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The Physics of Hydrocephalus and Shunts

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This is my senior seminar research project for my BS Physics, at the University of Texas at Arlington. Hydrocephalus is something that is incredibly personal to me, as my husband has had 20 brain surgeries and has been permanently disabled since 2011. In his honor, I created an awareness ribbon for Hydrocephalus that is now used worldwide.
This project is for educational purposes only. Please use the references on the last slide to find the original images for your own use. The information presented here has been obtained by reading several papers published in the medical community.
Do not crop and use any of the images of tattoos, artwork, or people. These are pictures that have been shared with me by people in the Facebook Hydrocephalus community.

Papers referenced:

1 CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV® 2.0: IN TOUCH WITH YOU," , .

2 Ian Piper, "Raised Intracranial Pressure After Head Injury" (2000) .

3 Erwin M Brown, Richard J Edwards and Ian K Pople, "Conservative Management of Patients with Cerebrospinal Fluid Shunt Infections," Neurosurgery 58 (4), 65 (2006).

4 CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , .

5 Dr Y. Rajalakshmi, Guide to Physiology, edited by Anonymous (S. Chand Publishing, Ram Nagar, New Delhi, 2010), pp. 157.

6 Roberta Di Terlizzi and Simon Platt, "The function, composition and analysis of cerebrospinal fluid in companion animals: Part I – Function and composition," The Veterinary Journal 172 (3), 422-431 (2006).

7 Romy Scholz et al., "Efficacy and safety of programmable compared with fixed anti-siphon devices for treating idiopathic normal-pressure hydrocephalus (iNPH) in adults – SYGRAVA: study protocol for a randomized trial," Trials 19 (1), 1-10 (2018).

8 Ulrich-W Thomale et al., "Shunt survival rates by using the adjustable differential pressure valve combined with a gravitational unit (proGAV) in pediatric neurosurgery," Childs Nerv Syst 29 (3), 425-431 (2013).

9 Marek Czosnyka et al., Cerebrospinal Fluid Dynamics, in Pediatric Hydrocephalus, edited by Giuseppe Cinalli, Christian Sainte-Rose and Wirginia June Maixner, (Springer Milan, Milano, 2005), pp. 47-63.

10 Sandip Chatterjee and L. Harischandra, "Cerebrospinal fluid shunts – How they work: The basics," Neurology India 66 (1), 24 (2018).

11 Edi Azali Hadzri et al., "Effects of irregular cerebrospinal fluid production rate in human brain ventricular system," AIP Conference Proceedings 1440 (1), 659-664 (2012).

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The Physics of Hydrocephalus and Shunts

