Transcript Medial medullary syndrome

Pathology Spectrum of the Medulla Oblongata:
A Neuroimaging Review
Jason Kramer MD
Kathleen Barry MD, FACR
Ay-Ming Wang MD, FACR
Anant Krishnan, MD
Jeffrey Wilseck, DO, FAOCR
Division of Neuroradiology
Department of Diagnostic Radiology and Molecular Imaging
Beaumont Health System
Oakland University William Beaumont School of Medicine
eEdE-11
• Anatomy of the medulla
oblongata
Cerebrovascular accident
Hypoxic ischemic
encephalopathy
Cavernous malformation
Dural arteriovenous fistula
Traumatic brain injury
Metastasis
Ependymoma
Glioblastoma multiforme
Multiple sclerosis
Hypertrophic olivary
degeneration
Multisystem atrophy
Wallerian degeneration
Viral encephalitis
Wernicke encephalopathy
Leigh disease
Chiari malformation
Conclusion
• The medulla oblongata is the lowest portion of the brainstem and
continuous with the pons superiorly and spinal cord inferiorly. It is a
vital anatomic structure as it is responsible for multiple autonomic
functions necessary for life. It contains the cardiac, respiratory,
vomiting, and vasomotor centers, therefore the medulla oblongata is
crucial for breathing, heart rate, and blood pressure. Neurons of the
reticular formation play a central role in transmission of motor and
sensory impulses and controls such functions as arousal and sleep. The
medulla oblongata also contains multiple reflex centers responsible for
vomiting, coughing, sneezing, and swallowing.
• The medulla oblongata may be anatomically divided into two main
parts: the ventral medulla and dorsal medulla (tegmentum).
• The ventral medulla contains the pyramids, within which course the
pyramidal tracts made up of the corticospinal tract and corticobulbar
tract, as well as the olivary bodies located laterally.
• The dorsal medulla forms the inferior fourth ventricle at its upper
aspect and contains the brainstem nuclei for cranial nerves IX-XII.
Pyramidal tracts
Corticobulbar tract: Two neuron white matter motor pathway connecting the cerebral cortex to the brainstems,
primarily involved in carrying the motor function of the nonoculomotor cranial nerves.
Corticospinal tract: Lateral and anterior components. Lateral corticospinal tract controls fine movement of
limbs. Anterior corticospinal tract also involves fine motor control of the limbs as well as more central axial and
girdle musculature.
Nucleus solitarius: Receives taste sensation, sensory information from the ear, chemoreceptors and
mechanoreceptors of the general visceral afferent pathway including the carotid and aortic bodies, heart,
lungs, airways, GI tract, pharynx, and liver. Mediates the gag reflex, carotid sinus reflex, aortic reflex, cough
reflex, baroreceptor and chemoreceptor reflexes, several respiratory reflexes, and reflexes mediating GI
motility and secretion.
Spinal trigeminal nucleus: Receives information about deep touch, pain, and temperature from the ipsilateral
face. Receives input from cranial nerves V, VII, IX, and X.
Inferior olivary nucleus: Closely associated with the cerebellum. Involved in control and coordination of
movements, sensory processing and cognitive tasks Hypertrophy has been associated with progressive
supranuclear palsy.
Nucleus ambiguus: Controls motor innervation of ipsilateral muscles of the soft palate, pharynx, larynx, and
upper esophagus. Preganglionic parasympathetics to the heart also course through the external formation of
the nucleus.
Medial lemniscus: Formed by the crossings of the internal arcuate fibers that compose the nucleus gracilis and
nucleus cuneatus. Part of the posterior column-medial lemniscus pathway which ascends from the skin to the
thalamus. Important for vibration and touch-pressure sensation from the skin and joints.
Nucleus cuneatus: Part of the posterior column-medial lemniscus pathway. Carries fine touch and
proprioception information from the upper body to the contralateral thalamus via the medial lemniscus.
Nucleus gracilis: Contains second-order neurons of the posterior column-medial lemniscus pathway.
Participates in fine touch and proprioception sensation of the lower body (legs and trunk).
