Título

SPECTRAL ANALYSIS OF THE UPPER EYELID KINEMATICS BEFORE AND AFTER BOTULINUM TOXIN IN HEMIFACIAL SPASM AND BENIGN ESSENTIAL BLEPHAROSPASM

Objetivo

Objective evaluation of eyelid spasms and eyelid cinematics have not been previously evaluated in hemifacial spasm and essential blepharospasm patients. The purpose of this study is to assess upper eyelid kinematics in patients with hemifacial spasm (HFS) and essential blepharospasm (BEB).

Método

The Fast Fourier Transform (FFT) was used for a spectral analysis of the spontaneous upper eyelid movements in HFS and BEB patients. We calculated the area of power spectrum density (PSD), which represents the function relating frequency versus energy of the movements, and symmetry of interocular eyelid motion (SIEM) expressed as the percentage of overlapping movements (0=no symmetry and 100=perfect symmetry). Ten patients were examined (5 for each group) before and 30 days after botulinum toxin-A (BoNT-A)

Resultado

A mean reduction of 72% in the area of PSD area was observed on both eyes in patients with BEB and in the affected eye in HFS. An increase of 35% was also observed for the normal eyes of HFS. Interocular symmetry of lid movements (75%) was not significantly changed after treatment. For the HFS patients, the mean lid motion symmetry increased from 55,9 to 68,2%. Different kinematics patterns could be observed in BEB patients.

Conclusão

Spectral analysis of lid movements with FFT is a useful tool for an objective evaluation of the therapeutical effects BoNT-A in facial dystonias patients. The frequency distribution of lid movements as well the degree of interocular motion are easily assessed. Spectral analysis of the upper lid with FFT in BEB and HFS patients showed reduction of the lid spasms frequency and reestablishment of motion symmetry in HFS cases.