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Radiological Studies on Hippocampal Development: Morphological Variants and their Relationship to Epilepsy
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för onkologi, radiologi och klinisk immunologi, Enheten för radiologi.
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

During fetal development, the hippocampal structures are folded forming the hippocampal sulcus which penetrates into the temporal lobe and then the entity rotates.  During this process, the hippocampal sulcus will be closed and the inverted hippocampus takes a rounded form. After complete inversion, the hippocampus has an oval form in a plane perpendicular to its long axis. If this process has not been completed the hippocampus remains the rounded form. That condition is called incomplete hippocampal inversion (IHI).

The aims of this study was to evaluate the frequency of IHI in non-epileptic and epileptic children and adults and to explore the development of the hippocampal region by studying premature neonates and fetuses.

Magnetic resonance (MR) images of 201 epilepsy patients and 150 non-epileptic subjects were evaluated without knowing clinical data. IHI was found in 19 % in seizure free controls (20 left-sided and 8 bilateral). 30% of the 201 epilepsy patients had IHI (40 left-sided, 4 right-sided, 16 bilateral). The difference was statistically significant (p<0.02). 25% of the temporal lobe epilepsy patients had IHI. The frequency was not significantly higher than in controls. There is no causality between temporal lobe epilepsy and IHI. 44% of the Rolandic epilepsy patients and 57% of the cryptogenic generalized epilepsy patients had IHI. IHI can be a sign of possible disturbed cerebral development in other parts of the brain.

Cranial ultrasound examinations of 160 premature children were analyzed. The age at examination was 23-24 GW in 24 children, 25-28 GW in 72 children, and 29-36 GW in 64 children. IHI was found in 50%, 25% and 14%, respectively. The frequency difference between the children < 25 GW and > 25 GW was statistically significant (p< 0.001). From 25 GW onwards, the frequency and laterality of IHI is similar to that in the adult population.

MRIs of 63 fetuses without intracranial pathology were reviewed independently by two radiologists. Three MRIs were performed post mortem at gestation week (GW) 17-18 and 60 in utero at GW 19-35. The hippocampal sulcus was open, bi- or unilaterally, in 35 fetuses at GW 17-32. The oldest of them was at GW 32.  The sulcus was closed at GW 21 at the earliest, unilaterally, and always from GW 33 onwards bilaterally. In 26/63 fetuses (41%), the hippocampal development was asymmetric and in 23 fetuses, the right side had developed faster.

Ort, förlag, år, upplaga, sidor
Uppsala: Institutionen för onkologi, radiologi och klinisk immunologi, Enheten för radiologi , 2010. , s. 50
Nyckelord [en]
MRI, Brain development, Hippocampus, Epilepsy
Nationell ämneskategori
Radiologi och bildbehandling
Forskningsämne
Radiologi
Identifikatorer
URN: urn:nbn:se:uu:diva-131996ISBN: 978-91-506-2156-3 (tryckt)OAI: oai:DiVA.org:uu-131996DiVA, id: diva2:356455
Disputation
2010-11-18, Grönwallsalen, Akademiska sjukhuset, ingång 70, Uppsala, 09:15 (Svenska)
Opponent
Handledare
Tillgänglig från: 2010-10-27 Skapad: 2010-10-12 Senast uppdaterad: 2010-10-27Bibliografiskt granskad
Delarbeten
1. Incomplete inversion of the hippocampus: a common developmental anomaly
Öppna denna publikation i ny flik eller fönster >>Incomplete inversion of the hippocampus: a common developmental anomaly
Visa övriga...
2008 (Engelska)Ingår i: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 18, nr 1, s. 138-142Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Incomplete inversion of the hippocampus, an imperfect fetal development, has been described in patients with epilepsy or severe midline malformations. We studied this condition in a nonepileptic population without obvious developmental anomalies. We analyzed the coronal MR images of 50 women and 50 men who did not have epilepsy. Twenty of them were healthy volunteers and 80 were patients without obvious intracranial developmental anomalies, intracranial masses, hydrocephalus or any condition affecting the temporal lobes. If the entire hippocampus (the head could not be evaluated) were affected, the incomplete inversion was classified as total, otherwise as partial. Incomplete inversion of the hippocampus was found in 19/100 subjects (9 women, 10 men). It was unilateral, always on the left side, in 13 subjects (4 women, 9 men): 9 were of the total type, 4 were partial. It was bilateral in six subjects (five women, one man): four subjects had total types bilaterally, two had a combination of total and partial types. The collateral sulcus was vertically oriented in all subjects with a deviating hippocampal shape. We conclude that incomplete inversion of the hippocampus is not an unusual morphologic variety in a nonepileptic population without other obvious intracranial developmental anomalies.

Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
urn:nbn:se:uu:diva-15863 (URN)10.1007/s00330-007-0735-6 (DOI)000252593500016 ()17828540 (PubMedID)
Tillgänglig från: 2008-06-18 Skapad: 2008-06-18 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
2. Incomplete hippocampal inversion-is there a relation to epilepsy?
Öppna denna publikation i ny flik eller fönster >>Incomplete hippocampal inversion-is there a relation to epilepsy?
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2009 (Engelska)Ingår i: European Radiology, ISSN 0938-7994, E-ISSN 1432-1084, Vol. 19, nr 10, s. 2544-2550Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Incomplete hippocampal inversion (IHI) has been described in patients with epilepsy or severe midline malformations but also in nonepileptic subjects without obvious developmental anomalies. We studied the frequency of IHI in different epilepsy syndromes to evaluate their relationship. Three hundred patients were drawn from the regional epilepsy register. Of these, 99 were excluded because of a disease or condition affecting the temporal lobes or incomplete data. Controls were 150 subjects without epilepsy or obvious intracranial developmental anomalies. The coronal MR images were analysed without knowledge of the clinical data. Among epilepsy patients, 30% had IHI (40 left-sided, 4 right-sided, 16 bilateral). Of controls, 18% had IHI (20 left-sided, 8 bilateral). The difference was statistically significant (P < 0.05). Of temporal lobe epilepsy (TLE) patients, 25% had IHI, which was not a significantly higher frequency than in controls (P = 0.34). There was no correlation between EEG and IHI laterality. A total of 44% of Rolandic epilepsy patients and 57% of cryptogenic generalised epilepsy patients had IHI. The IHI frequency was very high in some epileptic syndromes, but not significantly higher in TLE compared to controls. No causality between TLE and IHI could be found. IHI can be a sign of disturbed cerebral development affecting other parts of the brain, maybe leading to epilepsy.

Nyckelord
Hippocampus, Developmental brain anomalies, MRI, Epilepsy
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
urn:nbn:se:uu:diva-105372 (URN)10.1007/s00330-009-1438-y (DOI)000270268700029 ()19440714 (PubMedID)
Tillgänglig från: 2009-06-03 Skapad: 2009-06-03 Senast uppdaterad: 2017-12-13Bibliografiskt granskad
3. Hippocampal development at gestation weeks 23 to 36: An ultrasound study on preterm neonates
Öppna denna publikation i ny flik eller fönster >>Hippocampal development at gestation weeks 23 to 36: An ultrasound study on preterm neonates
2010 (Engelska)Ingår i: Neuroradiology, ISSN 0028-3940, E-ISSN 1432-1920, Vol. 52, nr 6, s. 489-494Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

INTRODUCTION: During fetal development, the hippocampal structures fold around the hippocampal sulcus into the temporal lobe. According to the literature, this inversion should be completed at gestation week (GW) 21. Thereafter, the hippocampal shape should resemble the adult shape. However, incomplete hippocampal inversion (IHI) is found in 19% of the common population. The aim of this study was to study fetal hippocampal development by examining neonates born preterm. METHODS: We analyzed cranial ultrasound examinations, performed as a part of the routine assessment of all preterm infants, over a 3-year period and excluded the infants with brain pathology. The final material consisted of 158 children born <35 GW. A rounded form (the ratio between the horizontal and vertical diameters of the hippocampal body <25 GW and >/=25 GW was statistically highly significant (p < 0.001). The frequency of bilateral IHI was highest in the youngest age group. In the other groups, the left-sided IHI was the most common. CONCLUSION: In about 50% of the neonates, hippocampal inversion is not completed up to GW 24; but from 25 GW onwards, the frequency and laterality of IHI is similar to that in the adult population.

Nyckelord
Fetal development, Ultrasonography, Hippocampus, Premature infants, Gestational age, Malrotation
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
urn:nbn:se:uu:diva-124857 (URN)10.1007/s00234-010-0673-x (DOI)000277790000003 ()20352419 (PubMedID)
Tillgänglig från: 2010-05-06 Skapad: 2010-05-06 Senast uppdaterad: 2017-12-12Bibliografiskt granskad
4. Asymmetric Development of the Hippocampal Region Is Common: A Fetal MR Imaging Study
Öppna denna publikation i ny flik eller fönster >>Asymmetric Development of the Hippocampal Region Is Common: A Fetal MR Imaging Study
2012 (Engelska)Ingår i: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959X, Vol. 33, nr 3, s. 513-518Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

BACKGROUND AND PURPOSE: Hippocampal development is poorly understood. This study evaluated the normal development of the hippocampal region during the fetal period by using MR imaging.

MATERIALS AND METHODS: MR images of 63 fetuses without intracranial pathology were reviewed independently by 2 radiologists with no knowledge of the fetal GA. Three MR images were performed postmortem and 60 in vivo. The progress of hippocampal inversion was analyzed in coronal sections, and the left and right sides of the hippocampal region were compared in every case.

RESULTS: The fetuses in the postmortem examinations were at GWs 17-18 and in the in vivo examinations, at GWs 19-36. The hippocampal sulcus was open, bi- or unilaterally, in 39 fetuses. The oldest was at GW 32. The sulcus was closed at GW 21 at the earliest, unilaterally. In 26/63 fetuses (41%), the deepening or closure of the hippocampal sulcus or hippocampal inversion was asymmetric; in 23 fetuses, the right side developed faster. A shallow collateral sulcus was found earliest at GW 17. A deep collateral sulcus was visible earliest at GW 26 unilaterally, but in all fetuses from GW 31 onward, it was seen bilaterally. The orientation of the collateral sulcus was not related to the GA.

CONCLUSIONS: There are wide individual temporal variations in the development and the inversion process of the hippocampal sulcus as well as in the formation of the collateral sulcus. Asymmetric development is common, and in most of the asymmetric cases, the right hippocampus develops faster.

Nationell ämneskategori
Radiologi och bildbehandling
Forskningsämne
Radiologi
Identifikatorer
urn:nbn:se:uu:diva-131994 (URN)10.3174/ajnr.A2814 (DOI)000301870300024 ()
Tillgänglig från: 2010-10-12 Skapad: 2010-10-12 Senast uppdaterad: 2017-12-12Bibliografiskt granskad

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