Abstracts

Rationale: The central tegmental tract is an important efferent pathway of the extrapyramidal tract leading from the red nucleus to the olivary nucleus. Recently, central tegmental tract lesions have been reported in various neurological disorders; however, the clinical significance of central tegmental tract lesions remains obscure. We report a case of West syndrome presenting with holoprosencephaly, in which MRI revealed bilateral central tegmental tract lesions.Methods: The subject was examined using brain MRI,EEG, routine laboratory examination and karyotyping during the course.Results: The subject, a 16-month-old girl who was born at 41 weeks of gestation through normal vaginal delivery developed dyspnea shortly after birth and she was diagnosed as having meconium aspiration syndrome. Although she was treated using mechanical ventilation, there was no apparent hypoxia. At 3 months of age, the patient developed flexion spasms with series formation, and her EEG revealed hypsarrhythmia. Thus, she was diagnosed as having West syndrome and at 5 months of age was referred to our hospital for treatment. On admission, the patient’s facial appearance was compatible with holoprosencephaly. Neurological examination revealed marked hypotonia. The patient had chromosomal aberrations of 18 partial monosomy and 21 partial monosomy. Her EEG revealed hypsarrhythmia and her ABR showed poor discrimination of waves, suggesting a brain stem dysfunction. MRI revealed a partial fusion of the cerebrum and a high intensity lesion of the bilateral central tegmental tract on T2- weighted and diffusion-weighted MR images. At 1 year of age, the central tegmental tract lesion had disappeared on diffusion-weighted images; however, it was still present on T2-weighted image. In addition, the patient was exceedingly hypotonic and her seizures were not controlled. Conclusions: This patient need mechanical ventilation shortly after birth due to meconium aspiration syndrome; however, she had no apparent episodes of hypoxic encephalopathy. The presence of a central tegmental tract lesion in this case may reflect a pathological condition of West syndrome or holoprosencephaly. Hayashi et al. reported that central tegmental lesions were present in 10% of 120 autopsies of patients with severe developmental disabilities. However, there have been no previous reports of central tegmental lesions in cases of holoprosencephaly. Central tegmental tract lesions have rarely been reported with the use of MRI in patients with neonatal hypoxic encephalopathy, a leukoencephalopathy with vanishing white matter and several congenital metabolic disorders. Although the exact pathophysiological mechanism of central tegmental tract lesions was remains obscure, it is speculated that disturbances in the connection to basal ganglia from the upper midbrain may be the cause of the lesions, which may in turn contribute to the etiology of West syndrome. Further study is necessary to elucidate the clinical and pathological mechanisms of central tegmental tract lesions.