Computed Tomography Lesions Research Articles

Memory complaints, memory disorders and focus localization in patients with partial epilepsy

Our study aimed at analysing effects of epileptic foci on memory function in patients with partial epilepsy. Twenty-eight patients with spontaneous memory complaints and psychometrically established memory disorders were assessed by 21-channel electroencephalography recorded both during cognitive testing and during 99mTc-HMPAO single photon emission computed tomography (SPECT). Computed tomography (CT) was performed on the same day. None of the epilepsy-related factors (seizure type, seizure frequency, type of epilepsy, age at onset of the seizures, type of antiepileptic treatment) could be related directly to severity or type of memory impairment (classified into the categories ‘global’, ‘verbal’ and ‘non-verbal’). Remarkably, this study found no significant relationship between EEG focus localization and severity of measured memory impairment. Most areas with hypoperfusion on the SPECT were found in the group with global (severe) amnesia, typically with a right frontal localization. Abnormalities on CT were predominantly found in the same group, however, with a right-sided parietal localization. An unanticipated finding was that the majority of temporal CT and SPECT lesions were found in the group with relatively better memory performance.

Vanishing CT lesions in epilepsy

Experience with computed tomography (CT) in patients with epilepsy has drawn attention to specific type of cerebral lesions widely prevalent in this part of the world. The lesions disappear spontaneously while patients receive only anticonvulsant therapy. The exact nature of these lesions is not yet understood. One-hundred and twenty-two such patients (M 77; F 45) were studied. Their age ranged from 3 to 57 (mean 21.8 ± 12.7) years. Seizures were partial motor in 86 (70.5%), generalised tonic clonic in 31 (25.4%), complex partial in 4 and atonic in one case. Postictal hemiparesis was seen in 6 patients who completely recovered within 5 min to 7 days. One hundred patients underwent EEG examination. It was abnormal in 84 cases; 40 patients showed localisation which correlated with CT findings. Plain CT showed low attenuation lesions in all cases. Morphology on contrast enhancement was ring lesion in 50 (40.9%), disc lesion in 47 (38.5%), target lesion in 3 (2.5%), mixed lesion in 2 (0.8%), no enhancement in 18 (14.8%) and a speck with oedema in 2 (0.8%) cases. All lesions were cerebral, present at cortical-subcortical junction. The first follow-up scan was performed in 78 (63.9%) patients within 6–12 weeks. It showed complete disappearance of the lesion in 47 (60.3%) cases. Reduction in size of the lesion and surrounding oedema was observed in 24 (30.8%) cases. The follow-up scans in these 24 cases revealed disappearance of lesion in 11 cases and almost complete resolution of the lesion with a remaining speck in 13 cases. Cerebrospinal fluid (CSF) was normal in 95 out of 100 cases in which it was performed. All patients received only antiepileptic drugs except 5 cases with unresolving lesions and ancillary evidence of tuberculosis who were given additional antitubercular chemotherapy. The vanishing CT lesions are unlikely to be a postictal phenomenon since these are rarely encountered in patients with seizures from the Western countries. These appear to be inflammatory and self-limiting in nature although they may not be due to single aetiology.

A correlative study of electroencephalography and computed tomography in partial complex seizures in adults

To further elucidate relationships between the EEG and computed tomography (CT) in partial complex seizures (PCS), we retrospectively reviewed the EEGs and CT scans in nonselected, predominantly male patients with refractory PCS. We further correlated EEG and CT results with clinical data. All 78 patients in the study had EEGs and CT scans. The time span between the two procedures was 6 months or less. The ages of the patients ranged from 25 to 80, with an average of 51 years. Seizure chronicity ranged from 1 to 60 years, with an average of 15 years. Statistical analysis revealed a trend for unilateral CT and EEG abnormalities to be on the same side. There was no significant relationship between the location of abnormalities on EEG and on CT. The greatest degree of disagreement between CT and EEG occurred in patients with normal findings or diffuse atrophy on CT. There was no significant difference in the age between groups defined by different EEG categories (normal, right-sided, left-sided, or bilateral). The average age of patients with bilateral CT lesions was greater than that of patients with other CT lesions. This observation may reflect the influence of aging rather than the epileptic process on CT findings in PCS. We conclude that surface EEG and neuroimaging measure complementary aspects of cerebral pathology in PCS.

