Epidemiology
While the overall prevalence of OPLL remains low, it has been estimated by Epstein[12] that up to 25% of the North American and Japanese populations with cervical myelopathy exhibit characteristics of OPLL. This is predominantly found in the high cervical region (C2–4)[12] and occurs nearly twice as often in males as in females.[15,18] In the Japanese literature, where the disease has been studied extensively, the general prevalence of OPLL has been documented to be between 1.9% and 4.3%.[42,58,64] In other neighboring countries, including Taiwan and Korea, the rate in the population is near 3%.[69] In North American populations, it appears that the disease prevalence is much lower. Resnick and Niwayama[55] calculated that the rate of classic disease in Caucasian individuals from North America was 0.12%. These rates suggest that the predominant presentation of the disease is sporadic. However, there have been cases of familial OPLL in Caucasian and European populations.[65] Furthermore, genetic loci associated with cases of OPLL in Asian populations have also been linked to non-Asian Mediterranean familials.[22] In our limited experience, several of our non-Asian patients with OPLL have family origins from in or near these Mediterranean bloodlines. Also, quite importantly, a varying percentage of patients with DISH, a very prevalent disease in Caucasian populations, have OPLL.[22]
Neurosurg Focus. 2011;30(3):e10 © 2011 American Association of Neurological Surgeons
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