A Morphometric Study To Establish Subjective Index of Cerebellar Hypoplasia: A Special Emphasis on Cerebellar Hypoplasia in Trisomy 18
Yukichi Tanaka, Mio Tanaka, Rieko Ijiri, Keisuke Kato, Kiyoshi Gomi, Yasushi Itani, Hiroshi Ishikawa, Sumimasa Yamashita. Kanagawa Children's Medical Center, Yokohama, Kanagawa, Japan
Background: Cerebellar hypoplasia (CH) is one of the common abnormalities reported in trisomy 18 (T18) and has been described also in several disorders other than T18. However, CH is a poorly defined condition and no critical morphometric standard for CH has been established.
Design: Nineteen cytogenetically confirmed T18 cases and 63 age-matched control patients were selected from the autopsy files of Kanagawa Children's Medical Center during the last 22 years. In order to evaluate “congenitally small cerebellum”, we excluded patients whose ages were more than 6 days. After fixation in buffered formalin for more than two weeks, the cerebrum was cut-off at the level of mid-brain and the brain stem was cut-off at the level of inferior collicles under the standard protocol. The weights of the cerebrum, the brain stem, and the cerebellum were measured precisely. The entire brain weight (EBW) was defined as a sum of the weights of the three parts. Several weight ratios, including the cerebellum weight (CLW) to the EBW, the CLW to the body weight (BW), and the cerebrum weight (CRW) to the BW, were calculated.
Results: All 19 patients with T18 were delivered at over 30 weeks of gestation and were small for gestational age. The BW at autopsy ranged from 575g to 2,538g. The EBW after formalin-fixation ranged from 140.7g to 390.9g. The CLW ranged from 3.90g to 15.48g. The CLW/EBW of all T18 patients was below 4% ranging between 2.59% to 3.96%. Only 3 of the 63 age-matched controls showed the CLW/EBW to be below the standard range or within the range of T18 patients (Figure 1). Diagnoses of the 3 patients were thanatophoric dysplasia (2 patients) and Bowen-Conradi Hutterite syndrome (1 patient), both of which are considered to have CH.
The CLW/BW was apparently lower in T18 cases than control patients, and the CRW/BW was slightly higher in T18 cases than in control patients.
Conclusions: Although standard for CH is difficult to define, the CLW/EBW obtained from the T18 patients seems to show a distinct tendency. The graph, shown in this abstract, is useful and may serve as a guideline to define CH, with linear regression +20% of T18 cases and/or linear regression -20% of control cases being the borderline for CH.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 279, Tuesday Afternoon