Horner Syndrome

Variant: 1 Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
CTA head and neck with IV contrast	Usually Appropriate	☢☢☢
CT head without IV contrast and CTA head and neck with IV contrast	Usually Appropriate	☢☢☢☢
MRA head and neck with IV contrast	Usually Not Appropriate	O
MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without IV contrast	Usually Not Appropriate	O
MRI cervical spine with IV contrast	Usually Not Appropriate	O
MRI cervical spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical spine without IV contrast	Usually Not Appropriate	O
MRI head and orbits with IV contrast	Usually Not Appropriate	O
MRI head and orbits without and with IV contrast	Usually Not Appropriate	O
MRI head and orbits without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRI head without IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI neck with IV contrast	Usually Not Appropriate	O
MRI neck without and with IV contrast	Usually Not Appropriate	O
MRI neck without IV contrast	Usually Not Appropriate	O
MRI orbits with IV contrast	Usually Not Appropriate	O
MRI orbits without and with IV contrast	Usually Not Appropriate	O
MRI orbits without IV contrast	Usually Not Appropriate	O
MRI thoracic spine with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CT neck with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without and with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without IV contrast	Usually Not Appropriate	☢☢☢

Variant: 2 Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
CTA head and neck with IV contrast	Usually Appropriate	☢☢☢
CT head without IV contrast and CTA head and neck with IV contrast	Usually Appropriate	☢☢☢☢
MRA head and neck without and with IV contrast	May Be Appropriate	O
MRA head and neck without IV contrast	May Be Appropriate	O
MRI head without and with IV contrast	May Be Appropriate	O
MRI head without and with IV contrast and MRA head and neck with IV contrast	May Be Appropriate (Disagreement)	O
MRI head without and with IV contrast and MRA head and neck without and with IV contrast	May Be Appropriate (Disagreement)	O
MRI head without and with IV contrast and MRA head and neck without IV contrast	May Be Appropriate (Disagreement)	O
MRI head without IV contrast and MRA head and neck without IV contrast	May Be Appropriate (Disagreement)	O
MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without IV contrast	Usually Not Appropriate	O
MRI cervical spine with IV contrast	Usually Not Appropriate	O
MRI cervical spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical spine without IV contrast	Usually Not Appropriate	O
MRI head and orbits with IV contrast	Usually Not Appropriate	O
MRI head and orbits without and with IV contrast	Usually Not Appropriate	O
MRI head and orbits without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRI neck with IV contrast	Usually Not Appropriate	O
MRI neck without and with IV contrast	Usually Not Appropriate	O
MRI neck without IV contrast	Usually Not Appropriate	O
MRI orbits with IV contrast	Usually Not Appropriate	O
MRI orbits without and with IV contrast	Usually Not Appropriate	O
MRI orbits without IV contrast	Usually Not Appropriate	O
MRI thoracic spine with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CT neck with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without and with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without IV contrast	Usually Not Appropriate	☢☢☢

Variant: 3 Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI cervical and thoracic spine without and with IV contrast	Usually Appropriate	O
MRI cervical and thoracic spine without IV contrast	May Be Appropriate (Disagreement)	O
MRI cervical spine without and with IV contrast	May Be Appropriate	O
MRI cervical spine without IV contrast	May Be Appropriate	O
MRA head and neck with IV contrast	Usually Not Appropriate	O
MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine with IV contrast	Usually Not Appropriate	O
MRI cervical spine with IV contrast	Usually Not Appropriate	O
MRI head and orbits with IV contrast	Usually Not Appropriate	O
MRI head and orbits without and with IV contrast	Usually Not Appropriate	O
MRI head and orbits without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRI head without IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI neck with IV contrast	Usually Not Appropriate	O
MRI neck without and with IV contrast	Usually Not Appropriate	O
MRI neck without IV contrast	Usually Not Appropriate	O
MRI orbits with IV contrast	Usually Not Appropriate	O
MRI orbits without and with IV contrast	Usually Not Appropriate	O
MRI orbits without IV contrast	Usually Not Appropriate	O
MRI thoracic spine with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CT neck with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without and with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without IV contrast	Usually Not Appropriate	☢☢☢
CTA head and neck with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast and CTA head and neck with IV contrast	Usually Not Appropriate	☢☢☢☢

