This issue of CDR will qualify for 2 ABR Self-Assessment Module SAM (SA-CME) credits. See page 7 for more information.

Volume 38 • Number 13 June 30, 2015

Imaging Miscues in Pediatric Lee Nakamura, MD, Michael J. Paldino, MD, and Jeremy Y. Jones, MD

This module meets the American Board of Radiology’s (ABR’s) criteria for self-assessment toward the purpose of fulfilling requirements in the ABR Maintenance of Certification program. Please note that in addition to the SA-CME credits, subscribers completing the activity will receive the usual ACCME credits.

After participating in this activity, the radiologist should be better able to diagnose causes of headache in the pediatric population, and consequently to avoid diagnostic imaging miscues.

cerebellar tonsillar ectopia as a manifestation of Chiari I CME Category: Pediatric Radiology Subcategory: Neuroradiology malformation, and its mimics; (2) subtle imaging fi ndings of Modality: MRI vascular etiologies for headache, including circle of Willis vasculopathy and dural sinus thrombosis; and (3) typical imaging features of variants presenting in the pedi- Key Words: Imaging of Pediatric Headache, Pediatric atric population, including hemiplegic and ophthalmoplegic Headache migraine.

Much has been written regarding the indications for imag- Headache With Chiari I Malformation and Its Mimics ing in pediatric headache to facilitate the detection of poten- Chiari I malformation conventionally is defi ned as cer- tially catastrophic structural lesions (i.e., tumors and ebellar tonsillar descent below the level of the foramen ). Detection of such lesions is typically magnum by at least 5 mm, in the absence of intracranial straightforward with CT or MRI. Imaging correlates for cer- mass lesions, hydrocephalus, and cerebral or cerebellar tain well-described causes of pediatric headache, however, edema. As so defi ned, Chiari I malformation is noted in up may be more subtle and, therefore, potentially overlooked. to 3.6% of children referred for head MRI.1 Symptomatic Furthermore, the overlap of imaging patterns may result in patients with Chiari I malformation often present with head- the potential for misinterpretation. The purpose of this arti- aches that are short in duration, occipital or nuchal in location, cle is to highlight some of the entities in which imaging fi nd- and exacerbated by the Valsalva maneuver. Management ings are subtle and/or overlooked in this population of of symptomatic patients with Chiari I malformation is children with headache. In particular, we discuss: (1) inferior surgical, consisting of posterior decompression with infe- rior occipital craniectomy, C1 laminectomy, and possibly Dr. Nakamura is Pediatric Neuroradiology Fellow, Texas Children’s Hospital; duraplasty. Dr. Paldino is Assistant Professor, Baylor College of Medicine and a Neuro- radiologist, Texas Children’s Hospital; and Dr. Jones is Assistant Professor, Baylor College of Medicine and Neuroradiology Section Chief, Singleton Department of Radiology, Texas Children’s Hospital, 6701 Fannin St, Ste 470, Houston, TX Symptomatic patients with Chiari I malformation 77030; E-mail: [email protected] often present with that are short in The authors and all staff in a position to control the content of this CME activity duration, occipital or nuchal in location, and and their spouses/life partners (if any) have disclosed that they have no relation- exacerbated by the Valsalva maneuver. ships with, or fi nancial interests in, any commercial organizations pertaining to this educational activity.

Lippincott Continuing Medical Education Institute, Inc., is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. Lippincott Continuing Medical Education Institute, Inc., designates this enduring material for a maximum of 2 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity. To earn CME credit, you must read the CME article and complete the quiz and evaluation on the enclosed answer form, answering at least seven of the 10 quiz questions correctly. This continuing medical education activity expires on June 29, 2016. 1

