uog journal club: prenatal diagnosis and outcome of fetal posterior fossa fluid collections

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UOG Journal Club: June 2012 Prenatal diagnosis and outcome of fetal posterior fossa fluid collections Gandolfi Colleoni G, Contro E, Carletti A, Ghi T, Campobasso G, Rembouskos G, Volpe G, Pilu G, Volpe P Volume 39, Issue 6, Date: June 2012, pages 625–631 Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis Volpe P, Contro E, De Musso F, Ghi T, Farina A, Tempesta A, Volpe G, Rizzo N, Pilu G Volume 39, Issue 6, Date: June 2012, pages 632–635 Journal Club slides prepared by Dr Aly Youssef (UOG Editor for Trainees)

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Page 1: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

UOG Journal Club: June 2012Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Gandolfi Colleoni G, Contro E, Carletti A, Ghi T, Campobasso G, Rembouskos G, Volpe G, Pilu G, Volpe P

Volume 39, Issue 6, Date: June 2012, pages 625–631

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe P, Contro E, De Musso F, Ghi T, Farina A, Tempesta A,Volpe G, Rizzo N, Pilu G

Volume 39, Issue 6, Date: June 2012, pages 632–635

Journal Club slides prepared by Dr Aly Youssef(UOG Editor for Trainees)

Page 2: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Posterior Fossa Fluid Collections

Wide spectrum of different entities and associated outcomes

Similar anatomic as well as sonographic appearance

Diagnostic errors common

Advances in prenatal imaging allows more detailed evaluation

Background

Page 3: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Objective: to evaluate the diagnostic accuracy of fetal neurosonography and magnetic resonance imaging (MRI) in cases of posterior fossa fluid collections and to assess the

outcome of affected infants

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 4: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

• Prospective observational study

• All fetuses with abnormal posterior fossa fluid collections

• Detailed multiplanar neurosonographic evaluation

• Whenever possible, serial sonograms and prenatal MRI were

performed and fetal karyotype was obtained

• Prenatal diagnosis was compared with autopsy or postnatal MRI

• Follow-up through medical records or parental interviews

Methods

Outcomes

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 5: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Normal posterior fossa at midgestation

Sagittal view

Axial view

Cavum Septi Pellucidi

Cisterna Magna

Tentorium

Cerebellar vermis

NB The Torcular Herophili is difficult to image on ultrasound due to acoustic shadowing from the skull bones. In the current study its position was inferred by observing the angulation of the tentorium

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 6: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Blake’s pouch cyst Megacisterna magna Dandy–Walker malformation

Findings Upward rotation of an intact vermis with normal

torcular

Cisterna magna >10mm with intact and normally positioned cerebellum

Upward rotation of the vermis (normal or hypoplastic) with

elevated torcular

Sagittal

Axial

Categorization of posterior fossa fluid collections (1)

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 7: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Vermian hypoplasia Cerebellar hypoplasia Posterior fossa arachnoid cyst

Findings Hypoplastic vermis with normal torcular

Large cisterna magna with small cerebellum

Cyst with mass effect resulting in distortion of the cerebellum

Sagittal

Axial

Categorization of posterior fossa fluid collections (2)

coronal

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 8: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Cases

(n)

Associated

Anomalies

No

follow

up (n)

TOP

(n)

Regression

in utero

(n)

Sonographic

diagnosis

confirmed

(n)

Abnormal neurologicaldevelopment postnatally

Isolated PFFC (n)

PFFC with associated

anomalies (n)

Blake’s pouch cyst

32 8 3 2 11/27 17/18 1/20 1/5

Megacisterna magna

27 9 4 2 6/21 16/17 2/16 1/4

Dandy–Walker

malformation

26 16 7 11 0/8 16/19 3/5 2/2

Vermian hypoplasia

17 11 9 2 0/6 6/8 1/3 2/2

Cerebellar hypoplasia

2 2 0 2 0/0 2/2 0 0

Arachnoid cyst

1 0 0 0 0/1 1/1 1/1 0

Total (n, (%))

105 46 23 19/105 (18)

17/63 (27)

58/65 (89)

8/45 (16)

6/13

Sonography in fetuses with posterior fossa fluid collections (PFFC), associations withother anomalies, intrauterine regression, outcome and accuracy of prenatal diagnosis

Page 9: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Fetal sonography Fetal MRI Postnatal diagnosis

Blake’s pouch cyst Blake’s pouch cyst Arachnoid cyst

Blake’s pouch cyst Megacisterna magna Megacisterna magna

Megacisterna magna Megacisterna magna Arachnoid cyst

Dandy–Walker malformation Dandy–Walker malformationDandy–Walker malformation and

cortical malformation

Dandy–Walker malformation Dandy–Walker malformation Joubert syndrome

Dandy–Walker malformation Dandy–Walker malformation Hemorrhage

Vermian hypoplasia Vermian hypoplasiaVermian hypoplasia and cortical

malformation

Vermian hypoplasia Vermian hypoplasia Normal brain

Discordancies between fetal sonographic and MRI diagnoses and postnatal diagnoses in eight fetuses with posterior fossa fluid collections

Page 10: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

• Fetal neurosonography allows accurate prenatal diagnosis

• The diagnosis with sonography was correct in almost 90% of cases.

