الفهرس 
Introduction and RationaleOnly 14 pages are availabe for public view
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Abstract
The term visual vestibular mismatch was first used to describe “motion cue mismatch”. Present studies stated that VVM is a symptom set that arises as a result of pathology in the balance system, to the point where it can no longer act as the “template” against which other sensory information is compared. The result is an inappropriate reliance on environmental visual cues, even under circumstances in which they are orientationally inaccurate (Mallinson A, 2011).
Visual vestibular mismatch is difficult to diagnose because of severe lack of adequate investigation tools, limited ability to measure degree of injury in these patients, and because there is a wide inter-individual variability between degree of injury and intensity of symptoms (Mallinson A, 2011).
This study was conducted to identify visual-vestibular mismatch disorders in dizzy patients, study the vestibular function in patients with visual-vestibular mismatch and evaluate the efficacy of applying a specific vestibular rehabilitation program in dizzy patients with visual- vestibular mismatch disorders.
Study was conducted on 30 patients (18 females and 12 males) suffering from symptoms suggesting a visual-vestibular mismatch according to the inclusion criteria, their mean age was 38.1 +\- 12.3 years. All patients underwent; full neuro-otological history and full neurological examination. Basic audiological evaluation in the form of Pure Tone Audiometry, speech audiometry and Acoustic Immittance.
Vestibular office tests were also performed in the form of; Fukuda stepping test, Functional Reach, Dynamic Visual Acuity (DVA) and MCTSIB test. Vestibular test battery performed are VNG and cVEMP.
Vestibular Rehabilitation program was given to 26 patients only (four patients did not come back for the rehabilitation program) and lasted one month. The program was in the form of; optokinetic training program in the clinic (12 sessions) and home exercise (VOR X1).
Outcome of Vestibular Rehabilitation program was measured by reassessing patients by ; Modified VVM questionnaire ,DVA, Functional Reach test and MCTSIB at the end of the program.
Results showed that VVM patients represent 19.6% among dizzy patients, their most complaint was sense of rotation (43.3%) with associated visually induced symptoms, and 36.6% of patients had complained of nonspecific headache, 20% of patients have been diagnosed of having migranous attacks. The most common visually induced symptom according to modified VVM questionnaire was feeling dizzy when looking to moving fans (80%). 17% of patients were diagnosed as having bilateral mild to moderate high frequency sensorineural hearing loss most propably due to normal hyperacusis. Acoustic Immitance results were normal on all patients.
Regarding vestibular office tests, 96.7% of patients showed abnormal office test results (at least one abnormal test), 96.7% revealed abnormal MCTSIB test results, and 50% had shown abnormality in DVA test results and 26.7% had abnormal functional reach (FR) test results.
On the other hand Vestibular test battery was as follows;3% of patients revealed VNG abnormalities in the form of caloric test abnormality in all patients, and 50% of patients had shown abnormal cVEMP test results with 23.3% of patients revealed bilateral absent waves.
Statistical analysis showed presence of significant different between pre and post-rehabilitation performance of patients on modified VVM questionnaire, DVA test results and MCTSIB test results. On the other hand there was no significant difference regarding Functional Reach test results.
On individual basis, vestibular rehabilitation program seems to be effective for most study group patients; according to the modified VVM questionnaire 70 % of the study group patients had noticed improvement in their VVM symptoms and 6.7% have shown recovery from symptoms, 30% of patients had shown normal results after rehabilitation according to MCTSIB test, 40% of patients improved after rehabilitation according to DVA test, FR test was the less sensitive for rehabilitation outcomes as 3.3% (1patient) had improved.
In conclusion, results of this study gave an idea about VVM patient symptoms, and sensitivity of some office tests especially DVA test for diagnosis and role of vestibular evoked potentials in diagnosis of VVM.
Also this study pointed out to the role of combined vestibular rehabilitation program (home exercise and OPK training) on improvement of VVM symptoms and help patients to manage daily life activities.