Imaging of the Macrocephalic Pediatric Patient Mahmood, S; Koney NO, Heller G

Imaging of the Macrocephalic Pediatric Patient

Mahmood, S; Koney NO, Heller G

• Head circumference is a routinely measured surveillance parameter in children

• Normal head circumference falls within two standard deviations of the mean

• Head circumference normal distribution curves are age and sex specific

• The most common cause for a large head circumference is inaccurate measurement or inconsistent method of measurement

Imaging of the Macrocephalic Pediatric Patient

Etiologies

• Common

Benign external hydrocephalus

Communicating hydrocephalus

Non-communicating hydrocephalus

• Uncommon

Trauma

Metabolic causes

Neurocutaneous syndromes

Vascular malformations

Locational Classification

Scalp

Intra-axial

Locational Classification

Scalp

Intra-axial

SCALP anatomy

Imaging of the Macrocephalic Pediatric Patient

Caput succedaneum

- Defined as focal edema of subcutaneous, connective tissues

- Often associated with birth trauma- A limited process which resolves spontaneously with

time- Ultrasound imaging is ideal for evaluation

Coronal T1, Axial FLAIR, T and T2 images demonstrating focal scalp swelling crossing the midline of the skull (asterisks)

Scalp

Imaging of the Macrocephalic Pediatric Patient

- Hematoma occurring between the periosteum and the galeal aponeurosis secondary to emissary vein rupture

- Rare but potentially lethal. May lead to severe anemia, hypotension and jaundice

- Associated with vacuum assisted delivery and head trauma- Early diagnosis and management is key to survival

Sub-Galeal hematoma

Scalp

CMAJ. 2001 May 15; 164(10): 1452–1453.

Imaging of the Macrocephalic Pediatric Patient

Cephalhematoma

Scalp

- Hematoma occurring underneath the periosteum- Bound by suture lines because of periosteum unlike sub-

galeal hematomas which do cross suture lines

- Any scalp hematoma should prompt a search for injury deep to the scalp or on the contralateral side!!

Scalp HematomasFeatures Caput Succedaneum Sub-Galeal Cephalohematoma

Location Point of contact Beneath aponeurosis, may extend to neck and orbits

Usually over parietal bones, does NOT cross suture lines

Characteristic Finding

Vaguely demarcated Firm, ill defined borders, may have crepitus or fluid wave

Distinct margins

Timing Maximal size and firmness at birth

Progressively increases after birth

Increases after birth over 12 – 24 hours

Volume of Blood Loss

Minimal May be massive Rarely severe

CMAJ. 2001 May 15; 164(10): 1452–1453.

Locational Classification

Scalp

Intra-axial

- Overgrowth of brittle, thick, dense, and fragile bones - May be an autosomal recessive or an autosomal dominant

disorder- Only the autosomal recessive form occurs during the neonatal

period

Sagittal T1 images of the brain, showing extremely thickened skull( arrows). Curea, AJNR 2000.

Imaging of the Macrocephalic Pediatric Patient

Skull

Osteopetrosis

Osteopetrosis Complications

• Anemia secondary to bone overgrowth

• Cranial nerve foraminal encroachment can lead to cranial nerve dysfunctions including deafness and blindness

• Pacchionian granulations can lead to communicating hydrocephalus and macrocephaly

Imaging of the Macrocephalic Pediatric Patient

Skull

Osteopetrosis

Locational Classification

Scalp

Intra-axial

Imaging of the Macrocephalic Pediatric Patient

Benign enlargement of the subarachnoid space

Coronal T2, Sagittal T1 and Axial T2 images of the brain demonstrate expansion of the bifrontal subarachnoid space

- A common entity of macrocephaly in the pediatric population, also known as benign external hydrocephalus

- Patients usually born with a normal head circumference, followed by progressive enlargement

