Real Academia Española(2009) describes that the correlative prepositional construction [de ∼ a ∼] expresses movement between an origin and a destination. So we could expect an expression like 'de arriba a abajo' for the meaning of "from top to bottom", but Real Academia Española(2009: 2314) says that ‘de arriba abajo’ is preferred to ‘de arriba a abajo’. Earlier, Real Academia Española(2005) manifests that the preposition a is never allowed in the constructions like ‘*de arriba a abajo' or ‘*de dentro a afuera’ because the directional adverbs - abajo, arriba, atrás, adelante, adentro, afuera - already include the preposition a in their form. In spite of that, we can find many cases like 'El Camp Nou se reformará de arriba a abajo', where the appropriate use is ‘de arriba abajo’. We will try to show that the phonetic omission or the explicit realization of the preposition a in the correlative prepositional construction [de ∼ a ∼] is closely related to the morpho-syntactic properties of the prepositional prefix ‘a-’, which appears as a part of the directional adverbs in the lexicalization structure.