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## Complete Summary

#### GUIDELINE TITLE

Ataxia.

#### BIBLIOGRAPHIC SOURCE(S)

Brunberg JA, Seidenwurm DJ, Davis PC, De La Paz RL, Dormont PD, Hackney
DB, Jordan JE, Karis JP, Mukherji SK, Turski PA, Wippold FJ II,
Zimmerman RD, McDermott MW, Sloan MA, Expert Panel on Neurologic
Imaging. Ataxia. \[online publication\]. Reston (VA): American College
of Radiology (ACR); 2006. 10 p. \[80 references\]

#### GUIDELINE STATUS

This is the current release of the guideline.

This guideline updates a previous version: Johnson BA, Drayer BP,
Anderson RE, Braffman B, Davis PC, Deck MD, Hasso AN, Masaryk T,
Pomeranz SJ, Seidenwurm D, Tanenbaum L, Masdeu JC. Ataxia. American
College of Radiology. ACR Appropriateness Criteria. Radiology 2000
Jun;215(Suppl):573-8.

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

### COMPLETE SUMMARY CONTENT

 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 QUALIFYING STATEMENTS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

Ataxia

**Note**: Vertigo is a separate American College of Radiology (ACR)
Appropriateness Criteria® topic and will not be readdressed in this
guideline.

#### GUIDELINE CATEGORY

Diagnosis

#### CLINICAL SPECIALTY

Family Practice\
Internal Medicine\
Medical Genetics\
Neurology\
Pediatrics\
Radiology

#### INTENDED USERS

Health Plans\
Hospitals\
Managed Care Organizations\
Physicians\
Utilization Management

#### GUIDELINE OBJECTIVE(S)

To categorize the diverse disorders that may present with ataxia and to
suggest general imaging guidelines that may be useful for patients with
the most common clinical presentations and underlying disorders

#### TARGET POPULATION

Patients with ataxia

#### INTERVENTIONS AND PRACTICES CONSIDERED

1.  Magnetic resonance imaging (MRI)

    -   Brain, without and with contrast

    -   Cervical, thoracic and lumbar spine, without and with contrast

2.  MR angiography (MRA), head and neck, without and with contrast

3.  MR spectroscopy, (MRS), head

4.  Computed tomography (CT)

    -   Head, without and with contrast

    -   Temporal bone

5.  CT angiography (CTA), head and neck

6.  Positron emission tomography with fluorodeoxyglucose (FDG-PET),
    brain

#### MAJOR OUTCOMES CONSIDERED

Utility of radiologic examinations in differential diagnosis

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Searches of Electronic Databases

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

The guideline developer performed literature searches of peer-reviewed
medical journals and the major applicable articles were identified and
collected.

#### NUMBER OF SOURCE DOCUMENTS

The total number of source documents identified as the result of the
literature search is not known.

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

Weighting According to a Rating Scheme (Scheme Not Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

Not stated

#### METHODS USED TO ANALYZE THE EVIDENCE

Systematic Review with Evidence Tables

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

One or two topic leaders within a panel assume the responsibility of
developing an evidence table for each clinical condition, based on
analysis of the current literature. These tables serve as a basis for
developing a narrative specific to each clinical condition.

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

Expert Consensus (Delphi)

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

Since data available from existing scientific studies are usually
insufficient for meta-analysis, broad-based consensus techniques are
needed to reach agreement in the formulation of the appropriateness
criteria. The American College of Radiology (ACR) Appropriateness
Criteria panels use a modified Delphi technique to arrive at consensus.
Serial surveys are conducted by distributing questionnaires to
consolidate expert opinions within each panel. These questionnaires are
distributed to the participants along with the evidence table and
narrative as developed by the topic leader(s). Questionnaires are
completed by the participants in their own professional setting without
influence of the other members. Voting is conducted using a scoring
system from 1-9, indicating the least to the most appropriate imaging
examination or therapeutic procedure. The survey results are collected,
tabulated in anonymous fashion, and redistributed after each round. A
maximum of three rounds is conducted and opinions are unified to the
highest degree possible. Eighty percent agreement is considered a
consensus. This modified Delphi technique enables individual, unbiased
expression, is economical, easy to understand, and relatively simple to
conduct.

If consensus cannot be reached by the Delphi technique, the panel is
convened and group consensus techniques are utilized. The strengths and
weaknesses of each test or procedure are discussed and consensus reached
whenever possible. If \"No consensus\" appears in the rating column,
reasons for this decision are added to the comment sections.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

Not applicable

#### COST ANALYSIS

A formal cost analysis was not performed and published cost analyses
were not reviewed.