- Frequent family history of macrocephaly

Extra-axial

Imaging of the Macrocephalic Pediatric Patient

- Bilateral enlarged frontal subarachnoid space- Anterior fontanelle is large and soft to palpation.- Normal or minimally enlarged ventricles establishes the

diagnosis- Vessels crossing freely in subarachnoid space,

distinguishing this entity from subdural hematomas

Vessels freely cross the subarachnoid space( arrows)

Benign enlargement of the subarachnoid space

Extra-axial

Imaging of the Macrocephalic Pediatric Patient

- May produce macrocephaly during the neonatal period- Progressive increases in

head circumference- A potential complication is

communicating hydrocephalus

Sagittal T1, Coronal and Axial T2 MRI images, showing bilateral subdural hematomas in non-accidental injury

Coronal ultrasound image demonstrating bilateral subdural hematomas, external to the arachnoid matter

Extra-axial

Subdural Hematoma

Imaging of the Macrocephalic Pediatric Patient

Axial CT images demonstrating bilateral slightly hyperdense subdural hematomas

Subdural hematomas and macrocephaly in non-accidental trauma

Extra-axial

Subdural Hematoma

Imaging of the Macrocephalic Pediatric Patient

Extra-axial

- Trauma resulting in epidural hematoma is not a common mechanism of macrocephaly

Epidural Hematoma

Locational Classification

Scalp

Intra-axial

Intra-axial – Brain & Ventricular System

Macrocephaly

Brain tumor volume

Non-communicating hydrocephalus

Overproduction of CSF, e.g.,

Choroid papilloma

Imaging of the Macrocephalic Pediatric Patient

- Common tumors affecting the lateral ventricles include- Ependymomas, - Astrocytomas - Meningiomas- Choroid plexus papilloma

Axial T2, Coronal and Axial Enhanced T1 images, demonstrating large heterogeneous enhancing choroid plexus papilloma in the right lateral ventricle

Lateral ventricles

Intra-axial

Imaging of the Macrocephalic Pediatric Patient

Tumors affecting the 3rd ventricle include: - Astrocytoma - Choroid plexus papilloma - Craniopharyngioma, - Teratomas- Sub-Ependymal Giant Astrocytoma (SEGA)

Third Ventricle

Intra-axial

Imaging of the Macrocephalic Pediatric Patient

- Suprasellar tumors can obstruct at the floor of the 3rd ventricle

- Craniopharyngiomas arise from the craniopharyngeal duct extending from the hypothalamus to the sella turcica

- Most are cystic , calcified and enhancing

- MR spectroscopy demonstrates a broad lipid spectrum

Intra-axial

Third Ventricle

Imaging of the Macrocephalic Pediatric Patient

- Lesions affecting the Aqueduct of Sylvius/Cerebral Aqueduct leading to macrocephaly include:

- Congenital aqueductal stenosis- Germ cell tumors, - Pineal parenchymal tumors, - Tentorial meningioma, - Vein of Galen malformation

Aqueduct of Sylvius

Intra-axial

Imaging of the Macrocephalic Pediatric Patient

- Neonates with aneurysm of the vein of Galen may be macrocephalic at birth

- Mass effect with stenosis affecting the aqueduct of sylvius can lead to hydrocephalus

Vein of Galen Malformation

Intra-axial

Aqueduct of Sylvius

Imaging of the Macrocephalic Pediatric Patient

Multiple CT images demonstrating severe dilatation of the lateral ventricles, normal caliber of the fourth ventricle

Trans-cranial ultrasound coronal images show marked lateral ventricle dilatation

Congenital Acqueductal Stenosis

Intra-axial

Aqueduct of Sylvius

Imaging of the Macrocephalic Pediatric Patient

Multiple T1 and T2 weighted images of the brain demonstrate marked dilatation of the lateral and third ventricles and normal caliber of the fourth ventricle

- Initially the neural tube closes, the lumen is uniform in diameter throughout its length

- The aqueduct of sylvius narrows from about 5 weeks of gestational age until birth

- Stenosis can be congenital or acquired, usually at the superior colliculus level

- Can be familial and X-linked- Hydrocephalus is secondary to CSF dynamic changes

