Ziel/Aim We have shown that asymmetric hearing loss has a significant impact on glucose metabolism of the auditory pathway ([1]). This effect was weaker in patients with longer disease duration, possibly indicating reorganization at the cortical level. Here, we evaluate the association between metabolic activity in the primary auditory cortex (PAC) before cochlear implantation (CI) and speech recognition with CI to explore the possible value of F-18-FDG PET as a predictor of post-operative outcome.
Methodik/Methods We enrolled 7 asymmetrically hearing-impaired patients who underwent CI after F-18-FDG PET examination. Average normalized F-18-FDG uptake of 25 % of voxels with highest uptake was calculated for the PAC employing probabilistic atlas and cerebellar cortex as reference. Regional changes of normalized F-18-FDG uptake of the PAC were assessed by an asymmetry index (AI; difference of ipsi- and contralateral side [referring to the deaf ear] divided by the mean). Correlations were established between speech recognition with CI (OLSA at 6 months after CI) and AI of the PAC, duration of deafness and age.
Ergebnisse/Results The AI of the PAC (before CI) was significantly associated with speech recognition with CI (r = 0.83, p = 0.02). For patients with an AI > 3.5 % (e.g., mean ±SD absolute AI in controls = 2.5 ± 0.6 %), speech recognition and numerical understanding with CI were ≥50 % and ≥70 %, respectively, indicating a good to excellent CI outcome. Duration of deafness or age was not significantly associated with speech recognition with CI (r=-0.72, p = 0.06 and r = 0.44, p = 0.31, respectively).
Schlussfolgerungen/Conclusions Asymmetry of neural activity of the PAC, assessed by F-18-FDG PET, allows for a pre-operative prediction of speech recognition after CI. Considering the stronger association between the AI of the PAC and speech recognition compared to age or duration of deafness (current predictors of CI outcome), F-18-FDG PET may be a valuable addition to the pre-operative assessment of CI candidates. Further studies in larger cohorts are needed.
