Idiosyncratic compensation of the subjective visual horizontal and vertical in 60 patients after unilateral vestibular deafferentation.
OBJECTIVE
To investigate long-term compensation mechanisms of utricular function after translabyrinthine surgery for vestibular schwannoma. Correlations between the subjective visual horizontal (SVH) and subjective visual vertical (SVV) and other parameters of vestibular compensation were studied. The correlation between the SVH and SVV was also investigated to see whether these measurements are compatible for patients.


METHODS
Sixty consecutive patients were investigated 3 months before and 6 months after surgery by means of electronystagmography and SVH and SVV tests. Tumor size was measured using MRI.


RESULTS
The SVH and SVV increased significantly towards the ipsilesional side postoperatively. Preoperative tilt correlated with age. Postoperative tilt correlated weakly with preoperative caloric sensitivity and inversely with tumor size. The correlation between the SVH and SVV was high both before and after surgery (r(s) > 0.74; p < 0.001).


CONCLUSIONS
The long-term compensation of static tilt perception was dependent on age and not on dynamic canal functions. We propose an idiosyncrasy in the SVH and SVV compensation after unilateral vestibular deafferentation, incongruous with the general course of vestibular compensation. The results suggest a probable dependence on non-vestibular information, i.e. proprioception, in facilitating compensation of static vestibular deficits. The similarity between the SVH and SVV measurements confirms that either test can be used clinically for patients with vestibular lesions.
Hafström
Anna
A
Department of Otorhinolaryngology, Head and Neck Surgery, Lund University Hospital, Sweden. anna.hafstrom@onh.lu.se
Fransson
Per-Anders
PA
Karlberg
Mikael
M
Magnusson
Måns
M
D000293:Adolescent; D000328:Adult; D000344:Afferent Pathways / Q000601:surgery; D000367:Age Factors; D000368:Aged; D003051:Cochlea / Q000294:innervation / Q000601:surgery*; D003714:Denervation / Q000009:adverse effects; D004584:Electronystagmography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000601:surgery*; D013506:Otologic Surgical Procedures / Q000379:methods; D004856:Postural Balance / Q000502:physiology*; D012444:Saccule and Utricle / Q000502:physiology*; D016896:Treatment Outcome; D014722:Vestibule, Labyrinth / Q000294:innervation / Q000601:surgery*