Ictal SPECT in children with partial epilepsy due to focal cortical dysplasia

We studied the usefulness of ictal single-photon emission computed tomography in the presurgical evaluation of children with partial epilepsy resulting from focal cortical dysplasia. Fifteen children, age 1-18 years, were identified with partial epilepsy caused by focal cortical dysplasia (confirmed by histology) who underwent subtraction ictal single-photon emission computed tomography during presurgical evaluation. All children later underwent surgery at the Cleveland Clinic Epilepsy Center between 1996 and 2000. The findings of ictal single-photon emission computed tomography and brain positron emission tomography were classified as localized when "localizing and concordant" with the surgical resection site, nonconcordant when "localizing but not concordant" with the surgical resection, or nonlocalized when "no well-localized region of ictal hyperperfusion was observed on the difference image". In 15 patients, age 1.5-18 years (median age 8 years), epilepsy was classified as frontal in 7, posterior temporal/occipital in 3, temporal in 2, multilobar in 2, and parietal in 1. Of 15 patients, preoperative magnetic resonance imaging revealed focal cortical dysplasia in 11, positron emission tomography was localized in 9, and ictal single-photon emission computed tomography was localized in 8 patients. In 4 patients with normal magnetic resonance imaging but scalp electroencephalographic findings of partial epilepsy, ictal single-photon emission computed tomography and positron emission tomography were localized in 3 each. Fourteen patients were monitored for 6-39 months (mean 20 months). Six of 7 patients (85%) with localized ictal single-photon emission computed tomography compared with 4 of 7 (57%) with nonconcordant/nonlocalized ictal single-photon emission computed tomography had no seizures at follow-up. In 4 patients with normal magnetic resonance imaging, 3 patients with localized ictal single-photon emission computed tomography were free of seizures compared with 1 with nonconcordant ictal single-photon emission computed tomography who continued to have seizures. Ictal single-photon emission computed tomography is a useful adjunctive test in presurgical evaluation of children with refractory partial epilepsy due to focal cortical dysplasia, especially when brain magnetic resonance imaging is normal.     

Human herpesvirus 6 encephalopathy predominantly affecting the frontal lobes

Isolated cases of human herpesvirus 6 encephalopathy have recently been reported, although the pathophysiology remains largely unknown. To elucidate the changes specific to human herpesvirus 6 encephalopathy on diagnostic images, this study investigated magnetic resonance imaging findings in 10 patients with a diagnosis of human herpesvirus 6 encephalopathy including diffusion-weighted imaging in 6 of 10, and findings of cerebral blood flow imaging by single-photon emission computed tomography in 9 of 10 patients. No abnormalities were evident on T(1)-weighted, T(2)-weighted, or fluid-attenuated inversion-recovery magnetic resonance imaging during acute phases; however, diffusion-weighted imaging indicated abnormal hyperintensity in the subcortical white matter of the frontal lobes in all six patients during the acute phase. Cerebral blood flow single-photon emission computed tomography revealed decreased perfusion, predominantly in the frontal region of all nine patients during their clinical course. Disturbances predominantly affecting the frontal lobes (region) on magnetic resonance imaging and cerebral blood flow single-photon emission computed tomography were common in all patients, suggesting that the findings may be characteristic of human herpesvirus 6 encephalopathy.     

Hypoperfusion following encephalitis: SPECT with acetazolamide

At 4 weeks and 8 months following initial symptoms, we performed single-photon emission computed tomography (SPECT) with acetazolamide (ACZ) testing in a patient recovering from acute encephalitis, possibly acute disseminated encephalomyelitis (ADEM). Both regional hypoperfusion at baseline and diminished cerebrovascular reserve were seen after focal hyperintensities had disappeared in magnetic resonance imaging (MRI). The time course of SPECT abnormalities reflected the clinical course more closely than the time course of MRI abnormalities. Thus, persistent cerebral circulatory impairment probably contributed to cognitive and language deficits observed at the subacute stage.     

