Verbal fluency performance in patients with diffuse gliomas located in the supplementary motor area

Gliomas frequently arise in the supplementary motor area (SMA), with accumulating evidence indicating that this clinical population may experience cognitive impairment. However, the majority of existing studies have focused primarily on language disturbances associated with SMA damage, while relatively few have examined other cognitive domains, including executive functioning. The present study is the first to include a comprehensive evaluation of verbal fluency performance in patients with gliomas located in the SMA. It included 19 patients with low-grade gliomas (LGGs) 23 with high-grade gliomas (HGGs) and 44 healthy controls. The participants underwent an extensive assessment of verbal fluency encompassing phonemic, semantic, emotional and switching conditions. The findings demonstrated that patients with gliomas in the SMA generated fewer words than healthy volunteers in phonemic (p < 0.001), emotional ('positive', p = 0.009; 'negative', p < 0.001) and switching (p = 0.03) conditions. Patients with HGGs showed worse phonemic fluency performance than patients with LGGs (p < 0.001). There was a lateralisation effect in the switching condition (p = 0.012): patients with tumours in the left hemisphere performed significantly better than those with tumours in the right hemisphere. Epileptic seizures were associated with worse semantic (p < 0.05) and phonemic (p < 0.05) fluency performance. The tumour volume did not have an effect on performance. Lower scores obtained by patients with gliomas located in SMA contribute to understanding the specific cognitive difficulties of this group. This study has validated the importance of expanding assessment of verbal fluency beyond only phonemic and semantic conditions.