Variant: 4 Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
MRI head and orbits without and with IV contrast	May Be Appropriate (Disagreement)	O
MRI head and orbits without IV contrast	May Be Appropriate (Disagreement)	O
MRI head without and with IV contrast	May Be Appropriate	O
MRI head without and with IV contrast and MRA head and neck without and with IV contrast	May Be Appropriate (Disagreement)	O
MRI head without and with IV contrast and MRA head and neck without IV contrast	May Be Appropriate (Disagreement)	O
MRI head without IV contrast	May Be Appropriate	O
MRI orbits without and with IV contrast	May Be Appropriate (Disagreement)	O
MRI orbits without IV contrast	May Be Appropriate	O
CT head without IV contrast and CTA head and neck with IV contrast	May Be Appropriate	☢☢☢☢
MRA head and neck with IV contrast	Usually Not Appropriate	O
MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without IV contrast	Usually Not Appropriate	O
MRI cervical spine with IV contrast	Usually Not Appropriate	O
MRI cervical spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical spine without IV contrast	Usually Not Appropriate	O
MRI head and orbits with IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI neck with IV contrast	Usually Not Appropriate	O
MRI neck without and with IV contrast	Usually Not Appropriate	O
MRI neck without IV contrast	Usually Not Appropriate	O
MRI orbits with IV contrast	Usually Not Appropriate	O
MRI thoracic spine with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CT neck with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without and with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without IV contrast	Usually Not Appropriate	☢☢☢
CTA head and neck with IV contrast	Usually Not Appropriate	☢☢☢

Variant: 5 Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.

Procedure	Appropriateness Category	Relative Radiation Level
CTA head and neck with IV contrast	Usually Appropriate	☢☢☢
MRA head and neck with IV contrast	Usually Not Appropriate	O
MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical and thoracic spine without IV contrast	Usually Not Appropriate	O
MRI cervical spine with IV contrast	Usually Not Appropriate	O
MRI cervical spine without and with IV contrast	Usually Not Appropriate	O
MRI cervical spine without IV contrast	Usually Not Appropriate	O
MRI head and orbits with IV contrast	Usually Not Appropriate	O
MRI head and orbits without and with IV contrast	Usually Not Appropriate	O
MRI head and orbits without IV contrast	Usually Not Appropriate	O
MRI head with IV contrast	Usually Not Appropriate	O
MRI head with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck without and with IV contrast	Usually Not Appropriate	O
MRI head without and with IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI head without IV contrast	Usually Not Appropriate	O
MRI head without IV contrast and MRA head and neck without IV contrast	Usually Not Appropriate	O
MRI neck with IV contrast	Usually Not Appropriate	O
MRI neck without and with IV contrast	Usually Not Appropriate	O
MRI neck without IV contrast	Usually Not Appropriate	O
MRI orbits with IV contrast	Usually Not Appropriate	O
MRI orbits without and with IV contrast	Usually Not Appropriate	O
MRI orbits without IV contrast	Usually Not Appropriate	O
MRI thoracic spine with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without and with IV contrast	Usually Not Appropriate	O
MRI thoracic spine without IV contrast	Usually Not Appropriate	O
CT head with IV contrast	Usually Not Appropriate	☢☢☢
CT head without and with IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast	Usually Not Appropriate	☢☢☢
CT neck with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without and with IV contrast	Usually Not Appropriate	☢☢☢
CT neck without IV contrast	Usually Not Appropriate	☢☢☢
CT head without IV contrast and CTA head and neck with IV contrast	Usually Not Appropriate	☢☢☢☢