#### METHOD OF GUIDELINE VALIDATION

Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

Criteria developed by the Expert Panels are reviewed by the American
College of Radiology (ACR) Committee on Appropriateness Criteria.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

**ACR Appropriateness Criteria®**

**Clinical Condition: : Ataxia**

**Variant 1: Slowly progressive ataxia, or ataxia of long duration
(adult or child).**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  MRI, brain, without  8                    
  and with contrast                        

  MRI, brain, without  7                    
  contrast                                 

  MRI, cervical,       7                   Ataxia can be of spinal origin.
  thoracic and lumbar                      Consider if brain imaging is
  spine, without and                       negative or inconclusive.
  with contrast                            

  MRI, cervical        6                   Ataxia can be of spinal origin.
  thoracic, and lumbar                     Consider if brain imaging is
  spine, without                           negative or inconclusive
  contrast                                 

  CT, head, without    5                    
  and with contrast                        

  FDG-PET, brain       3                    

  MR spectroscopy      2                    
  (MRS), head                              

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 2: Acute ataxia (\<3 hours) as a manifestation of suspected
stroke (adult or child). (Also see the ACR Appropriateness Criteria®
topic for cerebrovascular disease).**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  MRI, brain, with or  8                   MR preferred if treatment is not
  without contrast                         unreasonably delayed. Combined
                                           vascular and cerebral evaluation
                                           should be considered. Fat
                                           saturated T1 axial images.

  MRA, head and neck,  8                   MR preferred if treatment is not
  with or without                          unreasonably delayed. Combined
  contrast                                 vascular and cerebral evaluation
                                           should be considered.

  CTA, head and neck   8                   MR preferred if treatment is not
                                           unreasonably delayed. Combined
                                           vascular and cerebral evaluation
                                           should be considered.

  CT, head, with or    8                   CT perfusion is less accurate in
  without contrast                         the posterior fossa. MR preferred
                                           if treatment is not unreasonably
                                           delayed. Combined vascular and
                                           cerebral evaluation should be
                                           considered.

  MRI, cervical spine, 5                   Fat saturated T1 axial images.
  without and with                         
  contrast                                 

  MRI, cervical spine, 4                    
  without contrast                         

  MR spectroscopy      2                    
  (MRS), head                              

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 3: Acute or subacute ataxia as a manifestation of suspected
infection (adult or child).**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  MRI, brain, without  8                    
  and with contrast                        

  MRI, brain, without  7                    
  contrast                                 

  MRI, cervical spine, 6                   Ataxia can be of spinal origin.
  without and with                         Consider if brain imaging is
  contrast                                 negative or inconclusive.

  MR spectroscopy      6                   May help distinguish abscess from
  (MRS), head                              other masses.

  MRI, cervical spine, 5                   Ataxia can be of spinal origin.
  without contrast                         Consider if brain imaging is
                                           negative or inconclusive.

  MRA, head, without   5                    
  and with contrast                        

  CTA, head            5                    

  CT, head, without    5                    
  and with contrast                        

  CT, temporal bone    5                   Useful when skull-based or middle
                                           ear disease suspected.

  MRA, head, without   4                    
  contrast                                 

  CT, head without     4                    
  contrast                                 

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 4: Acute ataxia following head trauma, less than 24 hours
(adult or child).**

  ---------------------------------------------------------------------------
  **Radiologic         **Appropriateness   **Comments**
  Procedure**          Rating**            
  -------------------- ------------------- ----------------------------------
  CT, head, without    9                    
  contrast                                 

  MRI, head, without   8                    
  contrast                                 

  CT, temporal bone    7                   Useful when skull-based or middle
                                           ear disease suspected.

  MRI, head, without   7                    
  and with contrast                        

  MRI, neck, without   6                    
  and with contrast                        

  CT, head, without    6                    
  and with contrast                        

  CTA, head and neck   6                    

  MRA, head and neck,  6                    
  with or without                          
  contrast                                 

  ***Appropriateness                       
  Criteria Scale*\                         
  1 2 3 4 5 6 7 8 9\                       
  1 = Least                                
  appropriate 9 = Most                     
  appropriate**                            
  ---------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Summary of Literature Review**

Ataxia is a term that is used to describe abnormality in the
coordination of movement. Manifestations commonly include a wide-based
unsteady gait and poor coordination of the extremities. There can be
associated abnormality in ocular motility and poor coordination of
speech.

