Sung Hun Kim

The effectiveness of 3T time-of-flight magnetic resonance angiography for follow-up evaluations after the stent-assisted coil embolization of cerebral aneurysms

Background Artifacts introduced by stents limit the value of magnetic resonance (MR) imaging as a follow-up modality after the stent-assisted coil embolization of cerebral aneurysms. Purpose To investigate the usefulness of 3 Tesla (3T) time-of-flight (TOF) MR angiography (MRA) for the follow-up evaluation. Material and Methods Twenty-two aneurysms of 20 patients treated with stent-assisted coil embolization were followed up with 3T TOF MRA and digital subtraction angiography (DSA) with three-dimensional rotational angiography (3DRA). The status of coiled aneurysms was compared with 3T TOF MRA and DSA with 3DRA in terms of complete occlusion, residual neck, and residual aneurysm. TOF MRA at 3T was performed 1 day before DSA with 3DRA, with a mean follow-up period of 20.1 ± 10.8 months. Results Twenty (90.9%) of 22 cases were concordant between the two modalities. The degree of agreement and correlation between them were high (κ = 0.771, P < 0.001; r = 0.832 and P < 0.001). When evaluating the status of residual neck, the sensitivity was 80% (4/5 cases); specificity was not available because there were no cases of complete occlusion. For the status of residual aneurysm, the sensitivity and specificity were 94.1% (16/17 cases) and 100% (all 5 cases), respectively. Conclusion TOF MRA at 3T with source images could be useful as a non-invasive follow-up modality after the stent-assisted coil embolization of cerebral aneurysms. Further study with a larger patient sample is needed to confirm the effectiveness of 3T TOF MRA.

Comparison of MRI features and surgical outcome among the subtypes of focal cortical dysplasia

PURPOSE Focal cortical dysplasia (FCD) is the most common pathological diagnosis in patients who have undergone surgical treatment for intractable neocortical epilepsy. However, presurgical identification of MRI abnormalities in FCD patients remains difficult, and there are no highly sensitive imaging parameters available that can reliably differentiate among FCD subtypes. The purpose of our study was to investigate the surgical outcome in FCD patients with identifiable MRI abnormalities and to evaluate the prognostic role of the various MRI features and the characteristics of FCD pathology. METHODS We retrospectively recruited epilepsy patients who had undergone surgical treatment for refractory epilepsy with focal MRI abnormalities and the pathological diagnosis of FCD. We evaluated the surgical outcome according to the pathological subtypes, and studied the prognostic roles of various MRI features. We used recently proposed three-tiered FCD classification system which included FCD type III when FCD occurs in association with other potentially epileptogenic pathologies. RESULTS A total of 69 patients were included, and 68.1% of patients became seizure free. Patients with FCD type III had a lower chance for achieving seizure freedom (7/15) than in patients with isolated FCD (FCD types I and II) (40/54, p=0.044). Cortical thickness and blurring of gray-white matter junction were more common in isolated FCD than in FCD type III, but most MRI features failed to differentiate between FCD types I and II, and only the transmantle sign was specific for FCD type II. We failed to find a prognostic value of specific MRI abnormalities of prognostic value in terms of post-epilepsy surgery outcome in FCD patients. CONCLUSIONS Our study showed that patients with FCD III have poor surgical outcome. Typical MRI features of isolated FCD such as cortical thickness and blurring of gray-white matter junction were less common in FCD type III and only transmantle sign was helpful in differentiating between FCD types I and II.

Lateralization of Hypoglycemic Encephalopathy: Evidence of a Mechanism of Selective Vulnerability

Background One of the characteristics of hypoglycemic encephalopathy (HE) is selective vulnerability of different brain regions. Case Report We observed a patient with unilateral HE affecting the right internal capsule and the subcortical white matter. The patient had a preexisting stroke in the opposite hemisphere. The hemisphere that was affected by HE exhibited greater regional blood flow (single positron-emission tomography) and higher fractional anisotropy (diffusion-tensor imaging) than the unaffected hemisphere. Conclusions This case suggests that the degree of metabolism required to maintain the function of brain structures and neuronal integrity is an important factor determining the selective vulnerability in HE.

Serial MR spectroscopy in relapsing reversible posterior leukoencephalopathy syndrome.

Background:Reversible posterior leukoencephalopathy syndrome (RPLS) in atypical locations is difficult to diagnose. Magnetic resonance spectroscopy (MRS) can help, but results to date are discrepant. We aimed to describe MRS findings in each phase of RPLS and evaluate their diagnostic potential. Methods:We performed MRS, diffusion-weighted imaging and conventional MR during 2 episodes in a patient with hypertensive encephalopathy. Results:There were multifocal edematous lesions in both frontal lobes, the left temporo-occipital region and both cerebellar hemispheres in the first episode, and in both cerebellar hemispheres and the left pons in the second. Apparent diffusion coefficient values were high. Choline was normal in the acute phase and elevated in the subacute period. N-acetylaspartate was low throughout, even after clinical recovery and disappearance of the lesion on conventional MR. No lactate peak was detected. Conclusions:MRS helps differentiate RPLS from several encephalopathies and a N-acetylaspartate decrease does not predict a poor outcome.

Familial hemiplegic migraine with prolonged coma and cerebellar atrophy: CACNA1A T666M mutation in a Korean family.

We report the first Korean patient with familial hemiplegic migraine type 1, with clinical and multimodal imaging findings. A 43-yr-old man was admitted for right hemianopia and aphasia, followed by coma. MRI showed only cerebellar atrophy. CT angiography showed mild vasodilation of intracranial blood vessels and increased vascularity in the left hemisphere and perfusion-weighted imaging showed elevated cerebral blood flow. Gene analysis of the patient and his mother led to the identification of a heterozygous point mutation (1997C→T, T666M) in exon 16 of the CACNA1A gene. Familial hemiplegic migraine should be considered in patients with episodic neurological dysfunction with cerebellar atrophy.

