Planum Temporale and Heschl Gyrus Volume Reduction in Schizophrenia

Background—Magnetic resonance imaging studies in schizophrenia have revealed abnormalities in temporal lobe structures, including the superior temporal gyrus. More specifically, abnormalities have been reported in the posterior superior temporal gyrus, which includes the Heschl gyrus and planum temporale, the latter being an important substrate for language. However, the specificity of the Heschl gyrus and planum temporale structural abnormalities to schizophrenia vs affective psychosis, and the possible confounding roles of chronic morbidity and neuroleptic treatment, remain unclear. Methods—Magnetic resonance images were acquired using a 1.5-T magnet from 20 first-episode (at first hospitalization) patients with schizophrenia (mean age, 27.3 years), 24 first-episode patients with manic psychosis (mean age, 23.6 years), and 22 controls (mean age, 24.5 years). There was no significant difference in age for the 3 groups. All brain images were uniformly aligned and then reformatted and resampled to yield isotropic voxels. Results—Gray matter volume of the left planum temporale differed among the 3 groups. The patients with schizophrenia had significantly smaller left planum temporale volume than controls (20.0%) and patients with mania (20.0%). Heschl gyrus gray matter volume (left and right) was also reduced in patients with schizophrenia compared with controls (13.1%) and patients with bipolar mania (16.8%). Conclusions—Compared with controls and patients with bipolar manic psychosis, patients with first-episode schizophrenia showed left planum temporale gray matter volume reduction and bilateral Heschl gyrus gray matter volume reduction. These findings are similar to those reported in patients with chronic schizophrenia and suggest that such abnormalities are present at first episode and are specific to schizophrenia. Reprints: Martha E. Shenton, PhD, or Robert W. McCarley, MD, Department of Psychiatry (116A), VAMC-Brockton, Harvard Medical School, 940 Belmont St, Brockton, MA 02301 ([email protected]; [email protected]). Dr Hirayasu is now with the Department of Neuropsychiatry, Kyorin University School of Medicine, Tokyo, Japan. Dr Kwon is now with the Department of Psychiatry, Seoul National University Medical College, Seoul, Korea. NIH Public Access Author Manuscript Arch Gen Psychiatry. Author manuscript; available in PMC 2010 April 6. Published in final edited form as: Arch Gen Psychiatry. 2000 July ; 57(7): 692–699. N IH PA Athor M anscript N IH PA Athor M anscript N IH PA Athor M anscript Structural brain abnormalities in schizophrenia have been extensively investigated using magnetic resonance imaging (MRI).1–5 Several studies have reported abnormalities in portions of the superior temporal gyrus (STG) in patients diagnosed as having schizophrenia,1–3 including planum temporale (PT) and Heschl gyrus (HG) (primary auditory cortex).6–14 The impetus for much of this work is based on the role that the left (dominant) hemisphere PT plays in language processing15–17 and the role that the HG plays in the initial processing of auditory information.1–3 DeLisi et al10 measured length of the sylvian fissure and reported asymmetry differences in patients with first-episode schizophrenia compared with controls. Reduced cortical PT volume was reported in a postmortem study in schizophrenia compared with controls,18 and we reported reduced left PT gray matter volume and a reversal of PT asymmetry in patients diagnosed as having chronic schizophrenia.6 Other investigators7,8 measuring PT area in schizophrenia also reported a reversal of the left larger than right PT asymmetry found in controls. However, several investigators9–13 have not reported abnormalities of PT asymmetry in schizophrenia. Of particular note, Kleinschmidt and colleagues11 reported no differences in PT area between first-episode patients with schizophrenia and controls. This lack of consistency in results is likely due to variations in the definition of PT, as discussed by Barta and coworkers.19 Fewer studies of HG have been conducted, although asymmetrical length has been reported in HG (left greater than right) in healthy patients in a postmortem study by Musiek and Reeves. 20 Only one group21 using MRI has reported a left HG volume greater than the right in controls and patients with paranoid schizophrenia. However, other investigators7,12,14 have reported no asymmetry between left and right HG and no difference in asymmetry between patients with schizophrenia and controls. To our knowledge, no studies have evaluated gray matter volume of HG and PT concurrently in patients with schizophrenia and those with affective psychosis at the time of first hospitalization. It remains uncertain whether the psychosis associated with affective disorder and schizophrenia represents manifestations of different disorders or variants of a single disorder with somewhat different expressions.22 The MRI studies that evaluate both patient groups may assist in answering this question. We previously reported23 that first-episode patients with schizophrenia showed smaller gray matter volume in a posterior segment of STG than firstepisode patients with affective disorder and controls. The MRI evidence also supporting pathophysiological differences comes from Pearlson and colleagues,24 who reported STG and medial temporal lobe abnormalities in patients with schizophrenia but not in patients with bipolar disorder. The posterior STG segment, reported previously by us, included only a fraction of the whole PT, and HG was not evaluated. In the present study, gray matter volume of PT and HG was measured to determine whether PT and HG abnormalities are present at first episode and specific to schizophrenia as contrasted with first-episode manic psychosis.