Ataxia can separately arise from disorders that involve the cerebellum,
spinal cord, brainstem, vestibular nuclei, thalamic nuclei, white matter
tracts of the brain stem and cerebral hemispheres, cerebral cortex
(especially the frontal lobes), and peripheral sensory nerves. Because
the anatomic regions responsible for ataxia are multiple, an effective
imaging evaluation is often complex. Additionally, in patients with
distinct clinical ataxia, appropriate magnetic resonance imaging (MRI)
or computed tomography (CT) imaging of the cerebellum itself, or of the
entire brain and spinal cord, may be entirely normal. This is most
likely to occur early in the course of toxic, metabolic, or other
progressive disorders associated with ataxia.

The medical disorders that cause ataxia are numerous and complex, and
they are often individually quite uncommon. The development of
prospective generalized recommendations for imaging, for the inclusion
of anatomic regions to be studied, and for the use of specific protocols
or pulse sequences is therefore imprecise. The purpose of this
discussion, and of the guidelines presented below, is to categorize the
diverse disorders that may present with ataxia and to suggest general
imaging guidelines that may be useful for patients with the most common
clinical presentations and underlying disorders. For individual
patients, study design will be significantly compromised if the history
that accompanies the patient is not precise or sufficient relative to
the clinical and family history, to specific physical findings and/or to
the results of relevant laboratory studies, many of which are quite
complex.

Ataxia-associated disorders have been the subject of several
classification schemes. For basic clinical and imaging purposes,
however, these disorders can be approached on the basis of age at onset,
potential disease mechanism, and anticipated clinical urgency for
excluding a disorder that requires immediate diagnosis and management.

**Classification of Disorders Causing Ataxia**

*Mass Lesions*

The exclusion of a posterior fossa mass lesion is often an important
consideration in evaluating a patient with ataxia. The suspected mass
can be primary or metastatic, and it can be intra-axial or extra-axial
in location. In pediatric patients the most common intra-axial posterior
fossa lesions are medulloblastoma, cystic astrocytoma, ependymoma, and
brain stem glioma. In adults, intra-axial hemangioblastomas, choroid
plexus papillomas, extra-axial meningiomas, and a host of intra-axial,
extra-axial, or diffuse leptomeningeal metastatic processes become more
prevalent. Isolated frontal lobe and thalamic mass lesions can also
present with varying manifestations of gait and limb ataxia. Unless
there is a contraindication, MRI, without and with contrast, is almost
always superior to CT for the initial exclusion and characterization of
a posterior fossa or other intracranial mass lesion.

Lhermitte-Duclos disease (dysplastic gangliocytoma) is a slowly growing
benign cerebellar hamartoma or congenital malformation. Symptoms
correlate with local mass effect. MRI demonstrates a cerebellar
hemisphere mass that involves the cortex and folia and is generally of
increased T2 signal intensity. There are also characteristic internal
curvilinear bands that are isointense with cerebellar cortex. The mass
does not enhance with contrast, and it may demonstrate restricted
diffusion. Cowden syndrome, an autosomal dominant disorder characterized
by cutaneous and noncutaneous hamartomas and by breast, thyroid,
gastrointestinal and urologic gastric ulcer and genitourinary (GU)
neoplasias, is frequently associated.

Paraneoplastic cerebellar degeneration is clinically characterized by
the subacute or acute onset of gait and limb ataxia, dysarthria, and
ocular dysmetria. It can occur in association with essentially any tumor
type but most commonly occurs with breast, gynecologic, and lung tumors,
and in association with Hodgkin\'s disease. Tumor seeding of brain
parenchyma is not demonstrated with tissue sampling or with imaging.
Several antineuronal antibodies have been identified in serum and in
tissue, depending on the originating tumor cell type. MRI is generally
normal until late stages of the simultaneously involved brain
parenchymal areas. CT imaging and/or positron emission tomography (PET)
imaging are indicated when an underlying primary is not evident.

*Vascular Disorders*

Strategically located ischemic or hemorrhagic insults can result in
distinct and often prominent ataxia. Infarction in the distribution of
the posterior inferior cerebellar artery (lateral medullary syndrome or
Wallenberg syndrome) is the most common pattern of brainstem infarction
that is associated with a specific syndrome of ataxia. Symptoms include
ipsilateral hemiataxia, vertigo, dysarthria, ptosis, and miosis. While
brainstem and cerebellar infarctions are predominately arterial in
origin, venous infarction should also be considered. The radiologic
evaluation of ataxia generally requires MRI, with water diffusion
characterization and with time-of-flight MR angiography. Use is also
made of neck vessel MRI, using T1-weighted images, without and with fat
saturation, to exclude the possibility of dissection. MR venography
should be accomplished if there is consideration of central or dural
venous thrombosis. Catheter-based diagnostic angiography and/or CT
angiography (CTA) is occasionally necessary.

