Hydrocephalus

Posted on by Dr.Nagesh
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Hydrocephalus ( VP Shunt) :

  • In amount of CSF resulting from disturbance of formation, flow or absorption of CSF thus resulting in enlarged cerebral ventricles.
  • Congenital or acquired.
  • Incidence of congenital hydrocephalous
  • 3/1000 live birth
  • Incidence of acquired – Not known.

Normal CSF Circulation

  • CSF is secreted from choroid plexus of ventricles and absorbed by the arachnoid granulations.
  • CSF flows from lateral Ventricle through one direction up to spine & then returns back again to the surface of brain to reach & absorbed by arachnoid granulation which CSF enter into venous circulation ,leading to sagital sinus.
  • The normal CSF pressure is 13 cm of H2o which range from 7- 18 cm H2o .

Causes Of CSF Blockade

  • Infection: Meningitis, Abscess, Encephalitis.
  • Neoplastic: Astrocytoma, choroid plexus .
  • Vascular: Arteriovenous malformations, aneurysm .
  • Congenital: Arnoid- chiari malformation,

Etiological Classification

  1. Overproduction Of CSF; e.g.Choroid plexus papilloma.
  2.    Blockade of CSF-1.communicating 2.Noncommunicating

communicating: Patent ventricles & all 4 ventricles are  enlarged.

Causes:

  •  Inflammatory
  • Intraventricular haemorrhage
  • Impaired CSF absorption in spina bifida

2.Non – communicating : causes are

  • Obstruction proximal to foramen of luschka, foramen of megendie
  • Cysts
  • Tumours
  • Infection & haemorrhage
  • Aqueductal stenosis
  • Congenital malformation à Arnoid chiari malformation ,Dandy walker malformation ,mucopolysacchridosis , Arachnoid cyst, Achondrooplastic disorders.

Arnold – Chiari Syndrome

  • Downward displacement of cerebellar tonsils & medulla through foramen .
  • Cerebellar signs, headache, visual disturbance ,hearing problem , muscle sorenenss,hydrocephalous, syringomyelia, connective tissue disorders.

Dandy – walker Malformation

  • Congenital brain malformation involving cerebellum & fluid filled space around it.
  • C/F à signs suggestive of raised ICT
  • Cerebellar signs
  • Problems with the nerves that  control eyes ,back & neck
  • Abnormal breathing pattern.

Clinical Presentation

  • Enlargement of cranium -> facial growth rate
  • Irritate , drowsy or lethargic child
  • Nausea , vomiting
  • Setting sun sign – upward gaze palsy due to pressure on the supraorbital region.
  • Macewan’s signs à Cracked pot sound on percussing over dilated ventricles.
  • Bulging fontanalle.
  • Enlargement & engorgement of scalp veins.
  • Poor head control
  • Delayed milestones
  • Cranial nerve palsies à
    • Gaze palsy 6th n . palsy
    • Vagus N .over tip of jugular foramen
    • N – cortical blindness
    • Occulomotor N . à visual backing dird.
  • Irregular respiration
  • Splaying of cranical sutures – plain x-ray
  • In older children à papilledema observed
  • Clinical picture
  • X –ray skull
  • CT scan – confirms dilated ventricles
  • Serial head circumference measurements.
  • Shunt scan if in place.
  • T | t à Mainly surgical
  • Medical à tried for premature, started before sx to optimise the pt’s condition.
  • Diuretic therapy – acetazolamide
  • Correction of acidosis
  • Correction of sr . electrolytes.
  • Repeated ultrasound & CT scan.

Surgery

  • Choroid plexectomy – for communicating.
  • Elimination of obstruction à shunting procedures.
  • Third ventriculostomy

Different types of shunting procedures

  • Ventriculoperitoneal
  • Ventriculoatrial
  • Ventriculopleural
  • Torkildson
  • Lumboperitoneal

2 types of shunts

☛ I Pressure regulating –  complication is  overdrainage.
☛ II Flow regulating –  complication is Blockade.