CCDRv38n13.inddDRv38n13.indd 1 55/6/15/6/15 2:172:17 AMAM A subgroup of patients with Chiari I malformation, recently dens, reduced craniocervical angle, basilar invagination, platy- described as “complex ,” may require addi- basia, and atlanto-occipital assimilation.2 tional posterior occipitocervical fusion and/or ventral decom- Peg-like cerebellar tonsils meeting these measurement cri- pression for optimal therapy. In addition to cerebellar tonsillar teria are not specifi c for Chiari I malformation. They also may descent, these children with complex Chiari malformation are occur in the setting of intracranial hypotension. The headache identifi ed by descent, with an obex position below in patients with intracranial hypotension is characteristically the level of the and a dorsal cervicomedullary orthostatic, increased with sitting or standing, and improved hump (Figure 1). This constellation of findings has been in the supine position. Intracranial hypotension results from referred to as “Chiari 1.5.” Osseous anomalies of the craniocer- low cerebrospinal fl uid (CSF) pressure/volume of any cause, vical junction commonly are demonstrated in patients with including from a persistent CSF leak in the spine. Although complex Chiari malformation, including retrofl exion of the most commonly seen after violation of the spinal dura (e.g., after lumbar puncture), leaks may be spontaneous and are thought to result from tearing at a site of congenital or acquired weakness of the dura, such as a spinal diverticulum or dural ectasia. As such, patients with connective tissue disorders may be at increased risk for spontaneous intracranial hypotension. In our practice, overshunting is probably the most common cause of cerebellar tonsillar descent from intracranial hypo- tension. Regardless of the cause, treatment of intracranial hypotension with surgical posterior fossa decompression is inappropriate. Therapeutic options to treat the cause of the spi- nal leak include epidural blood patch, fi brin glue injection, or surgery.3 Although potentially similar in appearance to Chiari I malformation on MRI, often there are additional MR signs that suggest the diagnosis of intracranial hypotension. These additional MR signs include diffuse, smooth pachymeningeal enhancement; venous sinus distension, enlargement of the pituitary gland; and descent of the brain (including reduction in size or effacement of the prepontine or interpeduncular cisterns, inferior displacement of the optic chiasm, and descent of the iter, which is the entrance of the cerebral aqueduct) (Figure 2).

Patients with connective tissue disorders may be at increased risk for spontaneous intracranial hypotension.

Figure 1. Complex Chiari malformation in a 4-year-old boy with Idiopathic intracranial hypertension also can be associated recurrent headaches and vomiting for 3 months. Sagittal with inferior cerebellar tonsillar ectopia, with the tonsils T1-weighted MR image demonstrates pointed cerebellar tonsils extending 5 mm below the foramen magnum in as many as extending to the posterior arch of C1, an obex below the foramen 21% of individuals in a recent adult series.4 Headache is the magnum, a dorsal cervicomedullary hump (long arrow), a short most common presentation and tends to be variable in char- clivus (asterisk), and basilar invagination (arrowhead). The obex is the point on the midline of the dorsal surface of the medulla acter. The diagnosis usually is made by the constellation of oblongata that marks the caudal angle of the fourth ventricle. Note headache, papilledema, elevated opening CSF pressure, and syrinx in the cervical cord. absence of an intracranial mass lesion or hydrocephalus. Its

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Figure 2. Intracranial hypotension in a 13-year-old girl with head- ache after shunting a posterior fossa arachnoid cyst. A: Sagittal, T1-weighted MR image demonstrates pointed cerebellar tonsils extending to the posterior arch of C1 (arrowhead), effacement of the prepontine cistern, a reduction in the mamillopontine distance (arrow), loss of CSF about the suprasellar cistern from “brain sag,” and A a cervical syrinx. B: Coronal, T2-weighted MR image reveals a low- lying optic chiasm (arrow) just above the pituitary gland (arrowhead).

etiology is unclear but may be secondary to altered CSF Headache With Vasculopathy and resorption or altered venous outfl ow. Although idiopathic Headache often accompanies arterial ischemic stroke in intracranial hypertension most often occurs in adolescent children. In these individuals, clinical fi ndings and/or the obese girls, there is no defi nitive sex dominance or relation presence of cerebral infarction on diffusion-weighted MR to weight before puberty. Idiopathic intracranial hypertension images leads to appropriate vascular imaging. However, may be diffi cult to distinguish from Chiari I malformation headache occasionally can occur in the setting of pediatric on MRI, but ancillary MR fi ndings such as papilledema, tor- vasculopathy in the absence of ischemia; in such cases, tuous or dilated optic nerve sheaths, and a partially empty abnormal fi ndings on conventional MR images may be sella turcica should raise the possibility of idiopathic intrac- overlooked. ranial hypertension (Figure 3). The most well known of the cerebral vasculopathies pre- senting in the pediatric age group is moyamoya disease. The In adolescents, idiopathic intracranial moniker comes from the Japanese term for “puff of smoke,” hypertension most often occurs in obese girls. which is in reference to the lenticulostriate collateral arteries observed on conventional cerebral angiography. Moyamoya