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(a., b.) Diffusion weighted imaging and ADC map demonstrates diffusion restriction in the left medulla oblongata consistent with acute/early subacute
ischemia. (c.) Coronal MRA 3D MIP image demonstrates critical stenosis of the left vertebral artery V4 segment.
• The arterial supply of the medulla oblongata is via:
• Posterior inferior cerebellar artery (PICA): Supplies the lateral medulla oblongata
• Anterior spinal artery: Supplies the medial medulla oblongata
• Direct branches arising from the vertebral artery and proximal basilar artery: Supply an area between the other two main
arteries.
• Ischemia to different vascular distributions produce different characteristic neurologic deficits.
• Lateral medullary syndrome (Wallenberg syndrome): Acute ischemic infarct of the lateral medulla oblongata, most commonly due to
occlusion of the intracranial vertebral artery or PICA, characterized by:
• Vestibulocerebellar symptoms: Falling towards the side of the lesion, diplopia, and multidirectional nystagmus (inferior
cerebellar peduncle and vestibular nucleus)
• Autonomic dysfunction: Ipsilateral Horner’s syndrome, hiccups
• Sensory symptoms: Initial sharp pain at the ipsilateral face followed by contralateral loss of pain and temperature sensation
(spinal trigeminal nucleus involvement)
• Ipsilateral bulbar muscle weakness: Hoarseness, dysphonia, dysphagia, dysarthria, decreased gag reflex (nucleus ambiguus)
• Medial medullary syndrome (Dejerine syndrome): Rare entity typically caused by thrombotic or embolic occlusion of anterior spinal
artery, small perforating branches arising from the vertebral or proximal basilar artery supplying the medial aspect of the medulla
oblongata characterized by:
• Contralateral hemiplegia/hemiparesis of trunk and extremities
• Contralateral loss of proprioception, discriminative tactile sensation, and vibration sensation from the trunk and extremities
• Ipsilateral hypoglossal palsy (tongue weakness, fasciculations, and atrophy, due to involvement of the hypoglossal nucleus)
• Vertigo
• Nausea
• Ipsilateral limb ataxia
Diffusion weighted imaging demonstrates bilateral symmetric diffusion restriction in the medulla oblongata, pons, midbrain, medial temporal lobes
and hippocampi, thalami, basal ganglia, mammillary bodies, and cerebral cortex.
• Potentially devastating neurologic injury developing in varying
regions in the brain depending on severity and duration of
hypoperfusion and oxygenation.
• Particular sites with high energy demands are most vulnerable to
cytotoxic crisis in the event of hypoxia/hypoxemia.
• Usual neuroanatomical locations include the cerebral cortex,
cerebellum, hippocampus, basal ganglia, and thalamus. More
severe cases may involve the entire limbic system, cerebral white
matter, and brainstem.
• Most conspicuous neuroimaging findings include diffusion
restriction at the sites of injury on DWI. Subtle FLAIR
hyperintensity may be detectable. In more severe cases, global
cerebral edema may occur.
• White matter involvement may be overlooked on conventional
T2WI because markedly edematous grey matter may make the
white matter appear to have relatively low signal intensity and
therefore appear normal. DWI greatly facilitates avoiding this
pitfall.
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(a-c) Axial CT images without contrast demonstrate small parenchymal hemorrhages in the dorsal medulla oblongata, left pons, and left lentiform
nucleus secondary to multiple underlying cavernous malformations. (d-f) Axial gradient echo T2* images demonstrate susceptibility artifact in the
dorsal medulla, left pons, and left lentiform nucleus due to hemosiderin. (g,h) Axial T1W1 with contrast images demonstrate heterogeneous signal
consistent with blood products of different ages. There is no enhancement.
• Slow flow vascular malformation defined in histologic terms by blood cavities
surrounded by a single layer of endothelium without muscular tissue or
intervening brain parenchyma.
• Often asymptomatic, although may present with seizures, hemorrhage, focal
neurologic signs, and headache.
