J Neurol Surg B Skull Base 2016; 77 - FP-23-06
DOI: 10.1055/s-0036-1592558

An Evolutionary Approach to Seizures and Thermoregulation

Alexandra R. Kunz 1, Sandeep Sood 2
  • 1Evolutionary Anthropology, Harvard University (Extension), Cambridge, Massachusetts, United States
  • 2Neurosurgery Department, Wayne State Medical School, Detroit, Michigan, United States

Introduction: Seizures (S) post-cranial base surgery present potential complications, their predictors/rates significantly understudied.

Methods: Here, S are explored from comparative “evolutionary pressure” datasets for contributing age-dependent vulnerability factors.

Results and Discussion: Thermoregulation's (TR) evolutionary quest is optimal temperature for maximal performance: for insects/viruses, a growth focus; for ectotherms, a natural selection focus; for endotherms', birds'/mammals', promoting heat-loss focus. Mammalian brains' selective brain cooling (SBC), is a special evolutionary case within thermal cores because hyperthermia, causing S, limits performance; SBC separates brain temperature (T) regulation from body to keep Tbrain < Ttrunk, p < 0.01.

Species-specific SBC mechanisms in hyperthermia reverse blood flow, brain → skin to skin → brain, to cool/maintain cerebral metabolism. A 4-part pathway connects extracranial diploic/emissary veins to intracranial meningeal veins/sinuses; primate emissary veins respond immediately to hyperthermia; their parietal/mastoid/condyloid/post-glenoid foramina prominence shift in an evolutionary pattern: Tarsius 0, 0, 0, and 100%; Lemurs 0, 74.4, 0, and 99%; chimpanzee 8.7, 14, 16.5, and 0%; human 60.5, 68, 77, and 0.6%. The richly vascularized/complex human diploe has an age dependent developmental pattern, potentially fully established, age 5, large variations at each age.

Brain geometry plays important evolutionary role in TR patterns/heat distribution. Perinatal discontinuity of ontological size/shape changes in chimps/humans, 2–4 months, p < 0.0044, produces topographical vascular changes; expanded human frontoparietal volume, now globular, with highest diploic/emissary veins' concentration, affects heat dissipation. Brain surface:volume values for chimps/humans, 1.59 versus 0.91, respectively, confirms globular shape decreases TR values in heat transfer.

Conclusion: In light of evolution, human ontological shape variations offer an option to S' unsolved puzzle.