When the posterior fossa or supratentorial brain parenchyma is involved,
vascular malformations, angiopathy, or aneurysm rupture can each lead to
the acute development of ataxia. When there is consideration of acute or
subacute hemorrhage, CT imaging of the brain and CTA may replace or
supplement MRI.

MRI is the definitive diagnostic procedure for characterizing
superficial siderosis. In this disorder hemosiderin accumulates in
subpial layers of brain and spinal cord as the result of recurrent,
often silent, subarachnoid hemorrhage. The most prominent symptoms are
slowly progressive ataxia and hearing loss. With MRI there is low
superficial T2 signal intensity over cortex, brain stem, and/or spinal
cord with usual cerebellar atrophy.

*Infectious and Postinfectious Processes*

A number of infectious and postinfectious processes can be responsible
for the development of ataxia. To detect infectious-process-related
alterations in the cerebellum, MRI without and with contrast
administration, provides a distinct advantage over CT. This advantage is
due to superior contrast resolution of MRI, and to the absence of
CT-related artifacts that can occur in association with bone at the
margins of the posterior fossa.

Bacterial cerebellitis can occur in association with meningitis or with
cerebritis involving the cerebral hemispheres. It can also occur
independently. Penetrating trauma or transdural extension of an epidural
process, most commonly from the temporal bone, also needs to be
considered. Diffusion imaging and MR spectroscopy can narrow the
differential diagnosis. Multiple viral processes, including herpes and
arbovirus, can also be associated with brainstem or cerebellar
involvement.

Variant Creutzfeldt-Jakob disease (vCJD), also known as bovine
spongiform encephalopathy (BSE), familial Creutzfeldt-Jakob disease
(fCJD), and sporadic Creutzfeldt-Jakob disease (sCJD) are the most
common prion-associated spongiform encephalopathies. Both vCJD and sCJD
present with behavioral, emotional, and intellectual deterioration,
followed by development of ataxia and dysarthria. Progression is to
stupor and coma, with associated myoclonus being prominent in sCJD. The
clinical course is more prolonged in vCJD. MRI demonstrates increased T2
signal intensity, and increased signal intensity on inversion recovery
and diffusion-weighted sequences, in the heads of the caudate nuclei,
the putamen, and regions of frontal, parietal, and occipital cortex.
These alterations in signal intensity can initially be asymmetric. There
is eventual diffuse volume loss. While all forms of CJD can have
increased T2 signal intensity and restricted diffusion in the thalamic
nuclei and in the pulvinar bilaterally, this focal alteration is
especially prominent in vCJD.

Acute cerebellitis, also called acute cerebellar ataxia, is a
para-infectious disorder that predominately, but not exclusively, occurs
in childhood. Symptoms include headache, ataxia, photophobia, and
varying findings associated with potential increased intracranial
pressure or brainstem involvement. MRI demonstrates increased T2 signal
intensity in the cerebellar hemispheres with associated mass effect.
Bilateral abnormality is more common than unilateral abnormality. There
may be obstruction of cerebrospinal fluid (CSF) flow with enlargement of
the lateral ventricles and upward herniation of posterior fossa
structures. There may also be cerebellar meningeal enhancement following
contrast administration. Surgical decompression of the posterior fossa
may be necessary. Follow-up imaging may demonstrate cerebellar atrophy.

Bickerstaff encephalitis is a brainstem and cerebellar inflammatory
disorder that most commonly follows a viral illness. It is characterized
by ataxia and ophthalmoplegia, with MRI demonstrating mass effect,
increased T2 signal intensity, and restricted diffusion within portions
of the pons, medulla, and cerebellum.

Fisher syndrome, a variant of the Guillain-Barré syndrome, involves the
peripheral and central nervous system. It is clinically characterized by
ophthalmoplegia and cerebellar ataxia, and it is associated with
transient high T2 signal intensity within the cerebellum and/or
brainstem. Enhancement of cranial nerves and spinal nerve roots can be
demonstrated, and there may be increased T2 signal intensity within the
posterior portions of the spinal cord. Fluid attenuated inversion
recovery (FLAIR) images often demonstrate this alteration to greatest
advantage in the acute phase. Cerebellar atrophy is generally
demonstrated during the convalescent phase.

