Summary:Purpose: Previous studies using diffusion MRI in patients with temporal lobe epilepsy have shown abnormal water diffusion in the hippocampus. Because thalamus and lentiform nuclei are considered important for the regulation of cortical excitability and seizure propagation, we analyzed diffusion tensor imaging (DTI) abnormalities in these subcortical structures and in hippocampus of children with partial epilepsy with and without secondary generalization.Methods: Fourteen children with partial epilepsy involving the temporal lobe underwent MRI including a DTI sequence. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained in the hippocampus, thalamus, and lentiform nucleus, and compared with DTI data of 14 control children with no epilepsy, as well as glucose positron emission tomography (PET) findings.Results: Decreased FA (p < 0.001) and increased ADC (p = 0.003) values were found in the hippocampi ipsilateral to the seizure focus. Significant FA decreases (p = 0.002) also were seen in the contralateral hippocampi, despite unilateral seizure onset and excellent surgical outcome in patients who underwent surgery. ADC values showed a trend for increase in the thalami ipsilateral to the epileptic focus in the seven children with secondarily generalized seizures (p = 0.09). No group differences of ADC or FA were found in the lentiform nuclei. The DTI variables did not correlate with regional glucose metabolism in any of the structures analyzed.Conclusions: Increased ADC values in hippocampus can assist in lateralizing the seizure focus, but decreased FA in the contralateral hippocampus suggests that it too may be dysfunctional despite unilateral seizure onset. Less-robust thalamic abnormalities of water diffusion in patients with secondarily generalized seizures suggest secondary involvement of the thalamus, perhaps due to recruitment of this structure into the epileptic network; however, this must be confirmed in a larger population. DTI appears to be a sensitive method for detection abnormalities in children with partial epilepsy, even in structures without apparent changes on conventional MRI. Key Words: EpilepsyHippocampus-Thalamus-MRI-Diffusion tensor imagingAnisotropy.Alterations in temporal and subcortical structures in patients with temporal lobe epilepsy (TLE) have been demonstrated by using various imaging methods, including positron emission tomography (PET) of glucose metabolism (1-4) and flumazenil binding (1,3,5), volumetric MRI (3,6-8), proton MR spectroscopy (9-11), and single-photon emission computed tomography (SPECT) of cerebral blood flow (12)(13)(14). Diffusion tensor imaging (DTI) of the human brain is a relatively new MRI method that allows noninvasive modeling of the diffusive transport of water molecules by means of a diffusion tensor (15)(16)(17). Of the several indices used to characterize the diffusion tensor, those most commonly used include the Accepted July 27, 2005. Address correspondence and reprint requests to Dr. H.T. Chugani at Pediatric...

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Object After untethering of spinal dysraphism, some patients present with neurological deterioration, defined as retethered cord syndrome. It is known that surgical untethering is an option for improving the symptoms of retethered cord syndrome. Previous reports have shown that postoperative improvement in retethered cord syndrome was noted in the majority of patients presenting with pain, and in more patients with motor weakness than in those with urological symptoms. The authors speculate that subjective symptoms may be detected while symptoms are still reversible. In contrast, changes in urological function are less easy to diagnose, and delays in treatment may be complicated by advanced symptoms. In this study, patients with retethered cord syndrome were evaluated to investigate the benefits of performing routine urodynamic study to detect detrusor overactivity, which is considered to be a subclinical change of urological function, and to investigate the efficacy of early untethering surgery on the symptoms of retethered cord syndrome. Methods Surgical indications and outcomes of 78 untethering operations (20 for myelomeningocele, 58 for spinal lipoma) for retethered cord syndrome were examined. Diagnosis of retethered cord syndrome was defined by a multidisciplinary spina bifida team, and included routine urodynamic study. Results Preoperative symptoms included urological symptoms (70%), lower-extremity symptoms (45%), and others. The most frequent urological symptom was detrusor overactivity detected by urodynamic study (88.7%). Urinary incontinence was only found in 9.4% of patients. Postoperatively, progressive motor weakness improved in all patients, and sensory symptoms improved in 94%. Urological symptoms improved in 80% of the patients with urinary incontinence and in 75% of the patients with detrusor overactivity. Postoperative urodynamic study showed a significant increase in bladder volume (p < 0.05). The most common complication was temporary lower leg paresthesia that recovered at follow-up. Aggravated dysuria was noted in 3 patients. Conclusions Early untethering operations offer symptomatic relief to patients with retethered cord syndrome. Urodynamic study findings, especially detrusor overactivity, are considered to be the most significant indicators for early diagnosis of retethered cord syndrome.