• MRI is most sensitive modality for diagnosis. There is classically susceptibility
artifact on gradient recalled echo sequence as well as a peripheral halo of T2
shortening due to the presence of hemosiderin. These lesions do not typically
enhance and are angiographically occult.
• Most commonly occur sporadically as a solitary lesion, although rarely may occur
as an autosomal dominant familial form with multiple lesions (most often
described in the Hispanic American population.)
• Most commonly supratentorial (80-85%), although may occur throughout the
CNS.
• Present with hemorrhage at time of diagnosis in approximately 15% of cases.
• Commonly associated with developmental venous anomalies.
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(a.) Axial T2WI and (b.) FLAIR images demonstrate hyperintense signal within the medulla oblongata secondary to venous congestion and associated
vasogenic edema. (c.) Axial contrast-enhanced T1WI demonstrates prominent vessels adjacent to the medulla oblongata (arrow) relating to a dural
arteriovenous fistula. (d.) Digital subtraction angiography in the lateral projection with transcatheter injection of the right ascending pharyngeal artery
branch of the external carotid artery (yellow arrow) demonstrates early venous filling at the site of the dural arteriovenous fistula (blue arrow) and
multiple prominent venous structures coursing along the brainstem and medulla oblongata (red arrows). This was a confirmed dural arteriovenous
fistula with arterial supply from the neuromeningeal branches of the ascending pharyngeal artery.
CBF
MRI perfusion demonstrates decreased cerebral blood flow
(CBF) and cerebral blood volume (CBV) at the medulla
oblongata with increased time-to-peak (TTP). These findings
relate to decreased perfusion from steal phenomenon caused
by the dural arteriovenous fistula.
TTP
CBV
• Fistulous communication between arteries that would normally feed the meninges,
bone, or muscles, but not the brain, and small venules within the dura matter.
• Account for 10-15% of all intracranial arteriovenous shunts.
• Several classification systems have been described, with perhaps the simplest
method being to group lesions into those with and those without cortical venous
reflux.
• Lesions without cortical venous reflux (Borden type 1) almost never lead to
neurologic deficits.
• Lesions with cortical venous reflux (Borden types 2 and 3) often have an aggressive
clinical course including intracranial hemorrhage, seizure, dementia, altered
consciousness, and focal neurologic symptoms due to venous congestion or
rupture. Dural AVF with cortical venous reflux will manifest with abnormal vessels
present outside the brain parenchyma.
• Neuroimaging findings include dilated cortical veins which manifest as abnormal
enhancing tubular structures or flow voids within the cortical sulci with no true
nidus within the brain parenchyma.
• MRA, CTA, and DSA will demonstrate early venous filling with arterial supply from
external carotid artery branches.
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(a.) Axial noncontrast CT images demonstrate parenchymal hematomas in the right frontal and occipital lobes and subarachnoid hemorrhage within
the left Sylvian fissure. (b., c.) Axial FLAIR and (d.) T2WI demonstrates hyperintense signal within the right ventral medulla oblongata presumably
related to traumatic contusion. The patient was status post motor vehicle accident and was comatose upon presentation.
• CT is the first imaging test performed in the emergency setting
for evaluation of head trauma, the goal being to identify lesions
requiring emergent neurosurgical treatment.
• CT is important in the emergency setting of traumatic brain injury
due to its fast acquisition time and widespread availability.
• MRI is reserved for evaluation when CT does not fully explain
patient symptoms or to better delineate CT findings. MRI is being
increasingly used in the emergency setting for these reasons.
• MRI has much higher sensitivity for detecting microhemorrhages
and diffuse axonal injury, especially when protocol includes a T2*
gradient recall echo sequence or susceptibility weighted imaging
(SWI).
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(a.) Axial T1WI with contrast demonstrates a peripherally enhancing intra-axial mass in the right frontal
lobe with surrounding vasogenic edema consistent with a large metastatic focus. (b.) Coronal T1WI with
contrast demonstrates a peripherally enhancing mass in the left upper medulla oblongata consistent with
a metastatic lesion. (c, d.) Axial and sagittal T1WI with contrast demonstrates the peripherally enhancing
metastatic lesion in the posterior upper medulla oblongata. (e.) Axial chest CT demonstrates a spiculated
central mass in the right upper lobe proven to be a primary squamous cell carcinoma of the lung.