B Figure 3. Idiopathic intracranial hypertension in a 19-year-old girl with headache and suspected mild Chiari I malformation on CT (not shown). A: Sagittal, T1-weighted MR image demonstrates mild inferior cerebellar tonsillar ectopia of 4 to 5 mm (arrow). B: Axial, T2-weighted MR image shows bilateral papilledema (arrows). CSF drainage after a measured opening CSF pressure A of 27 cm H2O provided headache relief. The normal opening CSF pressure generally is below 20–25 H2O. 3

CCDRv38n13.inddDRv38n13.indd 3 55/6/15/6/15 2:172:17 AMAM disease is defi ned more formally as the triad of idiopathic stenosis or occlusion of the terminal internal carotid artery Moyamoya disease consists of stenosis or and/or its proximal branches, local arterial collateral networks occlusion of the terminal internal carotid artery (making up the puff of smoke), and bilaterality. With time, and/or its proximal branches, local arterial the arteriopathy may progress to involve the posterior cere- collateral networks, and bilaterality. bral circulation as well. When the fi ndings are unilateral, the terms “probable moyamoya disease” or “moyamoya syn- drome” have been employed. Moyamoya syndrome also has Cerebral Sinovenous Thrombosis been applied in the literature when these vascular changes Headache is one of the most common, and occasionally the are demonstrated in combination with an associated disorder only symptom of cerebral sinovenous thrombosis involving such as sickle cell disease, neurofi bromatosis type I, or Down school-age children and adolescents; other nonspecifi c signs syndrome; or after radiation therapy involving the brain. and symptoms include , motor defi cits, altered mental Although transient ischemic attacks and completed status, nausea, vomiting, and papilledema. A variety of risk are the dominant pattern of presentation in children, up to factors associated with cerebral sinovenous thrombosis may 20% of pediatric patients have headache as one of their major 5 prompt clinical consideration of dedicated CT or MR venous symptoms. In such cases, headaches typically are described imaging in the setting of headache, including dehydration, as migrainous in character. central infection, prothrombotic states, chronic With conventional MR images, fi ndings may be subtle. A systemic disease, use of oral contraceptives, iron-defi ciency reduced caliber of the distal supraclinoid internal carotid anemia, pseudotumor cerebri, or malignancy in general. artery or its anterior and middle cerebral artery branches may However, cerebral sinovenous thrombosis often is not a clini- be identifi ed (Figure 4A). There may be numerous small cal consideration at the time of routine imaging. In addition, collateral vessels in the suprasellar cistern as appreciated on signs suggesting sinus thrombosis may be overlooked easily T2-weighted MR images or in the basal ganglia as appreci- on an unenhanced head CT scan, which typically is obtained ated on T1-weighted MR images. The so-called ivy sign, / in the urgent or emergent setting. Direct evidence of cerebral representing collateral pial branches and or pial vascular sinovenous thrombus, as manifested by increased density in congestion, may be appreciated on fl uid-attenuated inversion expanded cerebral veins or dural sinuses, may or may not be recovery (FLAIR) or postcontrast T1-weighted MR images. present. Indirect signs of cerebral sinovenous thrombosis, When any of these MR fi ndings are present in a child with including parenchymal edema or hemorrhage, also are vari- headache, dedicated vascular imaging is indicated, which ably present (Figure 5). Classically, parasagittal distribution might include MR angiography (MRA), CT angiography of parenchymal edema/hemorrhage raises the possibility of (CTA), or catheter cerebral angiography (Figure 4B). superior sagittal sinus thrombosis. A posterior temporal loca- Although MRA and CTA can be diagnostic, cerebral angio- tion suggests lateral sinus/vein of Labbe thrombosis. A tha- graphy remains the gold standard for assessment of moyamoya lamic distribution potentially indicates deep venous system disease, particularly for those patients in whom surgical man- thrombosis. In infants and young children, or in those with agement is being contemplated. In children, moyamoya disease polycythemia, the dural sinuses are often dense on a phys- is often progressive, and surgical revascularization can result iologic basis, confounding assessment. From a practical in signifi cant symptom reduction. Early recognition is thus cru- cial to optimal clinical management, as outcomes are improved when the diagnosis is made at an earlier stage of the disease.

