Vestibulo-Ocular Reflex Stabilization after Vestibular Schwannoma Surgery: A Story Told by Saccades.
OBJECTIVE
To evaluate vestibular compensationviameasurement of the vestibulo-ocular reflex (VOR) following vestibular schwannoma surgery and its relationship with changes in saccades strategy after surgery.


METHODS
Thirty-six consecutive patients with vestibular schwannomas, without brainstem compression, underwent surgical resection. Patients were recruited from University Hospital of Salamanca, Spain.


METHODS
We assessed the age, sex, tumor size, degree of canalicular weakness, and preoperative video head impulse test (gain and saccade organization measured with PR score). Gain and saccade organization were compared with postoperative values at discharge and also at 1, 3, and 6 months. PR scores are a measure of the scatter of refixation saccades.


RESULTS
Patients with normal preoperative caloric function had higher PR scores (saccades were scattered) following surgery compared to patients with significant preoperative canal paresis (p< 0.05). VOR gain and the presence of covert/overt saccades preoperatively did not influence the PR score (p> 0.05), but a group of patients with very low VOR gain (<0.45) and covert/overt saccades before surgery had lower PR scores after surgery. The differences after 6 months were not significant.


CONCLUSIONS
Patients with more severe vestibular dysfunction before vestibular schwannoma surgery show significantly faster vestibular compensation following surgery, manifested by changes in VOR gain and PR score. The scatter of compensatory saccades (as measured by the PR score) may be a surrogate early marker of clinical recovery, given its relationship to the Dizziness Handicap Inventory.
Otoneurology Unit, Department of Otorhinolaryngology, University Hospital of Salamanca, IBSAL, Salamanca, Spain; Skull Base Unit, Department of Otorhinolaryngology, University Hospital of Salamanca, IBSAL, Salamanca, Spain.
Angel
A
Batuecas-Caletrio
Otolaryngology Unit ORL Gipuzkoa, Clinica Quiron , San Sebastian , Spain.
Jorge
J
Rey-Martinez
Otoneurology Unit, Department of Otorhinolaryngology, University Hospital of Badajoz , Badajoz , Spain.
Gabriel
G
Trinidad-Ruiz
Department of Otorhinolaryngology, Hospital General de Catalunya , Barcelona , Spain.
Eusebi
E
Matiño-Soler
Otoneurology Unit, Department of Otorhinolaryngology, University Hospital of Salamanca, IBSAL, Salamanca, Spain; Skull Base Unit, Department of Otorhinolaryngology, University Hospital of Salamanca, IBSAL, Salamanca, Spain.
Santiago Santa
SS
Cruz-Ruiz
Otoneurology Unit, Department of Otorhinolaryngology, University Hospital of Salamanca, IBSAL, Salamanca, Spain; Skull Base Unit, Department of Otorhinolaryngology, University Hospital of Salamanca, IBSAL, Salamanca, Spain.
Angel
A
Muñoz-Herrera
Otoneurology Unit, Department of Otorhinolaryngology, Clínica Universidad de Navarra, University Hospital and Medical School, University of Navarra , Pamplona , Spain.
Nicolas
N
Perez-Fernandez
PR score; caloric; covert saccade; overt saccade; vestibular compensation; vestibular schwannoma; video head impulse test