eMedicine Specialties > Radiology > Pediatrics
Dandy-Walker Malformation: Imaging
Updated: Sep 11, 2009
Radiography
Findings
On conventional radiographs, the posterior fossa is disproportionately enlarged, with characteristic thinning and bulging of the occiput. Increased pressure from the massively dilated fourth ventricle along with prominent CSF pulsations through the cyst fluid causes widening of the diastatic lambdoid sutures and erosive scalloping of the occiput. Torcular herophili and lateral sinus grooves are located high above the lambdoid angle (torcular-lambdoid angle inversion).9
Degree of Confidence
Plain radiographs have diagnostic importance in imaging bony abnormalities and in the evaluation of ventriculoperitoneal shunt malfunction.
Computed Tomography
Findings
CT is used to diagnose Dandy-Walker malformation and to follow ventricular shunt function in shunted patients. Nonenhanced CT examination successfully delineates multiple components of Dandy-Walker malformation, which includes partial or complete absence of the cerebellar vermis; posterior fossa cyst contiguous with the fourth ventricle; small and widely separated cerebellar hemispheres; anterior and lateral displacement of hypoplastic cerebellar hemispheres; anterior displacement of pons; elevated imprint of the transverse sinuses, with thinning and bulging of the bones of the posterior fossa; scalloping of petrous pyramids; and hydrocephalus.
An axial computed tomography (CT) scan in a 7-year-old girl with hydrocephalus showing a large cerebrospinal fluid cyst in the posterior fossa and hypoplastic cerebellar hemispheres with a winged appearance (c).
An axial CT scan in a 1-day-old boy that shows a large posterior fossa cyst, separation of the lambdoid sutures (large arrows), and concavity of the petrous ridges (small arrows).
Three-dimensional (3D) CT and CT angiography studies can be used to evaluate osseous malformation and the relationships between vascular and bony structures. For these studies, 1-mm thickness, an axial plane, and 3D reconstruction are used.
Degree of Confidence
CT scans can depict the malformation relatively well, but a slice may miss the relevant presence of the vermis. Clearly distinguishing Dandy-Walker complex subtypes using axial CT images is difficult.
False Positives/Negatives
See Degree of Confidence, above.
Magnetic Resonance Imaging
Findings
Malformations of the CNS are best delineated using MRI. The diagnosis is straightforward when typical MRI findings are present. MRI is usually required for better anatomic resolution prior to surgical intervention.28
Nonenhanced routine cranial MRI can image the altered anatomy and provide excellent images in all projections (sagittal, axial, coronal), of which the sagittal view is one of the most useful.
A sagittal T1-weighted magnetic resonance imaging (MRI) scan in a 5-year-old girl (also see Images 2-3 in Multimedia Section) shows a large posterior fossa cyst elevating the torcular herophili and sinus rectus (short arrow). The hypoplastic vermis is everted over the posterior fossa cyst (long arrow). The cerebellar hemispheres and brainstem (b) are hypoplastic. Thinned occipital squama is seen (arrowheads).
This sagittal T1-weighted MRI scan in an 11-day-old boy (also see Image 5 in Multimedia Section) shows agenesis of the corpus callosum, a hypoplastic brainstem (b), elevation of the torcular herophili (lambdoid-torcular inversion, large arrow), a large fourth ventricle, and a markedly hypoplastic vermis that is rotated superiorly (small arrow).
This sagittal T1-weighted MRI shows agenesis of the corpus callosum and a hypoplastic inferior vermis in a 13-year-old girl with thoracal scoliosis and Dandy-Walker variant. The fourth ventricle is slightly enlarged, but the posterior fossa typically is normal in size.
Hypoplasia or absence of the cerebellar vermis is best detected using thin-sectioned midline sagittal T1-weighted images (see Image 1, Image 4, Image 8). Wide separation of the cerebellar hemispheres without intervening vermis can be seen in axial or coronal images. In some patients, the inferior lobules of the vermis appear to be hypoplastic, while in others, they appear to be intact. Remnants of the dysplastic upper vermis are rotated anterosuperiorly, compressed, and attached to the tentorium (see Image 1, Image 4). Axial images alone may be misleading in revealing the upwardly rotated vermis.
An enlarged posterior fossa, cyst formation in the posterior fossa, anterolaterally winged cerebellar hemispheres (winged outward), absence of falx cerebelli, and scalloping of petrous pyramids are well-demonstrated on T1-weighted images (see Images 1-5).
Sagittal MRI can help evaluate an abnormally high position of the straight sinus, torcular herophili, tentorium, high tentorial insertion (lambdoid-torcular inversion), hypoplastic and compressed brainstem, and obstructive hydrocephalus secondary to cystic dilatation of the fourth ventricle in patients with Dandy-Walker malformation.24
An axial T1-weighted MRI (also see Image 4, in Multimedia Section) showing an elevated, anteriorly displaced torcular herophili (arrow) and a superiorly displaced posterior fossa cyst.
