillain-Mollaret.
• Clinical manifestation: classical symptomatic palatal tremor (PT), also
known as palatal myoclonus.
• Pathophysiology: loss of synaptic, afferent input to the olivary nucleus
resulting in initial hypertrophy followed by atrophy.
• Typical MRI findings: Initial hypertrophy & T2 hyperintensity with
subsequent atrophy & residual hyperintensity.
• Can develop secondary to a variety of pathologies: tumor, hemorrhage,
vascular malformations, infarction, trauma, demyelination, & surgery.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Guillain-Mollaret triangle
Illustration of Guillain-Mollaret
triangle, consisting RN, ON, and
contralateral DN as its three corners.
RN – red nucleus
ON – inferior olivary nucleus
DN – dentate nucleus
SCP – superior cerebellar peduncle
MCP – middle cerebellar peduncle
ICP – inferior cerebellar peduncle
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Axial FLAIR & T1 images demonstrate a
4th ventricular tumor (arrow head) in a
27 year old patient
10 month F/U MRI demonstrates hyperintesity
in bilateral medullary olives (arrow heads)
consistent with olivary degeneration.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
HOD in a 70 year old with history of left cerebellar hemorrhage
Axial FLAIR & T2 images demonstrate T2 hyperintensity in right medullary olive.
Axial SWI images demonstrate susceptibility in left dentate nucleus consistent
with prior hemorrhage.
On axial SWI image, left red nucleus is less conspicuous compared to the right side
consistent with red nucleus degeneration.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Axial T2 image in a pediatric patient
with history of posterior fossa tumor
surgery demonstrates HOD right
olivary degeneration (arrow head, top
image)
Axial SWI image demonstrates
decreased signal intensity in right red
nucleus (arrowhead, bottom image)
compared to right consistent with
degeneration.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Posterior column of the spinal cord
Illustration of the posterior column
medial lemniscus fiber tracts, with
sensory fibers from the lower body
traveling within the gracile fasciculus
and fibers from the upper body traveling
within the cuneate fasciculus, which
terminates in the ipsilateral cuneate /
gracile nuclei in the medulla, where the
second order neurons arise, whose
fibers decussate in the medulla to travel
in the contralateral medial lemniscus to
terminate in the ventral posterolateral
and ventral posteromedial nuclei of the
thalamus, where the third order neuros
arise and project to the sensory areas of
the cerebral cortex.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Wallerian degeneration in posterior column of the spinal cord
Initial thoracic spine MRI in a pediatric
patient demonstrated abnormal signal
intensity in posterior column of mid thoracic
cord. Cervical spine MRI was normal, and
patient was diagnosed with transverse
myelitis.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Follow-Up MRI demonstrated linear abnormal
signal in posterior column of upper thoracic and
cervical cord consistent with WD of posterior
column of the cord.
Penn Radiology
WD in posterior column of the spinal cord
48 Y/M with history of recurrent ependymoma.
MRI: Enhancing, mildly expansile lesion centered
at C4-C5, with edema.
3 month F/U MRI shows contraction
of the resection cavity with new
hyperintensity in the posterior
column consistent with WD of the
posterior column.
F/U MRI 2 weeks after resection demonstrates
the resection cavity.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Corpus callosum (CC)
• Largest commissural fiber that connects the cerebral hemispheres of the brain.
• Callosal axons exhibit a topographical distribution, with the different CC regions
serving the different cortical regions.
• Genu and the rostrum of the CC have connections between the prefrontal
brain regions.
• Most caudal region & splenium contain connections between the occipital,
temporal & parietal regions.
• White matter tracts of CC are significantly influenced by cortical damage. Atrophy
of the CC has been well described in patients with cerebral infarcts.
• DTI is more sensitive than the morphologic MR imaging in the evaluation of WD
within the CC.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
WD in CC
Axial T2 & FLAIR images in
a pediatric patient following
left occipital AVM resection.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Axial diffusion image & ADC
map demonstrate restricted
diffusion in the splenium of CC
consistent with acute WD.
Penn Radiology
Mammillary bodies & Fornix
• The hippocampus, fornix, & mamillary bodies are components of a
single limbic circuit. The hippocampal fibers project to the mamillary
body via the fornix.
• Neuronal damage of the hippocampus may cause atrophy of the
ipsilateral fornix & mamillary body as a result of neuronal
degeneration.
• Asymmetrically small fornix or mamillary body is a useful presurgical
lateralizing sign of hippocampal sclerosis in patients with temporal
lobe epilepsy.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
WD of mammillary body
Coronal T2 & FLAIR images in a 43 Y/M
with complex partial seizure demonstrate
hyperintensity and volume loss in left
hippocampus consistent with mesial
temporal sclerosis.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Axial T2 weighted image
demonstrates atrophy of left
mammillary body.
Penn Radiology
Conclusion
 WD occurs throughout various tracts in the central
nervous system.
 Familiarity of radiologists with imaging findings of the
different types of WD is essential to make the correct
diagnosis & avoid unnecessary work-up.
 Given the more widespread use of advanced MRI
sequences, early detection of WD can play an important
role in prognostication of different brain pathologies.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Selected References
1. Mazumdar A, Mukherjee P, Miller JH, Malde H, McKinstry RC. Diffusion-weighted imaging of acute corticospinal tract
injury preceding Wallerian degeneration in the maturing human brain. Am J Neuroradiol. 2003 Jun-Jul;24(6):1057-66.
2. Vossough A, Ziai P, Chatzkel JA. Red nucleus degeneration in hypertrophic olivary degeneration after pediatric
posterior fossa tumor resection: use of susceptibility-weighted imaging (SWI). Pediatr Radiol. 2012 Apr;42(4):481-5.
3. Nabavizadeh SA, Mowla A, Mamourian AC. Wallerian degeneration of the bilateral middle cerebellar peduncles. J
Neurol Sci. 2015 Feb 15;349(1-2):256-7.
4. Kashani H, Farb R, Kucharczyk W. Magnetic resonance imaging demonstration of a single lesion causing Wallerian
degeneration in ascending and descending tracts in the spinal cord. J Comput Assist Tomogr. 2010 MarApr;34(2):251-3.
5. Puig J, Pedraza S, Blasco G et al. Wallerian degeneration in the corticospinal tract evaluated by diffusion tensor
imaging correlates with motor deficit 30 days after middle cerebral artery ischemic stroke. Am J Neuroradiol. 2010
Aug;31(7):1324-30.
6. Thomalla G, Glauche V, Weiller C, Röther J. Time course of wallerian degeneration after ischaemic stroke revealed by
diffusion tensor imaging. Neurol Neurosurg Psychiatry. 2005 ;76(2):266-8.
7. DeVetten G, Coutts SB, Hill MD, et al; MONITOR and VISION study groups. Acute corticospinal tract Wallerian
degeneration is associated with stroke outcome. Stroke. 2010 Apr;41(4):751-6.
8. Kim JH, Tien RD, Felsberg GJ, Osumi AK, Lee N. Clinical significance of asymmetry of the fornix and mamillary body
on MR in hippocampal sclerosis. Am J Neuroradiol. 1995 Mar;16(3):509-15.
9. Gu CN, Carr CM, Kaufmann TJ, Kotsenas AL et al. MRI Findings in Nonlesional Hypertrophic Olivary Degeneration. J
Neuroimaging. 2015 Sep-Oct;25(5):813-7.
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology
Thank You for reviewing our exhibit
[email protected]
[email protected]
Baltimore,
Maryland
Perelman
School of Medicine
at University of Pennsylvania
Penn Radiology