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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