Prevalence of Hippocampal Malrotation in a Population without Seizures: Fig 1.

Gamss, Rebecca; Slasky, Shira E.; Bello, Jacqueline A.; Miller, Todd S.; Shinnar, Shlomo

doi:10.3174/ajnr.a1657

Cited by 70 publications

(86 citation statements)

References 2 publications

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“…Follow-up imaging of these children should help determine whether IHI predisposes them to temporal lobe epilepsy and mesial temporal sclerosis. Therefore, imaging findings of IHI may raise suspicion of an underlying potential for the presence of a seizure disorder (7). All patients with hippocampal atrophy were excluded from our study since their hippocampi were collapsed and they may not have preserved the original form.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of hippocampal infolding angle and incomplete hippocampal inversion in pediatric patients with epilepsy and febrile seizures

Acay¹,

Köken²,

Ünlü³

et al. 2017

Diagn Interv Radiol

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Section: Discussionmentioning

confidence: 99%

Evaluation of hippocampal infolding angle and incomplete hippocampal inversion in pediatric patients with epilepsy and febrile seizures

Acay¹,

Köken²,

Ünlü³

et al. 2017

Diagn Interv Radiol

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“…1,5,12,31 The exact definition of HIMAL has been debated, and the inclusion of multiple, potentially related findings has not been accepted by all researchers. 1,12 The association between HIMAL and febrile status has also recently been questioned. 9 Even the term "hippocampal malrotation" has been debated as an appropriate term with some authors suggesting that "incomplete hippocampal inversion" is a more embryologically appropriate description.…”

Section: Developmental Factorsmentioning

confidence: 99%

“…1,12 Some studies have also demonstrated an increased prevalence of this morphology in children with febrile status epilepticus, suggesting that there may be an etiological link, 31 although this has recently been questioned. 9 This morphology has been variously described depending on the defining criteria chosen in each study (e.g., "hippocampal malrotation," or HIMAL, "incomplete hippocampal inversion," or "hippocampal morphologic modification").…”

mentioning

confidence: 99%

“…9 This morphology has been variously described depending on the defining criteria chosen in each study (e.g., "hippocampal malrotation," or HIMAL, "incomplete hippocampal inversion," or "hippocampal morphologic modification"). 1,2,4,5,12,20 Imaging criteria for HIMAL have varied but have typically included asymmetrical medialized rounded hippocampal shape, vertical collateral sulcus, internal architecture blurring, and ipsilateral low fornix position. 1,2,12 Prior studies have reported a wide variation in HIMAL prevalence, from 1%-19% in healthy controls to 6%-30% in patients with epilepsy (mostly adult studies), 1,2,5,31 with the highest prevalence in significant anomalies of brain development (64%-85%).…”

mentioning

confidence: 99%

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Mesial temporal lobe morphology in intractable pediatric epilepsy: so-called hippocampal malrotation, associated findings, and relevance to presurgical assessment

Leach¹,

Awwad²,

Greiner

et al. 2016

PED

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OBJECTIVE Diagnostic criteria for hippocampal malrotation (HIMAL) on brain MRI typically include a rounded hippocampus, vertical collateral sulcus, and architectural blurring. Relationship to epileptogenesis remains speculative, and usefulness for surgical guidance is unknown. The study was performed to determine the prevalence of hippocampal rotational anomalies in a cohort of pediatric patients with intractable epilepsy undergoing evaluation for surgery and to determine the significance of this finding in the context of surgical planning. METHODS Forty-eight surgically treated children with intractable epilepsy were compared with matched healthy subjects; reviewers were blinded to surgical side. Each temporal lobe was evaluated for rounded hippocampus, blurring, vertical collateral sulcus, wide choroidal fissure, enlarged temporal horn, low fornix, hippocampal signal, and findings of hippocampal sclerosis. A mesial temporal lobe (MTL) score was calculated by summing the number of features, and the collateral sulcus angle (CSA) was measured in each temporal lobe. Surgical side, pathological diagnosis, and imaging findings elsewhere in the brain were tabulated. Presence of HIMAL, associated imaging features, and MTL score were compared between sides, between epilepsy and control groups, in relationship to side of surgery, and in relationship to postoperative outcome. RESULTS Only 3 epilepsy patients (6.2%) and no controls exhibited all 3 features of HIMAL (p = 0.12). Eight of 48 (16.7%) epilepsy versus 2 of 48 (4.6%) control subjects had both a rounded hippocampus and vertical collateral sulcus (suggesting HIMAL) (p = 0.045). In control and epilepsy subjects, most findings were more prevalent on the left, and the left CSA was more vertical (p < 0.0001). Epilepsy subjects had higher MTL scores (z = −2.95, p = 0.002) and more acute CSAs (p = 0.04) than controls. Only lateralizing raw MTL score had a significant association with surgical side (p = 0.03, OR 7.33); however, this was not significant when hippocampal sclerosis cases were excluded. HIMAL findings were more prevalent and MTL scores were higher in patients with resections involving the temporal lobes. On group analysis, HIMAL findings did not predict eventual surgical side and did not predict outcome, although the numbers are small. In 4 patients the abnormally rotated hippocampus was resected and showed hippocampal sclerosis and/or dysplastic changes on histopathology. All of these patients had a good outcome after surgery. CONCLUSIONS While increased in prevalence in children with intractable epilepsy, imaging findings of HIMAL did not have preoperative lateralizing utility in this group. Findings of HIMAL (including round hippocampus, architectural blurring, and vertical collateral sulcus) did not predict outcome after surgery, although the small number of patients with these findings limits evaluation. In the small number of patients in which the malrotated hippocampus was removed, outcome was good. Further research is needed to continue to define this association in children with intractable epilepsy, focusing on a temporal lobe cohort.

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“…Bernasconi and colleagues, observed hippocampal malrotation in 49% of 76 patients with malformations of cortical development, and 43% of 30 patients with temporal lobe epilepsy and 10% of 50 healthy control patients 3 . In 497 patients without epilepsy who underwent MRI, no patients had all diagnostic features of hippocampal malrotation but six patients had two or more features 6 . In this issue of the journal, Andrade and colleagues reported hippocampal malrotation using 3 Tesla MRI in 9 of 14 adults with 22q11.2 deletion syndrome, a population with a 7 fold increased risk of developing epilepsy compared to the general population 7 .…”

mentioning

confidence: 99%

Hippocampal Malrotation and Temporal Lobe Epilepsy: What is the Relationship?

Connolly

2013

Can. J. Neurol. Sci.

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Prevalence of Hippocampal Malrotation in a Population without Seizures: Fig 1.

Cited by 70 publications

References 2 publications

Evaluation of hippocampal infolding angle and incomplete hippocampal inversion in pediatric patients with epilepsy and febrile seizures

Evaluation of hippocampal infolding angle and incomplete hippocampal inversion in pediatric patients with epilepsy and febrile seizures

Mesial temporal lobe morphology in intractable pediatric epilepsy: so-called hippocampal malrotation, associated findings, and relevance to presurgical assessment

Hippocampal Malrotation and Temporal Lobe Epilepsy: What is the Relationship?

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