Insurers often exclude coverage for experimental procedures since they have not yet been proven safe and effective and, therefore, involve higher-than-normal risks. Yet, because underwriters do not usually price their policies to incorporate such risks, claims resulting from experimental procedures are frequently excluded. (An example of such an experimental procedure is the implanting of a permanent intercranial device in hydrocephalus patients at Mexico's National Neurology and Neurosurgery Institute, which was alleged to be responsible for 370 patient deaths between 1994 and 2007, as reported in "Experimental Medical Procedure Blamed for 370 Deaths in Mexico," Fox News Latino, November 12, 2011.) Some insurers will agree to remove this exclusion, especially in cases where the insured physician performs a significant number of experimental or unapproved (e.g., by the US Food and Drug Administration, among other regulatory bodies) procedures. In such instances, insurers will remove the exclusion in return for additional premium.