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• Neoplasms with tendency to metastasize to the
brain, spinal cord, or meninges may also
metastasize to the medulla oblongata.
• Metastatic disease to the medulla oblongata may
cause dysfunction of vital medullary nuclei and
lower cranial nerve palsies either by direct
infiltration or by associated vasogenic edema .
• Cases of fatal autonomic dysfunction have been
described in the literature attributed to metastatic
disease to the medulla oblongata.
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(a.) Sagittal T2WI image demonstrates an expansile intrinsic mass in the posterior medulla oblongata with a large cystic component. (b-e) Sagittal,
coronal, and axial contrast-enhanced T1WI demonstrate the expansile intrinsic mass in the posterior medulla oblongata. The mass is
predominantly cystic, but demonstrates an enhancing solid component at its anterior aspect suggestive of neoplasm. This mass was surgically
resected and pathologically proven to be an ependymoma.
• WHO grade II or III glial neoplasm arising from ependymal
cells with a variety of subtypes.
• May occur anywhere along the neuraxis, therefore imaging the
entire neuraxis is important prior to treatment.
• Most commonly located in the posterior fossa, classically
arising from the floor of the 4th ventricle and often protruding
out the foramen of Luschka (“plastic tumor”).
• Demonstrates heterogeneous neuroimaging characteristics due
to propensity to hemorrhage and contain calcifications.
• May appear as a solid tumor or cystic with solid components.
• When tumor involves the medulla oblongata, complete surgical
resection is often difficult due to infiltrating nature of the tumor
and adherence to adjacent structures vital to autonomic
functions necessary for life.
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(a.) Axial contrast-enhanced T1WI demonstrates a large intra-axial mass in the right parieto-occipital lobe with irregular peripheral enhancement and
central necrosis. There is significant mass effect with effacement of the right lateral ventricle and leftward subfalcine herniation. (b.) Sagittal contrastenhanced T1WI demonstrates a smaller enhancing mass at the dorsal caudal medulla oblongata. (c.) Axial contrast-enhanced T1WI demonstrates the
smaller enhancing mass at the left dorsal medulla oblongata. This was pathologically proven to represent multicentric glioblastoma multiforme.
• GBM is the most common glial tumor of the adult brain, however primary
GBM of the medulla oblongata is rare.
• Neuroimaging features of GBM of the medulla oblongata are consistent
with those of GBM at other sites, often appearing as a heterogeneous mass
with ring-like enhancement, a poorly defined margin, and tumoral
hemorrhage. When located in the caudal brainstem, it may demonstrate
an exophytic nature. Although rare, GBM should be included in the
differential diagnosis of tumors of the caudal brainstem.
• WHO grade IV tumor with poor prognosis, median survival approximately 2
years.
• Complete surgical resection may prolong survival somewhat, although may
severely impair quality of life due to infiltrative and adherent nature of the
tumor. Total surgical resection may have dire consequences on autonomic
functions of the medulla oblongata with associated dysfunction of the lower
cranial nerves, and therefore subtotal resection is a considered treatment
option. However, with subtotal resection, tumor progression will inevitably
impair function as well.
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(a.) Axial FLAIR image demonstrates focal hyperintense signal in the right lateral medulla oblongata relating to a demyelinating lesion in the setting of
multiple sclerosis. (b.) Axial T1WI demonstrates corresponding hypointense signal at the demyelinating lesion. Presence of hypointense signal on
T1WI has been associated with worse prognosis. (c, top image.) Sagittal T2 FLAIR demonstrates multifocal signal hyperintensities in the
periventricular white matter. The lesions are oriented perpendicular to the callososeptal interface in a perivenular distribution along the path of the
deep medullary veins, which is characteristic of the demyelinating lesions in the setting of multiple sclerosis. These lesions are commonly referred to
as “Dawson’s fingers”. (c, bottom image) Sagittal T2 FLAIR demonstrates the focal demyelinating lesion in the upper medulla oblongata. (d.) Axial
FLAIR image demonstrates multiple demyelinating lesions in the bilateral periventricular white matter.
