Regional cerebral blood flow measurements with Xenon-CT in the prediction of delayed encephalopathy after carbon monoxide intoxication

Reported evaluations of CBF with Xe/CT were performed in 11 patients during the lucid interval following CO intoxication. Results were compared with clinical and SPECT data. Two patients developed neuropsychiatric behavior (delayed encephalopathy) one month following the initial recovery. The symptoms persisted in one of them 15 months later. Their CBF values as well as those in most of the other patients, monitored at the basal ganglia and white matter areas, were in relation with the clinical outcome, However, further studies with a larger number of patients, are needed to confirm the predictive significance of Xe/CT measurements for the long term sequelae of CO poisoning.

Chronic elemental mercury intoxication: neuropsychological follow-up case study

In initial and follow-up investigations of neuropsychological function in a patient with elemental mercury intoxication, his scores were compared with those of a group of normal control subjects matched for sex, age and education. Each subject received a comprehensive neuropsychological examination including a personality inventory. On the initial examination the results indicated that the patient had a significant depression of performance intellectual functioning, impairments of attention, non-verbal short-term memory and visual judgement of angles and directions, psychomotor retardation and personality changes including depression, anxiety, desire to be alone, lack of interest and sensitivity to physical problems. Such an impairment picture is compatible with the previous observations of individuals with chronic exposure to elemental, organic or inorganic mercury. The follow-up study was undertaken about 1.5 years later. The results show that the patient's cognitive and personality functions were fully recovered. Our findings thus suggest a reversibility of impaired neuropsychological function in persons with elemental mercury poisoning if a prompt removal from the toxic environment is accomplished, together with proper medical treatment.

Reinduction of hyponatremia improves survival in rats with myelinolysis-related neurologic symptoms

Brain myelinolysis occurs after excessive correction (delta SNa > 20 mEq/1/24 hours) of chronic hyponatremia. However, we showed recently that the mechanisms leading to brain myelinolysis remain reversible. Indeed, reinduction of the hyponatremia by water administration despite 12 hours of sustained excessive correction could prevent the development of demyelination in rats still asymptomatic at that time. Whether this therapeutic maneuver could be also beneficial to rats with preexisting myelinolysis-related neurologic symptoms is unknown. Therefore we evaluated here the effect of reinduction of the hyponatremia on the survival and on brain damage in rats presenting obvious neurologic symptoms after excessive correction of hyponatremia. After 3 days of severe hyponatremia induced by 2.5 D-glucose in water and continuous infusion of AVP, rats were submitted to a large correction (delta SNa approximately 30 mEq/l) by 2 i.p. injections of hypertonic saline given over 24 hours. In group I (n = 15) the rats developing neurologic symptoms during the first 24 hours of correction received one i.p. injection of distilled water which rapidly decreased the natremia to a final correction gradient <20 mEq/l/24 hour. In group II (n = 13, controls) the symptomatic rats were left permanently overcorrected. In group I, after water administration, the neurological manifestations were generally attenuated or disappeared. Seven of the 15 rats (47%) in this group survived up to day 10 with a mean survival time of 7.5 +/- 2 days, an outcome clearly improved as compared to group II (controls): only 1 of the 13 rats (7%, p < 0.03) was still alive on day 10 and the mean survival time was 3.3 +/- 2 days (p < 0.001) in this group II. The duration of the symptoms also influences the prognosis. In group I, in 9 rats the water administration was performed 4 hours after symptoms onset. These rats had a better outcome than the 6 rats with more sustained (8-10 hours) neurologic symptoms before water loading. Brain analysis in the 7 surviving rats of group I demonstrated demyelinating lesions in only 2 of them, suggesting the reversibility of the process even when neurologic manifestation developed. In conclusion, after exposure to an excessive correction of chronic hyponatremia, even when rats have developed myelinolysis-related neurologic symptoms, hypotonic fluids administration could improve survival and could prevent the subsequent development of brain myelinolysis.

A neurological dissociation between shape from shading and shape from edges

We studied the ability of a neurological patient, who has deficits in various aspects of form perception, to perform region segregation tasks requiring discriminations based on several image properties that are related to the three-dimensional structure of objects. The patient could discriminate the apparent three-dimensional structure and orientation of shapes defined by shading gradients, but could not make such discriminations for shapes in which edges were depicted as lines or as luminance discontinuities. These results suggest that the neural pathways that compute shape from shading gradients may be independent of those that compute shape based on edges, and, based on the patient's pattern of brain damage, they also indicate a relatively early functional separation in the requisite inputs.

