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Research Update

Research Update. Sukhi Basati PhD Candidate Laboratory for Product and Process Design Director: Prof. Andreas Linninger 3/31/2011. Microcontroller Unit. Shunt. Subcutaneous. 3.4 mm. 350 µm. Thesis aims. An implantable system for intracranial volume measurements in hydrocephalus.

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Research Update

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  1. Research Update Sukhi Basati PhD Candidate Laboratory for Product and Process Design Director: Prof. Andreas Linninger 3/31/2011

  2. Microcontroller Unit Shunt Subcutaneous 3.4 mm 350 µm Thesis aims An implantable system for intracranial volume measurements in hydrocephalus • Develop sensor based on an impedance technique to measure volume • Computer aided design • Microfabricate sensor with biocompatible materials • Electronics design and fabrication • Bench-top analysis to optimize parameters • Validate measurements in an acute hydrocephalic animal model • Animal protocol to induce HC and implant sensor into hydrocephalic rat • Develop chronic, implantable measurement device • Wireless data communication and microcontroller implementation

  3. Spring 2011 research aims • Initiate HC experiments on west campus • Priority: High • Induce HC in weanling rats (only need n=10) (experiments should not last longer than end of February) • 2nd surgery involves implanting sensor into hydrocephalic ventricles and CSF removal • Submit acute volume measurement paper • Priority: High • JNS - pediatrics • Design and fabricate long term electronics consisting of surface mount components (microcontroller + wireless transmitter) • Priority: Medium • Write draft of HC simulation in weanling rats • Priority: Medium

  4. Instrumentation Pump CSF 4.8 mm 500 µm Acute HC Measurements Lambda Bregma? • Some problems… • Still cannot remove CSF. • We observe CSF leakage. • Is it possible that ventricle collapses, and we are trying to remove fluid from ECS?

  5. 3 week old rat, 21 day post kaolin – H1115 New Coordinates 7.3 mm 8.5 mm 2 mm Old Coordinates 5 mm 1 cm T2w; RARE (FSE); T2eff 54ms; TR 1640ms; NA 6; TT 5m14s FOV 3.0x3.5cm2; SLTH 1mm; SSDI 2mm; matrix 256x256

  6. 3 week old rat, 21 day post kaolin – H1115 9 mm 7 mm 1 cm 1 cm T2w; RARE (FSE); T2eff 54ms; TR 1640ms; NA 6; TT 5m14s FOV 3.0x3.0cm2; SLTH 1mm; SSDI 2mm; matrix 256x256

  7. Discussion with Pat McAllister • Works a lot with rat model of HC • Currently comparing kaolin induced HC with kaolin failures, however he usually does not get many failures • He injects Kaolin via surgical cutdowns • >90% successful induction • You also can see where your injecting • Advice given: • Percutaneous Injection • Keep needle bevel facing upwards. • We can try holding the animal, as to keep neck flexed. • Make sure we puncture antlanto-occipital membrane. • We can try only implanting the needle until CSF leaks out, and then we connect the kaolin-filled syringe. • A neurosurgeon in Cleveland only had 10% induction rate! • Just keep practicing Adjunct ProfessorProfessor of Neurosurgery Director of Basic Hydrocephalus Research • Acute Shunting • after implanting shunt in HC animal, you don’t see ventricular collapse. • at most 30% decrease in size • it takes 3-5 days for ventricular volume to decrease if shunt is successful. • and even then the size does not come back to normal • He has previously used a syringe pump in HC kittens • he even used a rate of 0.3 mL/hr over 20-25 minutes • Offered to send rats, wouldn’t mind collaborating…

  8. Location of Sensor • Shunt failure occurs often due to misplacement during surgery. • Surgery is often followed by MRI to confirm location within ventricles • It is a serious problem in animal models of HC. If shunt placement was successful, the ventricles drain. • Even though my device is designed for volume measurements, at least it indicates when you are in a fluid filled region… Ventricle location

  9. Rat Sensor Simulations Purpose: Sensor Simulations on HC rat geometry will provide design decisions such as electrode placement and catheter angle. This data will be input to optimization algorithms. • Model Geometry: • Rat HC ventricles, ranging from 21 day HC to 7 day HC. • Brain Parenchyma modeled as simple ellipsoid. • Next steps: • Work with Forrest on generating functions.

  10. Future Work • Purchase pressure transducer • Simulate Rat CSF dynamics and ventricular expansion • Develop power control circuit • Prepare DMD talk • Begin writing dissertation

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