• MS is the most common chronic inflammatory demyelinating disease
affecting the central nervous system.
• MRI criteria for diagnosis of MS in patients with clinical syndrome
suggestive of MS include demonstration of disease dissemination in time
and space.
• Active lesions may demonstrate diffusion restriction and/or enhancement.
• Lesions that appear hypointense on T1WI, aka “black holes”, are
associated with more severe tissue damage.
• Characteristic neuroimaging findings include demyelinating lesions in the
periventricular white matter which are classically oriented perpendicular to
the corpus callosum in a perivenular distribution along the path of the
deep medullary veins (“Dawson’s fingers”).
• Enhancement of the optic nerves is also a characteristic finding in the
presence of optic neuritis.
• Brainstem and spinal cord involvement is common. Brainstem lesions may
result in cranial neuropathies and even autonomic dysfunction.
• MS involvement of the medulla oblongata has rarely been associated with
sudden cardiac death. Sudden arrhythmias have occurred with MS lesions
affecting the medulla oblongata due to dysfunction of the cardiac
autonomic innervation which the medulla oblongata controls.
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(a.) Sagittal T1WI, (b.) axial T2WI, and (c.) axial FLAIR image demonstrates intraparenchymal hemorrhage within the caudal midbrain
and posterior pons in a patient who presented with hemorrhagic stroke and later developed bilateral hypertrophic olivary degeneration
(next slide).
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Follow up imaging 2 years later. (a.) Axial T2WI, (b.) FLAIR, and (c.) T1WI demonstrates prominence of the medulla oblongata inferior olivary
nuclei with associated T1 and T2 prolongation related to demyelination and vacuolization. Note the bilateral nature of the lesions. Hypertrophic
olivary degeneration is most commonly a unilateral process, however can be bilateral if caused by a lesion involving the midbrain corresponding
to the region of the Werneking decussation (decussation of the superior cerebellar peduncle or brachium conjunctivum), as in our patient.
• Trans-synaptic degeneration with neuronal loss and reactive gliosis in the
medullary olives after losing synaptic input from injury to their afferent fibers.
• HOD is a unique form of degeneration because it results in enlargement of the
affected structure rather than atrophy.
• Follows injury to the dentato-rubral-olivary pathway, or “triangle of Guillain
and Mollaret”, which is the afferent pathway to the medullary olive comprised
of connections between the inferior olivary nucleus, red nucleus, and
contralateral dentate nucleus.
• Onset is typically preceded by a pontine hemorrhage involving the ipsilateral
central tegmental tract, contralateral superior cerebellar peduncle, or dentate
nucleus, although may be preceded by any type of injury to these structures.
• Clinical symptoms include palatal myoclonus and uncontrollable tremor,
presumably caused by loss of inhibitory control.
• Neuroimaging findings include a non-enhancing T1 isointense, T2
hyperintense enlargement confined to the olivary nucleus related to
demyelination, vacuolization, and cell death of neurons and astrocytes. The
findings develop around 6 months after then event and resolve after 3-4
years, however clinical symptoms persist.
(a.) Sagittal T1WI demonstrates marked
atrophy of the brainstem with flattening of the
anterior pons and medulla oblongata. (b.) Axial
FLAIR image demonstrates atrophy of the
medulla oblongata. Note the atrophy of the
cerebellar vermis. (c.) Axial FLAIR
demonstrates marked atrophy of the pons and
middle cerebellar peduncles with subtle
hyperintense signal abnormality. (d.) Axial
FLAIR demonstrates atrophy of the midbrain
with associated abnormal hyperintense signal.
(e.) Axial T2WI demonstrates cruciform signal
abnormality within the pons. This is the “hot
cross bun sign”. (f). Axial T2WI demonstrates
marked hypointense signal in the bilateral
putamina secondary to iron deposition. Note
the subtle hyperintense signal along the lateral
putaminal margins. This is the “putaminal rim
sign”.
