Intracranial hypotension, intracranial hypovolemia and cerebrospinal fluid leak

Abstract

Intracranial hypotension is a syndrome of which the predominating symptom is orthostatic headache caused by cerebrospinal fluid leakage. First identified over 70 years ago, this syndrome is not a newly established clinical entity. However, this syndrome attracts much attention today, because of the possible relationship between this syndrome and whiplash injuries that occur after traffic accidents. The term cerebrospinal fluid hypovolemia is used almost synonymously; however, it has no unequivocal definition as it includes cases were the cerebrospinal fluid pressure does not fall below the threshold of intracranial hypotension. From 2007, the Cerebrospinal Fluid Hypovolemia Research Group (directed by Takamasa Kayama), benefici­ary of a scientific research grant from the Ministry of Health, Labour and Welfare, has worked to solve issues related to this syndrome. In October 2011, the research group published their "Diagnostic imaging criteria for cerebrospinal fluid leakage" with the approval of academic societies studying the syndrome. In this paper, we present an overview of the criteria including the reasons why the research group decided to provide criteria for cerebrospinal fluid leak, and not for cerebrospinal fluid hypovolemia.