• High diagnostic accuracy may be due to the multiplanar approach

• MRI of limited value with the use of meticulous neurosonography

(1/51 cases in the present study)

Discussion

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 11: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Strength of the study

Weakness• About one quarter of our patients were lost to follow-up

• Postnatal assessment of survivors was performed by different pediatricians who did not use a standard protocol.

• This is the largest prospective series published so far of posterior fossa fluid collections recognized in utero

• Results provide useful information for assessment and counseling in these cases.

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 12: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Ultrasound and fetal MRI perform similarly in the characterization of fetal posterior fossa abnormalities, and a correct diagnosis can be made inabout 90% of cases

Megacisterna magna and Blake’s pouch cysts are the most common antenatal diagnoses. They are risk factors for associated anomalies. When isolated, they have a good chance of intrauterine resolution and a normal developmental outcome in over 90% of cases

Dandy–Walker malformation and vermian hypoplasia have a guarded prognosis, with a very high likelihood of associated anomalies and/or neurologic impairment

Conclusions

Prenatal diagnosis and outcome of fetal posterior fossa fluid CollectionsGandolfi Colleoni et al., UOG 2012

Page 13: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

• Fetal posterior fossa fluid collections associated with upward rotation of the cerebellar vermis range from benign asymptomatic conditions to severe abnormalities associated with neurological impairment

• The most frequent of these anomalies, Blake’s pouch cyst, vermian hypoplasia and Dandy–walker malformation, have a similar sonographic appearance but a very different prognosis

• A specific diagnosis with either ultrasound or magnetic resonance imaging is possible, but is frequently difficult and relies mostly upon subjective criteria

Background

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 14: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

2

1

1. Brainstem–vermis (BV) angle (between a line drawn tangentially to the dorsal aspect of the brain stem and a second line drawn tangentially to the ventral contour of the cerebellar vermis)

2. brainstem–tentorium (BT) angle (between the first line and a third line tangential to the lower edge of the tentorium)

Median view of the fetal brain

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 15: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Objective: to evaluate the diagnostic contribution of anobjective approach based on the brainstem–vermis (BV)

angle and the brainstem–tentorium (BT) angle to the diagnosis of posterior fossa fluid collections

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 16: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

• Retrospective study

• BV and BT angles were measured in fetuses with posterior fossa

fluid collections with upward rotation of the cerebellar vermis

• Prospectively collected normal fetuses at mid-gestation (controls)

• Measurements were obtained from median views of the fetal brain

• Both 2D images and 3D volumes were used for measurements

Methods

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 17: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Results

Ultrasound findings n BV angle (◦) BT angle (◦)

Mean SD Range Mean SD Range

Controls 80 9.1 3.5 4–17 29.3 5.8 21–44

Blake’s pouch cyst 12 23.0 2.8 19–26 42.2 7.1 32–52

Vermian hypoplasia 7 34.9 5.4 24–40 52.1 7.0 45–66

Dandy–Walker malformation

12 63.5 17.6 45–112 67.2 15.1 51–112

Blake’s pouch cyst Dandy–Walker malformationVermian hypoplasia

1= BV angle 2= BT angle

Page 18: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

• Controls always had a BV angle <18º and a BT angle<45º• The BV and BT angle significantly increased in each of the three subgroups of anomalies• The angle increasing with increasing severity of the condition.• There was more overlapping of the BT angle among groups

BT angleBV angle

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 19: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Limitations of the study

• Retrospective study

• Reproducibility and repeatability of measurements unknown

• The number of abnormal cases was relatively small (esepecially vermian hypoplasia)

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 20: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Conclusion

Brainstem–vermis and brainstem–tentorium angles are objective findings which may be useful in differentiating fetal posterior fossa fluid collections that are sonographically similar but carry a very different prognosis

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

Page 21: UOG Journal Club: Prenatal diagnosis and outcome of fetal posterior fossa fluid collections

Discussion points

Brainstem–vermis and brainstem–tentorium angles allow accurate categorization of fetal upward rotation of cerebellar vermis

Volpe et al., UOG 2012

• What are the different types of posterior fossa fluid collections?

• Is it possible to accurately classify these fetal posterior fossa fluid collections by 2D/3D prenatal ultrasound?

• What is the role for fetal MRI in patients with fetal posterior fossa fluid collections?

• Does this paper provide concrete evidence to base accurate prognoses for the different fetal posterior fossa fluid collections?

• In the light of the present data, how should women with fetal posterior fossa fluid collections be counselled?