Neuroradiological study of patients with amyotrophic lateral sclerosis and parkinsonism-dementia complex on the Kii peninsula of Japan

BACKGROUND: The Kii peninsula of Japan, together with Guam and West New Guinea, has one of the highest incidences of amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia complex (PDC) in the world. OBJECTIVE: To perform neuroimaging studies on patients with ALS and PDC on the Kii peninsula. METHODS: Results of computed tomography, magnetic resonance imaging, and single-photon emission computed tomography were studied in 4 patients with ALS and in 10 patients with PDC from the Hohara village on the Kii peninsula of Japan. RESULTS: In patients with PDC, there was mild to severe atrophy of the frontal and temporal lobes on computed tomography and magnetic resonance imaging and a marked decrease in cerebral blood flow on single-photon emission computed tomography. In contrast, in patients with ALS, there was a decrease in cerebral blood flow of the frontal and temporal lobes, although the patients did not show signs of clinical dementia or obvious brain atrophy on computed tomography or magnetic resonance imaging. CONCLUSION: The finding of an obvious decrease in cerebral blood flow of the frontal and temporal lobes in patients with PDC and ALS with or without cerebral atrophy supports the concept that the 2 conditions are different manifestations of a single frontotemporal tauopathy.     

MRI and SPECT in influenzal encephalitis.

Repeated magnetic resonance imaging studies were performed in a 22-month-old boy with influenzal encephalitis. T2-weighted magnetic resonance images disclosed multifocal hyperintense areas in the cortex and subcortical white matter of the left frontal, temporal, parietal, and right frontal lobes. 123I single photon emission computed tomography (SPECT) brain images demonstrated decreased uptake in the same regions. SPECT revealed larger areas of decreased uptake as compared with magnetic resonance imaging. One year after the onset of encephalitis, these brain lesions continue to be observed, although the patient has no apparent neurologic sequelae.     

The role of brain single photon emission computed tomography in the diagnosis of primary progressive aphasia.

We present two cases of primary progressive aphasia studied with neuropsychologic measures, computed tomography or magnetic resonance imaging, and single-photon emission computed tomography with technetium Tc99m-labeled hexamethylpropyleneamine oxime. Clinical and neuropsychologic observations revealed a marked, progressive loss of language functions over time with relative preservation of nonlanguage cognitive functions in both patients. The brain single-photon emission computed tomographic scan revealed marked left frontal and minimal left temporal and parietal hypoperfusion in case 1 and marked left posterior frontal and minimal left temporal hypoperfusion in case 2. The value of brain single-photon emission computed tomography in distinguishing primary progressive aphasia from Alzheimer's disease is described.     

Neuroimaging findings in Alexander's disease

We present the findings from magnetic resonance imaging, computed tomographic scan, and single photon emission computed tomography of the brain in a 2-year-old girl with Alexander's disease. Computed tomographic scans showed prominent low-density white matter throughout the cerebral hemispheres. Magnetic resonance imaging showed increased T2 signal from the cerebral white matter but not the cerebellum or brain stem. Single photon emission computed tomography revealed diminished cerebral metabolism, particularly in the frontal regions, as compared with the cerebellum.     

Frontal lobe-dominant cerebral blood flow reduction and atrophy can be progressive in Duchenne muscular dystrophy