CSF flow and cine MRI techniques are valuable imaging methods for demonstrating patency of the CSF pathways at the level of the incisura or aqueduct of Sylvius. Shunting of the cyst alone in the presence of aqueductal obstruction may result in downward transincisural herniation of the cerebrum and atria of the lateral ventricles; however, shunting of the lateral ventricles alone when the aqueduct is obstructed may lead to an upward herniation of the posterior fossa cyst, resulting in a characteristic "snowman" appearance in the sagittal plane in the absence of communication. The hydrocephalus in patients with Dandy-Walker is frequently communicating in type with patency of the aqueduct.29
Assessing the presence of associated supratentorial anomalies is important, since the prognosis for patients is much better in the absence of the anomalies (see Image 2, Image 4, Image 8). MRI affords an accurate, objective, and detailed identification of supratentorial anomalies. Recently, MRI and US have been used as diagnostic tools in the antenatal period.
Degree of Confidence
MRI is reliable and is the diagnostic method of choice in differentiating Dandy-Walker malformation from other posterior fossa pathologies.
False Positives/Negatives
MRI findings in Dandy-Walker malformation may be confused with mega cisterna magna, arachnoid cyst, isolated fourth ventricle, and Joubert syndrome.
This sagittal T1-weighted MRI shows a large retrocerebellar cerebrospinal fluid collection and a normal fourth ventricle and vermis in a patient with mega cisterna magna in Dandy-Walker malformation.
A posterior fossa arachnoid cyst in a 15-month-old girl with a lumbar pilonidal sinus. The sagittal T1-weighted MRI shows a large posterior fossa cyst that is compressing the cerebellar hemispheres, vermis, fourth ventricle (arrow), and brainstem.
Joubert syndrome in an 8-month-old boy. The axial CT scan obtained near the pontomesencephalic junction shows a batwing configuration of the fourth ventricle and unusual definition of the superior cerebellar peduncles at this level (arrows). The vermis is dysgenetic, and the 2 cerebellar hemispheres appose each other in the midline.
Ultrasonography
Findings
Classic abnormal findings described on cranial CT and MRI scans can also be demonstrated on cranial sonography. Commercially available equipment is used, with transducers of 3-7.5 MHz (depending on the size of the patient's head). Transducers of 5-7.5 MHz are used for newborns, and transducers of 3-5 MHz are used for older infants.
On US, a large posterior fossa midline cyst that communicates with the fourth ventricle is best demonstrated on midline sagittal sections. The anterolaterally displaced hypoplastic cerebellar hemispheres are best seen in the coronal projection. Sagittal and coronal sections can demonstrate enlargement of the posterior fossa, high position of the tentorium, and dilated third and lateral ventricles.
Scans performed with the transducer can show a large posterior fossa cyst and hypoplastic cerebellar hemispheres. This is accomplished by using the transfontanel approach as well as by placing the transducer directly over the posterior or posterolateral fontanelle.
In these patients, it is important to assess the supratentorial compartment for associated anomalies, such as callosal agenesis.
Using US, Dandy-Walker malformation is usually discovered before birth, although prominence of the cisterna magna is often confused with Dandy-Walker malformation in utero.
An in utero sonogram of Dandy-Walker malformation; note the abnormal cerebellar vermis in association with a posterior fossa cyst (arrow) and splaying of the cerebellar hemispheres. Image courtesy of Ecker et al.
Prenatal diagnosis of Dandy-Walker malformation should not be made before the 18th week of gestation because development of the cerebellar vermis may be incomplete at that time. Although great variability exists in intracranial findings in fetuses, sagittal measurements exceeding 10 mm help confirm the presence of a Dandy-Walker cyst. US examination, including fetal echocardiography, should be directed toward identifying additional supratentorial and extracranial anomalies. Follow-up sonograms are useful for monitoring cyst size and ventriculomegaly. Three-dimensional US reportedly proved most helpful in delineating the exact nature and anatomic level of the anomaly in utero.21,25,30,31,32
Degree of Confidence
US is heavily operator-dependent. Associated findings of Dandy-Walker malformation, such as pachygyria, polymicrogyria, heterotopias, and dural abnormalities, may be missed.
False Positives/Negatives
Fetal US can demonstrate Dandy-Walker malformation and variant, but caution should be exercised because the normal developing cerebellum can mimic hypoplasia.