Disappearing CT lesions in epilepsy.

A striking but reversible computed tomographic (CT) lesion corresponding to seizure activity is reported in a series of 46 epileptic patients. None of these patients had evidence of tuberculosis or cysticercosis, and all were treated with antiepileptic drugs only. Maximal radiological changes occurred in the area of maximal epileptic discharge; however, multiple lesions were seen in three cases. The CT lesion reappeared with recurrence of the ictus in four cases during follow-up, and this, too, disappeared after complete arrest of the seizures. The clinical, CT scan, and other investigatory findings suggest that the seizures may occasionally cause a CT-demonstrable focal abnormality, probably cerebral edema, a consequence of abnormal vascular permeability. Awareness of this radiological entity should avoid misdiagnosis of cerebral tumor, infarction or tuberculoma in patients with seizure disorder.

Influence of lesions detected by computed tomography on outcome and neuropsychological recovery after severe head injury.

Outcome at 6 months after severe head injury was determined in 117 patients whose computed tomographic (CT) examinations demonstrated diffuse axonal injury (DAI), diffuse swelling (DS), or focal injuries. Neuropsychological sequelae were ascertained from two examinations in 30 of the conscious survivors within the 1st year after injury. Outcome differences varied with the type of CT lesion. DS and focal injuries resulted in more favorable (good recovery) outcomes. Mortality was higher after DAI. Neuropsychological outcome varied with the type of CT lesion and the function measured. Overall differences in memory and learning were revealed among the three CT lesion categories, whereas differences in intelligence and visuomotor functions were not significant. Levels of memory, learning, and visuomotor speed were higher after DS injuries, but improvement was less. Greater improvement of memory, learning, and visuomotor speed occurred after DAI. After focal injuries, visuomotor speed improved, but not recall and learning. The results suggest that the type of injury incurred differentially influences the outcome and the neuropsychological aftermath of severely head-injured adults.

Die Single-Photon- Emissionstomographie (SPECT) mit 123J-Amphetamin bei zerebralen ischämischen Durchblutungsstörungen

The uptake of 123l-amphetamine (IMP) in brain mainly corresponds to regional perfusion. Distribution of IMP can be visualized in tomographic slices by single-photon emission computed tomography (SPECT). For better evaluation and comparison in follow-up studies, right/left ratios were computed and an asymmetry index calculated. The most sensitive asymmetry index was achieved by 120 average circumferential profiles. In 52 patients with stroke and 16 controls the respective sensitivities of IMP-SPECT, computed tomography (CT), static and dynamic brain scanning and angiography were evaluated. In patients with TIA and PRIND the IMP-SPECT had the highest sensitivity of all non-invasive methods. In patients with completed stroke, the sensitivity of IMP-SPECT was comparable with that of CT (90 vs. 93%). There was a significant correlation between the IMP asymmetry index and the clinical and social score (p <0.001). The IMP asymmetry index was significantly correlated to the size of the CT lesion (p <0.001). In most patients, the size of the IMP lesion was larger than that of CT. In a prospective study, 28 patients with completed stroke were examined. 14 patients underwent surgical treatment (6 endarterectomies, 5 EIA, 3 combined operations), 14 patients had medical treatment only. Both groups were reexamined after 10 and 6.5 months, respectively. In both groups, neither the IMP asymmetry index nor the size of the CT lesion were changed, but the clinical and social scores improved (p <0.01). The outcome in both groups was the same. A positive effect of surgery could not be demonstrated.