Intra-axial

Aqueduct of Sylvius

Imaging of the Macrocephalic Pediatric Patient

Bithalamic glioma causing obstructive hydrocephalus

Bithalamic Glioma

Pineal Germinoma

Pineal germinoma causing hydrocephalus

Intra-axial

Aqueduct of Sylvius

Imaging of the Macrocephalic Pediatric Patient

4th Ventricle

- Common posterior fossa masses affecting the 4th ventricle include:- Brain stem glioma- Ependymomas- Astrocytoma (most common in pediatrics patients)- Medulloblastomas (e.g. PNET)

Intra-axial

Scalp

Intra-axial Space Other/Zebras

Imaging of the Macrocephalic Pediatric Patient

Neurofibromatosis IDevelopmental & Neurocutaneous Syndromes

Other

- Enlarged head circumference maybe one of the clinical features in this multisystem genetic disorder

Optic glioma involving right optic nerve with spongiform dysplasia in dentate nuclei of cerebellum

Imaging of the Macrocephalic Pediatric Patient

- Subependymal giant cell astrocytoma in tuberous sclerosis

Tuberous SclerosisDevelopmental & Neurocutaneous Syndromes

Other

Imaging of the Macrocephalic Pediatric Patient

May present with macrocephaly during the neonatal period, usually results from an enlarged posterior fossa

Dysgenesis of the cerebellar vermis

Cystic dilatation of the fourth ventricle

Elevated tentorium and torcula

Dandy Walker MalformationDevelopmental & Neurocutaneous Syndromes

Other

Imaging of the Macrocephalic Pediatric Patient

Chiari II malformation enlarge the head circumference by causing hydrocephalus

Chiari II MalformationDevelopmental & Neurocutaneous Syndromes

Other

Imaging of the Macrocephalic Pediatric Patient

Metabolic Disorders

Metabolic disorders do not usually present in the neonatal period

Exceptions to this are glutaric acidemia type I, Canavan disease, and Alexander disease.

Other

Imaging of the Macrocephalic Pediatric Patient

Metabolic Disorders

Glutaric Aciduria type 1

Imaging features include diffuse atrophy predominating in the frontotemporal areas and bilateral necrosis of the of the caudate nuclei and the putaman

Other

- Rare disorder resulting from glutaryl-coenzyme A dehydrogenase deficiency leading to an error in the catabolism of lysine, hydroxylysine, and tryptophan

- Autosomal recessive disorder

- Macrocephaly is present at birth

- Usually no neurological deficits are present during neonatal period

Imaging of the Macrocephalic Pediatric Patient

Metabolic Disorders

Canavan’s Disease

Other

Clinical features include:- macrocephaly and diffuse leukodystrophy- Usually presents with rapid head growth during the first

weeks of life, marked hypotonia, and nystagmus

Imaging of the Macrocephalic Pediatric Patient

Metabolic Disorders

Canavan’s Disease

Elevated NAA peak on MR spectroscopy. Michel S J , Given C A Radiology 2006;241:310-324

Other

- Infantile neurodegenerative disease caused by mutations in the gene encoding the enzyme aspartoacylase

- Increased levels of N-acetylaspartic acid in urine, elevated N-acetyl aspartate (NAA) peak by MRI spectroscopy of the brain

- Confirmed by demonstrating decreased aspartoacylase activity in cultured fibroblasts

Imaging of the Macrocephalic Pediatric Patient

Metabolic Disorders

Alexander Disease

Five MR imaging criteria: Four of five criteria needed for an MR imaging-based diagnosis.extensive cerebral white matter changes with frontal predominance

• a periventricular rim with high signal on T1-weighted images and low signal on T2-weighted images

• abnormalities of basal ganglia and thalami• brain stem abnormalities• contrast enhancement of affected gray and white matter structures

AJNR 2001 22: 541-552 van der Knapp

Other

Imaging of the Macrocephalic Pediatric Patient

Somatic Overgrowth Syndromes

Soto Syndrome (Cerebral Gigantism)

