Diagnosis of Isolated Saccular Dysfunction Using Trapezius cVEMP: A Detailed Vestibular Assessment

<b>Background and Clinical Significance</b>: Vestibular disorders include a wide range of conditions with overlapping symptoms such as dizziness, vertigo and imbalance, often offering diagnostic challenges when distinguishing between peripheral and central etiology. Accurate differentiation is essential for establishing effective treatment plans. In rare or atypical cases with subtle findings, comprehensive diagnostic tools-such as extended vestibular tests and structured questionnaires like the Dizziness Handicap Inventory (DHI)-are critical for diagnosis and monitoring patient recovery. <b>Case Presentation</b>: A 35-year-old female presented with chronic imbalance and motion-induced dizziness persisting for four years. The patient had a surgical history of right-sided functional neck dissection for a parotid tumor. A comprehensive audiovestibular evaluation was performed, including pure tone audiometry (PTA), tympanometry, videonystagmography (VNG), cervical vestibular evoked myogenic potentials (cVEMP), ocular vestibular evoked myogenic potentials (oVEMP), video head impulse testing (vHIT), computerized dynamic posturography (CDP), and magnetic resonance imaging (MRI). The Dizziness Handicap Index (DHI) was administered at baseline and post-treatment to monitor subjective symptom changes. Objective testing revealed marked right-left amplitude asymmetry on cVEMP, which were recorded from the trapezius muscle due to prior neck dissection surgery, indicating isolated right-sided saccular hypofunction. Following targeted vestibular rehabilitation and pharmacologic treatment, the 3-month reassessment demonstrated resolution of symptoms and a reduction in DHI scores from 24 to 6. <b>Conclusions</b>: Comprehensive vestibular testing, performed in a single diagnostic session, enabled the accurate identification of isolated right-sided saccular hypofunction in this complex post-surgical case. Combining cVEMP, CDP, and DHI assessment provided a complete functional profile, guided targeted rehabilitation, and allowed objective monitoring of recovery.