Presentation on theme: "Hydrocephalus and Neuro Shunting"— Presentation transcript:
1Hydrocephalus and Neuro Shunting Sales TrainingApril 2001
2Hydrocephalus: From the Greek word hydro (water) & cephalo (head).A pathological condition where thereis a disturbance in production,circulation and/or absorption of CSF,with subsequent accumulation of CSFin the fluid-filled compartments of thebrain (ventricles).
3About CSF (Cerebrospinal Fluid) Clear, colorless fluidBathes, nourishes & protects brain and spinal cord.Average CSF production-20ml/hr adults and 8ml/hr children400 to 500cc produced daily contains 15 to 45mg/100ml protein,some glucose, salts, urea and WBC’s
4Ventricular System 2 Lateral Third Fourth Foramen of Monro Fluid filled cavities deep in cerebrum w/ pressure of mmH2OFour ventricles2 LateralThirdFourthConnected byForamen of MonroAqueduct of Sylvius
8CSF Flow-pathCSF flows in a caudal direction through the lateral, third and fourth ventriclesExits through foramina of Luschka and Magendie into subarachnoid space around spinal cord and brain.Absorption occurs through the arachnoid granulations into the venous system.
9Types of Hydrocephalus CommunicatingNon-communicating or ObstructiveNormal Pressure HydrocephalusCongenitalAcquired
11Etiology of Hydrocephalus CommunicatingOverproduction/underabsorption of CSFChoroid Plexus Papilloma-overproduces CSFSAHInfectionNeoplasms affecting the meningesTrauma
12Etiology of Hydrocephalus Non-Communicating (Obstructive)Aqueductal StenosisArnold-Chiari Malformation (Cerebellar tonsils protrude into Foramen Magnum)CystsMyelomeningoceleIVHTumors (particularly posterior fossa)
13Normal Pressure Hydrocephalus Usually present in elderlyVentricular dilation despite normal CSF pressureTriad of symptoms1) dementia2) gait disturbances (usually earliest)3) urinary incontinence
14Signs & Symptoms Associated with Hydrocephalus InfantsIncreased head sizeBulging FontanelsSeparation of Cranial SuturesProminent Scalp VeinsPersistent VomitingLethargy or irritability“Setting Sun” eyesSeizuresDelayed Development
23Historical Treatment of Hydrocephalous Hippocrates recognizes water accumulation in the brain.1545-Thomas Phaire-1st non-surgical treatment--Herbal plasters, head wraps18th Century--ventricular puncture--death from meningitis common1800’s-Variety of materials used to “wick” CSF from ventricles to subarachnoid space (i.e., linen threads, glass wool, rubber tube)1898-first lumboperitoneal shunt
24Historical Treatment of Hydrocephalous, con’t 1922-Dandy-third ventriculostomy through subfrontalapproach1923-Mixter-1st endoscopic 3rd Vent., choroid plexectomy(L’Espinasse, Hildebrande, Dandy, Putnam and Scarff)1950’s-First effective CSF diversion with a one-way valveusing biocompatible synthetic materials.John Holter-1st Silicone ValveRobert Pudenz-Silicone distal slit valvePeritoneum chosen as better absorptive site than thevascular system
25Heyer Schulte and Shunt Industry History 1953: Dr. Robert Pudenz and W.T. (Ted) Heyer team up on hydrocephalus research1955: Pudenz ventriculo-atrial shunt is developed1959: Rudy Schulte joins Heyer and Pudenz1959: Pudenz flushing valve is developed1960: Codman distributes Heyer-Schulte products1960: Holter valve is created1965: Cordis begins U.S. presence1965: Extra-Corporeal buys Holter1973: Codman dropped as Heyer-Schulte distributor
26Heyer Schulte and Shunt Industry History 1974: American Hospital Supply buys Heyer-Schulte1975: Codman introduces their own product line1977: Anasco, PR manufacturing facility is built1978: Codman buys Extra-Corporeal1983: AHS folds Heyer-Schulte into V. Mueller1984: Dr. Pudenz and Rudy Schulte found P-S Medical1986: Baxter-Travenol acquires AHS
27Heyer Schulte and Shunt Industry History The 90’sNeuroCare Group acquires Heyer-SchulteRadionics introduces full shunt lineMedtronic acquires P-S MedicalPhoenix Biomedical enters the marketCodman acquires CordisElekta acquires CordisNMT acquires CordisIntegra acquires Heyer-Schulte
28What is a Shunt?A shunt is a device that diverts CSF from the CNS (usually the lateral ventricle or the lumbar subarachnoid space) to an alternate body cavity (usually the peritoneum or the right atrium) where it is reabsorbed.