Cannabis and the brain

OBJECTIVE

The aim of the paper is to review the effects of Cannabis sativa on the human brain.

METHOD

A selective literature review was undertaken.

RESULTS/CONCLUSIONS

Cannabis sativa causes an acute and, with regular heavy ingestion, a subacute encephalopathy. There is no evidence of irreversible cerebral damage resulting from its use, although impairment of information processing might be a long-term consequence of heavy prolonged use. The precise relationship of cannabis to the functional psychoses such as schizophrenia has yet to be clarified.

Cortical hyperintensity on proton density-weighted images: An MR sign of cyclosporine-related encephalopathy

PURPOSE

To describe cortical hyperintensities in proton density-weighted images in six patients with presumed cyclosporine-induced neurotoxicity.

METHODS

In six patients with clinical evidence of cyclosporine-related encephalopathy, MR imaging was performed after the onset of symptoms and signs (mean, 24 days after liver transplantation). Five of these patients had serial MR imaging for a period that varied from 2 to 20 months. Along with the imaging studies, the patients' clinical status was evaluated and various laboratory parameters, including blood pressure and levels of cyclosporine, cholesterol, and magnesium, were monitored.

RESULTS

In all six patients, initial MR studies showed hyperintensity of several cerebral gyri that was unequivocal only on proton density-weighted images. Although in five patients these signal abnormalities were limited to the cortex, one patient had increased signal in the subjacent white matter as well. In one patient, the images were also remarkable for areas of cortical hyperintensities on T1-weighted images. In another patient, cortical enhancement occurred after administration of gadopentetate dimeglumine, with a normal cortical signal on the precontrast images. The abnormal cortical signal began to fade after cyclosporine reduction, but in two patients it remained visible for at least 20 months. The neurologic symptomatology associated with cyclosporine-induced neurotoxicity included seizures (three patients), speech disorder (three patients), and disturbance of consciousness (three patients).

CONCLUSION

Cyclosporine-induced neurotoxicity occurring in patients after liver transplantation appears to affect the cerebral cortex preferentially. Because its MR equivalent resembles changes resulting from hypoxic injury or cortically centered vasculitis, we suspect the underlying mechanism may be a vascular injury that results in cortical hypoperfusion.

MR in trichloroethane poisoning

We present a case of acute trichloroethane intoxication caused by inhalation of typewriter correction fluid. CT and MR findings revealed lesions in the basal ganglia and cortex similar to those observed in patients with methanol and carbon monoxide poisoning.

Carmofur-induced leukoencephalopathy: MRI

Carmofur, a derivative of 5-fluorouracil, has recently been noted to have an infrequent but serious association with leukoencephalopathy. To our knowledge, there has been no report of early MRI findings in this leukoencephalopathy. We describe a case in which diffuse high signal intensity of the entire cerebral white matter, including the corpus callosum, was seen on T2-weighted magnetic resonance images. Although similar findings can be seen in many other diseases, carmofur-induced leukoencephalopathy should be suspected in a patient treated with carmofur. It is important to know the clinical and MRI characteristics of this condition, for early diagnosis and better prognosis.

Focal cerebral ischemia during anesthesia with etomidate, isoflurane, or thiopental: a comparison of the extent of cerebral injury

An investigation was performed to compare the cerebral protective properties of etomidate, isoflurane, and thiopental. In separate groups of spontaneously hypertensive rats, etomidate, isoflurane, or thiopental was administered to achieve and maintain burst-suppression of the electroencephalogram (3-5 bursts/min) for the duration of the experiment. A fourth group received 1.2 minimal alveolar concentration halothane. All groups underwent 3 hours of middle cerebral artery occlusion and then 2 hours of reperfusion. Thereafter, the animals were killed and the volume of injured brain was determined by staining with 2,3,5-triphenyltetrazolium. Physiological parameters did not differ among the four groups during the investigation, with the exception that hemolysis occurred in the etomidate group (free hemoglobin levels, approximately 0.4 g.dl-1). The volume of injured brain in the thiopental group (56 +/- 10 mm3) was significantly smaller than that in the halothane control group (99 +/- 13 mm3). The volumes of injured brain in the etomidate and isoflurane groups (145 +/- 11 mm3 and 139 +/- 14 mm3, respectively) were significantly larger than those in the control and thiopental groups. We speculate that the apparently detrimental effect of etomidate may be the result of the binding of nitric oxide of cerebral endothelial origin by the iron component of free hemoglobin. Intracranial pressure was not recorded, and in the isoflurane group, there may have been adverse effects on cerebral perfusion pressure associated with vasodilation caused by high concentrations of isoflurane. The results are consistent with a protective effect by barbiturates.

