Postural instability in Charcot-Marie-Tooth type 1A patients is strongly associated with reduced somatosensation.

In order to determine the influence of somatosensory impairments, due to the loss of large myelinated fibres, on the postural stability of Charcot-Marie-Tooth 1A (CMT) patients, a cross-sectional balance assessment was done. Nine CMT patients were compared with eight patients with a distal type of Spinal Muscular Atrophy (SMA), and 11 healthy control subjects. The balance assessment consisted of four tasks: quiet barefoot standing on a stable versus compliant surface, with eyes opened or closed. Force plate signals were used to calculate the velocity of the centre of pressure of the ground reaction forces. The patients' distal muscle force (MRC scale), vibration detection threshold (Rydel-Seiffer tuning fork) and superficial tactile sensation (Semmes-Weinstein monofilaments) were clinically assessed. Compared to the healthy subjects, postural stability of both patient groups was seriously impaired, however, increased visual dependency was only found in the CMT patients. The postural instability of the CMT patients correlated significantly with decreased vibration sense only. The strength of the correlation increased with task complexity. It is concluded that somatosensory deficits substantially contribute to impaired postural stability and increased visual dependency in CMT patients.

Is visuospatial hemineglect really a determinant of postural control following stroke? An acute-phase study.

OBJECTIVE: The purpose of this study was to determine the independent contribution of visuospatial hemineglect to impaired postural control in the acute phase (<2 weeks) of stroke compared with other possible clinical and biological determinants. METHODS: This study was conducted in 4 hospitals in the mid-east region of the Netherlands. A total of 78 consecutive patients with a first-ever acute supratentorial stroke was included. Functional balance was measured with the Trunk Impairment Scale, the Trunk Control Test, the Berg Balance Scale, and the Functional Ambulation Categories. Visuospatial hemineglect was assessed by means of an asymmetry index obtained from the Behavioral Inattention Test. The Motricity Index, vibration threshold, sustained attention, and the presence of hemianopia were registered as other possible clinical determinants. Stepwise backward multiple linear regression analysis was performed introducing all selected clinical determinants as well as age and poststroke time as possible biological determinants. RESULTS: Hemineglect was present in 17 patients (21.8%). The groups with and without hemineglect were different for gender and the proportion of right hemisphere strokes, but not for age, type of stroke, or poststroke time. Neglect patients had on average lower scores on all functional balance tests as well as on the clinical assessments. Multivariate linear regression showed that, besides hemineglect, only muscle strength and age independently contributed to impaired balance explaining 65% to 72% of variance of the selected outcomes. CONCLUSION: This study showed that hemineglect independently contributes to impaired postural control in the acute phase of stroke.