MRI Volumetric Study of the Hippocampal Formation in Patients with Malformations of Cortical Development.
Abstract number :
C.07
Submission category :
Year :
2001
Submission ID :
2716
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
M.A. Montenegro, MD, Neurology, University of Campinas, Campinas, SP, Brazil; L.M. Li, MD, PhD, Neurology, University of Campinas, Campinas, SP, Brazil; M.M. Guerreiro, MD, PhD, Neurology, University of Campinas, Campinas, SP, Brazil; C.A.M. Guerreiro, MD
RATIONALE: The neuroimaging characteristics of the normal temporal lobe is well known, and hippocampal atrophy can be diagnosed in vivo by MR, with a consistent relationship between the imaging finding of hippocampal atrophy and its pathological correlation of hippocampal sclerosis. There are reports of hippocampal abnormalities associated to malformations of cortical development (MCD); however, to our knowledge these abnormalities have not been systematically evaluated in a large series of patients with MCD. The objective of this study is to perform volumetric studies of the hippocampal formation in a large series of patients with MCD.
METHODS: We evaluated 75 consecutive patients (34 men, ages ranging from 4 to 58 years; mean=19.9) with the diagnosis of MCD confirmed by MRI. High resolution MRI was performed in a 2.0 T scanner (Elscint Prestige). Volumetric measurements were performed manually using NIH software. Hippocampal volumes were corrected for intracranial volumes and compared to the values of 20 healthy volunteers. Values below or above 2 SD from the mean of the control group were considered abnormal.
RESULTS: Twenty-four patients had MDC due to abnormal neuronal proliferation (focal cortical dysplasia and hemimegalencephaly), 18 had MCD due to abnormal neuronal migration (nodular heterotopia, subcortical laminar heterotopia, agyria/pachigyria), and 33 had MCD due to abnormal cortical organization (schizencephaly and polymicrogyria). Hippocampal atrophy was present in 2/23 of patients with focal cortical dysplasia, 1/2 of hemimegalencephaly, 2/4 of unilateral nodular heterotopia, 3/29 of polymicrogyria and 2/4 of schizencephalaly. The hipocampal formation was proportionally enlarged in 2/4 of patients with agyria pachigyria, 2/4 of subcortical laminar heterotopia and 1/2 of hemimegalencephaly.
CONCLUSIONS: We found hippocampal developmental abnormalities in 20% of patients with MCD. The pattern of hippocampal abnormality varied according to the type of MCD. Enlarged hippocampal formation was found in 50% of patients with MCD due to diffuse migration disorders. Conversely, atrophic hippocampal formation was found in 16% of patients with focal MCD (focal cortical dysplasia, polymicrogyria, schizencephaly and unilateral nodular heterotopia), all ipsilateral to the lesion. This suggests that a vascular injury may have caused both the hippocampal atrophy and focal dysplastic lesion.
Support: Supported by FAPESP.