Clearer image here: https://drive.google.com/file/d/1uBUTSobejeq0ALii7vxe-9hi_cVTircp/view?usp=sharing 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 listed 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. Papers referenced: 1 CHRISTOPH MIETHKE GMBH & CO. KG, "proGAV® 2.0: IN TOUCH WITH YOU," , . 2 Ian Piper, in , Anonymous 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).

1. Draining the Brain: The Physics of Hydrocephalus and Shunts
Desiree Bates • University of Texas at Arlington
Abstract
Suspended in a sea of cerebrospinal fluid, our brain controls every thought, every organ, every process of our human existence. This fluid, CSF, acts as a barrier between the brain and our rigid skull, protecting it from impact and regulating our intracranial
pressure, as well as carrying nutrients to the brain and removing waste product. How could it be possible for such a vital fluid to become so dangerous? Our skull is a confined space, and a buildup of CSF applies pressure to the brain, sometimes causing
irreversible damage. This condition is known as Hydrocephalus, or “water on the brain.” The increase in intracranial pressure must be resolved by siphoning the additional fluid from the head and re-routing it to another part of the body, typically the
peritoneal cavity. To resolve this, a mechanical device called a shunt, based on hydrostatic pressure, is inserted into the brain. The shunt drains the excess CSF from the ventricles, allowing a balance in intracranial equilibrium.
Produced within the ventricles of the brain and partially
by the choroid plexus, and is absorbed by the dural
venous sinuses
Composition:
99.13% Water
0.87% Both organic and inorganic solids:
• Organic: proteins, amino acids, sugar, cholesterol,
uric acid, creatinine, lactic acid
• Inorganic: Na, Ca, K, Mg, Cl, PO₄, HCO₃, SO₄
• Blood Cells: 5 lymphocytes/cu. Mm
Function:
• Regulates intracranial pressure (ICP)
ICP must be constant: Blood and CSF are displaced as
necessary to maintain intracranial equilibrium
• Cushions and protects the brain
• Carries nutrients to the brain
• Removes waste products
Surgically implanted device that drains excess CSF
Over 400 types of shunts
3 main parts:
Proximal (Ventricular) catheter: Drains fluid from ventricles; 15-23cm in length;
Inner diameter 1.0-1.6mm; External diameter 2.1-3.2 mm; May be straight,
flanged, or J-shaped
Distal catheter: Routed from the burr hole in the skull; 90-120 cm in length; Inner
diameter 0.7-1.3mm; External diameter 2.1-2.5 mm; can be routed to: Heart
(Ventriculoatrial (VA) shunt); Lungs (Ventriculopleural (VPLS) shunt); Abdomen
(Ventriculoperitoneal (VP) shunt (most common))
Shunt valve: 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)
• Differential Pressure Valves (DPV): 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
Under normal conditions:
𝑉𝑏𝑟𝑎𝑖𝑛 + 𝑉𝑏𝑙𝑜𝑜𝑑 + 𝑉𝐶𝑆𝐹 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡 → ∆𝑉𝑏𝑟𝑎𝑖𝑛 + ∆𝑉𝑏𝑙𝑜𝑜𝑑 + ∆𝑉𝐶𝑆𝐹= 0
Including a shunt as CSF drainage:
∆𝑉𝑏𝑟𝑎𝑖𝑛 + 𝑐𝑒𝑟𝑒𝑏𝑟𝑎𝑙 𝑏𝑙𝑜𝑜𝑑 𝑖𝑛𝑓𝑙𝑜𝑤 − 𝑎𝑟𝑡𝑒𝑟𝑖𝑎𝑙 𝑏𝑙𝑜𝑜𝑑 𝑠𝑡𝑜𝑟𝑎𝑔𝑒
− 𝑣𝑒𝑛𝑜𝑢𝑠 𝑏𝑙𝑜𝑜𝑑 𝑠𝑡𝑜𝑟𝑎𝑔𝑒 − 𝑐𝑒𝑟𝑒𝑏𝑟𝑎𝑙 𝑏𝑙𝑜𝑜𝑑 𝑜𝑢𝑡𝑓𝑙𝑜𝑤 + 𝐶𝑆𝐹 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛
− 𝐶𝑆𝐹 𝑠𝑡𝑜𝑟𝑎𝑔𝑒 − 𝐶𝑆𝐹 𝑜𝑢𝑡𝑓𝑙𝑜𝑤 − 𝐶𝑆𝐹 𝑑𝑟𝑎𝑖𝑛𝑎𝑔𝑒 = 0
Assuming constant volume of the brain and blood volumes:
𝐶𝑆𝐹 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 = 𝐶𝑆𝐹 𝑠𝑡𝑜𝑟𝑎𝑔𝑒 + 𝐶𝑆𝐹 𝑜𝑢𝑡𝑓𝑙𝑜𝑤 + 𝐶𝑆𝐹 𝑑𝑟𝑎𝑖𝑛𝑎𝑔𝑒
Shunts
Sometimes referred to as “Water on the Brain,” Hydrocephalus is
an abnormal accumulation of cerebrospinal fluid in the ventricles
and surrounding the brain
The skull limits the expansion of cerebrospinal fluid; Increased fluid means
increased pressure on the brain.
