CASE 12763 Published on 14.06.2015

Hippocampal malrotation: a paediatric case report


Paediatric radiology

Case Type

Clinical Cases


Gonca Koc¹, Selim Doganay¹, Mehmet S Dogan¹, Sureyya B. Gorkem¹, Gul D. Kaya Ozcora², Saliha Ciraci¹, Huseyin Per², Abdulhakim Coskun¹

¹Erciyes University School of Medicine,
Pediatric Radiology;
Melikgazi 38090
Kayseri, Turkey
²Erciyes University School of Medicine,
Pediatric Neurology;
Melikgazi 38090
Kayseri, Turkey

9 years, female

Area of Interest Neuroradiology brain ; Imaging Technique MR
Clinical History
A 9-year-old girl was being followed-up with the diagnosis of complex partial seizure in the paediatric neurology clinic of our institution. The electroencephalogram (EEG) revealed no epileptogenic focus and the patient was referred for the acquisition of brain magnetic resonance imaging (MRI).
Imaging Findings
On coronal T2-weighted (Fig. 1), and T1-weighted inversion recovery images (Fig. 2) obtained with 2 mm slice thickness, the left hippocampus was detected to be in a round configuration without any size or signal abnormality. The hippocampal internal signal intensity was blurred. The collateral sulcus was in vertical orientation while the fornix was displaced inferiorly on the same side. Therefore, along with all the findings, the left hippocampus was considered to be incompletely inverted.
Malrotation of the hippocampus is defined as the incomplete inversion of the hippocampus that occurs out during fetal life and has been reported in children with prolonged febrile seizures [1]. The diagnosis of hippocampal malrotation is based on some radiologic criteria detected on MRI; 1) Round shape of hippocampus without any volume loss or signal abnormality, 2) Blurring of internal structure of hippocampus, 3) Vertically orientated same-sided collateral sulcus, 4) Inferiorly located same-sided fornix, 5) Normal-sized temporal lobe and temporal horn of lateral ventricle.
Although few studies in the literature reported the association of hippocampal malrotation with temporal lobe epilepsy, prolonged febrile seizures, and a variety of epilepsy syndromes, it may be encountered in about 18% of healthy subjects without any structural abnormalities [2-4]. Gamss et al found hippocampal malrotation in 30% of their patients with epilepsy but there was no correlation with EEG findings [4]. Even though incompletely inverted hippocampus does not act as an epileptogenic focus, it may be a sign of inadequate brain development that may be speculated to cause epilepsy.
In conclusion, although hippocampal malrotation may be detected in patients with epilepsy, its role in epilepsy is controversial. In order to reveal its frequency in the general population and association with various forms of epilepsy, further studies are needed.
Differential Diagnosis List
Hippocampal malrotation, incomplete inversion of hippocampus
Mesial temporal sclerosis
Cortical dysplasia
Final Diagnosis
Hippocampal malrotation, incomplete inversion of hippocampus
Case information
DOI: 10.1594/EURORAD/CASE.12763
ISSN: 1563-4086