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prenatal diagnosis of brainstem anomalies Kate Guskich – Senior Sonographer

OVERVIEW

CCCSP

Vermis

3rd

4th

https://www.kenhub.com/en/library/anatomy/cerebellum-and-brainstem

OVERVIEW

https://www.kenhub.com/en/library/anatomy/cerebellum-and-brainstem

Brainstem:Ultrasound Anatomy;

Ultrasound Assessment;Cases.

1. Midbrain

2. Pons

3. Medulla Oblongata

2

3

4

REVIEW: CEREBELLAR VERMIS

Anatomy:

1. Pac man shape

2. 4th ventricle

3. Fastigial point

4. Primary fissure

5. Declive

S

I

REVIEW: CEREBELLAR VERMIS

Biometry:

• Cranio-caudal diameter = ½ GA

• Relative growth of superior and inferior lobes ( S = I )

REVIEW: CEREBELLAR VERMIS

Tegmento-vermian angle:

• Normal <18˚

• Abnormal >40˚

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ON ULTRASOUND: BRAINSTEM

1. Midbrain

2. Pons

• Anterior contour

3. Medulla Oblongata

ON ULTRASOUND: BRAINSTEM

1. Midbrain

2. Pons• Anterior arch contour

• Straight posteriorly

• Bulbo-protuberential sulcus

• Ventral part more echogenic than dorsal part

3. Medulla Oblongata

ON ULTRASOUND: BRAINSTEM

1. Midbrain

2. Pons• Anterior arch contour

• Straight posteriorly

• Bulbo-protuberential sulcus

• Ventral part more echogenic than dorsal part• Basilar artery

3. Medulla Oblongata

ON ULTRASOUND: BRAINSTEM

1. Midbrain

2. Pons• Anterior arch contour

• Straight posteriorly

• Bulbo-protuberential sulcus

• Ventral part more echogenic than dorsal part• Basilar artery

3. Medulla Oblongata

ON ULTRASOUND: BRAINSTEM

1. Midbrain

2. Pons• Anterior arch contour

• Straight posteriorly

• Bulbo-protuberential sulcus

• Ventral part more echogenic than dorsal part• Basilar artery

3. Medulla Oblongata

ULTRASOUND TECHNIQUE: GETTING THE VIEW

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ULTRASOUND TECHNIQUE: GETTING THE VIEW ULTRASOUND ASSESSMENT: BRAINSTEM

ULTRASOUND ASSESSMENT: BRAINSTEM• Criteria for normal brainstem growth

• Anatomical

• Ultrasound

• Fetal growth charts

• Pons

• Vermis/pons ratio

• Anterior edge of pons arch to edge of 4th ventricle

• Perpendicular to axis of the stem

• Perpendicular to craniocaudal diameter of vermis

WHAT GOES WRONG: BRAINSTEM MALDEVELOPMENT

• Associated with significant neurodegenerative malformations

• Pontocerebellar hypoplasia (PCH)

• Malformations of cortical development• Lissencephaly

• Cobblestone malformations

• Various syndromes

BACKGROUND: PONTOCEREBELLAR HYPOPLASIA

• Group of rare neurodegenerative disorders

• Caused by genetic mutations • 10 types: PCH1, PCH2, PCH3-10

• Autosomal recessive

• Progressive atrophy of cerebellum and pons• Continues after birth

• Very poor prognosis • Severe developmental delay; problems with movement, hypotonia; vision impairment;

speech impairment; breathing difficulties; feeding difficulties, seizures• Many only live into infancy or childhood

Normal Flat Pons

CASE 1:

• 22+2. G6 P4-1. Phx NND due to microcephaly and breathing difficulties

• MRI 5 days later:

• A motion degraded suboptimal quality study.

• The vermis is present but limited views and size prevent definitive visualisation of the primary fissures and all lobules.

• The pons appears mildly flattened and reduced in AP diameter.

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CASE 1: CASE 1: FOLLOW UP ULTRASOUNDS

(Further MRI studies declined)

HC: 1.7th → 0.4th → 0.01st → <0.01st centile

TCD: 0.6th → 0.03th → <0.01st centile

CASE 1: FOLLOW UP ULTRASOUNDS: VERMIS HEIGHT

Height of Vermis

(Greatest height of vermis, parallel to axis of brainstem [sagittal])

Gestation Average SD

Average -3SD (0.2nd

centile)

Average -2SD (2.3rd

centile)

Average -1SD (15.9th

centile)

Average (50

th

centile)

Average +1SD (84.1st

centile)

Average +2SD (97.7th

centile)

Average +3SD (99.8th

centile)16 4.73 0.43 3.44 3.87 4.30 4.73 5.16 5.59 6.0217 5.65 0.39 4.48 4.87 5.26 5.65 6.04 6.43 6.8218 6.70 0.63 4.81 5.44 6.07 6.70 7.33 7.96 8.5919 7.19 0.80 4.79 5.59 6.39 7.19 7.99 8.79 9.5920 8.11 1.07 4.90 5.97 7.04 8.11 9.18 10.25 11.3221 8.96 1.45 4.61 6.06 7.51 8.96 10.41 11.86 13.3122 9.97 1.00 6.97 7.97 8.97 9.97 10.97 11.97 12.9723 11.23 1.32 7.27 8.59 9.91 11.23 12.55 13.87 15.1924 11.84 0.83 9.35 10.18 11.01 11.84 12.67 13.50 14.3325 12.05 0.84 9.53 10.37 11.21 12.05 12.89 13.73 14.5726 13.54 1.19 9.97 11.16 12.35 13.54 14.73 15.92 17.1127 14.87 0.88 12.23 13.11 13.99 14.87 15.75 16.63 17.5128 15.38 1.46 11.00 12.46 13.92 15.38 16.84 18.30 19.7629 15.87 0.98 12.93 13.91 14.89 15.87 16.85 17.83 18.8130 16.64 1.55 11.99 13.54 15.09 16.64 18.19 19.74 21.2931 17.51 0.82 15.05 15.87 16.69 17.51 18.33 19.15 19.9732 18.31 1.58 13.57 15.15 16.73 18.31 19.89 21.47 23.0533 19.12 0.97 16.21 17.18 18.15 19.12 20.09 21.06 22.0334 19.79 1.30 15.89 17.19 18.49 19.79 21.09 22.39 23.6935 20.09 1.29 16.22 17.51 18.80 20.09 21.38 22.67 23.9636 22.32 3.10 13.02 16.12 19.22 22.32 25.42 28.52 31.62

>37 22.33 1.97 16.42 18.39 20.36 22.33 24.30 26.27 28.24

22/40 = 9mm = 15th centile

25/40 = 10.6mm = 5-10th centile

29/40 = 12.8mm = 0.2nd centile

Ref: Kline-Fath, Bulas, Bahado-Singh Fundamental and Advanced Fetal Imaging p861

CASE 1: FOLLOW UP ULTRASOUNDS: BRAINSTEM25+229+2

CASE 1: POST NATAL – PCH4 CASE 2: MULTIPLE BRAIN ABNORMALITIES

• Agenesis of the corpus callosum

• Hypoplastic vermis with rotation

• Flat pons

• Delayed sulcation

• HC 5th →1st centile

• Not typical of PCH due to large cerebellar hemispheres

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CASE 2: 32+2 CASE 2: 32+2

CASE 2: POST-NATAL

• Autosomal dominant TUBA1A related brain cortical malformation syndrome.

• Tubulinopathy: Wide and overlapping range of brain malformations caused by mutations of one of seven genes encoding different isotypes of tubulin

IN CONCLUSION