Correlation between qualitative balance indices, dynamic posturography and structural brain imaging in patients with progressive supranuclear palsy and its subtypes

Objectives: To compare the clinical, balance, and radiological profile of progressive supranuclear palsy (PSP) of Richardson type (PSP-R) and Parkinsonian type (PSP-P). Materials and Methods: Twenty-nine patients with PSP (PSP-R: 17, PSP-P: 12) satisfying the probable/possible National Institute of Neurological Disorders and Stroke-PSP criteria were recruited and assessed with Unified Parkinson's Disease Rating Scale-Ill, PSP rating scale (PSPRS), Berg balance scale (BBS), Tinetti performance-oriented mobility assessment gait and total (TPG and TPT) score, dynamic posturography (DP), and magnetic resonance imaging. Data were compared with 30 age-and gender-matched healthy controls. Results: The mean ages of PSP-R, PSP-P, and controls were comparable (62.5 +/- 6.6, 59 +/- 8.9, and 59.8 +/- 7.6 years). The PSP group had significantly poor DP scores and more radiological abnormalities than controls. The PSPRS, TPG, and TPT scores were significantly more impaired in PSP-R compared to PSP-P (P = 0.045, P = 0.031, and P = 0.037, respectively). In DP, the limits of overall stability were most significant (P < 0.001) and PSP-R had lower scores. PSP-R compared to PSP-P had more often Humming Bird sign (P < 0.001), Morning Glory sign (P < 0.008), and generalized cortical atrophy (P < 0.001). The area of midbrain (P < 0.002) and midbrain/pons ratio (P < 0.013) was significantly lower in PSP-R. In PSP-P, the overall balance index significantly correlated with BBS, TPG, and TPT (r = -0.79, P = 0.002; r = -0.772, P = 0.003; and r = -0.688, P = 0.013) and the midbrain axial anterior-posterior diameter significantly correlated with the TPG and TPT (r = 0.74, P = 0.01; r = 0.66, P = 0.018). Conclusions: While balance and radiological abnormalities were more severe in PSP-R, the qualitative and quantitative measurements of severity of balance in PSP-P rather than PSP-R was a better reflection of the pathology of the midbrain.