Striatal Aphasia : Clinical-CTscan Correlation and Prognosis

Fourteen patients with subcortical aphasia secondary to vascular lesions predominantly in the basal ganglia were demonstrated on computed tomographic (CT) scans and studied. The results obtained were as follows : 1) clinical features ; At the onset, the speech disorders rainged from muteness, Broca's aphasia, transcortical motor aphasia with severe dysarthria and diminished motivation to a mild Wernicke aphasia. In the course of recovery, however, relativeiy homogeneous aphasic symptoms were observed. In spite of the nonfluent speech output of some patients, the predominant aphasia pattern for these fourteen cases was that of good grammatical structures and long phrase lengths with prominent paraphasias. Auditory comprehention was relatively good. Nonparaphasic repetition and reading comprehention were the best preserved functions. Confrontation naming and writing were variably impaired. 2) CT lesions ; The difference in lesion volume between cases was relatively large. All of these lesions were deep but some were not subcortical, because they involved the insular cortex. In many cases, they were truly subcortical and confined to the left basal ganglia and neighboring white matter. The common lesion in all patients was in the putamen. 3) prognosis ; The average recovery rate based on serial testing with the Standard Language Test of Aphasia (initial and 3 months later) was significantly higher than any other aphasic group. On the basis of these findings, we suggested that the separate aphasic syndrome of these cases could be defined as “striatal” aphasia or “putaminal” aphasia.

Local Cerebral Blood Flow Mapping by SPECT of N-isopropyl-p-[<SUP>123</SUP>I] Iodoamphetamine in Comparison with <SUP>81m</SUP>Kr Image

Local cerebral blood flow in 28 patients (aged from 13 to 71) with cerebrovascular disorders was studied 37 times by single photon emission computed tomography (SPECT) using N-isopropyl-p-[123I] iodoamphetamine (IMP), and compared with findings of X-ray computed tomography (CT) and 81mKr (Kr) perfusion images. There were three patients with occlusion of the internal carotid artery, two with stenosis of the internal carotid artery, six with occlusion of the middle cerebral artery, five with occlusion of the bilateral vertebral arteries, five with moyamoya disease, two with aortitis syndrome, and five with cerebral arteriovenous malformation. Examinations were performed using a rotating gamma camera with dual heads in both SPECT-IMP and SPECT-Kr. In the IMP study, both SPECT and planar images were obtained 30 and 120 minutes after intravenous injection of IMP. SPECT-Kr was performed by continuous infusion into the ascending aorta of 81mKr generated by an 81Rb-81mKr generator. Sampling time was about 20 minutes in 22 examinations and about 10 minutes in 15 examinations by SPECT-IMP, and about 4 minutes in all the examinations by SPECT-Kr. SPECT-IMP images 30 minutes after injection showed low perfusion area in all but four examinations in three patients: one patient with transient ischemic attack alone and two patients with aortitis syndrome. In 26 of the 33 examinations, SPECT-IMP images 30 minutes after injection revealed more extensive or obvious low perfusion areas than the low density lesions in X-ray CT, and low perfusion even in the areas without low density lesions. In all of the 33 examinations, low perfusion areas shown in SPECT-IMP images 30 minutes after injection became obscure after 120 minutes. In respect to representation of local cerebral blood flow, SPECT-IMP images 30 minutes after injection seemed to be better than after 120 minutes. In 26 of the 33 examinations, low perfusion areas in SPECT-Kr images were more extensive and obvious than in SPECT-IMP images. However, SPECT-IMP images seemed to show a more definite anatomy than SPECT-Kr images. The nidus of a cerebral arteriovenous malformation was shown to be a low perfusion area in SPECT-IMP images, but appeared as a high perfusion area in SPECT-Kr images. It is likely that SPECT-Kr images showed mainly intravascular flow of the nidus. In comparison with SPECT-Kr, SPELT-IMP was considered to be an easy and noninvasive three dimensional study of local cerebral blood flow.

Computed Tomography and EEG in Patients Without Focal Neurologic Findings

We studied 136 patients without focal neurologic findings by EEG and computed tomographic (CT) scanning. Six patients (4.4%) had focal CT lesions. All six had abnormal EEGs, and in four the EEG findings were focal. The initial complaint did not influence the yield of focal CT lesions. The findings suggest that neurologic examination and EEG can be used to screen for focal CT abnormalities.