annormalities of head size and shape

Abnormalities of Head Size and Shape

Mr.Riyaz KhanAug-2012 BatchVI th SemsterDepartment of PediatricsNepalgunj Medical College-Kohalpur

MACROCEPHALY

• Definition: Head circumference ( occipito frontal ) > 2 standard deviation(SD) above the mean for age and sex.

1 SD = 1.25 CM

Macrocephaly > 2 SD i.e. 2.5 cm

Microcephaly < 3 SD i.e 3.75 cm

Take 50 centile as base line

1. Megalencephaly-Benign Familial-Neurocutaneous syndromes: Neurofibromatosis, tuberous sclerosis-Fragile X syndrome-Leucodystrophies & Lysosomal storage disease

2. Increased Cerebrospinal fluid-Hydrocephalous-Benign enlargement of subarachnoid space

3. Enlarged Vascular compartment-Arteriovenous malformation-Subdural, epidural, subarachnoid or intraventricular hemorrhage

Causes of Macrocephaly

cont….

4. Increase in bony compartment Bone disease: Achondroplasia, osteogenesis imperfecta, osteopetrosisBone marrow expansion: Thalassemia major

5. Miscellaneous causesIntracranial mass lesions: Cyst, abscess or tumorRaised intracranial pressure: Idiopathic pseudotumor cerebri, lead

poisoning, galactosemia

Head Circumference

Normal head circumference growth velocity:

• Birth-35cm • 0-3 months : +2

cm/month(41cm)• 3-6 months :+ 1

cm/month(44cm)• 6-12 months :+

0.5cm/month(47cm)• 1-3 year : 0.25 cm/ mnth• 3-6 year : 1 cm/year

• History • Examination including auscultation of the skull for bruit • Developmental history• Rate of head growth – serial measurements

Investigations :1. Urea/electrolytes2. Thyroid function test 3. Plasma amino acids4. Urine amino acids and organic acids, glycosaminoglycans5. CT head/MRI head preferably 6. Bone profile

APPROACH

TREATMENT

-generally require no tx

- Infants with hydrocephalus may require neurological intervention( e.g. placement of a ventriculo-peritoneal shunt).

MICROCEPHALYDefinition: Head circumference < 3 SD below the mean

for age, sex and gestation.

Types :1.Primary (Genetic)

2. Secondary (non-genetic)

1. PRIMARY ( Genetic ) MICROCEPHALY

• Condition associated with reduced generation of neurons during neural development and migration.

• Refers to group - associated with specific genetic syndromes.

• Usually have slanting forehead.

• Identified at birth itself

Causes for primary

• Familial - AR• Autosomal dominant• Syndromes :

1. Down Syndrome 2. Cri du chat3. Edward4. Cornelia de Lange5. Rubinstein Tyabi

• Results from noxious agents that may affect a fetus in utero or an infant during periods of rapid brain growth, particularly the first 2 years of life

2. Secondary ( non genetic) Microcephaly

1. Radiation2. Congenital infections – rubella, CMV, toxoplasmosis,

HIV, Syphilis3. Drugs – fetal alcohol, fetal hydantoin4. Meningitis/encephalitis5. Metabolic – maternal diabetes6. Hypoxic ischemic encephalopathy7. Malnutrition8. Hyperthermia

Causes for secondary microcepahaly

APPROACH• History (perinatal – family history) • Examination – dysmorphic features – malformations • Development • Growth – serial measurements of HC

INVESTIGATIONS• Baseline biochemistry, metabolic screen • Genetic testing – karyotype, molecular genetics• TORCH screen • Ophthalmology• MRI brain

• No treatment for microcephaly• Baby’s head cannot be returned to a normal size &

shape• According to the cause

– Anticonvulsants– Physiotherapy– Hearing and speech therapy– Dietary management for failure to thrive– Genetic counseling

Management

CRANIOSYNOSTOSIS

Definition: premature fusion of one or more cranial sutures, either major(e.g metopic, coronal, sagittal, and lambdoid) or minor( frontnasal, temporosquamosal, and frontosphenoidal).

DEFORMITIES OF SKULL

1. Plagiocephaly2. Scaphocephaly3. Trigonocephaly4. Turencephaly5. Brachycephaly

-Fusion of either right or left side of the coronal suture

-Causes the normal forehead and the brow to stop growing

-Produces flattening of the forehead and the brow on the affected side, with the forehead tending to be excessively prominent on the opposite side

PLAGIOCEPHALY

SCAPHOCEPHALY

Early closure or fusion of the sagittal suture

Fusion causes a long, narrow skull .Prominent occiput and forehead

Usually only craniosynostosis which is relatively harmless

TRIGONOCEPHALY

Fusion of the metopic (forehead) suture

Fusion result in a prominent ridge running down the forehead -looks pointed, like a triangle, with closely placed eyes (hypotelorism).

• Turriencephaly – cone shaped head . Fusion of coronal and speno frontal or fronto

ethmoid sutures.

• Brachycephaly – premature closure of coronal suture expands skull parallel to coronal suture , thus broadening of forehead with short AP diameter. Eg – in many syndromes like Downs Syndrome

Diagnosis

• Palpation of suture reveals prominent bony ridge.

• Fusion may be confirmed by x-ray skull

• Associated syndromes – Crouzon , Alperts, Carpenter

Management

• Premature fusion of single suture rarely causes any neurological deficit . Thus, in this situation the only indication is cosmetics.

• 2 or more suture fusion – more complications eg. ↑ ICT, hydrocephalus, optic atrophy, DNS, choanal atresia --- operative surgery essential – craniectomy with craniofacial correction.

• Usually good prognosis with non syndromic infants……………

Thank You