Approach to Macro and Microcephaly

Dr. Kalpana MallaMD Pediatrics

Manipal Teaching Hospital

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

MACROCEPHALY

Head circumference > 3 standard deviations below the mean for age and sex

MICROCEPHALY

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

• Familial• Congenital : Achondroplasia, Cranioskeletal

dysplasia, Hydrocephalus, Porencephaly.• Degenerative : white matter degeneration• Infectious : Hydrocephalus, sudural

effusion/empyema

CAUSES OF LARGE HEAD

• Metabolic : GM1 gangiosidosis, mucopolysaccharidosis, hypoparathyroid.

• Space occupying : tumors, hematoma• Neurocutaneous defects : tuberous sclerosis,

neurofibroma• Thickened Skull: Rickets, hemolytic anaemia,

fibrous dysplasia of bone

CAUSES OF LARGE HEAD

Head circumference

• Normal head circumference growth velocity:

• Birth-35cm • 0-3 months : +2 cm/mon(41cm)• 3-6 months :+ 1 cm/mon(44cm)• 6-12 months :+ 0.5cm/mon• 1-3 year : 0.25 cm/ mon• 3-6 year : 1 cm/year

• Pathological increase in ventricular volume due to abnormal CSF accumulation

• Imbalance between CSF production and flow leading to ventricular enlargement

HYDROCEPHALUS

• CSF secreted @ 500ml/day @ 20 ml/hr

• Total CSF volume in infant = 50 mlin adult = 150ml.

• 80% CSF – produced from choroid plexus of lateral, 3rd and 4th ventricle.

• 20% CSF – from cerebrum and spinal cord

Physiology of CSF

CSF DRAINAGECSF Lateral Ventricles

Interventricular Foramen of MONRO

3rd VENTRICLE

AQUEDUCT OF SYLVIUS

4th VENTRICLE

MEDIAN FORAMEN OF MAGENDIE

Paired Lateral FORAMEN OF LUSCHKA

80 % Enters into CISTERNAL SYSTEM

20 % Enters Subarachnoid Space OF SPINAL CORD

Then flows into VENOUS SINUSES Due to increased HYDROSTATIC PRESSURE Through ARACHNOID VILLI AND GRANULATIONS

1. Obstruction to flow2. Decreased absorbtion3. Increased production- rarely by choroid

plexus papilloma

Pathophysiology:

• Obstructive/ Non Communicating/ Internal:• Obstruction is within ventricular system upto

and including outlet foramina of 4th ventricle.• SAS is compressed - ventricles can’t

communicate with subarachnoid space

CLASSIFICATION OF HYDROCEPHALUS

• Aqueductal stenosis: - 70% of congenital - 2% are inherited, mostly secondary to IVH,

meningitis.• Arnold chiari malformation esp. type 2• Dandy walker syndrome• Chromosomal anomalies

OBSTRUCTIVE/ NON COMMUNICATING - causes

• Intra uterine infections• Midline brain tumors - Cerebellar tumors• Vein of Galen malformation• Posterior fossa subdural hematoma• Congenital septa or membrane block at outlet of

4th ventricle

OBSTRUCTIVE/ NON COMMUNICATING/ INTERNAL:

• Non Obstructive/ Communicating/ External:

• Obstruction is distal to 4th ventriclular outlet - foramina in cisterns, subarachnoid space or arachnoid villi

• Patent ventricular system - SAS space is enlarged

• Post infectious - Meningitis ( TB COMMONEST, also pnemococcal), Intra uterine infections – toxoplasma, CMV,

• Sub arachnoid hemorrhage • Meningeal leukemic infiltrates• Secondary to excessive CSF production-papilloma

of choroid plexus• Mucopolysacchridosis, achondroplasia• Craniosynostosis

NON OBSTRUCTIVE/ COMMUNICATING – causes

• Congenital :

Eg. IUI, IVH AV-malformations Cong. tumors

• Acquired :

Eg . TBM, meningitis,

Post. fossa tumor,

CLASSIFICATION

• 50% may be asymptomaticSymptoms• Vomiting, headache• Drowsiness• Failure to thrive, poor appetite• Shrill cry, irritability, lethargy• Delayed motor milestones – mainly motor• Progressive enlargement of head• Abnormal shape of head – inverted triangle• Slow mental deterioration

Clinical Features

Signs• Progressive increase in OFC (>1cm/wk )• Head shape abnormal, forehead is broad,

frontal bossing• Ant fontanel: wide open and bulging, non

pulsatile• Open squamo parietal suture

• Macrocephaly• Skin of skull – shiny, tense,

dilated veins• Transillumination test: • MacEwen Sign: percussion of

the skull produces a “cracked pot” sound

Signs

Trans illumination of headWhen Translucency extends beyond 2 CM in frontal area and over 1 CM in occipital area is abnormal and S/O – sub dural effusion Hematoma, hydrocephalus , Hydranencephaly

SOME PART OF SKULL LIGHTED- HYDROCEPHALUS

ENTIRE SKULL IS LIT UP - HYDRANENCEPHALY.

