Transcript of "Approach to Macro and Microcephaly"
Approach to Macro and Microcephaly Dr. Kalpana Malla MD Pediatrics Manipal Teaching HospitalDownload more documents and slide shows on The Medical Post [ www.themedicalpost.net ]
MACROCEPHALY• Head circumference ( occipito frontal ) > 2 standard deviation above the mean for age and sex MICROCEPHALYHead circumference > 3 standard deviationsbelow the mean for age and sex
Take 50 centile as base line 1 SD = 1.25 CMMacrocephaly > 2 SD i.e. 2.5 cm Microcephaly < 3 SD i.e 3.75 cm
CAUSES OF LARGE HEAD• 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
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
HYDROCEPHALUS• Pathological increase in ventricular volume due to abnormal CSF accumulation• Imbalance between CSF production and flow leading to ventricular enlargement
Physiology of CSF• CSF secreted @ 500ml/day @ 20 ml/hr• Total CSF volume in infant = 50 ml in adult = 150ml.• 80% CSF – produced from choroid plexus of lateral, 3rd and 4th ventricle.• 20% CSF – from cerebrum and spinal cord
CSF DRAINAGECSF Lateral Ventricles Interventricular Foramen of MONRO 3rd VENTRICLE AQUEDUCT OF SYLVIUS 4th VENTRICLE Paired Lateral MEDIAN FORAMEN OF LUSCHKA FORAMEN OF MAGENDIE
80 % Enters into 20 % EntersCISTERNAL SYSTEM Subarachnoid Space OF SPINAL CORD Then flows into VENOUS SINUSES Due to increased HYDROSTATIC PRESSURE Through ARACHNOID VILLI AND GRANULATIONS
Pathophysiology:1. Obstruction to flow2. Decreased absorbtion3. Increased production- rarely by choroid plexus papilloma
CLASSIFICATION OF HYDROCEPHALUS• 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
OBSTRUCTIVE/ NON COMMUNICATING - causes• 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/ INTERNAL:• 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
• 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
NON OBSTRUCTIVE/ COMMUNICATING – causes• 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
Clinical Features• 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
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
Signs• Macrocephaly• Skin of skull – shiny, tense, dilated veins• Transillumination test:• MacEwen Sign: percussion of the skull produces a “cracked pot” sound
Trans illumination of headWhen Translucency extends beyond 2 CM in frontal area and over1 CM in occipital area is abnormal and S/O – sub dural effusionHematoma, hydrocephalus , Hydranencephaly ENTIRE SKULL IS LIT UP - HYDRANENCEPHALY. SOME PART OF SKULL LIGHTED - HYDROCEPHALUS
MACEWEN’S SIGN Aka. Crack pot sign Elicited by percussion of skull Amplified 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
Eyes signs• 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
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
Pseudo bulbar palsy• Presents as difficulty in feeding, sucking, drooling, aspiration• Due to - - Disruption of B/L cortico bulbar fibers - Can be due to arnold chiari malformation
Investigation:• 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
TREATMENT• 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
SURGICALVENTRICULO 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.
EVALUATION OF SHUNT• 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
• SHUNT FAILURE CAN OCCUR DUE TO:Shunt infection, calcifications, malposition.• Shunt infection - mostly due to staph epidermis, staph aureus.
Prognosis• “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
Post Meningitis with enlarging head CT, CSF EXAM, FUNDOSCOPY LOOK FOR CSF CELLS PROTEINS, INTRA CRANIAL PRESSURE PERIVENTRICULAR OOZE SignificantRAISED ICT Mild hydro, hydroc.LOW CELLS ICT NOT RAISED High cells Ooze +, highLOW PROTEIN High cells, proteins protein SHUNT MEDICAL Try to avoid Shunts. Treat External medically drainage
POST TBM HYDROCEPHALUSIN Acute Stage not indicated as high PROTEINS -GREATER SHUNT BLOCK also it responds well to ATT ANDSTEROIDS.INDICATION FOR SURGERY BEING – Persistentdecerebration no improvement in sensorium in 10days
Follow up• 1,3,6 months then yearly.• Check – HC, neurological signs, Fundus, shunt function, IQ testing.
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
MICROCEPHALYIs defined as head circumference > 3 standard deviations below the mean for age and sex
PRIMARY ( Genetic ) MICROCEPHALYRefers 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.
Secondary ( non genetic) Microcephaly• 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