Panel Members

Prachi Dubey, MBBS, MPH^a; Nitesh Shekhrajka, MBBS^b; Amy F. Juliano, MD^c; Mohit Agarwal, MD^d; Aileen A. Antonio, MD^e; Moises Auron, MD^f; Paul M. Bunch, MD^g; Judah Burns, MD^h; Gregory Compton, MBBS, BAⁱ; Elliott R. Friedman, MD^j; Maria K. Gule-Monroe, MD^k; Mari Hagiwara, MD^l; Vikas Jain, MD^m; Daniel E. Meltzer, MDⁿ; Rohini N. Nadgir, MD^o; Joseph F. Rizzo III, MD^p; Bradley D. Shy, MD^q; Andrew T. Trout, MD^r; Bruno Policeni, MD, MBA^s.

Summary of Literature Review

Introduction/Background

Special Imaging Considerations

Initial Imaging Definition

Initial imaging is defined as imaging at the beginning of the care episode for the medical condition defined by the variant. More than one procedure can be considered usually appropriate in the initial imaging evaluation when:

There are procedures that are equivalent alternatives (ie, only one procedure will be ordered to provide the clinical information to effectively manage the patient’s care)

There are complementary procedures (ie, more than one procedure is ordered as a set or simultaneously wherein each procedure provides unique clinical information to effectively manage the patient’s care).

Discussion of Procedures by Variant

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
A. CT head with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
B. CT head without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
C. CT head without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
D. CT head without IV contrast and CTA head and neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
E. CT neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
F. CT neck without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
G. CT neck without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
H. CTA head and neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
I. MRA head and neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
J. MRA head and neck without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
K. MRA head and neck without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
L. MRI cervical and thoracic spine with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
M. MRI cervical and thoracic spine without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
N. MRI cervical and thoracic spine without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
O. MRI cervical spine with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
P. MRI cervical spine without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
Q. MRI cervical spine without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
R. MRI head and orbits with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
S. MRI head and orbits without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
T. MRI head and orbits without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
U. MRI head with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
V. MRI head with IV contrast and MRA head and neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
W. MRI head without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
X. MRI head without and with IV contrast and MRA head and neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
Y. MRI head without and with IV contrast and MRA head and neck without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
Z. MRI head without and with IV contrast and MRA head and neck without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
[. MRI head without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
\. MRI head without IV contrast and MRA head and neck without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
]. MRI neck with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
^. MRI neck without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
_. MRI neck without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
`. MRI orbits with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
a. MRI orbits without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
b. MRI orbits without IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
c. MRI thoracic spine with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
d. MRI thoracic spine without and with IV contrast

Variant 1: Adult. Acute onset Horner syndrome with or without localizing neurological signs or symptoms. History of recent trauma or painful. Initial imaging.
e. MRI thoracic spine without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
A. CT head with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
B. CT head without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
C. CT head without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
D. CT head without IV contrast and CTA head and neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
E. CT neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
F. CT neck without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
G. CT neck without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
H. CTA head and neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
I. MRA head and neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
J. MRA head and neck without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
K. MRA head and neck without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
L. MRI cervical and thoracic spine with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
M. MRI cervical and thoracic spine without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
N. MRI cervical and thoracic spine without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
O. MRI cervical spine with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
P. MRI cervical spine without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
Q. MRI cervical spine without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
R. MRI head and orbits with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
S. MRI head and orbits without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
T. MRI head and orbits without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
U. MRI head with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
V. MRI head with IV contrast and MRA head and neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
W. MRI head without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
X. MRI head without and with IV contrast and MRA head and neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
Y. MRI head without and with IV contrast and MRA head and neck without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
Z. MRI head without and with IV contrast and MRA head and neck without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
[. MRI head without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
\. MRI head without IV contrast and MRA head and neck without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
]. MRI neck with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
^. MRI neck without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
_. MRI neck without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
`. MRI orbits with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
a. MRI orbits without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
b. MRI orbits without IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
c. MRI thoracic spine with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
d. MRI thoracic spine without and with IV contrast

