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,
- Overproduction Of CSF; e.g.Choroid plexus papilloma.
- Blockade of CSF-1.communicating 2.Noncommunicating
communicating: Patent ventricles & all 4 ventricles are enlarged.
- Intraventricular haemorrhage
- Impaired CSF absorption in spina bifida
2.Non – communicating : causes are
- Obstruction proximal to foramen of luschka, foramen of megendie
- 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.
- 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.
- Choroid plexectomy – for communicating.
- Elimination of obstruction à shunting procedures.
- Third ventriculostomy
Different types of shunting procedures
2 types of shunts
☛ I Pressure regulating – complication is overdrainage.
☛ II Flow regulating – complication is Blockade.
Common Complications Of Shunt Procedure
- Seizure –in 5.5 % cases
- Hardware erosion this skin
- Silicone allergy
- Conduit for metastasis
Complications in VP shunt
- Inguinal hernia
- Volvulus ,intestinal obstruction
- CSF ascitis
- Tip Migration.
- Comlete blood count
- Renal function
- Sr electrlytes
- CT scan, X –ray skull.
- 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.
- Level of consciousness
- Cranial nerve palsies.
- Signs of ↑ ICP.
- Chances of pulmonary aspiration
- Congenital cardiac diseases.
- Volume status.
Optimisation of the condition before sx
- Proper hydration of the patient.
- 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.
- 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.
- 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.
- Done with flexometallic tube to avoid kinking.
- If large head, pillow under shoulder or head supported by assistant & shoulder at edge.
- 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 .
- 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
- 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.
- Pulse oximetry
- rectal / esophageal
- Precordial stethoscope
- Intra – arteial BP – in severely ill patient.