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• Neurodegenerative disorder clinically resembling
Parkinson’s disease with neuronal loss and gliosis in the
inferior olives, pons, cerebellum, substantia nigra, locus
ceruleus, striatum, and intermediolateral column of the
spinal cord.
• May be grouped into parkinsonian type in which substantia
nigra is the main site affected and cerebellar ataxia type in
which the olivopontocerebellar system is mainly involved.
• Neuroimaging findings include olivopontocerebellar
atrophy, putaminal atrophy, and abnormal T2 prolongation
within the pons and middle cerebellar peduncles thought to
relate to degeneration of pontocerebellar fibers. This
signal abnormality may be cruciform (“hot cross bun
sign”). Additional findings include hypointensity in the
putamina on T2* and T2WI related to iron deposition, and
a thin rim of T2 prolongation along the posterolateral
putamina related to reactive microgliosis and astrogliosis
(“putaminal rim sign”).
Axial T2WI demonstrate volume loss within the left cerebral peduncle and left medulla oblongata secondary to Wallerian degeneration in an 11
month old patient with remote left middle cerebral artery territory infarction. There is cystic encephalomalacia seen in the ipsilateral temporal lobe.
• Process of axonal degeneration distal to injury of the neuronal cell body or
proximal axon which may begin within 1 week of damage and continue
during next 6 months. Signifies irreversible loss of neuronal function.
• Most common cause is cerebral infarction, but may also result from
hemorrhage, neoplasm, trauma, white matter disorders, and multisystem
atrophy.
• Most frequently observed in the corticospinal tract following infarction of the
motor cortex or internal capsule.
• Has also been described in the optic radiations, corpus callosum, spinal cord,
and limbic system.
• Presence or absence of Wallerian degeneration may influence clinical
outcome after stroke.
• Neuroimaging findings are time-dependent and best detected on MRI.
Initially will appear T1 hyperintense and T2 hypointense, then T1 hypointense
and T2 hyperintense, and finally with ipsilateral brainstem atrophy sometimes
with persistent signal abnormality.
• Diffusion weighted imaging may detect Wallerian degeneration in its earliest
stage before T1/T2 signal abnormalities present.
• Diffusion tensor imaging may distinguish between a primary lesion and
associated Wallerian degeneration.
Diffusion weighted images (above left) demonstrate hyperintense signal within the dorsal medulla oblongata, central tegmental tract, cerebellar
vermis, midbrain periaqueductal gray matter, hippocampi, and medial thalami in a bilateral symmetric distribution. There was corresponding
hypointense signal on ADC map consistent with diffusion restriction. There was also hyperintense signal on T2WI/FLAIR at the sites of abnormality,
as demonstrated on the FLAIR images above right.
Follow up imaging was performed 5 days later after treatment. The FLAIR (top) and diffusion (bottom) signal abnormalities had resolved.
• Severe neurologic complication of influenza, typically affecting young children,
characterized by an abrupt onset of seizures and coma within a few days of
developing a high fever.
• Most feared complications are acute necrotizing encephalopathy, Reye’s syndrome
(rapidly progressive postviral encephalopathy), and hemorrhagic shock.
• Adult onset is associated with increased incidence of stroke and myocardial
infarction.
• Mortality rate is as high as 30% without treatment.
• Neuroimaging findings are variable and may include symmetric T2 prolongation
involving the supratentorial white matter, thalamus, splenium, brain stem, and/or
cerebellum, often associated with diffusion restriction. These findings are thought
to relate to an influx of inflammatory cells and macromolecules causing cytotoxic
edema.
• Anti-influenza treatments such as a selective neuraminidase inhibitor (oseltamivir
phosphate), corticosteroids, and hypothermia are quite effective.
• Clinical improvement may precede radiologic improvement.
TOP: Diffusion weighted imaging demonstrate symmetric diffusion restriction in the bilateral dorsal medulla oblongata, facial colliculi, periaqueductal
gray matter, and medial thalami. BOTTOM: Axial FLAIR images demonstrate hyperintense signal intensity at the sites of diffusion restriction.
• Acute neurological syndrome resulting from thiamine (vitamin B1) deficiency.
