Association of Pontine Small Infarction (Lacuna) with Disturbance of Postural Stability

Imbalance in multiple sclerosis and neuromyelitis optica: association with deep sensation disturbance

Abnormality in balance is one of the most important causes of gait disturbance which has a direct impact to disability and medical cost in multiple sclerosis (MS) and neuromyelitis optica (NMO). However, characteristics of imbalance in these two diseases have not been fully elucidated. The aim of this study was to evaluate the degree and features of imbalance using stabilography, the degree of deep sensation disturbance using tibial nerve somatosensory evoked potentials (SEP), and their association with clinical impairment, in patients with MS and NMO. Seven NMO patients and seven MS patients with balance disturbance were examined. The relationship among stabilography measurements representing the degree and features of imbalance, height-adjusted P38 peak latency of SEP, and neurological functional disability, were analyzed. Stabilography evaluation showed a significantly severer degree of imbalance in NMO than in MS. Romberg quotient of the patients with brainstem lesions was significantly larger than those without them. In all patients, length of excursion per second significantly correlated positively with anterio-posterior-axis power spectra at intermediate frequency band. In all patients and in NMO, P38 peak latency adjusted by height significantly correlated positively with anterio-posterior-axis power spectra at intermediate frequency band. These findings suggest that the degree of imbalance of MS and NMO possibly correlate with deep sensation disturbance, which could be evaluated by anterio-posterior-axis power spectra at intermediate frequency band by stabilography. Severer imbalance in NMO than MS may be associated with the severe longitudinally extensive spinal cord lesions.

The effects of acute treatment with paroxetine, amitriptyline, and placebo on the equilibrium function in healthy subjects: a double-blind crossover trial

OBJECTIVE

Depression is common in old age, and is treatable with antidepressants. However, antidepressants use can increase the risk of falls. Thus, we assessed the effects of antidepressants on equilibrium function using posturography.

METHODS

This study recruited 10 healthy male volunteers (35.3 ± 3.7 years). In this double-blinded, three-way crossover trial, they received acute doses of 10 mg paroxetine, 25 mg amitriptyline, and placebo. They were administered posturography at baseline and 4-h postdosing.

RESULTS

At 4-h postdosing, amitriptyline significantly decreased the locus length per unit area (L/A) and increased the envelope area compared with those at baseline. Meanwhile, the total length and the locus length per time (L/T) at 4-h postdosing of amitriptyline did not show significant differences from those at baseline. After paroxetine treatment, there were no significant differences in total length, L/T, L/A, and the envelope area between baseline and 4-h postdosing.

CONCLUSION

An acute dose of amitriptyline significantly decreased L/A and increased the envelope area as markers of body sway. Evaluation of equilibrium function is important for preventing the potential risk of falls and body sway after taking antidepressants.

Role of ocular convergence in the Romberg quotient

The Romberg test generally shows that postural stability is better with eyes open than eyes closed; the Romberg quotient (RQ) is generally 2.5. This study examines the possible role of vergence angle on the RQ. Eighteen young (25.3+/-2.7 years) and 17 old (61.6+/-4.4 years) subjects were required to fixate a target at 40 cm or at 200 cm inducing different vergence angle (i.e. 8.6 degrees and 1.7 degrees, respectively) either with eyes open or closed. Postural stability of subjects was measured with force platform (TechnoConcept). The RQ was about 2 at 40 cm but dropped to 1 at 200 cm. In a second experiment, 15 subjects (26.7+/-5.5 years) run the Romberg test with eye movement measures (Chronos). Subjects were required to fixate a target placed at 20 cm, 40 cm, 90 cm, 200 cm or 350 cm either in light or in dark. The RQ at 20 cm and 40 cm was close to 2 and dropped to 1 at 90 cm and beyond. In parallel, the vergence angle at 20 cm and 40 cm changed significantly between light and dark, while at 90 cm and beyond it was stable (about 2 degrees both in light and dark). The distance had a significant effect on the co-variance between the RQ based on the anterior-posterior sway, and the change of vergence angle. We suggest different ways of control of posture according to the viewing distance: at near distance and in the light, the CNS uses vision coupled with oculo-motor convergence signals (efferent and afferent) leading to high RQ; at intermediate and far distances, it would use mostly internal signals (vestibular, proprioceptive, somatosensory), and similarly in the light and in the dark.