29How Shunts WorkDivert CSF from the CNS to another body cavity (R atrium, peritoneum) for absorption.Mechanical device that regulates flow out of the ventricle.One-way valve opens when the sum of the forces acting on it exceed some threshold. (the difference between the inlet or ventricular pressure and outlet or peritoneal pressure.
30Shunt Systems Ventriculo-peritoneal Ventriculo-atrial Lumbar-peritoneal
42Valve Mechanisms Differential Pressure Valves Valves open when difference between the ventricular pressure and the peritoneal pressure exceeds some threshold.Pressure difference at which a valve opens is called the opening pressure.Pressure difference at which a valve closes is called the closing pressure.
43Valve Types Burr Hole - shaped to fit the hole made in the skull. The reservoir is an integral part e.g. PudenzFlat Bottom - rests flat against the skull distal to theventricular catheter e.g. LPV II, NovusCylindrical/In Line - appears “seamless” between theventricular and peritoneal catheterse.g.. Ultra VS
53Valve Internal Mechanisms High spring rate valves- open slowly, close quickly (miter, slit)Low spring rate valves- open quickly, close slowly (diaphragm, ball & spring, prone to siphon)
54Valve MechanismsSlit valves - a slit in a curved rubber layer. The flow arriving from the concave side opens slit, size of opening relating to the upstream pressureCan be proximal or distalDisadvantage:”stickiness” of silicone rubber can affect openingPrecision?Varies with age of valve?
58Valve Mechanisms “stickiness” of silicone rubber can affect opening Mitre valves - the leaves of the “duckbill” part in response to the pressure differential. Pressure characteristics of mitre valve are related to size,shape, thickness and length of leaves.Disadvantage :“stickiness” of silicone rubber can affect opening
61Valve MechanismsSpring valves/Ball in cone - a metallic spring which applies force to a ball (usually ruby or sapphire) located in an orifice. Opening pressure is defined by spring stiffnessDisadvantage:prone to obstruction from CSF debris or high protein contentsubject to siphoning
64Valve MechanismsDiaphragm valves - a round diaphragm rests on or under a valve seat. Pressure causes the diaphragm to be detracted from the seat allowing CSF to flowDisadvantage:prone to siphoningin some designs flow is not laminar making it prone to obstruction
68Valve Mechanisms Flow regulating mechanisms Maintains same flow rate at any differential pressure by increasing or lowering its resistance to pressureMay be achieved by a solid conical cylinder inserted inside a ring attached to a pressure sensitive membrane
69Valve Mechanisms Inner diameter of ring is greater than larger outer diameter ofconical cylinderBy reducing surfacearea, mechanismrestricts amount of fluidthat can go throughOuter cylinder movesto compensate forreduced surface areato maintain flow rate.
72Valve Mechanisms At very low pressures acts like a DP valve At high pressures the ring moves beyond the central cylinder to give a “blow off” valve.
73Treatment for Siphoning In a vertical position, negative pressure from hydrostatic column can cause overdrainageSiphoning control achieved by adding siphon resistive devices to the shunt system.Functions as a second valve in line that closes in response to peritoneal pressure
79MetopicSutureCoronalSutureAnteriorFontanelleSagittalSuturePosteriorFontanelleLamboidalSutureSkull of a newborn seen from aboveAdult human skull seen from above
80Indications For Use of a Lumbar-Peritoneal Shunt Communicating Hydrocephalus - when ventricles are small and it would be difficult to cannulate with a ventricular catheter.Normal Pressure Hydrocephalus - shunting without necessitating a cranial procedure.
81Goals of Shunt Design & Development Restoration of “normal physiology” in the shunted individualMaximize the potential quality of life for each patientExpand the population of successfully treated patients