This study aimed to clarify the characteristics and progressive changes of brain image abnormalities in Duchenne muscular dystrophy (DMD). Brain images of 39 adult patients (median age, 24 years) were retrospectively reviewed, along with intellectual and/or neurodevelopmental test results. On magnetic resonance imaging (n = 13), atrophy of the frontal lobe, pars opercularis (without other frontal atrophy), and cerebellum was observed in 6, 1, and 1 patients, respectively. On computed tomography (n = 32), atrophy of the frontal lobe, pars opercularis, temporal lobe, and occipital lobe was observed in 20, 1, 1, and 1 patients, respectively. Re-imaging of 12 patients revealed progression of cerebral atrophy in 6. All 18 patients who underwent single photon emission computed tomography had reduced total and/or focal blood flow. Reduced total cerebral blood flow was observed significantly more frequently in patients with deleterious Dp140 mutations compared to those without. Re-examination 4 years later revealed worsening of reduced blood flow in the frontotemporal lobe in 1 patient. Abnormalities were detected by at least one imaging modality in 32 of 39 patients. No significant relationship was observed between imaging abnormalities and developmental disorders or intelligence quotient. In conclusion, DMD patients frequently exhibit frontal lobe-dominant cerebral blood flow reduction and atrophy, and may be at risk of progressive cerebral atrophy and reduced cerebral blood flow. MRI, CT, and/or brain single photon emission CT are useful for detecting brain abnormalities in adult DMD patients.     

Viral Infections of the Brain

Brain infections are generally well visualized by contrastenhanced computed tomography or magnetic resonance imaging. However, these modalities are often unrevealing in the encephalopathy produced by the human immunodeficiency virus and in the early stages of herpes simplex encephalitis. Several studies have documented the greater sensitivity of perfusion single-photon emission computed tomography (SPECT) in human immunodeficiency virus encephalopathy. In herpes simplex encephalitis, a few case reports have documented that SPECT may depict increased perfusion m the characteristically involved temporal and other l1mb1c structures when computed tomography and magnetic resonance imaging are normal.     

Application of modern neuroimaging technology in the diagnosis and study of Alzheimer's disease

Neurological abnormalities identified via neuroimaging are common in patients with Alzheimer's disease. However, it is not yet possible to easily detect these abnormalities using head computed tomography in the early stages of the disease. In this review, we evaluated the ways in which modern imaging techniques such as positron emission computed tomography, single photon emission tomography, magnetic resonance spectrum imaging, structural magnetic resonance imaging, magnetic resonance diffusion tensor imaging, magnetic resonance perfusion weighted imaging, magnetic resonance sensitive weighted imaging, and functional magnetic resonance imaging have revealed specific changes not only in brain structure, but also in brain function in Alzheimer's disease patients. The reviewed literature indicated that decreased fluorodeoxyglucose metabolism in the temporal and parietal lobes of Alzheimer's disease patients is frequently observed via positron emission computed tomography. Furthermore, patients with Alzheimer's disease often show a decreased N-acetylaspartic acid/creatine ratio and an increased myoinositol/creatine ratio revealed via magnetic resonance imaging. Atrophy of the entorhinal cortex, hippocampus, and posterior cingulate gyrus can be detected early using structural magnetic resonance imaging. Magnetic resonance sensitive weighted imaging can show small bleeds and abnormal iron metabolism. Task-related functional magnetic resonance imaging can display brain function activity through cerebral blood oxygenation. Resting functional magnetic resonance imaging can display the functional connection between brain neural networks. These are helpful for the differential diagnosis and experimental study of Alzheimer's disease, and are valuable for exploring the pathogenesis of Alzheimer's disease.     

Cerebellitis in an adult with abnormal magnetic resonance imaging findings prior to the onset of ataxia

BACKGROUND: Brain magnetic resonance imaging (MRI) findings during acute cerebellar ataxia in cases of postinfectious cerebellitis are frequently normal. This has resulted in the use of other imaging modalities, such as single-photon emission computed tomography, to aid diagnosis. OBJECTIVE: To illustrate the chronologic occurrence of cerebellar ataxia, abnormal findings on MRI, and cerebral spinal fluid pleocytosis in an adult case of postinfectious cerebellitis. METHODS: Case report. RESULTS: A patient with a 6-week history of occipital headaches and only mild tandem gait difficulty had abnormal MRI findings that were consistent with cerebellar inflammation. As cerebellar ataxia progressed in parallel with cerebral spinal fluid pleocytosis, MRI findings indicative of cerebellar inflammation resolved, while single-photon emission computed tomography showed cerebellar hyperperfusion. Recovery of neurologic function was accompanied by clearing of the pleocytosis and residual MRI-detected cerebellar atrophy. CONCLUSION: This case demonstrates that transient abnormalities can be detected by MRI before clinical manifestations of cerebellitis appear, while hyperperfusion detected by single-photon emission computed tomography is prolonged.     

