Phonemic and semantic fluencies in traumatic brain injury patients with focal frontal lesions

The purpose of this study was to investigate the effect of focal frontal le sions, identified by magnetic resonance imaging (MRI), in a group of trauma tic brain injured (TBI) patients, in order to clarify the sensitivity of ph onemic and semantic fluency tasks as tests of frontal lobe functioning. Thi rteen TBI patients were included and matched with a normal control group of 26 subjects. Frontal lobe patients produced significantly fewer words than the control group in the phonemic fluency condition. Semantic performance correlated with lesion size, but phonemic performance did not, corroboratin g the idea that the two have different brain-based substrates. Although, as a group effect, frontal lesions impaired fluency, not all patients were im paired, even in the presence of large bilateral frontal lesions.