Neuropathological Findings in Spina Bifida Patients

Topic: In this study, we systematically analysed the neuropathological findings of spinal cord and brain in spina bifida patients.

Material and Methods: All cases with ICD 10 diagnoses Q05 and Q76, which were examined in the Institute of Neuropathology of Charité Berlin in the period from 1974 to 2000, were re-evaluated. In total, 92 cases could be included. There were a detailed file analysis and photographic documentation of the microscopic findings, as well as the preparation of additional sections and new stainings to clarify unclear diagnoses.

Results: 63 patients died prenatally, 46 by abortion, 17 due to miscarriage. The 29 liveborn patients mostly died within the first month of life. Balanced gender ratio was found in all age groups (f:m 43%:41%, 14% unknown). Myeloschisis was the most frequently diagnosed neuropathological finding (n = 34, 37%). Histologically the spinal cord represented as a neural plate with an ependymal layer exposed to the surface similar to an open book. 25 patients (27%) had myelomeningocele, and it was striking that the dura mater was thinned or missing in the area of the defect. The diagnosis spina bifida occulta could be confirmed in 8 patients (9%). In addition to spinal cord malformations, 4 patients had cephalocele and 3 had anencephaly. Regarding the level of the lesion, the majority of cases showed involvement of the lumbar and/or sacral spine (n = 74, 80%). 55 patients (60%) had associated hydrocephalus. 25 patients (27%) had Chiari II malformation in addition to spinal cord malformations, including 24 with hydrocephalus. These associated anomalies already occurred in the 19th and hydrocephalus already in the 17th week of pregnancy. Brain abnormalities included heterotopia, migration disorders, hypoplasia of corpus callosum, stenogyria, polymicrogyria, and aqueduct malformations.

Discussion: This study provides new and detailed information on the pathomorphology of spina bifida. We confirm the association of myelomeningocele with brain malformations and are able to assess a strong correlation of myeloschisis with hydrocephalus and Chiari II malformation. It is interesting that hydrocephalus and Chiari II malformation can already be detected in fetuses with neural tube defects at very early weeks of pregnancy, which suggests a parallel development of the malformations rather than a temporal sequence.

Conclusion: Intrauterine occlusion of the neural tube cannot prevent the development of hydrocephalus and Chiari II malformation.

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