Familial Creutzfeldt-Jakob disease with a mutation at codon 180 presenting with an atypical phenotype.

The clinical features of familial Creutzfeldt-Jakob disease (fCJD) with a mutation at codon 180 (V180I) are less typical than those of patients with sporadic CJD. We describe a patient with pathologically confirmed CJD carrying the V180I mutation who had atypical cerebrospinal fluid and electroencephalography findings. Similar to other prion protein mutations, this report suggests that the V180I mutation is not the exclusive determinant of the phenotype.

Acute Marchiafava-Bignami disease with selective involvement of the precentral cortex and splenium: a serial magnetic resonance imaging study.

IntroductionMarchiafava-Bignami disease (MBD) is defined pathologically as callosal degeneration associated with chronic alcoholism. We report a patient with MBD with acute lesions confined in the precentral cortex and splenium. Various magnetic resonance imaging (MRI) modalities were performed sequentially to elucidate the pathophysiology. Case ReportA 52-year-old man with chronic alcoholism developed acute confusion and dysarthria. He improved incompletely with nutritional supplementation. Diffusion-weighted imaging MRI disclosed the presence of reversible lesions with low apparent diffusion coefficient values in the precentral cortex and splenium. Perfusion-weighted imaging revealed that the cerebral blood volume and flow decreased and subsequently increased, and the mean transit time and time to peak were persistently prolonged. On magnetic resonance spectroscopy, choline was initially normal and became elevated during the recovery period, whereas N-acetylaspartate was low initially and after the resolution of the lesion on conventional MRI. ConclusionsThe precentral cortex and splenium are the most vulnerable areas in acute MBD. The lesions have reversible restricted diffusivity and hypoperfusion. The magnetic resonance spectroscopy findings correlate well with the clinical status.

Vasogenic edema in striatum following ingestion of glufosinate-containing herbicide

Glufosinate-ammonium (GLA) is a broad-spectrum herbicide used worldwide. We report a patient who attempted suicide by ingesting a liquid herbicide containing GLA. A diffusion-weighted MRI showed cytotoxic edema in the hippocampus as well as vasogenic edema in the striata. To our knowledge, vasogenic edema caused by GLA-containing herbicide involving the striatum has not been reported in association with cytotoxic edema in the hippocampus. We assume that this herbicide affected the central nervous system via different mechanisms to produce both cytotoxic and vasogenic edema in the same patient.

Postpartum cerebral angiopathy presenting with non-aneurysmal subarachnoid hemorrhage

Parturition increases the risk of strokes of various types, including postpartum cerebral angiopathy (PCA), which is characterized by reversible multifocal vasoconstriction of the cerebral arteries. We describe an unusual presentation of PCA associated with postpartum non-aneurysmal subarachnoid hemorrhage (SAH). A 31-year-old multiparous woman complained of sudden headache 3 hours after an uncomplicated vaginal delivery. She had no history of pregnancy-induced hypertension. SAH was found over the bilateral frontoparietal convexities with multifocal vasculopathy. Her symptoms resolved completely within 1 week. The findings of a follow-up neurological examination, cerebral angiography, and brain MRI were normal after 2 months. PCA syndrome may be associated with postpartum non-aneurysmal SAH.

Ictal spect using an attachable automated injector: clinical usefulness in the prediction of ictal onset zone

Background: Ictal single-photon emission computed tomography (SPECT) is a valuable method for localizing the ictal onset zone in the presurgical evaluation of patients with intractable epilepsy. Conventional methods used to localize the ictal onset zone have problems with time lag from seizure onset to injection. Purpose: To evaluate the clinical usefulness of a method that we developed, which involves an attachable automated injector (AAI), in reducing time lag and improving the ability to localize the zone of seizure onset. Material and Methods: Patients admitted to the epilepsy monitoring unit (EMU) between January 1, 2003, and June 30, 2008, were included. The definition of ictal onset zone was made by comprehensive review of medical records, magnetic resonance imaging (MRI), data from video electroencephalography (EEG) monitoring, and invasive EEG monitoring if available. We comprehensively evaluated the time lag to injection and the image patterns of ictal SPECT using traditional visual analysis, statistical parametric mapping-assisted, and subtraction ictal SPECT coregistered to an MRI-assisted means of analysis. Image patterns were classified as localizing, lateralizing, and nonlateralizing. The whole number of patients was 99: 48 in the conventional group and 51 in the AAI group. Results: The mean (SD) delay time to injection from seizure onset was 12.4±12.0 s in the group injected by our AAI method and 40.4±26.3 s in the group injected by the conventional method (P=0.000). The mean delay time to injection from seizure detection was 3.2±2.5 s in the group injected by the AAI method and 21.4±9.7 s in the group injected by the conventional method (P=0.000). The AAI method was superior to the conventional method in localizing the area of seizure onset (36 out of 51 with AAI method vs. 21 out of 48 with conventional method, P=0.009), especially in non-temporal lobe epilepsy (non-TLE) patients (17 out of 27 with AAI method vs. 3 out of 13 with conventional method, P=0.041), and in lateralizing the seizure onset hemisphere (47 out of 51 with AAI method vs. 33 out of 48 with conventional method, P=0.004). Conclusion: The AAI method was superior to the conventional method in reducing the time lag of tracer injection and in localizing and lateralizing the ictal onset zone, especially in patients with non-TLE.