Physiological, pharmacological and neurohormonal assessment of autonomic function in progressive supranuclear palsy

The clinical features of progressive supranuclear palsy (PSP) overlap with other parkinsonian syndromes, including multiple system atrophy (R-ISA), Au tonomic dysfunction is a characteristic of MSA, but has also been described in PSP, We therefore report results from a series of physiological studies of cardiovascular autonomic function in 35 PSP and 20 MSA. subjects, and 2 6 age-matched healthy control subjects, The response to growth hormone-clon idine testing, a neuropharmacological assessment of central adrenoceptor fu nction, was also assessed in 14 PSP and 10 MSA subjects, and compared with 10 controls. None was on meditation which may have affected the results. Or thostatic hypotension did not occur in PSP subjects or controls, unlike II- ISA subjects. Overall there was no evidence of sympathetic vasoconstrictor failure in PSP subjects, unlike MSA subjects, although the presser response to mental arithmetic was reduced, Cardiac parasympathetic function was aff ected in only a minority (three of 35) of PSP subjects and was abnormal in MSA subjects. After clonidine administration, growth hormone rose in PSP su bjects (median increase 4.3; interquartile range 1.8-7.8 mU/l) and controls , unlike MSA subjects (0.9; 0.3-2.4 mU/l; P < 0.005, Mann-Whitney U-test), In conclusion, in PSP subjects, responses to both physiological and pharmac ological tests provided evidence against widespread autonomic dysfunction; this differed markedly from MSA subjects. Thus, cardiovascular autonomic dy sfunction should be an exclusionary feature in the diagnosis of PSP.