Angiography
Findings
Radiographic angiography can demonstrate angiographic features of Dandy-Walker malformation. In the arterial phase, the posterior cerebral vessels are elevated. The superior cerebellar arteries are displaced anterosuperiorly above the posterior cerebral arteries. The posterior inferior cerebellar arteries (PICAs) are shortened, with high tonsillar loop. The inferior vermian branches of the PICA are absent. In some patients, the entire PICA is absent or hypoplastic. In the venous phase, arteriography shows absence of the inferior vermian veins, elevation of the great vein of Galen, and high position of the transverse sinuses.33
More on Dandy-Walker Malformation |
| Overview: Dandy-Walker Malformation |
 Imaging: Dandy-Walker Malformation |
| Follow-up: Dandy-Walker Malformation |
| Multimedia: Dandy-Walker Malformation |
| References |
| Further Reading |
| « Previous Page | Next Page » |
References
Murray JC, Johnson JA, Bird TD. Dandy-Walker malformation: etiologic heterogeneity and empiric recurrence risks. Clin Genet. Oct 1985;28(4):272-83. [Medline].
Richter EO, Pincus DW. Development of syringohydromyelia associated with Dandy-Walker malformation: treatment with cystoperitoneal shunt placement. Case report. J Neurosurg. Mar 2006;104(3 Suppl):206-9. [Medline].
Cakmak A, Zeyrek D, Cekin A, Karazeybek H. Dandy-Walker syndrome together with occipital encephalocele. Minerva Pediatr. Aug 2008;60(4):465-8. [Medline].
Dandy WE, Blackfan KD. Internal hydrocephalus: an experimental, clinical and pathological study. Am J Dis Child. 1914;8:406-82.
BENDA CE. The Dandy-Walker syndrome or the so-called atresia of the foramen Magendie. J Neuropathol Exp Neurol. Jan 1954;13(1):14-29. [Medline].
D'AGOSTINO AN, KERNOHAN JW, BROWN JR. THE DANDY-WALKER SYNDROME. J Neuropathol Exp Neurol. Jul 1963;22:450-70. [Medline].
Hart MN, Malamud N, Ellis WG. The Dandy-Walker syndrome. A clinicopathological study based on 28 cases. Neurology. Aug 1972;22(8):771-80. [Medline].
Altman NR, Naidich TP, Braffman BH. Posterior fossa malformations. AJNR Am J Neuroradiol. Mar-Apr 1992;13(2):691-724. [Medline].
Barkovich AJ, Kjos BO, Norman D, Edwards MS. Revised classification of posterior fossa cysts and cystlike malformations based on the results of multiplanar MR imaging. AJR Am J Roentgenol. Dec 1989;153(6):1289-300. [Medline].
Sasaki-Adams D, Elbabaa SK, Jewells V, Carter L, Campbell JW, Ritter AM. The Dandy-Walker variant: a case series of 24 pediatric patients and evaluation of associated anomalies, incidence of hydrocephalus, and developmental outcomes. J Neurosurg Pediatrics. Sep 2008;2(3):194-9. [Medline].
Strand RD, Barnes PD, Poussaint TY, Estroff JA, Burrows PE. Cystic retrocerebellar malformations: unification of the Dandy-Walker complex and the Blake's pouch cyst. Pediatr Radiol. 1993;23(4):258-60. [Medline].
Salihu HM, Kornosky JL, Alio AP, Druschel CM. Racial disparities in mortality among infants with Dandy-Walker syndrome. J Natl Med Assoc. May 2009;101(5):456-61. [Medline].
Salihu HM, Kornosky JL, Druschel CM. Dandy-Walker syndrome, associated anomalies and survival through infancy: a population-based study. Fetal Diagn Ther. 2008;24(2):155-60. [Medline].
Raybaud C. Cystic malformations of the posterior fossa. Abnormalities associated with the development of the roof of the fourth ventricle and adjacent meningeal structures. J Neuroradiol. 1982;9(2):103-33. [Medline].
Taggart JK, Walker AE. Congenital atresia of the foramens of Luschka and Magendie. Arch Neurol Psychiat. 1942;48:583-612.
Bordarier C, Aicardi J. Dandy-Walker syndrome and agenesis of the cerebellar vermis: diagnostic problems and genetic counselling. Dev Med Child Neurol. Apr 1990;32(4):285-94. [Medline].
Cavalcanti DP, Salomao MA. Dandy-Walker malformation with postaxial polydactyly: further evidence for autosomal recessive inheritance. Am J Med Genet. Jul 16 1999;85(2):183-4. [Medline].
Ulm B, Ulm MR, Deutinger J, Bernaschek G. Isolated Dandy-Walker malformation: prenatal diagnosis in two consecutive pregnancies. Am J Perinatol. 1999;16(2):61-3. [Medline].
Lavanya T, Cohen M, Gandhi SV, Farrell T, Whitby EH. A case of a Dandy-Walker variant: the importance of a multidisciplinary team approach using complementary techniques to obtain accurate diagnostic information. Br J Radiol. Oct 2008;81(970):e242-5. [Medline].
