Intracranial Dynamics and its Role in Hydrocephalus TreatmentIntracranial Dynamics and its Role in Hydrocephalus TreatmentS.S. BasatiBasati, B. , B. SweetmanSweetman, J. Lancaster, A. Linninger, J. Lancaster, A. Linninger

Laboratory for Product and Process Design, Department of Bioengineering, University of Illinois at ChicagoMid t Bi di l E i i C f 2011

Model PredictionsModel Predictions

Midwest Biomedical Engineering Conference , 2011

Model GenerationModel GenerationMR

imagingGeometry

reconstructionGrid

generationComputational

results

MotivationMotivationAnswer�fundamental�questions�about�brain�mechanicsAnswer�fundamental�questions�about�brain�mechanicsAddress�need�for�better�treatments�of�brain�diseasesAddress�need�for�better�treatments�of�brain�diseases

CSF�Flow�Direction�and�Pressures�in�Spinal�Canal�and�Cranial�Space

I: CINE-MRI measures CSF flow rates and velocities.

II: Discrete MR images converted to 3-D surface meshes.

What is CSF pressure?

Why does CSF pulsate?

Do abnormalities in vessel, tissue, CSF interaction contribute to CSF-related disorders?

Why is the treatment ineffective?

CostCost involvedinvolved withwith hydrocephalushydrocephalus treatmenttreatment11

An abnormal accumulation of cerebrospinal fluid (CSF) leads to a condition known asHydrocephalusHydrocephalus. Over 150,000 people are diagnosed with this disease in the U.S. each year.Modeling additional information not offered by imaging may lead to better treatment.

10

15

20

/s] CFD Simulation

CINE-MRIN N=6 15

20

/s] CFD Simulation

CINE MRIN HC=5

• Flow in pontine cistern is twice thatin hydrocephalic patients

• Flow in aqueduct is increased tentimes in hydrocephalic patientscompared to normal.

Cerebrospinal SystemPorous Parenchyma (black)CSF pathways (light blue)

Fluid EquationsContinuity

Momentum

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III: Grid generation leads to a computational domain.

IV: Transport quantities are predicted in computational domain. Normal Hydrocephalus

Objectives:

• Investigate complex mechanical interaction between major components of centralnervous system

• Quantify mechanical properties of brain tissue, cerebral vasculature, and CSF

• Advance understanding of central nervous system physics

-20

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0

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0 20 40 60 80 100

% Cardiac Cycle

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ocity

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Lower Aqueduct

-20

-15

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-5

0

5

10

0 20 40 60 80 100

% Cardiac Cycle

CSF

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ocity

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I t i l

Novel Therapy DesignNovel Therapy Design

Computer aided Sensor Design and Simulation

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• Supplement computer models with design of new treatment options

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• Intracranial pressureamplitude and pressurewave speed are dependenton spinal compliance.

• Reduction in CSFreabsorption can causeCSF to accumulate.

• Fluid flows fromparenchyma to ventricles innormal cases, but reversesits direction underh d h li diti

Exploit electrical conductivity differences between CSF and brain tissue.Exploit electrical conductivity differences between CSF and brain tissue.

Conclusions and Future DirectionsConclusions and Future Directions

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hydrocephalic conditions.1.13( / )CSF S m �0.2( / )BRAIN S m �

• Generate internal electric field and

calculate the electric potential.

• Distribution of current is a function Conclusions and Future DirectionsConclusions and Future DirectionsConclusionsConclusions•• AA changechange inin aqueductalaqueductal toto prepontineprepontine

flowflow ratioratio waswas quantifiedquantified withwith ourourmodel,model, andand changeschanges thatthat occuroccur obeyobeyfirstfirst principleprinciple explanationsexplanations..

•• We are able to reproduce the complexflow patterns in the subarachnoidal

f

Future Directions•• FluidFluid--structurestructure interactioninteraction modelmodel

includingincluding patientpatient--specificspecific vasculature,vasculature,CSFCSF spaces,spaces, andand brainbrain tissuetissue..

•• DetermineDetermine changeschanges inin regionalregional bloodbloodflowflow pre/postpre/post shuntingshunting..

•• QuantifyQuantify intracranialintracranial dynamicsdynamics withwith A k l d tA k l d t

0 20 40 60 80 100% Cardiac Cycle

0 20 40 60 80 100% Cardiac Cycle

I II• With constant CSF production from choroid plexus, brain movement is driven by blood flow.

• In communicating hydrocephalus, distensible spinal canal and the resultant pressureprofiles allow predictions to be made.

of volume.

FabricationFabrication ofof ringring electrodeselectrodes ontoonto cathetercatheter

•• DicingDicing sawsaw usedused toto createcreate 6060 µmµm holesholes..

•• Pt/IrPt/Ir cylinderscylinders bondedbonded toto wireswires andand passedpassedthroughthrough..

•• SensorSensor coatedcoated withwith paryleneparylene--CC forfort bilitt bilit spaces and other areas of the brain

and are now able to quantify states thatcannot be easily measured such asdeformations, strains, anddisplacements of brain tissue.

• Novel treatment was proposed thatdirectly monitors volume as opposed topassive, pressure based valves.

•• RealReal--timetime changeschanges inin intracranialintracraniali li l ll bb dd ii

QuantifyQuantify intracranialintracranial dynamicsdynamics withwithrespectrespect toto changeschanges inin vasculaturevasculaturecompliancecompliance..

•• ChronicChronic implantationimplantation intointo prepre--hydrocephalichydrocephalic animalanimal modelmodel..

•• IncorporateIncorporate pressurepressure measurementsmeasurementstoto dynamicallydynamically recordrecord pressurepressure--volumevolume..

•• IncorporateIncorporate microcontrollermicrocontroller forforf db kf db k t lt l dd i li l d td t

AcknowledgementsAcknowledgementsstabilitystability..

B

Acute animal hydrocephalus measurement protocol

• Verify functionality of treatment option.

• First ever dynamic volume measurements.

Financial support provided for part of this research under NIH grant 5R21EB4956 isacknowledged. The treatment device is patent pending (# WO/2008/005440).

We would also like to thank:• Dr. Richard Penn, UIC • Michael LaRiviere, University of Chicago

• Dr. MR Del Bigio, University of Manitoba • Materialise, Inc. • Tim Harris, UIC

ventricularventricular volumevolume cancan bebe measuredmeasured ininvivo,vivo,

•• AnimalAnimal modelmodel isis developeddeveloped toto measuremeasureacuteacute andand dynamicdynamic changeschanges ininintracranialintracranial ventricularventricular volume,volume,

feedbackfeedback controlcontrol andand wirelesswireless datadatacommunicationscommunications.. ReferencesReferences

1. Linninger A, Basati S, Dawe R, Penn R. “An impedance sensor to monitor and control cerebral ventricular volume”. Medical engineering& physics. 2009 Sep;31(7):838-45.

2. A. Linninger, B. Sweetman and R. Penn. Normal and hydrocephalic brain dynamics; reduced cerebrospinal fluid reabsorption andventricular enlargement, Annals of Biomedical Engineering. DOI: 10.1007/s10439-009-9691-4, 2009.

3. Basati, S, Harris, T, Linninger, A. “Dynamic brain phantom for intracranial volume monitoring”. IEEE Trans. Biomed. Eng., 2010.

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