Brain SPECT findings in Wernicke’s encephalopathy

Abstract. Wernickes encephalopathy, a neurologic disease caused by thiamine deficiency, is observed chiefly in chronic alcoholics. We performed magnetic resonance imaging and single-photon emission computed tomography (SPECT) in an alcoholic patient who had developed Wernickes encephalopathy. Although cranial MRI detected no pathology, brain SPECT revealed bilateral frontal and frontoparietal hypoperfusion as well as right basal ganglia hypoperfusion.     

Diaschisis in chronic viral encephalitis with Koshevnikov syndrome.

The authors report a 61-year-old man with chronic viral encephalitis and Koshevnikov syndrome occurring 42 months after initial symptom of right hemiparesis. Serial computed tomography of the brain showed changes in the attenuation of the left temporal lobe lesion over time. Magnetic resonance images of the brain showed enlargement of left temporoparietooccipital lobes with cortical gyral enhancement on T1-weighted images following intravenous administration of gadolinium-DTPA. 99mTc-HMPAO single-photon emission computerized tomography showed increased radioactivity and hyperperfusion in the left temporoparietal region with paradoxically decreased local tissue perfusion at the contralateral right hemisphere. Follow-up magnetic resonance images of the brain 4 years later showed atrophy of bilateral cerebral hemispheres. We postulate that a "transcallosal diaschisis" with subsequent degeneration is a possible mechanism. A brain biopsy from the left temporal lobe lesion showed pictures compatible with viral encephalitis probably herpes simplex encephalitis.     

99Tc-HmPAO SPECT in 13 patients with classic lissencephaly

In this study, technetium-99 ((99)Tc)-hexamethylpropyleneamine-oxine single-photon emission computed tomography (SPECT) was performed on 13 children with classic lissencephaly (nine with epileptic seizures, four without seizures). Focal or multifocal hypoperfusions were observed in 12 patients. The hypoperfused areas observed on SPECT scanning did not correlate with the localization of agyric-pachygyric regions in all patients. The distribution of perfusion abnormalities by SPECT and the localization of agyria-pachygyria as detected by magnetic resonance imaging did not correlate strongly. All nine patients with seizures and three of the four patients without seizures had focal or multifocal cerebral blood flow abnormalities on the SPECT scans. The presence of brain perfusion abnormalities detected by SPECT and the occurrence of epileptic seizures did not have a significant relationship. These results suggest that the role of SPECT studies in classic lissencephaly is not clearly defined. More sophisticated methods are needed to clarify the correlation between structural and functional abnormalities of patients diagnosed with lissencephaly.     

Superiority of Functional over Structural Neuroimaging in the Diagnosis of Primary Progressive Aphasia

For a 68-year-old man with the syndrome of primary progressive aphasia, functional brain imaging techniques (single-photon emission computed tomography and topographic electroencephalographic mapping) proved superior to anatomical imaging techniques (magnetic resonance imaging and computed tomography) in delineating the left temporal lobe abnormality.     

Introduction to the special issue on psychiatry in Asia

Abstract

Neuroimaging studies in schizophrenia help clarify the neural substrates underlying the pathogenesis of this neuropsychiatric disorder. Contemporary brain imaging in schizophrenia is predominated by magnetic resonance imaging (MRI)-based research approaches. This review focuses on the various imaging studies from India and their relevance to the understanding of brain abnormalities in schizophrenia. The existing studies are predominantly comprised of structural MRI reports involving region-of-interest and voxel-based morphometry approaches, magnetic resonance spectroscopy and single-photon emission computed tomography/positron emission tomography (SPECT/PET) studies. Most of these studies are significant in that they have evaluated antipsychotic-naïve schizophrenia patients – a relatively difficult population to obtain in contemporary research. Findings of these studies offer robust support to the existence of significant brain abnormalities at very early stages of the disorder. In addition, theoretically relevant relationships between these brain abnormalities and developmental aberrations suggest possible neurodevelopmental basis for these brain deficits.     

