When investigating the symptoms of PSP on the internet, there seems to be little information about neck position/flexure. Many descriptions tend to borrow off each other, and mostly refer to PSP being associated with retrocollis (while Parkinson's is associated with antecollis).
I found a quote of a quote of a neurologist on the CurePSP site to be very questionable! They said " you can go into a movement disorder clinic waiting room and deteremine if people have PSP or MSA based upon where their neck points. Antecollis (neck forward) is common in MSA. Retrocollis (neck flexure backwards) is common in PSP".
I am assuming those who have replied to this little survey have the correct diagnosis of PSP, with supranuclear gaze palsy (and not Parkinson's or MSA - that rarely have gaze palsy). Then, if I've counted correctly, out of 19 PSP sufferers, 8 showed retrocollis, 10 showed antecollis and 1 had neither.
I have seen the occasional reference that implies retrocollis is not necessarily a predominant feature of PSP. This should probably be reflected in future literature written on the subject of PSP symptoms. It would be good if a movement disorder neurologist could comment on such findings on this forum.