Plessen Kerstin J, Wentzel-Larsen Tore, Hugdahl Kenneth, Feineigle Patricia, Klein Joel, Staib Lawrence H, Leckman James F, Bansal Ravi, Peterson Bradley S
New York State Psychiatric Institute, 1051 Riverside Dr., Unit 74, New York, NY 10032, USA.
Am J Psychiatry. 2004 Nov;161(11):2028-37. doi: 10.1176/appi.ajp.161.11.2028.
The corpus callosum is the major commissure connecting the cerebral hemispheres. Prior evidence suggests involvement of the corpus callosum in the pathophysiology of Tourette's disorder. The authors assessed corpus callosum size and anatomical connectivity across the cerebral hemispheres in persons with Tourette's disorder.
The size of the corpus callosum was determined on the true midsagittal slices of reformatted, high-resolution magnetic resonance imaging scans and compared across groups in a cross-sectional case-control study of 158 subjects with Tourette's disorder and 121 healthy comparison subjects, ages 5-65 years.
In the context of increasing midsagittal corpus callosum area from childhood to age 30 years, children with Tourette's disorder had smaller overall corpus callosum size, whereas adults with Tourette's disorder on average had larger corpus callosum size, yielding a prominent interaction of diagnosis with age. Corpus callosum size correlated positively with tic severity. Corpus callosum size also correlated inversely with dorsolateral prefrontal and orbitofrontal cortical volumes in both the subjects with Tourette's disorder and the comparison subjects, but the magnitudes of the correlations were significantly greater in the group with Tourette's disorder. The effects of medication and comorbid illnesses had no appreciable influence on the findings.
Given prior evidence for the role of prefrontal hypertrophy in the regulation of tic symptoms, the current findings suggest that neural plasticity may contribute to smaller corpus callosum size in persons with Tourette's disorder, which thereby limits neuronal trafficking across the cerebral hemispheres and reduces input to cortical inhibitory interneurons within the prefrontal cortices. Reduced inhibitory input may in turn enhance prefrontal excitation, thus helping to control tics and possibly contributing to the cortical hyperexcitatibility reported previously in patients with Tourette's disorder.
胼胝体是连接大脑半球的主要连合纤维。先前的证据表明胼胝体参与了抽动秽语综合征的病理生理过程。作者评估了抽动秽语综合征患者的胼胝体大小以及大脑半球间的解剖连接性。
在一项横断面病例对照研究中，对158例年龄在5至65岁的抽动秽语综合征患者和121名健康对照者进行了重新格式化的高分辨率磁共振成像扫描，在真正的正中矢状面上确定胼胝体的大小，并在两组之间进行比较。
从儿童期到30岁，正中矢状面胼胝体面积逐渐增加，抽动秽语综合征儿童的胼胝体总体尺寸较小，而抽动秽语综合征成人的胼胝体平均尺寸较大，诊断与年龄之间存在显著的交互作用。胼胝体大小与抽动严重程度呈正相关。在抽动秽语综合征患者和对照者中，胼胝体大小也与背外侧前额叶和眶额叶皮质体积呈负相关，但在抽动秽语综合征组中相关性的强度明显更大。药物治疗和共病对研究结果没有明显影响。
鉴于先前有证据表明前额叶肥大在抽动症状调节中起作用，目前的研究结果表明，神经可塑性可能导致抽动秽语综合征患者的胼胝体尺寸较小，从而限制了大脑半球间的神经元传输，并减少了前额叶皮质内皮质抑制性中间神经元的输入。抑制性输入的减少可能反过来增强前额叶的兴奋性，从而有助于控制抽动，并可能导致先前报道的抽动秽语综合征患者的皮质过度兴奋性。
