Hydrocephalus

Hydrocephalus

Introduction 

Defined as abnormal accumulation of CSF in ventricles and/or subarachnoid space, typically associated with ventricular dilatation and raised ICP

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Incidence as isolated congenital disorder 1/1000 live births and with spina bifida in 1/1000 live births

Normal CSF physiology 

Produced by choroid plexus in lateral,third & fourth ventricles by ultrafiltration at rate of 0.3 – 0.35 ml/min i.e. 500ml/day

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Average CSF volume is 65 to 140 ml

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Normal CSF pressure is 4-5cms of water in infants, 4-10cms in older children & 15cms in adults

CSF flow

Classification On location of block  Communicating  Non communicating

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On cause Physiologic – due to overproduction by CP papilloma Nonphysiological – due to any other cause

Pathology

Signs & Symptoms Premature infants    

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Infants

Older children

Drowsiness, irritability

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Headache

Vomiting

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Vomiting

Macrocephaly, tense fontanelle

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Lethargy

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Diplopia, blurred vision

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Papilledema ,Lateral rectus palsy

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Hyperreflexia, clonus

Apnea Bradycardia Tense AF Rapid head growth Globoid head

Frontal bossing Distended scalp veins Poor head control Lateral rectus palsy, sun set sign

Signs & Symptoms in adults progressive headache  vomiting  progressive dementia  epileptic fits  urinary incontinence  limb weakness  papilloedema 

Investigations Goal of investigations: 

To confirm diagnosis

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Differentiating between communicating and non communicating

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To know site of obstruction

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To know anatomical detail

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For follow up

Head circumference 

35 – 37 cms at birth

Increases at rate of  2cm/ mth for 1st 3 mths  1cm/mth for next 3 mths  0.5cm/mth for the next 6 mths

CSF examination 

Lumbar puncture should be done with care as coning can occur in non communicating hydrocephalus

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Pyogenic meningitis, TBM, and intraventricular bleed can be diagnosed

Radiological investigations

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X RAY SKULL Widening of sutures

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Silver beaten appearance

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Enlargement of pituitary fossa with erosion of dorsal sella

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Shallow posterior fossa

Ultrasonography 

Non invasive, no exposure to radiation

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Can show lateral & third ventricle but not 4th ventricle or subarachnoid space

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Can measure resistive index which is a sensitive indicator

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atrial size most useful measurement of ventricular size

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Ventriculohemispheral ratio more than 35% indicates ventriculomegaly

CT scan 

Provide greater anatomical detail

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Can distinguish between communicating and non communicating

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With IV contrast tumours / abscess/ bleed/ Ca deposit can be seen

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Provides only axial image

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Inferior to MRI for visualization of brain stem/posterior fossa

CT scan

Magnetic resonance imaging  Provide greatest amount of anatomic detail  Differentiate between subdural effusion & enlarge sub arachnoidal spaces  Visualization of posterior fossa and brain stem  Cine MRI is useful to identify site of obstruction

Magnetic resonance imaging

Medical Management 

Mannitol decreases ICP

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Loop diuretics, Acetazolamide decrease CSF production for a few days

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Doesn't resolve ventriculomegaly or affect intellectual outcome

Surgical treatment 

Shunt surgeries

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Third Ventriculostomy

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Choroid plexectomies/ coagulation

Shunt surgery 

Ventriculoperitoneal shunt – most commonly done

Ventriculoatrial shunt  Ventriculopleural shunt  Ventriculogallbladder shunt  Lumboperitoneal shunt 

VP shunt classification 

According to type of valve - spring ball - slit valve - diaphragm

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According to pressure of opening - ultra low pressure - low - medium (most commonly used) - high

VP Shunt - Indications In newborn and children:    

Idiopathic hydrocephalus Communicating / obstructive hydrocephalus Myelodysplactic children with healing wound under tension Signs and symptoms of brain stem compression develop in presence of ventriculomegaly

In adults  Signs of elevation of ICP in high pressure hydrocephalus  Signs of brain herniation  Progressive dementia, gait and urinary disturbance  Arachnoid, porencephalic cyst  Spontaneous/ iatrogenic CSF leakage  Temporary neutralization of elevated ICP in tumours

VP shunt Contraindications Absolute  Infection specifically ventriculitis  Intraventricular hemorrhage  Recent peritonitis, Adhesions Relative  Arrested or atrophic hydrocephalus  Pending abdominal surgery

Lumbar Peritoneal Shunt Indications  Communicating hydrocephalus with or without small or collapsed ventricular system Advantages  Extracranial course  Avoid complication of IIIrd ventriculostomy Contraindication  Obstructive hydrocephalus Complication  Overdrainage (spinal headache)- most common)  Transient root symptom and sign  Scoliosis / hyper lordosis / kyphoscoliosis – rare

Complications of Shunt surgery  2.

Three main groups Mechanical failure – proximal, valve or distal

4.

Infection – mainly by staph. Epidermidis & aureus

6.

Overdrainage – causing headache

Endoscopic III Ventriculostomy Criteria  Obstructive hydrocephalus  Dilated III ventricle defined as > 1 cm in by coronal plane  Floor of the 3rd ventricle suitable for fenestration i.e., attenuated or bulging downward into interpeduncular cistern. Indication  Posterior fossa tumor 

Late onset (over 24 yrs of age) aqueduct block such as tectal tumor

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New born with myelomeningocele and associated blockage either at aqueductal or exists of the 4th ventricle

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In the patient with the repeated shunt failure

Endoscopic III Ventriculostomy Contraindication  Chronic meningitis  Sub dural haemorrhage / intra ventricular haemorrhage Complications  Infection  Bleeding from basilar artery can cause death  Hemiparesis, owing to damage to pedicle or its perforating arteries  Hypothalmic damage due to proximity to III ventricle

Treatment of Hydrocephalus diagnosed in utero

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Can cause cephalopelvic disproportion & inhibit labour

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USG used for diagnosis

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MRI after engagement of head used to visualise cerebral morphology

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Severe brain malformation treated by cephalocentesis

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Results of ventriculoamniotic shunts discouraging

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Babies with normal cerebral morphology delivered by LSCS when maturity documented & treated by shunt surgery

Fetal USG

Outcome & Prognosis 

Regular follow up essential

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Baseline scan post shunt for ventricular size

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Prognosis depends on brain morphology & factors like perinatal ischemia, IVH, ventriculitis

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Number of shunt revisions / malfunctions not key factors in outcome

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Cause of death in these pts is primary disease progression or factors related neither to hydrocephalus nor its treatment