Direction specific preserved limits of stability in early progressive supranuclear palsy: a dynamic posturographic study.
OBJECTIVE
To quantitatively detect the nature of balance impairment in patients with progressive supranuclear palsy (PSP) using dynamic posturography.


METHODS
Twenty clinically diagnosed PSP patients (8 women, 12 men; age: 62.1 ± 7.7 years; duration: 2.6 ± 1.3 years) and 20 healthy controls were studied. All subjects were right side dominant. They were evaluated by dynamic posturography (Biodex, USA). The measurements included (i) balance indices: ability to control balance in all directions (overall balance index, OBI), front to back (anterior-posterior index, API) and side-to-side (medio-lateral index, MLI), and (ii) the limits of stability (LOS) in 8 directions: forward (FW), backward (BW), right (RT), left (LT), forward-right (FW-RT), forward-left (FW-LT), backward-right (BW-RT) and backward-left (BW-LT).


RESULTS
Compared to controls, patients showed significantly higher OBI (p<0.001), API (p=0.003) and MLI (p<0.001), implying impaired balance. The total LOS score was significantly lower (implying poor stability) in PSP than in controls (18.3 ± 7.3 vs. 28.4 ± 8.5, p<0.001). Patients took significantly longer time to complete LOS test (262.7 ± 33.0 s vs. 135.4 ± 20.6 s, p<0.001). Direction-wise analysis showed that PSP patients had significantly lower LOS scores in FW, BW, RT, FW-RT, BW-RT and BW-LT directions compared to controls. However the scores in LT and FW-LT did not differ significantly.


CONCLUSIONS
PSP patients showed impaired balance indices and decreased overall LOS compared to controls. Though LOS is affected in PSP, the scores in the left (non-dominant side) and forward-left (non-dominant forward diagonal) directions were preserved.
Department of Neurophysiology, National Institute of Mental Health & Neurosciences, Bangalore 560029, India.
Mohan
M
Ganesan
Shaik Afsar
SA
Pasha
Pramod Kumar
PK
Pal
Ravi
R
Yadav
Anupam
A
Gupta
D017677:Age Distribution; D000368:Aged; D000704:Analysis of Variance; D000886:Anthropometry; D016022:Case-Control Studies; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000453:epidemiology / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D004856:Postural Balance / Q000502:physiology*; D011379:Prognosis; D012016:Reference Values; D018570:Risk Assessment; D012678:Sensation Disorders / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D012720:Severity of Illness Index; D017678:Sex Distribution; D013494:Supranuclear Palsy, Progressive / Q000150:complications* / Q000175:diagnosis; D013997:Time Factors