*Trauma*

Gait instability is a frequent component of concussion syndrome, and it
may persist in association with a posttraumatic encephalopathy. Symptoms
may be due to damage to the posterior fossa, vestibular, or brain stem
structures. Persisting ataxia can also relate to frontal lobe injury.
One possible explanation for the association of ataxia with a frontal
lobe lesion of any origin is interruption of the frontopontocerebellar
tract (Arnold\'s bundle). This tract originates in Brodmann\'s area 10
and carries information regarding intentional movement to the
contralateral cerebellum via the middle cerebellar peduncle.
Interruption of this tract along its course, or at its origin, deprives
the cerebellum of frontal cortical input, resulting in impaired
coordination and locomotion. In the presence of acute trauma, or in
subjects with progressive post-traumatic ataxia, an expanding cyst or
extra-axial hematoma should separately be considered.

*Demyelinating Disorders*

Multiple sclerosis patients commonly present with or subsequently
manifest persisting ataxia. In these patients, MRI (without and with
contrast), diffusion imaging, spectroscopy, perfusion imaging, and
magnetization transfer imaging can each support but not establish the
diagnosis. The presence of multiple oval periventricular regions of
increased T2 signal intensity, generalized cerebral volume loss,
callosal and optic nerve involvement, and ring enhancement of active
lesions is typical. MRI findings, and the utility of advanced MRI
techniques for patient evaluation and management, have recently been
reviewed.

*Congenital Disorders*

A large number of ataxia-associated disorders occur on a congenital
basis. In each of these processes MRI is preferred to CT. All of these
disorders will most commonly manifest ataxia during early childhood
development. Some of them are sporadic, while others have a known or an
apparent genetic basis. Clinical abnormalities that occur in association
with congenital ataxia can include mild to severe mental retardation,
hearing loss, optic atrophy, cataract, growth retardation, seizures,
cleft palate, and either spasticity or diminished muscle tone. In these
well-characterized congenital ataxia-associated disorders, imaging
findings generally include nonspecific hypoplasia of the cerebellar
vermis, hypoplasia of the entire cerebellum, or congenital cerebellar
developmental dysplasia. Additional associated imaging alterations can
include brain stem hypoplasia, lissencephaly, aprosencephaly,
microcephaly, or variable and less prominent cerebral developmental
alteration.

Though the disorders that can present as congenital ataxia are
individually uncommon, a small number are more frequently recognized.
Dandy Walker Syndrome, with ataxia, nystagmus, cranial nerve palsies,
apneic episodes, hydrocephalus, and cognitive dysfunction, is
characterized by hypoplasia of the cerebellar vermis with an associated
CSF collection that is predominately posterior to the cerebellum but
continuous with the fourth ventricle. The torcula is usually elevated
and the posterior fossa usually enlarged. Hydrocephalus is frequently
associated, and there may be anomalies of cerebral development that
involve the cerebral cortex and corpus callosum. Differentiation from
other congenital or acquired posterior fossa cysts is essential.

Joubert syndrome, with congenital ataxia, hypotonia, and oculomotor
ataxia, has unique imaging alterations that involve the midbrain and
cerebellum (\"molar tooth\" contour of brainstem or \"bat wing\"
configuration of fourth ventricle). Four types have been identified,
each with somewhat variable clinical and imaging features, and with
genetic alterations that involve different loci.

Rhombencephalosynapsis is a rare cerebellar dysplastic process that can
occur alone or in association with other developmental anomalies. In
rhombencephalosynapsis there is vermian agenesis with fusion of the
cerebellar hemispheres, apposition or fusion of the dentate nuclei, and
fusion of the superior cerebellar peduncles. There is usually
enlargement of the lateral ventricles, and there may be fusion of the
thalamic nuclei. There is a wide spectrum of clinical symptomatology,
and some patients are clinically normal.

Congenital ataxia can also occur in association with perinatal cerebral
infarction and in association with congenital cytomegalovirus or other
infectious processes of the central nervous system. Though uncommon
relative to other forms of cerebral palsy, the imaging correlates of
ataxic cerebral palsy have not been well defined.

