Interpeduncular angle: A new parameter for assessing intracranial hypotension in fetuses with spinal dysraphism

Abstract

Objective: To investigate the role of the interpeduncular angle (IPA) as a new indicator of intracranial hypotension in fetuses with open spinal dysraphism (SD).Methods: Two groups of fetuses undergoing magnetic resonance imaging (MRI) examination were identified. The study group included fetuses with open SD (n ¼ 21), while the control group included fetuses with a normal brain and spine (n ¼ 43). Two observers retrospectively evaluated axial T2-weighted images of the brain and the IPA was identified and measured. Other features of the Chiari II malformation were also evaluated in the study group and correlated with the IPA. Results:The average value (�SD) of the IPA for the study and control groups was 9.8°� 18.5°and 60.2°� 5.9°, respectively. The intergroup analysis of the IPA measurements revealed a statistically significant difference between the groups (p < 0.005). Brainstem slumping or cerebellar tonsillar descent, collapse of the fourth ventricle, and ventriculomegaly also had a significant correlation with a lower IPA (p ¼ 0.001). Conclusion:Measuring the IPA may be a useful technique for assessing the degree of intracranial hypotension in fetuses with open SD. This technique can also detect less severe cases of prenatal intracranial hypotension, even before cerebellar tonsillar descent. The lower IPA in fetuses with open SD further supports the theory that cerebrospinal fluid leakage, and not traction, is the underlying cause of Chiari II malformation. Key pointsWhat's already known about this topic? � Open spinal dysraphism (SD) in the fetus is almost always associated with Chiari II malformation.� In these cases, the Chiari II malformation has been ascribed to the chronic leakage of cerebrospinal fluid through the spinal defect.� The interpeduncular angle (IPA) is significantly lower in adults with intracranial hypotension than individuals with normal intracranial pressure. What does this study add?� The IPA is significantly reduced in fetuses with open SD compared to controls.

Open intrauterine repair of spina bifida aperta: Historical aspects, current availability, and clinical outcomes from the Latin American Spina Bifida Consortium

“…This is especially true in low‐income and developing countries such as those found in Latin America. One of the main goals of IRSBA is the effective closure of the spinal defect to stop leakage of CSF in order to restore the normal intracranial pressure, reduce the deleterious effect of obstructive ventriculomegaly on the fetal brain, and reduce the rate of postnatal rate of CSF diversion 9,34,35 . The lower rate of neonatal reoperation of the spinal defect would also hint at the open technique's superior efficacy when compared to the fetoscopic approach.…”

“…± 3.2 weeks' gestation (range,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Overall, severe premature delivery occurring at <30 weeks was recorded in 36 of these cases (11.5%), delivery between 30 and 34 weeks in 118 cases (37.6%), and delivery at ≥35 weeks in 160 cases (51.0%).…”

Getting earlier, smaller and regenerative: The next 10 years of in utero spina bifida repair

“…Hind brain herniation remains one of the eligibility criteria for consideration of pre‐natal surgery. However, as pointed out by Sepulveda et al 10 . descent of the cerebellar tonsils is only one component of the wider Chiari II complex, it is the end point of a process that likely began several weeks earlier 11 .…”

“…descent of the cerebellar tonsils is only one component of the wider Chiari II complex, it is the end point of a process that likely began several weeks earlier 11 . They suggest that the interpeduncular angle (IPA), the angle formed between the cerebral peduncles is reduced as a consequence of fetal intracranial hypotension, and that this finding might provide an earlier marker of the evolution of the Chiari II malformation 10 …”

“…11 They suggest that the interpeduncular angle (IPA), the angle formed between the cerebral peduncles is reduced as a consequence of fetal intracranial hypotension, and that this finding might provide an earlier marker of the evolution of the Chiari II malformation. 10 Currently there is limited data on long term neurocognitive outcome for prenatally repaired cases of spina bifida. It is anticipated that by reducing the impact of hydrocephalus, and its treatment associated morbidity, the effect will be favorable.…”