Viscosity of speech has been reported in the medical literature with temporal lobe epilepsy by Rao et al from the Medical College of Wisconsin. They describe it as "the behavioural tendency to talk repetitively and circumstantially (round and round on the same topic) about a restricted range of topics." In their study it was seen more often in patients with epilepsy arising from the left temporal region or both sides and was thought to reflect very subtle dysfunctions in language due to involvement of the temporal lobe. Another report from Memphis describe viscosity of speech and actions as "detailed and ordered." Hope that helps.