HYDROCEPHALUS

DEFINITION Dilatation of cerebral ventricles caused by an increase in CSF volume usually resulting from impaired absorption, and rarely from excessive secretion.

CSF formation and absorption CSF forms at a rate of 20ml/hr i.e approx 500ml/day. Secreted predominantly by choroid plexus of the lateral, 3 rd and 4 th vents Flows in caudal direction via hydrostatic gradient[—pressure in vent=180mmH20 and in sagg sinus 90mmH20] thru the vent syst. It then exits thru the foramina of Luschka and Magendie into the subarachnoid space. Absorption then occurs thru the arachnoid granulations into the venous syst.

CLASSIFICATION 1.Non-communicating /Obstructive-: obstruction within the vent syst. 2.Communicating-: obstruction outside the vent syst i.e. vent CSF communicates with the sub arachnoid space.

AETIOLOGY OBSTRUCTIVE- Congenital or Acquired Congenital causes  --aqueductal stenosis or forking  --Dandy Walker synd [Atresia of foramina of Magendie and Luschka]  --Arnold Chiari malformation [type 2- progressive hydroceph + myelomeningocele]  --Vein of Galen aneurysm.

Acquired causes  --acquired aqueductal stenosis[from adhesions sec to infections and haemorrhage]  --supratentorial masses causing tentorial herniation  --intraventricular haematoma  --Tumours[post fossa,vent,pineal region]  --Abscess/granuloma  --Arachnoid cyst

COMMUNICATING HYDROCEPHALUS --Results from thickening of the leptomeninges and/or involvement of the arachnoid granulations.  -- Infections-: -intrauterine infects -pyogenic,, [pneumococcal] -TB -fungal  --Subarachnoid haemorrhage[spontaneous,trauma]  --Leukaemic infiltrations  --Increased CSF viscosity e.g.high protein content.  --Excessive CSF production [choroid plexus papilloma] rare.

PATHOLOGICAL EFFECTS ↑CSF volume → vent dilat → CSF permeates into the perivent white matter → neuronal death, gliosis and scarring. spontaneous arrest ↑ICP ↓ Thinning of cerebral mantle ↓ Death

CLINICAL FEATURES Depend on-: -age of onset -nature of the lesion causing it -duration and rate of rise of ICP and include: Irritability Lethargy Poor appetite Vomiting Headache [prominent in older child] Gradual change in personality,, Deterioration in academic productivity,,

CLINICAL FEATURES CONTD  Accelerated rate of enlargement of the head  Wide open, bulging and tense anterior fontanelle  Thin scalp with dilated veins  Lid retraction  Impaired upward gaze[from pressure on midbrain tectum]  Broad fore head  ‘Cracked pot’ sound on skull percussion- [macewen sign] due to sutural diastasis.  Transillumination of skull may be positive[Dandy Walker, grossly enlarged vents]

 Impaired consciousness and vomiting  Long tract signs[brisk tendon reflexes,spasticity,clonus,Babinski sign]  Cerebellar ataxia  Delayed motor and cognitive milestones

DIAGNOSIS  Hx of familial cases -  X-linked hydroceph(Bicker Adam’s synd)  Hx of prematurity [with intracranial haemorrhage, meningitis] and mumps meningoencephalitis-  aqueductal stenosis  Café au lait spots [neurofibromatosis]--  aqueductal stenosis.  Midline lesions at the back[myelomeningocele, hair tuft,lipoma,or angioma]-  spinal dysraphism  Cranial bruit-  Galen A-V malformation  Transillumination of the skull [from massive dilatation of vents]-  Dandy Walker malformation.

