Narrative Review on Vestibular Complaints After Cochlear Implantation in Adults: Defining Heterogeneous Common Symptoms.

Cochlear implantation (CI) effectively restores hearing across the whole lifespan but may be followed by vestibular complaints, especially in adult recipients. The aim of this narrative review is to provide a comprehensive characterization of vestibular complaints after CI in adults, collecting clinical and instrumental data, as well as discussing the risk factors for their development. From data reported in the literature, we defined five recurring clinical presentations of postoperative vestibular disturbances (phenotypes): acute postoperative vestibular syndrome, benign paroxysmal positional vertigo (BPPV), delayed Ménière-like vertigo attributable to secondary endolymphatic hydrops, chronic postoperative disequilibrium, and stimulation-linked vertigo. According to the different pathogeneses underlying each presentation, the management of postoperative vestibular complaints should be phenotype-guided, including short-course vestibular suppressants and early mobilisation for acute presentations; canalith repositioning for BPPV; empiric therapy for hydropic-like episodes; and vestibular rehabilitation when imbalance is persistent, programming changes for stimulation-linked symptoms. Alongside this phenotype-driven approach, subjective symptoms are common across cohorts but are usually transient and persistent disability is uncommon. Furthermore, instrumental data across the studies indicate that objective abnormalities cluster in otolith and low-frequency canal measures: Cervical, ocular VEMP, and caloric responses are more often impaired than high-frequency canal function on vHIT, confirming histopathological studies showing preferential saccular involvement during the insertion of the electrode array. The risk of postoperative vestibular complaints not only appears to be modulated more by patient-related factors, especially pre-existing vestibular loss, but also by the aetiology of deafness, or age, rather than by device characteristics; atraumatic surgical approaches may further reduce this risk. This review emphasizes that future research on vestibular complaints after CI should adopt standardized phenotypes when evaluating symptoms, objective vestibular function, falls, and quality of life. Additionally, it should correlate these outcomes with hypothetical risk factors and detailed surgical reports.