*Hereditary and Idiopathic Degenerative Processes*

The hereditary ataxias are classified on the basis of their causative
gene (when known) and their pattern of inheritance (autosomal dominant,
autosomal recessive, x-linked, or mitochondrial). In each of these
disorders MRI is the preferred imaging modality. Among this group of
patients, a broad range of potential diagnostic considerations is often
suggested by family history, by findings on physical examination, and,
in symptomatic patients, by MRI evidence of atrophy involving the
cerebellum and varying combinations of the pons, medulla, spinal cord,
cerebral cortex and optic nerves. Dentate calcification may also be
identified on CT imaging. Definitive diagnosis, however, relies on
molecular genetic testing. While cerebellar ataxia is the dominant and
occasionally the only clinical finding, spasticity, neuropathy,
seizures, extrapyramidal symptomatology, mental retardation, cognitive
decline, nystagmus, visual loss, spasmodic cough, and migraine-like
episodes may also be associated.

Among the identified autosomal dominant spinocerebellar ataxias
(AD-SCAs), specific diagnostic nomenclature is replacing less specific
terms such as \"spinocerebellar degeneration,\" \"Marie\'s ataxia,\" and
olivopontocerebellar atrophy (OPCA). Among the AD-SCA disorders, 22
separate and distinct genetic abnormalities have now been identified.
The term OPCA continues to be used only as a label for cases that have a
clinical and pathology-related combination of \"cerebellar-plus\"
symptomatology, have imaging correlates of cerebellar and brainstem
atrophy, and have an (as yet) unidentified genetic basis. The
designation of \"idiopathic late onset cerebellar ataxia\" is separately
used to describe a different and significantly large group of adult
patients with predominant cerebellar symptomatology, absence of a family
history, and absence of an identified genetic marker. In these patients
MRI generally demonstrates cerebellar and pontine volume loss.

SCA2 is one form of AD-SCA. It is caused by the presence of 32 or more
CAG trinucleotide repeats on the ATXN2 gene. Symptoms include slowly
progressive ataxia, dysarthria, nystagmus and initially brisk but later
absent tendon reflexes, with associated peripheral neuropathy. Dystonia,
Parkinsonism, and dementia may also be present in SCA2. Symptoms are
more rapidly progressive when they have their onset before 20 years of
age. Imaging findings include cerebellar and pontine volume loss and
deep white matter alterations that may also involve the cerebral
hemispheres. Although SCA2 is a relatively common form of AD-SCA (13% of
AD-SCA cases in one study), clinical and imaging features do not allow a
definitive diagnosis. Molecular genetic analysis is necessary. Many, but
not all cases as Marie\'s ataxia and AD-OPCA are thought to represent
SCA2.

SCA3 (Machado-Joseph disease or MJD) accounts for 23% of patients with
AD-SCA. Symptoms most commonly include an onset in the second to fourth
decade of cerebella ataxia, spasticity, peripheral neuropathy, bulbar
dysfunction with facial and tongue atrophy, and occasional myoclonus or
intellectual impairment. Subtypes have been described. MRI alterations
include volume loss involving the cerebellum, pons and medulla, and a
linear region of high T2 signal intensity along the posterior and medial
margins of the globus pallidus.

Dentatorubral-pallidoluysian (DRPLA) is characterized by progressive
ataxia, choreoathetosis, and dementia or character changes when the
disorder occurs in adults. In children it is characterized by ataxia,
myoclonus, epilepsy, and progressive intellectual deterioration. MRI
demonstrates cerebellar and brainstem volume loss with cerebral cortical
atrophy. Less frequently there is increased T2 signal intensity in deep
white matter of the cerebral hemispheres, in the thalamus, and in the
brainstem. Diagnosis is established through the identification of \>48
CAG repeats in the DRPLA gene.

Autosomal recessive hereditary ataxias can be associated with multiple
underlying genetic disorders. Refer to the original guideline document
for a description of ataxia-telangiectasia, fragile X tremor/ataxia
syndrome, multiple system atrophy, and mitochondrial disorders.

*Paroxysmal Disorders*

Paroxysmal ataxia has been associated with several disorders, including
epilepsy and migraine, as well as with a transient limb and trunk ataxia
that can occur with high systemic fever in otherwise healthy children.
These disorders can be idiopathic or can be associated with
abnormalities in membrane calcium or potassium channel function, or with
altered synaptic glutamate transport. MRI may be normal, may demonstrate
cerebellar volume loss, or may demonstrate extensive areas of cortical
increased T2 signal intensity that may correlate with the possible
simultaneous occurrence of hemiplegic migraine or recent seizure
activity. MRI is the imaging modality of choice.

*Spinal Cord and Peripheral Nerve-Related Ataxia*

Ataxia that is potentially due to pathologic processes that originate
within the spinal cord, or within the roots/nerves that originate from
the spinal cord, requires high resolution T1 and T2-weighted axial and
sagittal imaging without and with contrast that focuses on the posterior
columns and on the nerve roots. Findings in pernicious anemia depend on
the duration and severity of the disorder.