MACEWEN’S SIGN

Aka. Crack pot signElicited by percussion of skullAmplified sound can be heard from Steth from other end - Indicative of separated sutures due to raised intra cranial tension

Physiologically present if AF is open

• Ocular signs: eyes deviated downward “sun setting sign”- due to pressure of 3rd ventricle supra pineal recess on mesencephalic tectum , causing impairment of upward gaze

• Squint - 6th n. palsy• Nystagmus, ptosis, Optic atrophy• Chorioretinitis (I.U. infec)• Papilledema

Eyes signs

• Pyramidal signs: spasticity, brisk tendon reflexes, clonus, Babinski sign due to compression & stretching of myelienated para central corticospinal fibers arising from leg area of motor cortex

• Others: mental retardation, gait anomaly, epilepsy

Signs

• Presents as difficulty in feeding, sucking, drooling, aspiration

• Due to - - Disruption of B/L cortico bulbar fibers - Can be due to arnold chiari malformation

Pseudo bulbar palsy

• Multiple café au- lait spots – NF• Cranial bruit – Vein of Galen malformation• NTD – Arnold chiari• DANDY WALKER - prominent occiput

Look for

• USG: when ant fontanelle is open. Assesses ventricular size, detects IVH

• Plain skull films- shows sign of ICP:- separation of sutures- erosion of the post. Clinoid process- increased convolutional markings (beaten silver appearance)

-Flat enlarged sella tursica

Investigation:

• CT: helps to identify the cause• MRI: better visualization of post fossa

pathologies• Opthalmological evaluation• Psychomotor assessment: using different dev

scales

Investigation:

• Medical :aims to decrease ICP&CSF formation1.MANNITOL 20% - 5ML/KG stat followed by

2ml/kg 6th hourly for 2 days.2.ACETAZOLAMIDE 50-100mg/kg/day to reduce

CSF production3.ORAL GLYCEROL4.FRUSEMIDE

TREATMENT

VENTRICULO PERITONEAL SHUNT • SILASTIC one way low pressure valve shunt –

Upadhya shunt• Indications for surgery:Papilledema/ periventricular ooze on

fundoscopy/CT.Cortical mantle < 2.5cm on initial neuroimagingProgressive thinning of mantle despite medical

treatment.

SURGICAL

• Pump the reservoir by finger pressure • Normally shunt empties and refills on release• IF FAILS TO REFILL = Proximal block = Due to

choroid plexus tissue• IF RESISTANCE TO EMPTYING= Distal block =

Omental block

EVALUATION OF SHUNT

• SHUNT FAILURE CAN OCCUR DUE TO:Shunt infection, calcifications, malposition.• Shunt infection - mostly due to staph

epidermis, staph aureus.

• “arrested hydrocephalus” - may undergo spontaneous arrest • Untreated : 50% mortality• These children are at an increased risk of:

– Dev. Disabilities with less IQ– Visual problems: visual field defects, strabismus, optic

atrophy– Behavioral problems: – Accelerated pubertal dev- due to increased

gonadotropin secretion in response to raised ICP

Prognosis

Post Meningitis with enlarging head

CT, CSF EXAM, FUNDOSCOPY

LOOK FOR CSF CELLS PROTEINS, INTRA CRANIAL PRESSURE PERIVENTRICULAR OOZE

RAISED ICTLOW CELLSLOW PROTEIN

SHUNT

Mild hydro,ICT NOT RAISED

MEDICAL

Significant hydroc.Ooze +, high cells,protein

Externaldrainage

High cellsHigh proteins

Try to avoid Shunts. Treat medically

POST TBM HYDROCEPHALUS

IN Acute Stage not indicated as high PROTEINS - GREATER SHUNT BLOCK also it responds well to ATT AND STEROIDS.

INDICATION FOR SURGERY BEING – Persistent decerebration no improvement in sensorium in 10days

• 1,3,6 months then yearly.• Check – HC, neurological signs, Fundus, shunt

function, IQ testing.

Follow up

Hydranencephaly

• The cerebral hemispheres are replaced by a thin-walled, fluid-filled cyst

• The aqueduct is usually atretic, and increased fluid pressure causes the cyst to enlarge

• The empty cranial cavity transilluminates

Is defined as head circumference > 3 standard deviations below the mean for age and sex

MICROCEPHALY

PRIMARY ( Genetic ) MICROCEPHALY

Refers to group - associated with specific genetic syndromes.

USUALLY have slanting forehead.Identified at birth itself

Causes for primary• Familial - AR• Autosomal dominant• Syndromes : Down, Cri du

chat, Edward, Cornelia de Lange, Rubinstein Tyabi, Smith Lemli Opitz.

• 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

Secondary ( non genetic) Microcephaly

• Radiation• Congenital infections – rubella, CMV, toxo• Drugs – fetal alcohol, fetal hydantoin• Meningitis/encephalitis

Causes for secondary microcepahaly

• Metabolic – maternal diabetes• Hypoxic ischemic encephalopathy• Malnutrition• Hyperthermia

Causes for secondary microcepahaly

Microcephaly • Shape of skull

usually normal• Suture line -

normal

Craniosynostosis • Shape of skull -

abnormal• Suture line –

ridged.

• Familial microcephaly needs exclusion• Detail birth history• OFC of siblings and parents should be

recorded• Examine for associated dysmorphism

Developmental assessment• Detailed neurological evaluation - seizures,

spasticity

Evaluation of microcephaly

• X ray skull -determine suture patency, overriding, fusion and calcification

• TORCH serology-• KARYOTYPE- if dysmorphism• Metabolic screening

Investigations

• CT Head- for evidence of HIE sequelae, and intracranial calcifications

• MRI- in cases of familial microcephaly and suspected migrational disorders

• Usually supportive• Treat neurological & sensory deficits• Treat seizures• If MR present, special schools may be

needed• Genetic councelling

Treatment and Prognosis

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