  1. 1. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  2. 2. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  3. 3. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 3: Brain with enlarged ventricles due to Hydrocephalus
  4. 4. 99.13% Water 0.87% Both organic and inorganic solids: Produced within the ventricles of the brain and partially by the choroid plexus, and is absorbed by the dural venous sinuses Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 4: The flow of cerebrospinal fluid
  5. 5. Skull (hard and rigid with a fixed volume) Brain Tissue Vascular System (arteries & blood) CSF Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  6. 6. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 6: Ventricles in a normal brain compared to a Hydrocephalic brain
  7. 7. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 7: Volume-Pressure relationship in the brain
  8. 8. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  9. 9. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  10. 10. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  11. 11. • • • Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  12. 12. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  13. 13. Over 400 types of shunts 3 main parts: • Proximal (Ventricular) catheter • Distal catheter • Shunt valve Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 10: Lateral view of shunt system Fig 9: Frontal view of shunt system Fig 8: Major components of a shunt system
  14. 14. • Drains excess fluid from the ventricles • Made from silicon rubber • May be coated with barium for x-ray visibility • Sometimes antibiotic impregnated (rifampicin and clindamycin) • 15 cm - 23 cm in length • Inner diameter 1.0-1.6mm • External diameter 2.1-3.2 mm • May be straight, flanged, or J-shaped Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 11: Imaging of a flanged catheter Fig 12: Types of catheters
  15. 15. • Routed from the burr hole in the skull • Made from silicon rubber • May be coated with barium for x- ray visibility • 90 cm - 120 cm in length • Inner diameter 0.7-1.3mm • External diameter 2.1-2.5 mm Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 13: Imaging of shunt catheter Fig 14: Imaging of shunt catheter (enhanced)
  16. 16. Distal end of the catheter can be routed to the: • Heart: Ventriculoatrial (VA) shunt • Lungs: Ventriculopleural (VPLS) shunt • Abdomen: Ventriculoperitoneal (VP) shunt Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  17. 17. • Regulate flow of CSF from ventricles • Nearly 200 types of shunt valves • Operation based on Hydrostatic Pressure: 𝐻𝑆𝑃 = 𝜌𝑔ℎ If patient is in horizontal position, less fluid flows (2 drops/min). If in vertical position, more fluid flows (4drops/min) Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 15: Hydrostatic pressure
  18. 18. • Function based on opening pressure (OP) and closing pressure (CP) of the valve Differential Pressure: DP = ICP + HSP – IAP OP < DP: valve opens CP < DP: valve closes *ICP Intracranial Pressure, *IAP Intraabdominal Pressure • Types include: Slit valves, Mitre valves, Diaphragm valves, Ball-in-cone valves • Ball-in-cone (Ball-spring valve) most efficient: offers maximum flow when DP > OP Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 16: Mechanical designs of valves
  19. 19. • Designed to avoid over-drainage resulting from change in HSP (siphoning) • Referred to as anti-siphoning devices • Three types: • Suction controlled devices – contains a flexible membrane valve that regulates pushing pressure and sucking pressure. When PP > SP, CSF flows. When PP < SP, no CSF flows • Flow reducing devices – CSF flow based on differential pressure • Gravitational valve – uses metal ball to regulate flow across opening Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  20. 20. proGAV 2.0® with ShuntAssistant® • Hybrid valve: proGAV Combines DPV with HSV to avoid siphoning • Able to regulate OP with posture changes Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates The bow spring controls the OP of the ball-in-cone valve. The tension of the spring (OP) is controlled by turning the rotor. The tantalum ball defines the OP of the valve, and the sapphire ball ensures the valve is fully closed. Fig 17: Schematic cross section of the proGAV 2.0 Fig 18: proGAV 2.0 shunt SAPPHIRE BALL BOW SPRING ROTOR CONNECTOR UNDER THE SILICONE CATHETER TANTALUM BALL SAPPHIRE BALL ADJUSTABLE UNIT GRAVITATIONAL UNIT
  21. 21. proGAV 2.0® with ShuntAssistant® Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates When patient is in the vertical position: a) Gravitational unit closes b) When: 𝑊𝑒𝑖𝑔ℎ𝑡 𝑇𝑎𝑛𝐵𝑎𝑙𝑙 < 𝑂𝑃𝐺𝑟𝑎𝑣𝑈𝑛𝑖𝑡  Fluid flows freely Fig 19: ShuntAssistant in vertical position a) closed, b) open Fig 20: ShuntAssistant in vertical position
  22. 22. proGAV 2.0® with ShuntAssistant® Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates When patient is in the horizontal position, the gravitational unit stays open, allowing fluid to flow freely Fig 21: ShuntAssistant in horizontal position Fig 22: ShuntAssistant in horizontal position Fig 23: Adjustable (Differential Pressure) DP-unit a) closed, b) open