Cerebral and cerebellar diaschisis following carbamazepine therapy

1. The regional cerebral blood flow was studied by SPECT in patients with partial epilepsy before and after 30 days of monotherapy with carbamazepine (CBZ). 2. Both a qualitative visual interpretation and a semiquantitative analysis of SPECT was performed. All patients underwent EEG, CT scan, and MRI studies. The CBZ serum concentrations were assayed. 3. After therapy, in three patients with focal epilepsy, both a crossed cerebral and cerebellar diaschisis were observed, with respect to the side of the epileptic focus in the opposite hemisphere. No morphologic changes were detected at MRI in the cerebral or cerebellar remote hypometabolic areas found at SPECT. 4. CBZ may have a depressant action on the corticopontocerebellar pathways and on the corticocallosal connections.

White matter changes caused by chronic solvent abuse

PURPOSE

To examine the brain damage of solvent abusers in Japan, where pure industrial toluene is frequently abused.

METHODS

Twenty solvent abusers 17 to 33 years of age with 7.2 +/- 4.0 years of abuse were examined with a 1.5-T MR imaging system.

RESULTS

White matter hyperintensities in cerebrum, brain stem, and cerebellum on T2-weighted images were found in seven cases. The extent of white matter change was most clearly shown on proton density-weighted images. The patients with restricted white matter change and intermediate white matter change showed white matter hyperintensities in the brain stem and cerebellum on T2-weighted images, in some cases, with additional hypointensities in the corresponding T1-weighted images. These patients had mainly abused pure toluene. The patients with diffuse white matter change showed obvious brain atrophy, including hippocampal atrophy and thinning of the corpus callosum. These patients had mainly abused lacquer thinner.

CONCLUSION

There are some patients with restricted but severe enough change to cause the neurologic symptoms in specific regions, such as the brain stem and/or cerebellum, before the brain atrophy becomes apparent. This suggests that the restricted white matter change represents not only an early change of diffuse white matter change, but at least in some cases also represents a qualitatively different change than that of diffuse white matter change. We suggest that pure toluene has a possible relation to this qualitative difference.

Neurobehavioral effects of developmental methylmercury exposure

Methylmercury (MeHg) is a global environmental problem and is listed by the International Program of Chemical Safety as one of the six most dangerous chemicals in the world's environment. Human exposure to MeHg primarily occurs through the consumption of contaminated food such as fish, although catastrophic exposures due to industrial pollution have occurred. The fetus is particularly sensitive to MeHg exposure and adverse effects on infant development have been associated with levels of exposure that result in few, if any, signs of maternal clinical illness or toxicity. High levels of prenatal exposure in humans result in neurobehavioral effects such as cerebral palsy and severe mental retardation. Prenatal exposure to MeHg in communities with chronic low-level exposure is related to decreased birthweight and early sensorimotor dysfunction such as delayed onset of walking. Neurobehavioral alterations have also been documented in studies with nonhuman primates and rodents. Available information on the developmental neurotoxic effects of MeHg, particularly the neurobehavioral effects, indicates that the fetus and infant are more sensitive to adverse effects of MeHg. It is therefore recommended that pregnant women and women of childbearing age be strongly advised to limit their exposure to potential sources of MeHg. Based on results from human and animal studies on the developmental neurotoxic effects of methylmercury, the accepted reference dose should be lowered to 0.025 to 0.06 MeHg microgram/kg/day. Continued research on the neurotoxic effects associated with low level developmental exposure is needed.

Cranial MRI in chronic thinner intoxication

We studied a 19-year-old man with thinner and toluene poisoning for 5 years by CT and MRI. Symmetrical lesions were seen in the basal ganglia and cingulate gyri.

Leukoencephalopathy in childhood hematopoietic neoplasm caused by moderate-dose methotrexate and prophylactic cranial radiotherapy--an MR analysis

PURPOSE

The main purpose of this study was to determine influential factors related to minor leukoencephalopathy (LEP) caused by moderate-dose methotrexate (MTX) and prophylactic cranial radiotherapy (CRT) in childhood hematopoietic malignancies. We also compared the incidence of LEP following this treatment to that reported in the literature following treatment with high-dose MTX alone.

