====== Posttraumatic leptomeningeal cyst epidemiology ======

[[Posttraumatic leptomeningeal cyst]]s are very rare, occurring in 0.05–0.6% of [[skull fracture]]s
((Ramamurthi B, Kalyanaraman S. Rationale for Surgery in Growing Fractures of the Skull. J Neurosurg. 1970; 32:427–430))
((Arseni CS. Growing Skull Fractures of Children. A Particular Form of Post-Traumatic Encephalopathy. Acta Neurochir. 1966; 15:159–172)).
Usually requires both a widely separated fracture AND a [[dural tear]]. 

Mean age at injury: < 1 year; over 90% occur before age 3 years
((Lende R, Erickson T. Growing Skull Fractures of Childhood. J Neurosurg. 1961; 18:479–489)) 
(formation may require the presence of a rapidly growing brain
((Gadoth N, Grunebaum M, Young LW. Leptomeningeal Cyst After Skull Fracture. Am J Dis Child. 1983; 137:1019–1020))), 
although rare adult cases have been described
((Britz GW, Kim DK, Mayberg MR. Traumatic leptomeningeal cyst in an adult: a case report and review of the literature. Surg Neurol. 1998 Nov;50(5):465-9. doi: 10.1016/s0090-3019(97)00233-4. PMID: 9842874.)),
((Halliday AL, Chapman PH, Heros RC. Leptomeningeal Cyst Resulting from Adulthood Trauma: Case Report. Neurosurgery. 1990; 26:150–153))
((Iplikciglu AC, Kokes F, Bayar A, et al. Leptomeningeal Cyst. Neurosurgery. 1990; 27: 1027–1028))
(a total of 5 cases in the literature as of 1998
((Britz GW, Kim DK, Mayberg MR. Traumatic leptomeningeal cyst in an adult: a case report and review of the literature. Surg Neurol. 1998 Nov;50(5):465-9. doi: 10.1016/s0090-3019(97)00233-4. PMID: 9842874.))).