Kalidasan V, Carroll T, Allcutt D, Fitzgerald RJ. The Dandy-Walker syndrome--a 10-year experience of its management and outcome. Eur J Pediatr Surg. Dec 1995;5 Suppl 1:16-8. [Medline].
Phillips JJ, Mahony BS, Siebert JR, Lalani T, Fligner CL, Kapur RP. Dandy-Walker malformation complex: correlation between ultrasonographic diagnosis and postmortem neuropathology. Obstet Gynecol. Mar 2006;107(3):685-93. [Medline].
Menon RK, Nadkarni TD, Desai KI, Goel A. Dandy-Walker malformation associated with polycystic kidneys: Goldston syndrome revisited. J Clin Neurosci. Oct 2006;13(8):875-7. [Medline].
Sato K, Kubota T, Nakamura Y. Adult onset of the Dandy-Walker syndrome. Br J Neurosurg. Feb 1996;10(1):109-12. [Medline].
McClelland S 3rd, Charnas LR, SantaCruz KS, Garner HP, Lam CH. Progressive brainstem compression in an infant with neurocutaneous melanosis and Dandy-Walker complex following ventriculoperitoneal shunt placement for hydrocephalus. Case report. J Neurosurg. Dec 2007;107(6 Suppl):500-3. [Medline].
Ecker JL, Shipp TD, Bromley B, Benacerraf B. The sonographic diagnosis of Dandy-Walker and Dandy-Walker variant: associated findings and outcomes. Prenat Diagn. Apr 2000;20(4):328-32. [Medline].
Marnet D, Vinchon M, Mostofi K, Catteau B, Kerdraon O, Dhellemmes P. Neurocutaneous melanosis and the Dandy-Walker complex: an uncommon but not so insignificant association. Childs Nerv Syst. Aug 27 2009;[Medline].
Hadzagic-Catibusic F, Maksic H, Uzicanin S, Heljic S, Zubcevic S, Merhemic Z, et al. Congenital malformations of the central nervous system: clinical approach. Bosn J Basic Med Sci. Nov 2008;8(4):356-60. [Medline].
Kölble N, Wisser J, Kurmanavicius J, Bolthauser E, Stallmach T, Huch A, et al. Dandy-walker malformation: prenatal diagnosis and outcome. Prenat Diagn. Apr 2000;20(4):318-27. [Medline].
Yildiz H, Yazici Z, Hakyemez B, Erdogan C, Parlak M. Evaluation of CSF flow patterns of posterior fossa cystic malformations using CSF flow MR imaging. Neuroradiology. Sep 2006;48(9):595-605. [Medline].
Bromley B, Nadel AS, Pauker S, Estroff JA, Benacerraf BR. Closure of the cerebellar vermis: evaluation with second trimester US. Radiology. Dec 1994;193(3):761-3. [Medline].
Hata T, Yanagihara T, Matsumoto M, Hanaoka U, Ueta M, Tanaka Y, et al. Three-dimensional sonographic features of fetal central nervous system anomaly. Acta Obstet Gynecol Scand. Aug 2000;79(8):635-9. [Medline].
Russ PD, Pretorius DH, Johnson MJ. Dandy-Walker syndrome: a review of fifteen cases evaluated by prenatal sonography. Am J Obstet Gynecol. Aug 1989;161(2):401-6. [Medline].
Wolpert SM, Haller JS, Rabe EF. The value of angiography in the Dandy-Walker syndrome and posterior fossa extra-axial cysts. Am J Roentgenol Radium Ther Nucl Med. Jun 1970;109(2):261-72. [Medline].
Cedzich C, Lunkenheimer A, Baier G, Müller J, Kühner A. Ultrasound-guided puncture of a Dandy-Walker cyst via the lateral and III ventricles. Childs Nerv Syst. Sep 1999;15(9):472-6. [Medline].
Further Reading
Related eMedicine topics
Arteriovenous Malformations
Atrioventricular Septal Defect, Complete
Management of Spina Bifida, Hydrocephalus and Shunts
Arachnoid Cyst
Ataxia with Identified Genetic and Biochemical Defects
Corpus Callosum, Agenesis
Clinical guidelines
ACR Appropriateness Criteria® ataxia. American College of Radiology - Medical Specialty Society. 1999 (revised 2006). 10 pages. NGC:005547
Clinical trials
Brain Development Research Program
Keywords
Dandy-Walker malformation, Dandy-Walker, Dandy-Walker syndrome, Dandy-Walker cyst, Dandy-Walker deformity, Dandy Walker, cerebellum, cerebellar disease, brain disease, central nervous system disease, Luschka-Magendie foramina atresia
