This causes extreme retroflexion, or backward bending, of the head in a "star-gazing" fashion. Rare post-operative complications include hydrocephalus and brain stem compression by retroflexion of odontoid. In the second stage, leveling of the sibilant system resulted in retroflexion (cf. Note on transcription&colon; rhoticity indicates half-retroflexion; doubled it indicates full retroflexion. Retroflexion also does not usually occur in Finland. Acoustically, retroflexion tends to affect the higher formants.