Videonystagmography as a tool to assess blepharospasm before and after botulinum toxin injection.
BACKGROUND
The aim of this paper was to study blinking parameters using a videonystagmography device, in order to objectively determine disability, and to assess the efficiency of botulinum toxin injection in patients with essential blepharospasm.


METHODS
Blinking was studied using the features of pupillary occlusion (PO) as recorded on a videonystagmography device. In 23 patients presenting with essential blepharospasm, we studied the frequency, the percentage, the mean duration of PO, and the longest PO in a 5-minute test period. Patients were tested prior to botulinum toxin injection, and 1 month and 3 months after injection, respectively. PO levels lower than 0.3 s and higher than 0.3 s were studied separately.


RESULTS
At 1 month after injection, botulinum toxin significantly influenced PO higher than 0.3 s, both in frequency (9.6/min +/- 8.2 on Day 0 and 4.7/min +/- 7.2 at Month 1; p = 0.004), and in mean duration (0.95 s +/- 0.84 on Day 0 and 0.58 s +/- 0.34 at Month 1; p = 0.03). On the other hand, we found no significant effect on PO lower than 0.3 s, both in frequency (32.4/min +/- 28.4 on Day 0 and 31.3/min +/- 29.0 at Month 1; p = 0.7) and in mean duration (0.16 s +/- 0.04 on Day 0 and 0.15 s +/- 0.03 at Month 1; p = 0.04). Botulinum toxin also significantly influenced the mean duration of the longest PO (6.44 s +/- 9.4 on Day 0 and 1.55 s +/- 1.9 at Month 1; p = 0.004) as well as the percentage of PO (29.95% +/- 24.6 on Day 0 and 13.44% +/- 11.1 at Month 1; p = 0.003).


CONCLUSIONS
PO can be used as the indirect sign of blinking. Videonystagmography provides a real-time result, and could be used to objectively evaluate the effect of botulinum toxin treatment in essential blepharospasm patients.
Casse
Guillaume
G
Ophthalmology Department, CHU Dupuytren, 2 Av Martin Luther King, 87042 Limoges Cedex, France. casse.guillaume@yahoo.fr
Adenis
Jean-Paul
JP
Sauvage
Jean-Pierre
JP
Robert
Pierre-Yves
PY
D000368:Aged; D000369:Aged, 80 and over; D001764:Blepharospasm / Q000175:diagnosis* / Q000188:drug therapy*; D001767:Blinking; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D003941:Diagnostic Techniques, Ophthalmological; D004185:Disability Evaluation; D005143:Eyelids / Q000473:pathology; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D011446:Prospective Studies; D011680:Pupil / Q000502:physiology; D014741:Video Recording
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A