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|LETTER TO EDITOR
|Year : 2016 | Volume
| Issue : 4 | Page : 787-788
A case of subcortical heterotopia presenting with focal motor seizures and sensory loss
Department of Anatomy, Faculty of Science, Mahidol University, Ratchathewi, Bangkok 10400, Thailand
|Date of Web Publication||5-Jul-2016|
Department of Anatomy, Faculty of Science, Mahidol University, Ratchathewi, Bangkok 10400
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Dharmasaroja P. A case of subcortical heterotopia presenting with focal motor seizures and sensory loss. Neurol India 2016;64:787-8
Much less is known about subcortical heterotopia (SCH) than other types of gray matter heterotopia. SCH has distinct clinicoradiological syndromes and a genetic predisposition. Patients with focal SCH typically have congenital fixed neurological deficits and present with variable degrees of hemiparesis and intellectual disturbances, depending on the size of the lesion, and the effect on the overlying cortex. Diagnosis is made by magnetic resonance imaging (MRI), on which masses of gray matter extend in the deep and subcortical white matter. Some SCH contain blood vessels and cerebrospinal fluid (CSF). The etiopathological factors responsible for their genesis remain to be elucidated.
A 19-year-old male high-school student presented with two episodes of focal motor seizures lasting for a minute in his right arm and leg for the past 6 days. He also complained of reduced sensation in his right arm, which was sustained until presentation. On examination, he had no aphasia, dysarthria, or impaired function of cranial nerves. Intelligence was generally appropriate for his age. A constant hypoesthesia was observed in the right arm without muscle weakness. The muscle tone and tendon reflexes were normal. The Babinski reflex was absent. His MRI scans showed the appearance of enfolded cortex in clear contiguity with the overlying cortex seated in the white matter [Figure 1]. The lesions were located in the left parietal, and to a lesser degree, in the temporal lobe, extending along the length of the malformed lateral sulcus. The signal intensity of the lesions was identical with the gray matter in all pulse sequences. No evidence of enhancement was observed. All were consistent with the diagnosis of a curvilinear SCH. Decreased volume of the left cerebral hemisphere with polymicrogyria was also observed, without evidence of lissencephaly or schizencephaly. The left lateral sulcus was abnormally widened and extended, starting from the anterior aspect of the hemisphere to the posterior part, dividing the hemisphere into the upper parietal lobe, and the lower, temporal, and occipital lobes. The short and long gyri of the insula and the posterior portion of the thalamus were dysplastic on the side of the heterotopia [Figure 2]. Notably, careful analysis revealed that blood vessel-like signals could be seen passing into the gray matter of the heterotopia [Figure 3]. The patient was prescribed 200 mg carbamazepine twice a day. He has had no episodes of seizures since then, with his hypoesthesia disappearing after 2 weeks of institution of the medication.
|Figure 1: (a-c) Coronal T1-weighted, (d and e) coronal gradient recalled echo T2*-weighted, and (f) coronal T1-weighted gadolinium-enhanced images showing the enfolded cortex seated in the white matter of the left parietal lobe, in clear contiguity with the overlying cortex starting from the anterior to the posterior parts of the brain (arrows). (g) A sagittal T1-weighted image showing the abnormally widened and extended left lateral sulcus, with the curvilinear heterotopia (arrow). (h and i) Sagittal T1-weighted images showing polymicrogyria (h), compared with normal gyri of the right hemisphere (i)|
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|Figure 2: (a) An axial T2-weighted fast spin echo image showing the dysplastic left insula. (b) A coronal T1-weighted image showing the dysplastic left posterior thalamus|
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|Figure 3: (a) An axial T2-weighted fast spin echo image, (b) an axial T1-weighted with gadolinium enhanced image, and (c) a sagittal T1-weighted gadolinium enhanced image showing blood vessel-like signals coursing within the gray matter of the heterotopia (arrows)|
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Most patients with SCH develop partial seizures and intellectual disturbances, usually in the first decade of their lives.,, The patient in this report had a normal intellectual level and developed focal motor seizures with localized hypoesthesia at an adolescent age. All of his symptoms and signs disappeared after a short period of taking an antiepileptic drug. These clinical observations may suggest a minor degree of dysfunction in the ectopic neurons in the heterotopia, aside from their small and thin size. In contrast to the lesion size, associated anomalies were rather extensive, which included polymicrogyria, widened and extensive lateral sulcus, dysplastic thalamus, and dysplastic insular gyri. A dysplastic thalamus is an uncommon entity, and most patients with SCH have a dysplastic basal ganglia. Concomitance of the heterotopia in the parietal lobe and a dysplastic thalamus may imply dysfunctional connectivity of the somatosensory pathway that led to a transient sensory loss in the patient. Structural and functional connectivity between the heterotopic lesions and the overlying cortex has also been reported.
The presence of blood vessels and cerebrospinal fluid (CSF) within SCH is rarely observed. Some SCH appear to contain blood vessels and CSF, suggesting continuity with the subarachnoid space. The present report shows blood vessel-like signals coursing within the curvilinear heterotopia without clear evidence of CSF. One proposed explanation is that pial capillaries were induced to perforate the heterotopic region by the same factors that induced perforation of blood vessels into the cerebral cortex during fetal development.,
Epilepsy due to the thin curvilinear SCH is typically responsive to antiepileptic medications. Surgical removal of heterotopia may be required in patients with more extensive lesions and in the presence of drug-refractory epilepsy.
The patient has been treated by PD at Ladphrao Hospital, Bangkok, Thailand.
Financial support and sponsorship
Faculty of Science, Mahidol University.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]