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1. Posttraumatic Epilepsy W Wallis CAA Meeting Wellington 30.8.10

8. Pathology of High Risk Brain injuries

10. Old Head Injuries: CT Predictions of High Risk for PTE

11. Low Risk CT

13. Risk of PTE Declines With Time Jennett 1975, 1000 +, consecutive Pts with head injuries Yearly increase incidence of PTE Regression Analysis of Initial (lifetime) Risk of PTE to the Residual Risk The regression analysis in table 3 and figure 1 were derived by a British neurosurgeon Dr. J Firth, using the follow-up data of 481 patients with PTE from the series of Jennett (2 ), and kindly supplied to me by Dr. Firth). 97% 10 years 95% 9 years 93% 8 years 92% 7 years 88% 6 years 85% 5 years 81% 4 years 77% 3 years 69% 2 years 56% I year Cumulative % of PTE beginning at end of each year Interval after injury

15. Cumulative Risk of PTE related to Severity of Injury ( Annegers 1998, 4541 pts followed prospectively) Note that the risk continues up to 20 yrs and differs from controls only with severe head injuries

16. Relative risk of epilepsy over 10 years in 78,572 Danish people after severe head injury, mild head injury, and skull fracture compared control reference group Christensen et al.. Lancet. 2009; 373:1105 -1110

17. Why estimate the risk? How to do it. Why? Consequences of seizure for most people are serious, particularly with certain occupations. Medico legal Implications. How? Clinical and laboratory features of head injuries allow a reasonably accurate estimate of the initial (lifetime) risk as well all the residual risk at any given time after the injury. i.e. an initial risk of 6% will decline to a residual risk of close to 1% in 5 years, but an initial risk of 20% not for 10 years ↓ Initial Risk (lifetime) ↓ Residual Risk ↔↓ A Residual risk of 1% is close to a control risk

18. An Example of Predicting Initial Risk PTE Annegers J.F. et al. NEJM 1998; 338:20-24 4531 patients followed up to 30 years Type of injury initial risk PTE f/u in yrs Comments Controls may have a lower risk than subjects prone to head injuries Up to 30 Just below 2% epilepsy Control population Some of these patients did not have intracerebral bleeding but only prolonged amnesia. Those with combined extra and intracerebral bleeding had a risk of 35%. Risk of PTE is this series would probably be higher if those with normal CT scans were removed. Up to 30 11% to 35% Severe injury Some patients probably had unrecognised intracerebral bleeding, as not all had CT scans. The true initial risk of PTE is probably only slightly higher than that of the general population. Up to 30 4% Moderate injury The risk of PTE is probably the same as the general population. Up to 30 2% Minor injury

19. Author % Developing PTE and F/U Other Examples from Literature Predicting PTE Single contusion 8.2%.Multiple contusions 25.2 + % . 60 + % with dural penetration. Combined extra and intracerebral bleeding as well as surgery increased risk PTE further. F/U only 2 years, so risk of PTE is higher than reported Englander et al 647 patients. All had CT scans 18 % with only contusions 45% with combined extra and intracerebral bleeding. F/U 5 to 7 years, so risk is higher D’Alessandro et al 219 patients all examined with CT scan within 3 days of injury