There may be early localized or relatively diffuse cord swelling with
increased T2 signal intensity that is usually most evident in the
posterior columns. Late atrophy and persistent gliosis may develop, or
all findings may resolve with treatment. In the presence of
hypertrophic, inflammatory, or postinfectious polyneuropathies, nerve
root enhancement and enlargement may be demonstrated with MRI.

*Nutritional Deficiency, Toxins and Drugs*

In each of these disorders MRI is the preferred imaging modality.
Solvent abuse or toxic exposure to solvents can result in gait
impairment and in encephalopathy. MRI abnormalities are characterized by
diffuse cortical atrophic changes and by hyperintensity on T2-weighted
images in the white matter, basal ganglia, and thalami.

Methyl-mercury poisoning (Minamata disease) is a neurological illness
caused by the ingestion of contaminated seafood and characterized by
ataxia, visual loss, and sensory disturbance. MRI in affected patients
demonstrates atrophy of the cerebellar vermis and hemispheres, as well
as the calcarine cortex.

Metronidazole (Flagyl)-induced cerebellar toxicity is associated with
symptoms of ataxia, with MRI findings of increased T2 signal intensity
and restricted diffusion in the dentate nuclei. With symptom resolution
MRI becomes normal.

In central pontine myelinolysis (osmotic demyelination syndrome),
cerebellar or extrapyramidal symptoms have been observed. More
typically, patients demonstrate coma, locked-in syndrome, or
quadriparesis. This disorder is typically seen in chronic alcoholics or
malnourished patients following the rapid correction of hyponatremia.
Increased T2 signal intensity in the pons is the characteristic finding.

A leukoencephalopathy with initial symptoms of ataxia has also been
reported to occur in association with the chronic inhalation of heroin
vapors.

Vitamin E deficiency can occur in association with several acquired
gastrointestinal disorders or with autosomal recessive defects in
vitamin E transport. Symptoms include ataxia with associated weakness,
areflexia, and retinal degeneration. Imaging has demonstrated cerebellar
atrophy and increased T2 signal intensity in the posterior columns of
the spinal cord.

Chronic ethanol abuse is associated with ataxia and multiple other
symptoms of neurologic dysfunction. These symptoms result from the
neurotoxicity of ethanol and its metabolic products, from associated
chronic liver disease, from secondary nutritional deficiencies, and from
the effect of other toxins that are simultaneously ingested. MRI
demonstrates atrophy of the cerebellar vermis, especially superiorly, as
well as volume loss involving pons, medulla, and cerebral hemispheres.

Wernicke encephalopathy is due to thiamine deficiency and classically
presents with ataxia, altered mental status, and abnormality of ocular
motility. MRI demonstrates increased T2 signal intensity, reversible
contrast enhancement, and reversible restricted diffusion in multiple
areas including mammillary bodies, hypothalamus adjacent to the third
ventricle, periaqueductal gray and white matter, pulvinar, and
dorsomedial portions of the thalamic nuclei. Small hemorrhagic foci can
also be demonstrated in these regions.

Reversible posterior leukoencephalopathy is most commonly characterized
by headache, altered consciousness, visual disturbance, and seizures.
Ataxia can be a component, especially when there is brainstem or
cerebellar involvement. Antecedent clinical conditions include
hypertension, eclampsia, renal disease, and the use of cytotoxic or
immunosuppressant drugs. MRI findings include the presence of bilateral
and generally symmetrically increased T2 signal intensity in the
posterior parietal and occipital lobes, with apparent early restricted
and subsequent increased diffusion in these same areas.

**Abbreviations**

-   CT, computed tomography

-   CTA, computed tomographic angiography

-   FDG, fluorodeoxyglucose

-   MRA, magnetic resonance angiography

-   MRI, magnetic resonance imaging

-   PET, positron emission tomography

#### CLINICAL ALGORITHM(S)

Algorithms were not developed from criteria guidelines.

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

The recommendations are based on analysis of the current literature and
expert panel consensus.

