ABSTRACT
INTRODUCTION Pericerebral collections (PCC) are fluid collections located in the subdural and subarachnoid spaces, and the cerebrospinal fluid (CSF) plays a prominent role in most of these. There is still much confusion in the medical literature regarding the classification and nosology of PCC. During the past century, several terms were coined such as subdural effusion (1,2), subdural hydroma, subdural hygroma (3), “meningitis serosa traumatica” (1), and external hydrocephalus (EH) (3); these different names are still often used regardless of the nature of the fluid, of its subdural or subarachnoid location, and of the clinical context. For example, clearly distinct entities like infantile subdural hematoma (SDH) and atrophic SDH in the elderly are both referred to as “chronic SDH”; on the other hand, such terms as SDH, hygroma, hydroma, or effusion, may all refer to a single entity, namely, infantile SDH (iSDH). Similarly, the term “external hydrocephalus” (EH) is often equated to “idiopathic macrocrania,” whereas head circumference may stay within normal limits in EH, and macrocrania can persist in a toddler after the excess of subarachnoid fluid has resolved.
