Surgical management of Hydrocephalus
Historical Background
The first shunt was a nail of glass wool communicating the lateral ventricle and the subgaleal space. Cushing – transvetebral cannulae draining the lumbar theca into the peritoneum Dandy- open third ventriculostomy. Yorkildsen- 1939: ventriculocisternostomy John Holter -1955: slit
Ventriculoperitoneal shunt: Scott (1955)
Alternatives
Excision of the obstructive lesion
Posterior fossa tumour Thalamic tumours Choroid plexus tumours Congenital lesions:
Aqueductal ACM
stenosis
cyst Dandy walker
Arachnoid
CSF diversion
Ventriculoperitoneal Ventriculo atrial Ventriculo pleural Theco peritoneal Endoscopic third ventriculostomy
Hydrocephalus should be treated if it is progressive or symptomatic Contraindications of shunt :
Ventriculitis Other inadequately treated infections Acute intraventricular hemorrhage Ventriculomegaly without elevated intracranial pressure Extreme brain pathology( hydrancephaly)
V-P shunt
Contraindications :
Active abdominal infections Diffuse peritoneal adhesions
Ventriculo pleural shunt
Absolute contraindications:
Active pulmonary infections Preexisting pleural effusions or adhesions
Relative contraindications:
Infancy Latent disease of pleura CRF,CHF, Connective tissue disorder
Ventriculo atrial
Not favoured :
Technically more demanding Revision difficult and more often required Complications more serious
Lumbo peritoneal
Indications :
Communicating hydrocephalus Pseudotumour cerebri CSF fistula
Shunt systems
System characteristics that minimize dhunt complications( Saint rose et al ):
One piece system Nonflanged ventricular catheter Proximal nonslit valve Open ended distal tubing
Valves
Differential pressure valves Variable resistance flow regulated valve.
Differential pressure valve
Low pressure : 20-40mm H2O Medium pressure : 40-70mm High pressure : 80-100mm Four designs:
Slit valve : Ball in cone : Diaphragm: Miter valve:
Holter Hakim Pudenz Mishler
Variable resistance constant flow valves
F = DP/R ( supine position )
F: DP: R:
csf flow differential pressure valve resistence
F = DP +H/R ( Upright position )
H: height
Shunt complications
Obstruction
Proximal end Distal end Disconnection
Wound complications Infections – 7-10% incidence Seizures -5-48% Extracerebral fluid collection
Subdural hematoma Spontaneous pneumocephalus Overdrainage syndrome Ascites Bowel perforation Slit ventricle syndrome
Vent –pleural :
Pneumocephalus Pleural effusion
Ventriculo atrial :
Infection Shunt nephritis Endocarditis Superior vena cava syndrome
Lumbo peritoneal
Radicular pain Scoliosis Chiari type I
ETV
Third ventriculostomy is intended to treat non communicating hydrocephalus with patent subarachnoid spaces and adequate CSF absorption.
Success rates
High success rates : (75%)
Acquired aqueductal stenosis Tumour obstructing ventriculat outflow
Tectal Pineal Thalamic Intraventricular
Intermediate success rates (5070%)
Myelomeningocele (previously shunted, Older patients) Congenital aqueductal stenosis Cystic abnormalities
cyst Dandy walker
Arachnoid
Previously shunted patients with malfunction
Slit
ventricle syndrome Recurrent shunt infection or
Low success rates (<50%)
Myelomeningocele( unshunted, neonates ) Posthemorrhagic hydrocephalus Post infectious hydrocephalus
Indications
Clinical
Causes of hydrocephalus in high or intermediate success group Age > 6 months No prior radiation therapy No history of hemorrhage or meningitis Patient previously shunted
Radiographic
Evidence of ventricular non communication
Obstructive
pattern of HCP Aqueductal anatomic obstruction Lack of aqueductal flow void on T2 MRI
Favourable third ventricular anatomy
Width
and foramen monro sufficient to accommodate endoscope
• Rigid >7mm • Flexible>4mm • Thinned floor of third ventricle
Down
ward bulge floor, draped over clivus Basilar posterior to mamillary bodies
Absence of structural anomalies
AVM or tumour obscuring third ventricular floor Insufficient space between mamillary bodies and basilar and clivus Basilar artery ectasia
Outcome
Morbidity- 3-12% Success rates – 60-70% Mortality – negligible
Complications
Hypothalamic injury Fever- irritation of ependyma from blood Cranial nerve paresis – III and VI Injury to fornix, caudate nucleus Basilar artery
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