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Modeling Idiopathic Intracranial Hypertension with a semi-collapsible sinus . Scott Stevens Penn State Erie. Idiopathic Intracranial Hypertension (IIH). High pressure (hypertension) In the head (intracranial) Unknown cause (idiopathic)

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modeling idiopathic intracranial hypertension with a semi collapsible sinus

Modeling Idiopathic Intracranial Hypertension with a semi-collapsible sinus

Scott Stevens

Penn State Erie

idiopathic intracranial hypertension iih
Idiopathic Intracranial Hypertension (IIH)
  • High pressure (hypertension)
  • In the head (intracranial)
  • Unknown cause (idiopathic)
  • Symptoms: headache, nausea, papilledema (swollen optic nerve), visual obscurations possibly leading to blindness
  • Often concurrent with intracranial venous-sinus stenosis
slide3

Sinus Stenosis: Blockage or compression?

J N P Higgins, C Cousins, B K Owler, N Sarkies and J D Pickard

Idiopathic intracranial hypertension: 12 cases treated by venous sinus stenting

Journal of Neurology Neurosurgery and Psychiatry 2003;74:1662-1666

Normal

Stenosed Sinus

prevalence
Prevalence
  • IIH prevalence < 1%
  • IIH without papilledema (IIHWOP) ?
  • 6.7% of 724 migraine patients – sinus stenosis.
  • 67.8% of these - IIHWOP.
  • Possibly 1.3 million in United States
  • Nine of ten CDH patients – IIHWOP with Pathological ICP waveforms

Bono 2006, Torbey 2004.

slide5

Clinically Observed Pathological ICP Waveforms in IIHWOP

A-waves (plateaus)

B-waves (spikes)

Risberg, Lundberg 1969

Torbey 2004

downstream starling resistor
Downstream Starling Resistor

Data: Heil (1997)

Model

slide15

Keep your eye on “m”:

the initial collapsibility parameter.

bifurcation diagram for p f in terms of the collapsibility parameter m

IIH begins

Still healthy

Limit Cycles

Bifurcation Diagram for PF in terms of the collapsibility parameter m

As the collapsibility parameter (m) increases, the situation gets worse.

slide21

Cerebral Blood Flow Perturbations.

Spikes and plateaus together.

slide22

Post saddle-node bifurcation: Similar to our previous results.

Two stable states: Normal and ElevatedTemporary perturbations cause fast, permanent transitions. Cerebral blood flow perturbation - Sleep apnea.

slide23

Potential Diagnostic/Validation Method: Bolus CSF withdrawal.

Collapsible sinus simulation

Rigid sinus simulation

slide24

Current Endeavors

Periodic ForcingGrazing BifurcationsStochastic influences

CBF autoregulation

Single DE system

Sigmoidal Resistor

thanks
Thanks
  • Jesse Stimpson, Senior, Penn State Erie
  • William D. Lakin, Mathematics, University of Vermont
  • Nimish Thakore, Neurology, Case Western Reserve University
  • Paul Penar, Neurosurgery, University of Vermont.
  • NASA - NSF
a fantastic web based direction field phase portrait utility rice university
A fantastic, web-based direction field / phase portrait utilityRice University

http://math.rice.edu/~dfield/dfpp.html

slide30
Previous ModelsIIH characteristics 1) Sinus Stenosis2) intermittent symptoms3) long term relief4) fast transitions between states5) treatment methodsStevens, Previte, Lakin, Thakore, Penar, and Hamschin: "Idiopathic Intracranial Hypertension and Transverse Sinus Stenosis: A Modeling Study". Mathematical Medicine and Biology 2007

Current ModelIIHWOP characteristics1) Retains previous results for IIH2) Demonstrates Pathological ICP wave-forms in IIHWOPStevens, Stimpson, Lakin, Thakore, and Penar “A model for idiopathic intracranial hypertension and associated pathological ICP wave-forms. Accepted by IEEE Transaction on Biomedical Engineering.