A B

Figure 4. Moyamoya disease in an 11-year-old girl with disorder and headaches. A: Axial, T2-weighted MR image demonstrates substantially decreased caliber of the right proximal middle cerebral artery (lateral arrowhead) and smaller supraclinoid internal carotid artery (medial arrowhead). B: Lateral projection cerebral angiogram from a right internal carotid artery injection shows severe narrow- ing of the distal right internal carotid artery (arrow), with collateral vessels contributing to the anterior cerebral artery and middle cerebral artery territories. Notice that the right posterior cerebral artery territory has already promptly opacifi ed (via the posterior communicating artery) during this early arterial phase. 4

CCDRv38n13.inddDRv38n13.indd 4 55/6/15/6/15 2:172:17 AMAM Segmental increases in dural sinus attenuation, increased deep venous attenuation, or typical patterns of parenchymal edema/hemorrhage suggest cerebral sinovenous thrombosis.

Hemiplegic Migraine Motor weakness during migraine aura qualifi es as hemiple- gic migraine, with a peak onset noted in childhood or adoles- cence. Hemiplegic migraine may be sporadic or familial and has been linked to several mutations in ion transport channels. Although imaging in hemiplegic migraine is usually normal, severe cases characterized by prolonged confusion, coma, and/or often have evidence of unilateral , with or without accompanying diffusion-weighted MR signal changes (Figure 6). Generally, these cross-sectional MRI abnormalities are reversible.7 Alterations of hemispheric perfusion with advanced imaging and vasospasm or dilation on angiographic imaging also have been reported. Raising the diagnosis of hemiplegic migraine as a differential diagnostic A consideration in the appropriate clinical setting is important to facilitate genetic testing in these patients. In practice, as severely affected patients may have fever and/or seizures accompanying their clinical presentation, and postictal edema usually are proffered differential diagnostic considerations until the diagnosis is established.

B

Figure 5. Cerebral sinovenous thrombosis in a 17-year-old girl with persistent headaches and vomiting. A: Axial, unenhanced CT scan with subtle left thalamic edema (arrow). B: Sagittal, unenhanced CT reconstruction demonstrates expanded and dense vein of Galen (black arrow) and straight sinus (white arrows), particularly with respect to the superior sagittal sinus (arrowheads). Figure 6. Hemiplegic migraine in an 11-year-old girl with a family his- standpoint, segmental increases in dural sinus attenuation, tory of hemiplegic migraine. She presented with acute onset of head- ache; right face, arm, and leg weakness; and confusion. Axial FLAIR increased deep venous attenuation, or typical patterns of paren- MR image demonstrates diffuse left hemispheric cortical edema. chymal edema/hemorrhage suggest the diagnosis and should Diffusion-weighted images (not shown) revealed no restriction. A genetic lead to appropriate head CT or MR venographic imaging.6 mutation in the sodium-potassium pump (ATP1A2) was confi rmed. 5

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Figure 7. Ophthalmoplegic migraine in an 8-year-old girl with recurrent right eye ptosis and orbital pain. Axial (A) and coronal (B) T1-weighted, postcontrast, fat-saturated MR images demon- strate enlarged and focally enhancing cisternal segment of the right oculomotor nerve (CN III) (arrows). The enhancement A improved after corticosteroid treatment (not shown).