Fragile X syndrome and cerebral perfusion abnormalities: single-photon emission computed tomographic study

Fragile X syndrome is an inherited disorder caused by a defective gene on the X chromosome. It is associated with developmental or behavioral symptoms and various degrees of mental retardation. Morphologic abnormalities and altered perfusion of various brain areas can underlie these functional disturbances. The aim of this study was to investigate the cerebral perfusion state in patients with fragile X syndrome using single-photon emission computed tomography (SPECT). Structural and functional assessment was also performed by magnetic resonance imaging (MRI) and electroencephalography (EEG). Eight boys with cytogenetically confirmed fragile X syndrome (mean age 8.8 +/- 4.4 years, range 5-18 years), were included. All patients had mental retardation, with a mean IQ of 58.9 +/- 8.8 (range 40-68), and additional neurobehavioral symptoms. SPECT revealed cerebral perfusion abnormalities in six patients (75%), most commonly in the frontoparietotemporal area and prominent in the right hemisphere. The SPECT and EEG findings were concordant: hypoperfused areas in SPECT corresponded to regions of persistent slow-wave paroxysms on EEG. On the other hand, cranial MRI was abnormal qualitatively only in two patients (25%) showing cerebellar and vermal hypoplasia and cerebral hemispheric asymmetry. Our results indicate that cerebral perfusion abnormalities, which are correlated with electrophysiologic findings but not necessarily with anatomic abnormalities, can underlie the pathogenesis of the clinical findings observed in fragile X syndrome.     

Cerebral blood flow and oxygen metabolism in patients with vascular dementia of the Binswanger type

We performed clinical and neuroradiologic studies, including positron emission tomography, in five patients with vascular dementia of the Binswanger type. The clinical features of these cases consisted of slowly progressive dementia, together with vascular risk factors such as hypertension and often a history of minor stroke, and characteristic white matter lesions on brain computed tomograms or magnetic resonance images. Digital subtraction angiography of the cervical and intracranial arteries demonstrated no occlusive lesion in any patient. Both cerebral blood flow and the cerebral metabolic rate for oxygen were markedly reduced in the white matter (54-77% of control values), and both were decreased in the parietal (73% of control), frontal (74-80%), and temporal (74-83%) cortices, where no abnormalities were detected by brain computed tomography or magnetic resonance imaging. We conclude that vascular dementia of the Binswanger type may be caused by disconnection between the cerebral cortex and subcortical structures due to ischemic damage in the white matter.     

Symptomatic hyperperfusion after superficial temporal artery–middle cerebral artery anastomosis in a child with moyamoya disease

Object Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). It is undetermined, however, how rapid increase in CBF affects ischemic brain at acute stage, especially in children. Case report A 4-year-old girl with moyamoya disease underwent right superficial temporal artery–middle cerebral artery (STA–MCA) anastomosis. She suffered temporary left facial palsy 5 days after surgery. Postoperative N-isopropyl-p-[¹²³I]iodoamphetamine single-photon emission computed tomography (¹²³I-IMP-SPECT) revealed focal intense increase in CBF at the sites of anastomosis. Magnetic resonance imaging/angiography showed the apparently patent STA–MCA anastomosis as a thick high signal without ischemic changes. Her symptom improved 9 days after surgery, and single-photon emission computed tomography (SPECT) 2 months later showed normalization of CBF. Surgical revascularization completely relieved the transient ischemic attack on her left hand that was seen before surgery. Conclusion We demonstrated, for the first time, that delayed focal neurological deficit after STA–MCA anastomosis can be caused by focal hyperperfusion in childhood moyamoya disease.