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

Selection of appropriate radiologic imaging procedures for evaluation of
patients with ataxia

#### POTENTIAL HARMS

Not stated

### QUALIFYING STATEMENTS

#### QUALIFYING STATEMENTS

An American College of Radiology (ACR) Committee on Appropriateness
Criteria and its expert panels have developed criteria for determining
appropriate imaging examinations for diagnosis and treatment of
specified medical condition(s). These criteria are intended to guide
radiologists, radiation oncologists and referring physicians in making
decisions regarding radiologic imaging and treatment. Generally, the
complexity and severity of a patient\'s clinical condition should
dictate the selection of appropriate imaging procedures or treatments.
Only those exams generally used for evaluation of the patient\'s
condition are ranked. Other imaging studies necessary to evaluate other
co-existent diseases or other medical consequences of this condition are
not considered in this document. The availability of equipment or
personnel may influence the selection of appropriate imaging procedures
or treatments. Imaging techniques classified as investigational by the
U.S. Food and Drug Administration (FDA) have not been considered in
developing these criteria; however, study of new equipment and
applications should be encouraged. The ultimate decision regarding the
appropriateness of any specific radiologic examination or treatment must
be made by the referring physician and radiologist in light of all the
circumstances presented in an individual examination.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

Personal Digital Assistant (PDA) Downloads

For information about
[availability](#identifying-information-and-availability), see the
\"Availability of Companion Documents\" and \"Patient Resources\" fields
below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

Living with Illness

#### IOM DOMAIN

Effectiveness

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

Brunberg JA, Seidenwurm DJ, Davis PC, De La Paz RL, Dormont PD, Hackney
DB, Jordan JE, Karis JP, Mukherji SK, Turski PA, Wippold FJ II,
Zimmerman RD, McDermott MW, Sloan MA, Expert Panel on Neurologic
Imaging. Ataxia. \[online publication\]. Reston (VA): American College
of Radiology (ACR); 2006. 10 p. \[80 references\]

#### ADAPTATION

Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

1999 (revised 2006)

#### GUIDELINE DEVELOPER(S)

American College of Radiology - Medical Specialty Society

#### SOURCE(S) OF FUNDING

The American College of Radiology (ACR) provided the funding and the
resources for these ACR Appropriateness Criteria®.

#### GUIDELINE COMMITTEE

Committee on Appropriateness Criteria, Expert Panel on Neurologic
Imaging

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

*Panel Members*: James A. Brunberg, MD; David J. Seidenwurm, MD;
Patricia C. Davis, MD; Robert L. DeLaPaz, MD; Pr. Didier Dormont; David
B. Hackney, MD; John E. Jordan, MD; John P. Karis, MD; Suresh Kumar
Mukherji, MD; Patrick A. Turski, MD; Franz J. Wippold II, MD; Robert D.
Zimmerman, MD; Michael W. McDermott; Michael A. Sloan, MD, MS

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

Not stated

#### GUIDELINE STATUS

This is the current release of the guideline.

This guideline updates a previous version: Johnson BA, Drayer BP,
Anderson RE, Braffman B, Davis PC, Deck MD, Hasso AN, Masaryk T,
Pomeranz SJ, Seidenwurm D, Tanenbaum L, Masdeu JC. Ataxia. American
College of Radiology. ACR Appropriateness Criteria. Radiology 2000
Jun;215(Suppl):573-8.

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

#### GUIDELINE AVAILABILITY

Electronic copies: Available in Portable Document Format (PDF) from the
[American College of Radiology (ACR) Web
site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonNeurologicImaging/AtaxiaDoc1.aspx).

ACR Appropriateness Criteria® *Anytime*, *Anywhere*™ (PDA application).
Available from the [ACR Web
site](http://www.acr.org/SecondaryMainMenuCategories/ACRStore/FeaturedCategories/QualityandSafety/ac_pda.aspx).

Print copies: Available from the American College of Radiology, 1891
Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

#### AVAILABILITY OF COMPANION DOCUMENTS

The following is available:

-   ACR Appropriateness Criteria®. Background and development. Reston
    (VA): American College of Radiology; 2 p. Electronic copies:
    Available in Portable Document Format (PDF) from the [American
    College of Radiology (ACR) Web
    site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/background_dev.aspx).

#### PATIENT RESOURCES

None available

#### NGC STATUS

This summary was completed by ECRI on July 31, 2001. The information was
verified by the guideline developer as of August 24, 2001. This NGC
summary was updated by ECRI Institute on April 27, 2007.

#### COPYRIGHT STATEMENT

Instructions for downloading, use, and reproduction of the American
College of Radiology (ACR) Appropriateness Criteria® may be found on the
[ACR Web
site.](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/ACRAppropriatenessCriteriaTermsandConditionsDoc1.aspx)

### DISCLAIMER

#### NGC DISCLAIMER

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Date Modified: 11/3/2008