Common Complications Of Shunt Procedure

  • Malfunction
  • Infection
  • Blockade
  • Overdrainage
  • Seizure –in 5.5 % cases
  • Hardware erosion this skin
  • Silicone allergy
  • Conduit for metastasis

Complications in VP shunt

  • Inguinal hernia
  • Volvulus ,intestinal obstruction
  • Peritonitis
  • Hydrocoelel
  • CSF ascitis
  • Tip Migration.

Investigation

  • Haemoglobin
  • Comlete blood count
  • ESR
  • Renal function
  • Sr electrlytes
  • CT scan, X –ray skull.

Pre-Op examination

  • Standard anesthetic history
  • Birth history – H/ O prematurity
  • Immunization History
  • H/o any allergies
  • H/o problems with previous anesthesia and sx.
  • Fasting status
  • associated anomalies
  • Possibility of co- morbidities
  • Thorough airway assessment.

Systemic

  1. CNS
    • Level of consciousness
    • Cranial nerve palsies.
    • Signs of ↑ ICP.
    • Chances of pulmonary aspiration
  2. CVS
    • Congenital cardiac diseases.
    • Volume status.

Optimisation of the condition before sx

  • Proper hydration of the patient.
  • Antibiotics
  • Correction of dyselectrolytemia.
  • Medical t/t may be started.
  • Close observation till sx, as respiration absent due to brain herniation should be treated immediately with ventilatory support.

Premedication

  • Opioids & sedatives avoided due to neurological deterioration & rerp. Depression & due to Paco2 – further in ICP.
  • In anxious child, midazolam syrup 0.5 ug or intranasal drops can be used cautiously.
  • Atropine may be given 20mcg/kg as immature sympathetic system but avoided.
  • Antibiotic to prevent or treat infection.
  • Pre – oxygenation with 100% O2 before induction is must.

Induction

  • Inhalational or intravenous technique both can be used but preferred is i.v .
  • Propofol 2 mg /kg used or thiopentone 4-5 mg/kg
  • I .v . Anesthetic ↓MAP and ↓CPP but offset by simultaneous    in ↓CMRO2.
  • Ketamine avoided due to ↑ ICP.
  • Inhalational preferred with sevoflurane as it maintains CPP than halothane.
  • V. anaesthetic preferred when rapid control of airway is needed and when intubation is easy.
  • Inhalational technique is preferred in difficult airway.
  • The goal to preserve CPP should be maintained during induction.
  • Muscle relaxation with succinylcholine can be used in difficult airway causes if benefit outweighs the risk of transient ↑ in ICP.
  • Otherwise non- depolarising NMB’s can be used.

Intubation

  • Done with flexometallic tube to avoid kinking.
  • If large head, pillow under shoulder or head supported by assistant & shoulder at edge.

Maintenance

  • N2O avoided due to its effect on ICP & post–op nausea and voniting.
  • O2 + sevoflurance/ isoflurane and fentanyl 1 – 3 mg/kg before incision and at the time of subcutaneous tunneling.
  • RL or NS are used as maintainance fluid as they are hyperomolar slighty & theorotically maintain ICP & doesn’t lead to cerebral edema.
  • 5% Dextrose avoided.
  • After drainage ,sudden hypotension may be thr .

Positioning

  • Release of pressure encountered due to on brainstem.
  • Bolster or pillow supporting shoulder.
  • Head turn toward contralateral side avoid excessive rotation
  • Anaesthesia monitors & machine & i.v. fluids to the side of anaesthetist good surgical access.
  • Avoid undue pressure an surgical site

Prophylatic antiemetic30- 60 min before extubation

Reversal

  • At the end of sx ,NMB are reversed with neostigmine & glycopyrrolate.
  • Avoid bucking, coughing to avoid ↑d ICP .
  • Extubate the pt. awake.
  • Patients with serve neurological impairement may need post –op ventilatory support due to respiratory problem.

Post – operative care

  • Nurse in flat position to avoid subarachnoid hacmorrhage due to ventricular collapse.
  • Post –op analgesia by i.v. paracetamol 15 mg/kg three times /day.
  • Ordplids for breakthmo pain.

Monitoring

  • ECG
  • Pulse oximetry
  • Etco2
  • rectal / esophageal
  • Precordial stethoscope
  • NIBP
  • Intra – arteial BP – in severely ill patient.

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