Radiopaedia.Org/Cases Sotos syndrome

Clinical features include:- Normal sized brain in larger than average skull, growth spurt

beyond the normal range during the first 3 years of life, resulting in macrosomia (especially of the head)

- Usually a sporadic condition, although familial cases have been reported

Other

Imaging of the Macrocephalic Pediatric Patient

Soto Syndrome (Cerebral Gigantism)

Radiopaedia.Org/Cases Sotos syndrome

Somatic Overgrowth Syndromes

Other

MRI diagnosis criteria:1. Enlarged extra-axial spaces2. Enlarged lateral ventricles3. Small corpus callosum 4. Midline anomalies: absent corpus callosum, cavum septum

pellucidum, mega cisterna magna) 5. Small cerebellar vermis

Imaging of the Macrocephalic Pediatric Patient

Beckwith Wiedemann Syndrome

Somatic Overgrowth Syndromes

Other

Ultrasound images demonstrate bilaterally enlargement of the kidneys.statdx.com

Clinical features include:- Macroglossia, umblilical hernia, hypoglycemia, propensity for

developing Wilms tumors- Rarely, patients can also develop macrocephaly

Imaging of the Macrocephalic Pediatric Patient

Simpson-Golabi Behmel Syndrome

Clinical features include:

Macrosomia and macrocephaly

Coarse facial features (macrostomia, macroglossia, palatal abnormalities)

Mild to severe intellectual disability with or without structural brain anomalies

Somatic Overgrowth Syndromes

Other

Imaging of the Macrocephalic Pediatric Patient

Weaver Syndrome

Somatic Overgrowth Syndromes

Other

Clinical features include:

- Macrocephaly (90%)- Dysmorphic facial features: broad forehead (100%), flattened

occiput, low set and large ears- Accelerated skeletal maturation- Limb anomalies- Development delay - Predisposition for tumors (e.g. neuroblastoma)

Take-Home Points

• Macrocephaly is head circumference above 2 standard deviations of the mean, and is age and sex specific

• Most common cause if inaccurate measurement

• Location – scalp, skull, extra and intra-axial : can be used to classify the more common causes of macrocephaly

• The more atypical causes of macrocephaly can be classified into neurocutaneous, metabolic and somatic overgrowth syndromes

References

1.Benign enlargement of sub-arachnoid spaces in infancy. Kuruvilla LC. J Pediatr Neurosci. 2014 May;9(2):129-31. doi: 10.4103/1817-1745.139309. PMID: 25250066

2. Osteopetrosis. Jenkins PF, Prieto P, Tang RA, Yousefi S. Am Orthopt J. 2013;63:107-11. doi: 10.3368/aoj.63.1.107. PMID: 24141761

3.Infantile Alexander disease: A rare leukodystrophy. Kumar KJ, Suryaprakash H, Manjunath VG, Harsha S. J Pediatr Neurosci. 2012 May;7(2):117-9. doi: 10.4103/1817-1745.102573. PMID: 2324869

4.Macrocephaly in neurofibromatosis type 1: a sign post for optic pathway gliomas? Schindera C, Wingeier K, Goeggel Simonetti B, Diepold M, Nauer CB, Fleischhauer J, Steinlin M. Childs Nerv Syst. 2011 Dec;27(12):2107-11. doi: 10.1007/s00381-011-1554-2. Epub 2011 Aug 7. PMID: 21822956

5. Benign external hydrocephalus: a review, with emphasis on management. Zahl SM, Egge A, Helseth E, Wester K.Neurosurg Rev. 2011 Oct;34(4):417-32. doi: 10.1007/s10143-011-0327-4. Epub 2011 Jun 7. Review.PMID: 2164759

6.Macrocephaly syndromes. Olney AH. Semin Pediatr Neurol. 2007 Sep;14(3):128-35. Review. PMID: 17980309

7. Garganta, C. L., Bodurtha, J. N. Report of another family with Simpson-Golabi-Behmel syndrome and a review of the literature. Am. J. Med. Genet. 44: 129-135, 1992. PubMed: 1456279