Variant 2: Adult. Acute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. No history of trauma. Initial imaging.
e. MRI thoracic spine without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
A. CT head with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
B. CT head without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
C. CT head without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
D. CT head without IV contrast and CTA head and neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
E. CT neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
F. CT neck without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
G. CT neck without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
H. CTA head and neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
I. MRA head and neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
J. MRA head and neck without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
K. MRA head and neck without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
L. MRI cervical and thoracic spine with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
M. MRI cervical and thoracic spine without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
N. MRI cervical and thoracic spine without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
O. MRI cervical spine with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
P. MRI cervical spine without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
Q. MRI cervical spine without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
R. MRI head and orbits with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
S. MRI head and orbits without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
T. MRI head and orbits without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
U. MRI head with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
V. MRI head with IV contrast and MRA head and neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
W. MRI head without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
X. MRI head without and with IV contrast and MRA head and neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
Y. MRI head without and with IV contrast and MRA head and neck without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
Z. MRI head without and with IV contrast and MRA head and neck without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
[. MRI head without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
\. MRI head without IV contrast and MRA head and neck without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
]. MRI neck with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
^. MRI neck without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
_. MRI neck without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
`. MRI orbits with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
a. MRI orbits without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
b. MRI orbits without IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
c. MRI thoracic spine with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
d. MRI thoracic spine without and with IV contrast

Variant 3: Adult. Acute or nonacute onset Horner syndrome with localizing spinal cord neurological signs or symptoms. No history of trauma. Initial imaging.
e. MRI thoracic spine without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
A. CT head with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
B. CT head without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
C. CT head without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
D. CT head without IV contrast and CTA head and neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
E. CT neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
F. CT neck without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
G. CT neck without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
H. CTA head and neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
I. MRA head and neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
J. MRA head and neck without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
K. MRA head and neck without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
L. MRI cervical and thoracic spine with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
M. MRI cervical and thoracic spine without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
N. MRI cervical and thoracic spine without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
O. MRI cervical spine with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
P. MRI cervical spine without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
Q. MRI cervical spine without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
R. MRI head and orbits with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
S. MRI head and orbits without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
T. MRI head and orbits without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
U. MRI head with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
V. MRI head with IV contrast and MRA head and neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
W. MRI head without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
X. MRI head without and with IV contrast and MRA head and neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
Y. MRI head without and with IV contrast and MRA head and neck without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
Z. MRI head without and with IV contrast and MRA head and neck without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
[. MRI head without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
\. MRI head without IV contrast and MRA head and neck without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
]. MRI neck with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
^. MRI neck without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
_. MRI neck without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
`. MRI orbits with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
a. MRI orbits without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
b. MRI orbits without IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
c. MRI thoracic spine with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
d. MRI thoracic spine without and with IV contrast

Variant 4: Adult. Nonacute onset Horner syndrome with localizing brain or cranial nerve neurological signs or symptoms. Initial imaging.
e. MRI thoracic spine without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
A. CT head with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
B. CT head without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
C. CT head without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
D. CT head without IV contrast and CTA head and neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
E. CT neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
F. CT neck without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
G. CT neck without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
H. CTA head and neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
I. MRA head and neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
J. MRA head and neck without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
K. MRA head and neck without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
L. MRI cervical and thoracic spine with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
M. MRI cervical and thoracic spine without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
N. MRI cervical and thoracic spine without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
O. MRI cervical spine with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
P. MRI cervical spine without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
Q. MRI cervical spine without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
R. MRI head and orbits with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
S. MRI head and orbits without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
T. MRI head and orbits without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
U. MRI head with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
V. MRI head with IV contrast and MRA head and neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
W. MRI head without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
X. MRI head without and with IV contrast and MRA head and neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
Y. MRI head without and with IV contrast and MRA head and neck without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
Z. MRI head without and with IV contrast and MRA head and neck without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
[. MRI head without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
\. MRI head without IV contrast and MRA head and neck without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
]. MRI neck with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
^. MRI neck without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
_. MRI neck without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
`. MRI orbits with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
a. MRI orbits without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
b. MRI orbits without IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
c. MRI thoracic spine with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
d. MRI thoracic spine without and with IV contrast