  23. 23. proGAV 2.0® with ShuntAssistant® Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 24: Calculating the intraventricular pressure for horizontal and vertical body position IVP Intraventricular pressure 𝑃𝐿 Opening pressure in horizontal position (adjustable DP-unit only) 𝑃𝑆 Opening pressure in vertical position (adjustable DP-unit + gravitational unit) 𝑃𝐵 Pressure in the abdominal cavity 𝑃 𝐻 Hydrostatic pressure
  24. 24. proGAV 2.0® with ShuntAssistant® Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates • DPV controlled externally with a magnetic “Compass” • Rotorbrake makes a clicking sound when released/locked • Shunt valve is MRI safe up to 3 Tesla Fig 25: Open and closed proGAV 2.0 Adjustment Tool Fig 26: Adjustment with the proGAV 2.0 Adjustment Tool
  25. 25. proGAV 2.0® with ShuntAssistant® Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 27: Pressure level recommendations
  26. 26. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  27. 27. • Diagnosed with spontaneous Hydrocephalus at age 12 • Had 15 shunt related surgeries in 3 years • Shunt was a free flowing shunt: the only way to regulate the amount of CSF was to change his position from sitting/standing to lying down • Received first programmable shunt in 2006 • Brain tear and damage from multiple surgeries left him permanently disabled in 2010 • Has had a total of 20 brain surgeries to date • Current shunt is a programmable proGAV 2.0® with ShuntAssistant® Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  28. 28. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates Fig 28: Placement of shunt system
  29. 29. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  30. 30. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  31. 31. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  32. 32. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  33. 33. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  34. 34. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  35. 35. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  36. 36. Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates
  37. 37. 1. “Faucet” https://www.kisspng.com/png-tap-water-royalty-free-clip-art-drinking-water-cli- 161360/ “Female head silhouette” https://openclipart.org/detail/275981/female-head-profile- silhouette “Brain” http://enosart.com/brain-clipart-372/ 2. “Biology to a physicist” Google image 3. “Hydrocephalus” https://en.wikipedia.org/wiki/Hydrocephalus#/media/File:Hydrocephalus_(cropped).jpg 4. “The flow of cerebrospinal fluid” http://soweb.me/anatomy-of-brain- parenchyma/anatomy-of-brain-parenchyma-glasgow-uni-medicine-ilos/ 5. “Brain with water drops” MSOffice 6. “Ventricles in a normal brain compared to a Hydrocephalic brain” https://www.semanticscholar.org/paper/Normal-pressure-hydrocephalus.- Anderson/54d34b78087c01503c56503c618fe51cd0c03269 7. “Volume-Pressure relationship in the brain” 8. “Major components of a shunt system” http://neuroanimations.com/Hydrocephalus/Shunts/VP_Shunt.html 9. “Frontal view of shunt system” http://neuroanimations.com/Hydrocephalus/Shunts/VP_Shunt.html 10. “Lateral view of a shunt system” http://neuroanimations.com/Hydrocephalus/Shunts/VP_Shunt.html 11. “Imaging of a flanged catheter” Personal medical files 12. “Types of catheters” Sandip Chatterjee and L. Harischandra, "Cerebrospinal fluid shunts – How they work: The basics," Neurology India 66 (1), 24 (2018). 13. “Imaging of a shunt catheter” http://www.wikiradiography.net/page/Radiography+of+VP+Shunts 14. “Imaging of a shunt catheter (enhanced)” http://www.wikiradiography.net/page/Radiography+of+VP+Shunts 15. “Hydrostatic pressure” Sandip Chatterjee and L. Harischandra, "Cerebrospinal fluid shunts – How they work: The basics," Neurology India 66 (1), 24 (2018). Draining the Brain: The Physics of Hydrocephalus and Shunts Desiree Bates 16. “Mechanical designs of valves” Sandip Chatterjee and L. Harischandra, "Cerebrospinal fluid shunts – How they work: The basics," Neurology India 66 (1), 24 (2018). 17. “Schematic cross section of the proGAV 2.0” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV® 2.0: IN TOUCH WITH YOU," , . 18. “proGAV 2.0 shunt” https://www.aesculapusa.com/products/neurosurgery/hydrocephalus- shunts/progav-2-0 19. “ShuntAssistant in vertical position a) closed, b) open” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , . 20. “ShuntAssistant in vertical position” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV® 2.0: IN TOUCH WITH YOU," , . 21. “ShuntAssistant in horizontal position” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV® 2.0: IN TOUCH WITH YOU," , . 22. “ShuntAssistant in horizontal position” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , . 23. “Adjustable (Differential Pressure) DP-unit a) closed, b) open“CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , . 24. “Calculating the intraventricular pressure for horizontal and vertical body position” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , . 25. “Open and closed proGAV 2.0 Adjustment Tool” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , . 26. “Adjustment with the proGAV 2.0 Adjustment Tool” CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV 2.0® Instructions for Use," , . 27. “Pressure level recommendations” 28. “Placement of shunt system” By Cancer Research UK - Original email from CRUK, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=34332972 29. Remaining images from personal collection/medical records

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