Hydrocephalus

Hydrocephalus

Introduction

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

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

Average CSF volume is 65 to 140 ml

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

On cause Physiologic – due to overproduction by CP

papilloma Nonphysiological – due to any other cause

Pathology

Signs & Symptoms

Premature infants

Apnea

Bradycardia

Tense AF

Rapid head growth

Globoid head

Older children

Headache

Vomiting

Lethargy

Diplopia, blurred vision

Papilledema ,Lateral rectus palsy

Hyperreflexia, clonus

Infants

Drowsiness, irritability

Vomiting

Macrocephaly, tense fontanelle

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

Differentiating between communicating and non communicating

To know site of obstruction

To know anatomical detail

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

Pyogenic meningitis, TBM, and intraventricular bleed can be diagnosed

Radiological investigations

X RAY SKULL Widening of sutures

Silver beaten appearance

Enlargement of pituitary fossa with erosion of dorsal sella

Shallow posterior fossa

Ultrasonography

Non invasive, no exposure to radiation

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

Can measure resistive index which is a sensitive indicator

atrial size most useful measurement of ventricular size

Ventriculohemispheral ratio more than 35% indicates ventriculomegaly

CT scan Provide greater anatomical detail

Can distinguish between communicating and non communicating

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

Provides only axial image

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

Loop diuretics, Acetazolamide decrease CSF production for a few days

Doesn't resolve ventriculomegaly or affect intellectual outcome

Surgical treatment

Shunt surgeries

Third Ventriculostomy

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

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

ContraindicationsAbsolute 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

Three main groups

1. Mechanical failure – proximal, valve or distal

2. Infection – mainly by staph. Epidermidis & aureus

3. 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

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

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

Can cause cephalopelvic disproportion & inhibit labour

USG used for diagnosis

MRI after engagement of head used to visualise cerebral morphology

Severe brain malformation treated by cephalocentesis

Results of ventriculoamniotic shunts discouraging

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

Fetal USG

Outcome & Prognosis

Regular follow up essential

Baseline scan post shunt for ventricular size

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

Number of shunt revisions / malfunctions not key factors in outcome

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