Side effects include: Nausea & vomiting, Pressure headaches, Visual
disturbances, Impaired motor skills and balance, Dizziness, Blindness,
Seizures, Death
Additional Acknowledgements
CSF is balanced in a normal, healthy brain:
𝑃𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑆𝐹
+ 𝐸𝑥𝑡𝑒𝑟𝑛𝑎𝑙 𝐼𝑛𝑓𝑢𝑠𝑖𝑜𝑛 𝑜𝑓 𝐶𝑆𝐹
= 𝑆𝑡𝑜𝑟𝑎𝑔𝑒 𝑜𝑓 𝐶𝑆𝐹 + 𝑅𝑒𝑎𝑏𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛 𝑜𝑓 𝐶𝑆𝐹
Reabsorption is CSF pressure (P) and pressure in
sagittal sinuses (𝑃𝑆𝑆), proportional to resistance
to reabsorption (𝑚𝑚𝐻𝑔 ∙ 𝑚𝑙−1
∙ 𝑚𝑖𝑛):
𝑅𝑒𝑎𝑏𝑠𝑜𝑟𝑝𝑡𝑖𝑜𝑛 =
𝑃 − 𝑃𝑆𝑆
𝑅
Storage is proportional to CSF compliance (C)
(𝑚𝑚𝐻𝑔/𝑚𝑙):
𝑆𝑡𝑜𝑟𝑎𝑔𝑒 = 𝐶 ∙
𝑑𝑝
𝑑𝑡
Compliance is inversely proportional to pressure
and cerebral elastance coefficient (E) (𝑚𝑙−1):
𝐶 =
1
𝐸 ∙ (𝑃 − 𝑃0)
For a final equation of:
1
𝐸 ∙ (𝑃 − 𝑃0)
∙
𝑑𝑝
𝑑𝑡
∙
𝑃 − 𝑃𝑏
𝑅
= 𝐼(𝑡)
Where 𝑃𝑏 is baseline pressure, and 𝐼(𝑡) is the rate
of external volume addition
Fig 2: Comparison of normal ventricles and ventricles with normal pressure
Hydrocephalus: https://www.semanticscholar.org/paper/Normal-pressure-hydrocephalus.-
Anderson/54d34b78087c01503c56503c618fe51cd0c03269
Fig 3: Shunt placement:
https://commons.wikimedia.org/w/index.php?curid=34332972
Fig 4: Major components of a shunt:
http://neuroanimations.com/Hydrocephalus/Shunts/VP_Shunt.html
Equilibrium in the Brain Using a Shunt
Fig 7: CT showing a
flanged shunt
Hybrid valve: proGAV Combines DPV with HSV to avoid siphoning
Able to regulate OP with posture changes
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.
• DPV controlled externally with a magnetic “Compass”
• Rotorbrake makes a clicking sound when released/locked
• Shunt valve is MRI safe up to 3 Tesla
Types include: Slit valves, Mitre valves, Diaphragm
valves, Ball-in-cone valves (Ball-spring valve) (most
efficient: offers maximum flow when DP > OP)
• Hydrostatic Valves (HSV): Designed to avoid
over-drainage resulting from change in HSP
(siphoning); Referred to as anti-siphoning
devices
Three types: (1) 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; (2)
Flow reducing devices – CSF flow based on
differential pressure; (3) Gravitational valve – uses
metal ball to regulate flow across opening
Fig 5: X-ray showing shunt system:
http://www.wikiradiography.net/page/Radiography+of+VP+Shunts
Awareness Campaign
In 2012, I created the Hydrocephalus Awareness
Ribbon that is now used worldwide
The ribbon uses light blue to represent pediatric patients,
dark blue to represent adults, with a water droplet for CSF.
Visit www.facebook.com/AdvocatesforHydrocephalusAwareness
for more information, and be sure to click on
the QR code to visit my blog and learn about
My amazing husband who is disabled from 20
Hydrocephalus related brain surgeries.
Fig 8: Schematic cross section of the proGAV2.0
Fig 12: Adjustment with the proGAV2.0 adjustment compass Fig 13: Physics calculations for intraventricular pressure for horizontal and vertical positions
Fig 6: Mechanical designs of shunt valves
1 CHRISTOPHMIETHKEGMBH & CO. KG, "proGAV® 2.0: IN TOUCH WITH YOU," , .
2 CHRISTOPH MIETHKEGMBH & CO. KG, "proGAV 2.0® Instructionsfor Use,", .
3 Sandip Chatterjeeand L. Harischandra, "Cerebrospinal fluid shunts – How they work: The basics," Neurology India 66 (1), 24 (2018).
4 Marek Czosnykaet 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.
5 Dr Y. Rajalakshmi,Guide to Physiology, edited by Anonymous(S. ChandPublishing, RamNagar, New Delhi, 2010), pp. 157.
Hydrocephalus
“Hydro”- Water • “Cephalo”- Head
proGAV 2.0® with ShuntAssistant®
Fig 1: The Flow of Cerebrospinal Fluid
http://soweb.me/anatomy-of-brain-parenchyma/anatomy-of-brain-parenchyma-glasgow-uni-medicine-ilos/
Cerebrospinal Fluid
IVP
𝑃𝐿
𝑃𝑆
𝑃𝐵
𝑃 𝐻
Intraventricular pressure
Opening pressure in horizontal position
(adjustable DP-unit only)
Opening pressure in vertical position
(adjustable DP-unit + gravitationalunit)
Pressure in the abdominal cavity
Hydrostatic pressure
When patient is in the vertical position:
a) Gravitational unit closes
b) When: 𝑊𝑒𝑖𝑔ℎ𝑡 𝑇𝑎𝑛𝐵𝑎𝑙𝑙 < 𝑂𝑃𝐺𝑟𝑎𝑣𝑈𝑛𝑖𝑡 → Fluid flows freely
Fig 9: Gravitational unit in vertical position a) closed b) open
When patient is in the horizontal position, the gravitational unit
stays open, allowing fluid to flow freely Fig 11: Adjustable DP-unit a) closed b) open
Fig 10: Gravitational unit in horizontal position