 Chorioretinitis on fundoscopy--  Toxoplasmosis [intra-uterine infection],papilloedema in the older child-  raised ICP.  Plain X-ray of the skull---signs of raised ICP --separation of sutures --erosion of posterior clinoid process --increased convolutional markings[silver or copper beaten appearance]  CT, MRI and U/S --  identify specific cause

Differential Diagnosis - Enlargement secondary to thickened cranium -chronic anaemic conds[SCA, THAL] -Rickets -osteogenesis imperfecta -epiphyseal dysplasia -Chronic subdural collections-  bilat parietal bone prominence -Megalencephaly ---abnormal storage of subs within the brain eg lysosomal dis[mucopolysacch,Tay Sachs] aminoacidurias[maple syrup urine dis] leucodystrophies[metachromatic,canavan dis]

--cerebral gigantism--  increase brain mass --Neurofibromatosis--,, -Hydranencephaly [cerebral hemispheres represented by membranous sacs. Midbrain and brain stem intact] -Achondroplasia. TREATMENT 1. Medical: Not alternative to surgery. 2. Surgical:

MEDICAL 4 Modalities 1.Removal of CSF(serial LP) 2.Reduce CSF production(Acetazolamide,Frusemide 3.Decrease brain water content(Osmotic diuretics eg mannitol, urea,glycerol) 4.Increase CSF absorption(hyaluronidase, streptokinase, urokinase, tissue plasminogen)

Surgical: Ventriculo-peritonial shunt Ventriculo-atrial shunt Lumbo-peritoneal shunt External ventricular drainage

Complications of shunting  Infection- meningitis, peritonitis, shunt nephritis -Common orgs—staph epidermides, staph aureus  Malfunction(obstn, disconnection,migration) Shunt obstruction [from choroid plexus, debris,bld clot, omentum, high CSF protein]  Subdural haematoma [from vent collapse]  Low pressure state: manifests as headache and vomiting on sitting or standing

COMPLICATNS CONTD Shunt overdrainage Seizures Pneumocephalus Cardiac complications asso with vasc shunts(endocarditis,arrythmias) Pulm complications(pulm thromboembolism) Peritonial shunt compl: Ascites,inguinal hernia,hydrocele,bowel perforation,peritonitis)

PROGNOSIS  Depends on the cause and associated co- morbidities.  Good with most children attaining normal IQ if treatment precedes irreversible brain damage.  Repeated complications carry significant morbidity.

Craniosynostosis Definition Premature fusion of single or multiple cranial sutures leading to deformity of skull and face. 2 types: Primary: due to abnormalities of skull development. Secondary: results from failure of brain growth and expansion.

Primary Incidence 1:2000 births Aetiology Unknown in majority of cases % associated with genetic syndromes like Crouzon’s synd,Apert’s synd,Carpenter’s synd. Clinical manifestations -Evident at birth;asymmetric craniofacial appearance -Skull deformity -Prominent bony ridge over suture and premature closure of fontanelles. X-ray and bone scan confirm fusion of sutures.

Depending on involved suture, the following result: Scaphocephaly-----[saggital suture] Plagiocephaly [coronal and/or lambdoid suture] Oxycephaly or Turricephaly----[all sutures  cone- shaped head or pointed head with severe MR and microcephaly. Brachycephaly (coronal synostosis)

 Premature closure of only one suture causes no neurological problem.  Complications such as hydrocephalus and raised ICP are more likely to occur if two or more sutures are involved. Treatment: Surgery Indications for Surgery 1.Cosmesis 2.Neurological complications [raised ICP, Hydrocephalus]

MICROCEPHALY

DEFINITION: Head circumference that is more than 3Std below the mean for age and gender OR HC that is below the 2 nd centile for age and gender. It is due to failure of normal brain growth. 2TYPES Primary microceph. Secondary microceph.

PRIMARY Freq genetically determined(autosomal recessive); associated dev delay. May be familial: Dev is normal. FEATURES 1.Small head present at birth; Xtic shape: -narrow forehead -slanting frontoparietal areas -pointed vertex -flat occiput -ears often large and abnormally formed

2.Gen hypertonia common. 3.Convulsions freq dev. 4.Profound learning disorder(MR) Primary micro also found in some recognizable synds like Trisomy 21,18,13 and non-chromosomal synds like Cornelia de Lange synd.

SECONDARY MICROCEPH Results from severe brain damage during preg or the first 2yrs of postnatal life. Developing brain is vulnerable to: -cong infections(TORCHES) -Drugs (incl alcohol) -Radiation -Hypoxia (HIE) -Metab disorders (maternal DM, maternal hyperphenylalaninaemia) -Neonatal meningitis -AIDS etc.

EVALUATION History: Exposure to above factors Family and birth hx Associated dysmorphic conds Head small or normal at birth TREATMENT Genetic and Family counselling.