Ophthalmoplegic Migraine Conclusion Ophthalmoplegic migraine is characterized by at least two This CME activity highlights the imaging appearance of episodes of headache with paresis involving the third, fourth, or some important etiologies of headache presenting in the sixth cranial nerves in the absence of an orbital apex, parasellar, pediatric population, with a focus on fi ndings that may be or brainstem lesion. Peak incidence is in childhood. On MR easily overlooked and/or misconstrued. It is our belief that images, ophthalmoplegic migraine typically manifests with third knowledge of such fi ndings will allow for accurate diagnosis cranial nerve enhancement and thickening, most pronounced in these cases and, therefore, will facilitate optimal patient near its root entry zone about the interpeduncular cistern management. (Figure 7). Importantly, on follow-up MRI after corticosteroid therapy, there should be a signifi cant reduction or resolution in Refe rences enhancement about the involved nerve. The pathophysiology is 1. Strahle J, Muraszko KM, Kapurch J, et al. Chiari malformation type I and syrinx in children undergoing magnetic resonance imaging. J Neurosurg unknown, with possibilities including recurrent demyelination Pediatr. 2011;8(2):20 5-213. or ischemia. As such, some authorities argue that the term “oph- 2. Bollo RJ, Riva-Cambrin J, Brockmeyer MM, et al. Complex Chiari malfor- thalmoplegic migraine” is a misnomer and that the syndrome mations in children: an analysis of preoperative risk factors for occipitocer- vical fusion. J Neurosurg Pediatr. 2012;10(2):13 4-141. might better be called “recurrent ophthalmoplegic cranial neu- 3. Schievink WI, Maya MM, Louy C, et al. Spontaneous intracranial hypotension ropathy.” The differential diagnosis includes other infectious, in childhood and adolescence. J Pediatr. 2013;163(2):50 4-510. infl ammatory, or neoplastic processes involving the third cranial 4. Aiken AH, Hoots JA, Saindane AM, et al. Incidence of cerebellar tonsillar ectopia in idiopathic intracranial hypertension: a mimic of the Chiari I mal- nerve, but the diagnosis should be considered with the appropri- formation. AJNR Am J Neuroradiol. 2012;33(10):1901 -1906. ate clinical history and evidence of reduced third nerve enhance- 5. Seol HJ, Wang KC, Kim SK, et al. Headache in pediatric moyamoya dis- ment on follow-up studies after treatment.8 ease: review of 204 consecutive cases. J Neurosurg. 2005;103(5 Suppl): 43 9-442. 6. Hedlund GL. Cerebral sinovenous thrombosis in pediatric practice. Pediatr Radiol. 2013;43(2):17 3-188. On MRI, ophthalmoplegic migraine manifests 7. Asghar SJ, Milesi-Halle A, Kaushik C, et al. Variable manifestations of famil- with third cranial nerve enhancement and ial hemiplegic migraine associated with reversible cerebral edema in children. thickening, most pronounced near its root entry Pediatr Neurol. 2012;47(3):20 1-204. 8. Gelfand AA, Gelfand JM, Prabakhar P, et al. Ophthalmoplegic “migraine” zone about the interpeduncular cistern. or recurrent ophthalmoplegic cranial neuropathy: new cases and a systematic review. J Child Neurol. 2012;27(6):759-766.

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CCDRv38n13.inddDRv38n13.indd 6 55/6/15/6/15 2:172:17 AMAM CME QUIZ: VOLUME 38, NUMBER 13 To earn CME credit, you must read the CME article and complete the quiz and evaluation on the enclosed answer form, answering at least seven of the 10 quiz questions correctly. Select the best answer and use a blue or black pen to completely fi ll in the corresponding box on the enclosed answer form. Please indicate any name and address changes directly on the answer form. If your name and address do not appear on the answer form, please print that information in the blank space at the top left of the page. Make a photocopy of the completed answer form for your own fi les and mail the original answer form in the enclosed postage-paid business reply envelope. Only two entries will be considered for credit. Your answer form must be received by Lippincott CME Institute, Inc., by June 29, 2016. At the end of each quarter, all CME participants will receive individual issue certifi cates for their CME participation in that quarter. These individual certifi cates will include your name, the publication title, the volume number, the issue number, the article title, your participation date, the AMA credit awarded, and any subcategory credit earned (if applicable). For more information, call (800) 638-3030. All CME credit earned via Contemporary Diagnostic Radiology will apply toward continuous certifi cation requirements. ABR continuous certifi cation requires 75 CME credits every 3 years, at least 25 of which must be self-assessment CME (SA-CME) credits. All SAM credits earned via Contemporary Diagnostic Radiology are now equivalent to SA-CME credits (www.theabr.org). Online quiz instructions: To take the quiz online, log on to your account at www.cdrnewsletter.com, and click on the “CME” tab at the top of the page. Then click on “Access the CME activity for this newsletter,” which will take you to the log-in page for http://cme.lww.com. Enter your username and password. Follow the instructions on the site. You may print your offi cial certifi cate immediately. Please note: Lippincott CME Institute will not mail certifi cates to online participants. Online quizzes expire on the due date.