OBJECT Some pediatric patients with middle cranial fossa arachnoid cysts present with symptoms of increased intracranial pressure (ICP) and require shunt placement after a cyst fenestration. However, factors concerning increased ICP after fenestration followed by shunt placement have not been elucidated. This study evaluated factors that are associated with shunt placement following cyst fenestration in pediatric patients with middle cranial fossa arachnoid cysts. METHODS Twenty-six pediatric patients with middle cranial fossa arachnoid cysts who were surgically treated at a single institution between 2004 and 2013 were retrospectively identified. The surgical indications for middle cranial fossa arachnoid cysts were as follows: 1) arachnoid cysts associated with symptoms such as headache and abnormally enlarging head circumference; 2) progressively expanding arachnoid cysts; and 3) large arachnoid cysts such as Galassi Type III. A cyst fenestration was performed as a first-line treatment, and shunt placement was required if symptoms associated with increased ICP were found following fenestration. The risk factors evaluated included age, sex, presenting symptoms, the presence of head enlargement, progressive cyst expansion, and subdural hematoma/hygroma. RESULTS Four patients (15.4%) required shunt placement after cyst fenestration. Younger age, abnormal head enlargement, and progressive cyst expansion before fenestration were significantly associated with the need for shunt placement following fenestration. Arachnoid cysts decreased in size in 22 patients (84.6%) after fenestration and/or shunt placement. The presence of symptoms was not associated with postoperative cyst size in this study. CONCLUSIONS In this study, younger age, abnormal head enlargement, and progressive cyst expansion were risk factors for shunt placement after cyst fenestration in pediatric patients with middle cranial fossa arachnoid cysts. It is important to consider that cyst fenestration may not be effective because of a latent derangement of CSF circulation in patients with these risk factors.

Filum terminale lipoma (FTL) causes various spinal symptoms known as tethered cord syndrome. The treatment for FTL is surgical untethering by sectioning the FTL, which can prevent symptom progression and often results in improvement of symptoms. This report describes a minimally invasive surgical strategy that we have introduced for FTL sectioning. The pediatric patients with FTL since 2007 were treated using this minimally invasive surgical strategy, which we refer to as an interlaminar approach (ILA). In summary, the surgical technique involves: minimal skin incision to expose the unilateral ligamentum flavum in the lower lumbar region; ligamentum flavum incision to expose the dural sac, and dural incision followed by identification and sectioning of the filum. Postoperatively, no bed rest was required. Prior to introducing ILA, we had used standard one level laminectomy/laminotomy (LL) with more than 1 week of postsurgical bed rest until 2007, providing an adequate control group for the benefit of the ILA. A total of 49 consecutive patients were treated using ILA. While 37 patients were treated using LL. Surgical complications that need surgery were seen only in one patient, who developed cerebrospinal fluid (CSF) leak in LL patients. No retethering or additional neurological symptoms were seen during follow-up. All patients complained of minimal postsurgical back pain, but no patients required postoperative bed rest in ILA patients, while LL patients need postsurgical bed rest because of back pain. The ILA strategy provides the advantage of a minimal tissue injury, associated with minimal postoperative pain, blood loss, and bed rest.

OBJECTIVESome pediatric patients with moyamoya disease (MMD) present with posterior cerebral artery (PCA) stenosis before and after anterior circulation revascularization surgery and require posterior circulation revascularization surgery. This study evaluated the factors associated with PCA stenosis and assessed the efficacy of posterior circulation revascularization surgery, including occipital artery (OA)–PCA bypass, in pediatric patients with MMD.METHODSThe presence of PCA stenosis before and after anterior circulation revascularization surgery and its clinical characteristics were investigated in 62 pediatric patients (< 16 years of age) with MMD.RESULTSTwenty-three pediatric patients (37%) with MMD presented with PCA stenosis at the time of the initial diagnosis. A strong correlation between the presence of infarction and PCA stenosis before anterior revascularization was observed (p < 0.001). In addition, progressive PCA stenosis was observed in 12 patients (19.4%) after anterior revascularization. The presence of infarction and a younger age at the time of initial diagnosis were risk factors for progressive PCA stenosis after anterior revascularization (p < 0.001 and p = 0.002, respectively). Posterior circulation revascularization surgery, including OA-PCA bypass, was performed in 9 of the 12 patients with progressive PCA stenosis, all of whom showed symptomatic and/or radiological improvement.CONCLUSIONSPCA stenosis is an important clinical factor related to poor prognosis in pediatric MMD. One should be aware of the possibility of progressive PCA stenosis during the postoperative follow-up period and consider performing posterior circulation revascularization surgery.

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A 70-year-old woman presented with mild left hemiparesis and intermittent global headache. Magnetic resonance imaging showed a 6 x 6 x 6-cm tumor in the right frontal lobe, and abdominal computed tomography revealed a 8 x 8 x 7-cm mass lesion in the left kidney. Magnetic resonance imaging showed that the brain tumor consisted of a central hyperintense cystic component and an outer hypointense component. The patient underwent total surgical excision of the intracranial mass. Histological and immunohistochemical examination showed that the lesion was a lipomatous meningioma harboring metastatic renal-cell carcinoma. Both of these tumors are rare. The magnetic resonance imaging findings are indicative of but not specific to meningioma harboring metastatic tumor.