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|Year : 2012 | Volume
| Issue : 2 | Page : 165-166
A sac in a shaking uncus
P Sandeep, A Cherian, T Iype, K Ayyappan
Department of Neurology, Government Medical College, Trivandrum, Kerala, India
|Date of Web Publication||14-Jun-2012|
Department of Neurology, Government Medical College, Trivandrum, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sandeep P, Cherian A, Iype T, Ayyappan K. A sac in a shaking uncus. J Postgrad Med 2012;58:165-6
Seizures as the presenting symptom of intracranial aneurysms are uncommon. Hδnggi et al., identified nine out of 347 patients with intracranial aneurysms (2.6%) presenting with epilepsy.  We report a 75-year-old lady who presented with uncinate seizures and had a left internal carotid artery (ICA) aneurysm on imaging.
Her complex partial seizures were characterized by an aura of unpleasant odor followed by stare and perioral automatism lasting 2 min with unawareness. Scalp electroencephalography (EEG) revealed theta slowing over the left anterior temporal region. Magnetic resonance (MR) imaging of brain (1.5 tesla) and MR angiography revealed a saccular aneurysm from bifurcation of the ICA which measured 16.5 X 20.9 mm with a 5-mm stalk [Figure 1] extending postero-latero-inferiorly compressing the left uncus. Ipsilateral hippocampus and temporal lobe did not reveal any other pathology. No peri-aneurysmal bleed was noticed. She was started on carbamazepine which helped in seizure control and she is awaiting surgical intervention.
|Figure 1: (a) Axial MR T1.weighted sequences showing circular lesion with hyperintense curvilinear border showing enhancement on (E) post.contrast sequences. (b) Axial MR Fluid Attenuated Inversion Recovery (FLAIR) sequences showing circular hypointense lesion (suggesting flow void) with minimal pressure effect on the left mesial temporal structures, uncus and amygdala evident on T2.weighted (c) axial and (d) coronal sections. (f) MR angiogram revealed a saccular aneurysm at the bifurcation of the left ICA measuring 16.5 X 20.9 mm with a 5.mm stalk|
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Our patient presented with prototypical 'uncinate fits' or complex partial seizures of mesial uncal temporal origin. Olfactory aura is rare and suggests origin of seizure in the uncus/amygdyla. Considering her age, possibility of a primary neoplasm was thought of but we were surprised when neuroimaging revealed a saccular aneurysm at the bifurcation of the left ICA compressing the uncus of the temporal lobe.
Only a few cases of epilepsy with intracranial aneurysms have been reported. The most common location for the aneurysm as a cause of seizure is the middle cerebral artery (MCA). In a series of five patients presenting with seizures two had aneurysm involving the MCA, two involved posterior communicating artery while only one involved the ICA.  Liang-fu and Da-jie reported epilepsy in two of 21 cases of giant aneurysms, both located at the MCA.  The mechanism of epileptogenesis by an aneurysm is unknown. The calcified walls of the aneurysm may act as hamartomas.  Recurrent minor bleeding from an aneurysm might produce localized brain damage with hemosiderin deposition and glial scarring. Seizures may also be due to ischemia produced secondary to embolization from a thrombosed aneurysm. Seizures in our patient could be due to the compressive effect of the aneurysm alone.
There is a previous report of an MCA aneurysm presenting as uncinate seizures which improved following surgical ablation.  To the best of our knowledge this is the first case of an ICA aneurysm presenting as uncinate seizures. Whether such patients should undergo amygdalohippocampectomy in addition to resection of the aneurysm is still controversial as there is concern about the neuropsychologic sequelae, especially with regard to memory function. Fried et al., suggested that patients with mesial temporal lesions and a history of early-onset seizures have profound cell loss in all hippocampal fields except cornu ammonis (CA)-2 and amygdalohippocampectomy be performed.  But in cases such as ours where the seizure onset is delayed, inclusion of mesial temporal structures is debatable. Adequate visualization of mesial temporal structures during the surgical procedure, and performance of electrocorticography may aid in decision-making.
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