All questions are ABR Self-Assessment Module (SAM) questions. Participants can claim credit for the SAM regardless of the test out- come. Notify the ABR of the SAM completion, or visit the ABR website at www.theabr.org to set up or log in to your personal database to record the number of SAMs you completed. Because CDR has been granted Deemed Status by the ABR, there will no longer be SAM ID numbers printed on the CME certifi cate. You may contact a MOC specialist at the ABR offi ce by calling 520-519-2152.

1. In which one of the following individuals in the pediatric 4. Figure 8 is an axial FLAIR head MR image of an 8-year-old population is idiopathic intracranial hypertension most likely boy who presented with migrainous headaches. Which one to develop? of the following MR fi ndings suggests the diagnosis of moy- A. An obese adolescent girl amoya disease? B. A normal-weight adolescent boy A. Cortical vein thrombosis C. A newborn B. “Ivy sign” D. An underweight 5-year-old boy C. Subacute cortical infarction E. A normal-weight 5-year-old girl D. Intracranial hypotension See Reference No. 4 for further study E. Intracranial hypertension See Reference No. 5 for further study 2. All of the following may be associated with inferior cerebel- lar tonsillar ectopia, except A. Chiari I malformation B. intracranial hypotension C. cerebellitis with edema D. ophthalmoplegic migraine E. idiopathic intracranial hypertension See Reference No. 1 for further study 3. All of the following are MR features of complex Chiari mal- formation, except A. a dorsal cervicomedullary hump B. a cerebellar mass lesion C. an obex position below the foramen magnum D. cerebellar tonsillar descent E. brainstem descent See Reference No. 2 for further study

Figure 8.

CME quiz continues on p. 8.

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CCDRv38n13.inddDRv38n13.indd 7 55/6/15/6/15 2:172:17 AMAM 5. Which one of the following is expected on follow-up head 8. All of the following conditions in the pediatric population are MR images of a 6-year-old girl recently treated with corticos- associated with moyamoya syndrome, except teroids for recurrent ophthalmoplegic cranial neuropathy with A. sickle cell disease enhancement of the third cranial nerve (CN III) on a prior B. neurofi bromatosis type I head MR examination? C. Down syndrome A. No change in CN III enhancement D. prior radiation therapy including the brain B. New CN IV and CN VI enhancement E. infantile hypothyroidism (cretinism) C. Worsening in CN III enhancement See Reference No. 5 for further study D. A new parasellar lesion E. Improvement in CN III enhancement 9. In addition to descended, pointed cerebellar tonsils, all of the following are MR features of intracranial hypotension, See Reference No. 8 for further study except 6. On head MR images, parenchymal thalamic edema/hemor- A. smooth dural enhancement rhage suggests venous thrombosis involving which one of B. pituitary enlargement the following structures? C. papilledema A. Superior sagittal sinus D. venous sinus distension B. Transverse sinus E. inferior displacement of the optic chiasm C. Vein of Labbe See Reference No. 3 for further study D. Deep venous system E. Cortical veins 10. All of the following are MR features of Chiari I malformation, except See Reference No. 6 for further study A. cerebellar tonsillar descent below the level of the foramen 7. All of the following are appropriate treatments for intracranial magnum by at least 5 mm hypotension resulting from a spinal CSF leak, except B. absence of an intracranial mass lesion A. inferior occipital craniectomy C. presence of hydrocephalus B. epidural blood patch D. absence of cerebral edema C. fi brin glue injection E. absence of cerebellar edema D. surgical CSF leak repair See Reference No. 1 for further study See Reference No. 3 for further study

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