Variant 5: Adult. Nonacute onset Horner syndrome nonlocalizable, not otherwise specified. Initial imaging.
e. MRI thoracic spine without IV contrast

Summary of Highlights

Supporting Documents

The evidence table, literature search, and appendix for this topic are available at https://acsearch.acr.org/list. The appendix includes the strength of evidence assessment and the final rating round tabulations for each recommendation.

For additional information on the Appropriateness Criteria methodology and other supporting documents, please go to the ACR website at https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Appropriateness-Criteria.

Gender Equality and Inclusivity Clause

The ACR acknowledges the limitations in applying inclusive language when citing research studies that predates the use of the current understanding of language inclusive of diversity in sex, intersex, gender, and gender-diverse people. The data variables regarding sex and gender used in the cited literature will not be changed. However, this guideline will use the terminology and definitions as proposed by the National Institutes of Health.

Appropriateness Category Names and Definitions

Appropriateness Category Name	Appropriateness Rating	Appropriateness Category Definition
Usually Appropriate	7, 8, or 9	The imaging procedure or treatment is indicated in the specified clinical scenarios at a favorable risk-benefit ratio for patients.
May Be Appropriate	4, 5, or 6	The imaging procedure or treatment may be indicated in the specified clinical scenarios as an alternative to imaging procedures or treatments with a more favorable risk-benefit ratio, or the risk-benefit ratio for patients is equivocal.
May Be Appropriate (Disagreement)	5	The individual ratings are too dispersed from the panel median. The different label provides transparency regarding the panel’s recommendation. “May be appropriate” is the rating category and a rating of 5 is assigned.
Usually Not Appropriate	1, 2, or 3	The imaging procedure or treatment is unlikely to be indicated in the specified clinical scenarios, or the risk-benefit ratio for patients is likely to be unfavorable.

Relative Radiation Level Information

Potential adverse health effects associated with radiation exposure are an important factor to consider when selecting the appropriate imaging procedure. Because there is a wide range of radiation exposures associated with different diagnostic procedures, a relative radiation level (RRL) indication has been included for each imaging examination. The RRLs are based on effective dose, which is a radiation dose quantity that is used to estimate population total radiation risk associated with an imaging procedure. Patients in the pediatric age group are at inherently higher risk from exposure, because of both organ sensitivity and longer life expectancy (relevant to the long latency that appears to accompany radiation exposure). For these reasons, the RRL dose estimate ranges for pediatric examinations are lower as compared with those specified for adults (see Table below). Additional information regarding radiation dose assessment for imaging examinations can be found in the ACR Appropriateness Criteria^® Radiation Dose Assessment Introduction document.

Relative Radiation Level Designations
Relative Radiation Level*	Adult Effective Dose Estimate Range	Pediatric Effective Dose Estimate Range
O	0 mSv	0 mSv
☢	<0.1 mSv	<0.03 mSv
☢☢	0.1-1 mSv	0.03-0.3 mSv
☢☢☢	1-10 mSv	0.3-3 mSv
☢☢☢☢	10-30 mSv	3-10 mSv
☢☢☢☢☢	30-100 mSv	10-30 mSv
*RRL assignments for some of the examinations cannot be made, because the actual patient doses in these procedures vary as a function of a number of factors (e.g., region of the body exposed to ionizing radiation, the imaging guidance that is used). The RRLs for these examinations are designated as “Varies.”

References

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Disclaimer

The 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 examinations 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 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.