• Clinical conditions associated with impaired thiamine absorption include chronic alcohol
abuse, gastrointestinal surgery, prolonged vomiting, chemotherapy, systemic infectious
and noninfectious disease, and dietary unbalance.
• Classical clinical triad of confusion, ataxia, and ophthalmoplegia is actually seen in a
minority of patients (16-38%).
• Ocular sings include nystagmus, bilateral lateral rectus palsies, and conjugate gaze
palsies reflecting involvement of the oculomotor, abducens, and vestibular cranial
nerves nuclei.
• Reversible cytotoxic edema is the most distinctive lesion of Wernicke encephalopathy
on MRI, represented by symmetric signal abnormality (hyperintense on long-TR
images) in the medial thalami, periventricular regions of the third ventricle, mammillary
bodies, tectal plate, and periaqueductal area. Signal alteration may also be seen in the
cerebellum, cerebellar vermis, cranial nerve nuclei, red nuclei, dentate nuclei, caudate
nuclei, splenium, cerebral cortex, and medulla oblongata. Enhancement of the
mammillary bodies is occasionally present.
• May be associated with parenchymal atrophy, particularly in alcoholic patients.
• Prognosis is dependent on time of onset of thiamine supplementation.
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Axial T1WI (a.) and T2WI (b-e) demonstrate bilateral symmetric signal abnormality in the medulla oblongata, inferior cerebellar peduncles, tectum,
dorsal midbrain, and ventral midbrain in the region of the substantia nigra. There was associated diffusion restriction at the sites of abnormality (not
shown).
• Progressive mitochondrial neurodegenerative disorder of childhood clinically
characterized by psychomotor delay or regression, muscular hypotonia,
brainstem signs including strabismus, nystagmus, and swallowing difficulties,
ataxia, pyramidal signs, respiratory insufficiency, lactate acidemia, and acute
deterioration after common infections.
• Neuroimaging findings include focal, bilateral, symmetric necrotic lesions in
the basal ganglia, cerebellum, and brainstem which appear hyperintense on
T2WI associated with demyelination, vascular proliferation, and gliosis.
• Atypical neuroimaging features include diffuse supratentorial leukodystrophy,
unifocal or multifocal infarctions, diffuse or focal cortical atrophy, or
predominant cerebellar atrophy.
• Basal ganglia often affected before the brainstem, and disease typically
progresses from upper to lower brainstem.
• Involvement of the lower brainstem indicates advanced stage of the disease,
with medulla oblongata involvement increasing occurrence of respiratory
failure and sudden death.
• Bilateral symmetric T2 prolongation involving multiple brainstem structures
associated with basal ganglia abnormalities in a child with neurological
problems should prompt consideration of Leigh disease.
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(a.) Axial T2WI demonstrates flattening of the medulla oblongata (red arrow) with effacement of the surrounding subarachnoid space due to extrinsic
compression between the C1-C2 vertebral bodies and low lying cerebellar tonsils within the foramen magnum (yellow arrow). (b.) Sagittal T1WI
demonstrates low-lying cerebellar tonsils in a peg-like configuration, consistent with Chiari I malformation. There is indentation on the medulla
oblongata due to the extrinsic mass effect.
• Congenital craniovertebral junction anomaly characterized by
elongated, peg-shaped cerebellar tonsils which extend below the
foramen magnum into the upper cervical spinal canal, often associated
with crowding of the posterior fossa and compression of the CSF
spaces.
• May be asymptomatic in up to half of cases. Most common symptoms
include headache, neck pain, and ataxia.
• When associated with mass effect on the medulla oblongata, may be
associated with bulbar symptoms and/or lower cranial nerve palsies.
This mass effect may result from direct extrinsic compression by the
ectopic cerebellar tonsils, odontoid, or even irregularly coursing
posterior inferior cerebellar arteries or vertebral arteries.
• Often associated with spinal cord syrinx which may extend to involve
the medulla oblongata and cause bulbar symptoms and/or or lower
cranial nerve palsies.
• Suboccipital decompression is surgical treatment of choice.