Causes

Below is a list of causes of macrocephaly from Swaiman's pediatric neurology: principles and practice noted in The Little Black Book of Neurology ^{[1] [2]}:

I. Hydrocephalus

Noncommunicating:

• Arnold-Chiari malformation
• Aqueductal stenosis
• X-linked hydrocephalus with stenosis of the aqueduct of Sylvius (HSAS) syndrome ( L1CAM)
• Dandy-Walker malformation
• Galenic vein aneurysm or malformation
• Neoplasms, supratentorial, and infratentorial
• Arachnoid cyst, infratentorial
• Holoprosencephaly with dorsal interhemispheric sac

Communicating:

• External or extraventricular obstructive hydrocephalus ( dilated subarachnoid space)

Arachnoid cyst, supratentorial

Meningeal fibrosis/obstruction:

• Postinflammatory
• Posthemorrhagic
• Neoplastic infiltration

Vascular:

• Arteriovenous malformation
• Intracranial hemorrhage
• Dural sinus thrombosis

Choroid plexus papilloma

Neurocutaneous syndromes:

• Incontinentia pigmenti

Destructive lesions:

• Hydranencephaly
• Porencephaly

Familial, autosomal-dominant, autosomal-recessive, X-linked

II. Subdural Fluid

• Hematoma
• Hygroma
• Empyema

III. Brain Edema (Toxic-Metabolic)

• Intoxication
• Lead
• Vitamin A
• Tetracycline
• Endocrine ( hypoparathyroidism, hypoadrenocorticism)
• Galactosemia
• Idiopathic ( pseudotumorcerebri)

IV. Thick Skull or Scalp (hyperostosis)

• Familial variation
• Anemia
• Osteoporosis, severe precocious autosomal-recessive osteoporosis ( CLCN7, TCIRG1)
• Pycnodysostosis ( CTSK)
• Craniometaphyseal dysplasia ( ANKH)
• Craniodiaphyseal dysplasia
• Pyle dysplasia
• Sclerosteosis ( SOST)
• Juvenile Paget disease
• Idiopathic hyperphosphatasia
• Familial osteoectasia
• Osteogenesis imperfecta
• Rickets
• Cleidocranial dysostosis
• Hyperostosis corticalis generalisata ( van Buchem disease)
• Proteus syndrome

V. Megalencephaly and hemimegalencephaly

Diagnosis

Macrocephaly is customarily diagnosed if head circumference is greater than two standard deviations (SDs) above the mean. ^[3] Relative macrocephaly occurs if the measure is less than two SDs above the mean, but is disproportionately above that when ethnicity and stature are considered.

Relative macrocephaly is likely to have been inherited by one or both parents and is considered benign or megalencephaly and is not associated with neurological disorders ^[4]. Diagnosis can be determined in utero or develop within eighteen 18-24 months after birth in some cases where head circumference tends to stabilize in infants ^[5]. Diagnosis in infants includes measuring the circumference of the child's head and comparing how significant it falls above the 97.5 percentile of children similar to their demographic and then check if there is any intracranial pressure present in the child ^[4]. If a patient is suspected of having macrocephaly molecular testing will be used to confirm diagnosis.

Neurodevelopment is also assessed for all cases and suspected cases of macrocephaly to determine if and what treatments may be needed and whether or not other syndromes may be present or likely to develop.

Treatment

Treatment varies depending on whether or not it occurs with other medical conditions in the child and where cerebrospinal fluid is present ^[5].

• If benign and found between the brain and skull then no surgery is needed ^[5].
• If excess is found between the ventricle spaces in the brain then surgery will be needed ^[5].

Syndromes with Macrocephaly

Below is a list of syndromes associated with macrocephaly. ^[6]

Include multiple major and or minor anomalies:

• Acrocallosal Syndrome
• Apert Syndrome
• Bannayan-Riley-Ruvalcaba
• Cardiofaciocutaneous syndrome
• Chromosome 14 - maternal dismoy
• Chromosome 22qter deletion
• Cleidocranial dysostosis
• Costello syndrome
• Encephalocraniocutaneous lipomatosis
• FG syndrome
• Hailermann-streiff syndrome
• Hydolethalus syndrome
• Hypomelanosis syndrome
• Hypomelanosis of Ito
• Kelvin Peter anomaly plus syndrome
• Lujan-fryns syndrome
• Macrocephaly-CM (MCAP)
• Marshall-Smith syndrome
• Neuhauser megalocornea/MR syndrome
• Neurofibromatosis I
• Nevoid basal cell carcinoma syndrome
• Noonan syndrome
• Ocular-ectodermal syndrome
• Osteopathia striata - cranial sclerosis
• Perlman syndrome
• Ritscher - schinzel syndrome
• Robinow syndrome
• Simpson-golabi-behmel syndrome
• Sotos syndrome
• Sturge-Weber syndrome
• Weaver syndrome
• Wiedermann-rautenstrauch syndrome

Secondary to a metabolic disorder:

• Glutaric aciduria type II
• GM1 gangliosidosis
• Hunter syndrome
• Hurler syndrome
• MPS VII
• Sanfilippo syndrome
• Zellweger syndrome

Associated with a skeletal dysplasia:

• Achondroplasia
• Camptomelic dysplasia
• Craniodiaphyseal dysplasia
• Craniometalphyseal dysplasia
• Hypochondrogenesis
• Hypochondroplasia
• Kenny-caffey
• Kniest syndrome
• Lenz-majewski
• Osteogenesis imperfecta III
• Osteopetrosis, autosomal recessive form
• Schneckenbecken dysplasia
• Sclerosteosis
• Short rib syndrome, beemer-langer type
• Short rib-polydactyly 2 (majewski type)
• Spondyleopiphyseal dysplasia congenita
• Thanatophoric dysplasia

  

With no obvious physical findings:

• Alexander disease
• Canavan
• Cobalamin deficiency (combined methylmalonic aciduria and homocystinuria)
• Dandy-Walker malformation
• Glutaric aciduria I
• L-2 hydroxglutaric aciduria
• Megalencephalic leukoencephalopathy
• Osteogenesis imperfecta IV
• Osteopathia striata-cranial sclerosis
• Periventricular heterotopia
• Sandhoff disease
• Tay-sachs

See also

• Microcephaly
• Megalencephaly
• Hydrocephalus