Shannon Criteria

The Shannon criteria constitute an empirical rule in neural engineering that is used for evaluation of possibility of damage from electrical stimulation to nervous tissue.[1]

The Shannon criteria relate two parameters for pulsed electrical stimulation: charge density per phase, D (μCoulombs/(phase•cm²)) and charge per phase, Q (μCoulombs/phase) with a dimensionless parameter k:

Shannon Plot

which can be written alternatively:

According to these criteria, stimulation parameters that yield k ≥ 1.85 (the lowest value where damage was observed in the two studies referenced in the original Shannon publication) could cause damage to the adjacent nervous tissue. Currently, this empirical law is applied in neuromodulation for development of implants for cortical, cochlear, retinal,[2][3] and deep brain stimulation.[4][5] Shannon categorizes the relationship between stimulating electrode and target neural tissue as either Near Field, Mid Field, or Far Field, and discusses how equation parameters may be chosen in each case. In the case of spinal cord stimulation,[6] for example, the Far Field category would apply.

Limitations

The data on which the Shannon model was built[7][8] are restricted to experiments performed in cat cerebral cortex with 7 hours of stimulation under light anesthesia at 50 pps with 400 µs pulses (charge-balanced, symmetric, biphasic, anodic-first) using platinum surface disc electrodes of 1 mm² or larger, recessed, anodized sintered tantalum-tantalum pentoxide pellet electrodes of 1 mm in diameter, or iridium penetrating microelectrodes of 6500 µm². As a result of these restricted methods, Shannon states "A more comprehensive model of safe levels for electrical stimulation would also account for the effects of pulse rate, pulse duration, stimulus duty cycle, and duration of exposure."[1] Additionally, further study has demonstrated that microelectrodes do not obey the Shannon criterion, and new approaches may be proposed to address these limitations.[9]

References
  1. Shannon, R.V. (April 1992). "A model of safe levels for electrical stimulation". IEEE Transactions on Biomedical Engineering. 39 (4): 424–426. doi:10.1109/10.126616. PMID 1592409. S2CID 30517996.
  2. Eiber, Calvin D; Lovell, Nigel H; Suaning, Gregg J (1 February 2013). "Attaining higher resolution visual prosthetics: a review of the factors and limitations". Journal of Neural Engineering. 10 (1): 011002. Bibcode:2013JNEng..10a1002E. doi:10.1088/1741-2560/10/1/011002. PMID 23337266. S2CID 8566782.
  3. Winter, Jessica O.; Cogan, Stuart F.; Rizzo, Joseph F. (January 2007). "Retinal prostheses: current challenges and future outlook". Journal of Biomaterials Science, Polymer Edition. 18 (8): 1031–1055. doi:10.1163/156856207781494403. PMID 17705997. S2CID 18343125.
  4. Testerman, Roy L; Rise, Mark T; Stypulkowski, Paul H (Sep–Oct 2006). "Electrical stimulation as therapy for neurological disorder". IEEE Engineering in Medicine and Biology Magazine. 25 (5): 74–8. doi:10.1109/memb.2006.1705750. PMID 17020202. S2CID 21291427.
  5. Grill, Warren M (July 2005). "Safety considerations for deep brain stimulation: review and analysis". Expert Review of Medical Devices. 2 (4): 409–420. doi:10.1586/17434440.2.4.409. PMID 16293080. S2CID 32804879.
  6. McCreery, DB; Agnew, WF (1988). "Comparison of neural damage induced by electrical stimulation with faradaic and capacitor electrodes". Annals of Biomedical Engineering. 16 (5): 463–81. doi:10.1007/BF02368010. PMID 3189974. S2CID 5704513.
  7. McCreery, DB; Agnew, WF (1990). "Charge density and charge per phase as cofactors in neural injury induced by electrical stimulation". IEEE Transactions on Bio-Medical Engineering. 37 (10): 996–1001. doi:10.1109/10.102812. PMID 2249872. S2CID 8708385.
  8. Cogan SF, Ludwig KA, Welle CG, Takmakov P (2016). "Tissue damage thresholds during therapeutic electrical stimulation". Journal of Neural Engineering. 13 (2): 021001. Bibcode:2016JNEng..13b1001C. doi:10.1088/1741-2560/13/2/021001. PMC 5386002. PMID 26792176.

Further reading
  • Merrill, Daniel R.; Bikson, Marom; Jefferys, John G.R. (February 2005). "Electrical stimulation of excitable tissue: design of efficacious and safe protocols". Journal of Neuroscience Methods. 141 (2): 171–198. doi:10.1016/j.jneumeth.2004.10.020. PMID 15661300. S2CID 7291172.
  • McCreery, Douglas (2004). "Tissue Reaction to Electrodes:The Problem of Safe and Effective Stimulation of Neural Tissue". In Horch, Kenneth W; Dhillon, Gurpreet S (eds.). Neuroprosthetics. Series on Bioengineering and Biomedical Engineering. Vol. 2. pp. 592–611. doi:10.1142/9789812561763_0018. ISBN 978-981-238-022-7.
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