METHODS AND MATERIALS

Thirty-eight pediatric patients of hematopoietic malignancies (37 acute lymphoblastic leukemias, 1 non-Hodgkin lymphoma) who were given CRT (18-24 Gy) as well as prophylactic intrathecal and per os MTX were studied for leukoencephalopathy by magnetic resonance (MR) imaging. All the patients were free from grave neuropsychiatric disturbances. The data were examined to elucidate the influential ones of five factors (patients' age, doses of intrathecal and per os MTX, dose of CRT, interval between treatment, and MR study) to develop LEP using multiple regression analysis. To compare the effect of moderate-dose MTX and prophylactic CRT on LEP to that of high-dose MTX alone, we conducted literature review.

RESULTS

Seven out of 38 patients (18%) developed LEP. From multiple regression analysis and partial correlation coefficients, the age and CRT dose seemed influential in the subsequent development of LEP. The incidence of LEP following treatment with moderate-dose MTX and prophylactic CRT appears to be less than that reported in the literature following treatment with intravenous high-dose MTX. However, even moderate-dose MTX in combination with CRT can result in a significant incidence of MR-detectable LEP, particularly in children 6 years of age or younger receiving 24 Gy.

CONCLUSION

Leukoencephalopathy was caused by moderate-dose MTX and prophylactic CRT in pediatric patients, probably less frequently than by high-dose MTX treatment alone. The influential factors were patient's age and CRT dose.

[Late effects of occupational organic brain damage in painters 6-8 years after diagnosis. Occurrence of mental and psychosomatic health problems and utilization of health services]

With the object of illustrating effects on health and social functions of occupational organic brain damage, a questionnaire study was carried out in 1986 concerning 192 brain-damaged painters and a reference group of 341 other painters. The study was repeated in 1990 to elucidate effects six to eight years after diagnosis. In 1986 a high prevalence of mental and psychosomatic symptoms was found among the brain-damaged painters. The prevalence correlated with severity of the disease, occupational situation and social network. In 1990 the same level of symptoms was found. In the reference group the prevalence of symptoms increased from 1986 to 1990. Besides the major difference in the prevalence of symptoms between the two groups, the level of symptoms correlated to the occupational situation in both groups. Twenty-seven percent of the brain-damaged painters were still at work in 1990. The high symptom level among the brain-damaged painters is considered to be chronic.

Mechanisms in the induction of neuronal heterotopiae following prenatal cytotoxic brain damage

Prenatal exposure to several neuroteratogens, such as ionizing radiation, ethanol, and cytotoxic drugs, induces the development of clusters of abnormally positioned neurons within the brain. These abnormalities have always been presumed to result from interference with normal neuronal migration, presumably via effects on radial glia. In our study, pregnant rats were injected with methylazoxymethanol acetate (MAM) on either E13, E14, or E15. Computerised reconstruction techniques, Golgi and immunocytochemical staining as well as electron microscopy were used to detect structural abnormalities of radial glia which might be responsible for the production of heterotopiae. Several structural abnormalities such as microcavitation, involvement of radial glial elements in rosettes, disturbance of the normal ventricular lining, and disruption of the attachment of radial glial endfeet to the pial surface were identified. We propose that periventricular heterotopiae result from disruption of the palisade arrangement of neuroepithelial cells in the ventricular zone and the involvement of radial glial elements in rosettes. Layer I heterotopiae may arise from abnormalities of the distal segments of radial glia and their attachment to the pia. No prenatal abnormalities in radial glia of the hippocampus were noted following MAM exposure at any of the 3 ages, consistent with the proposition that hippocampal heterotopiae arise by postnatal movements of pyramidal neurons without radial glial involvement.

Multiple choice vocabulary test MWT as a valid and short test to estimate premorbid intelligence

The discrepancy between current and premorbid ability is a relevant indicator of acquired mental impairment, which itself is closely related to general cerebral dysfunction. The use of tests sensitive to cerebral dysfunction, raises relatively few problems compared with tests being resistant that are used to estimate premorbid mental ability. For premorbid ability, verbal tests assessing knowledge, especially vocabulary, have been shown to be valid. A test, possibly more insensitive to brain dysfunction than the ones usually administered, is the multiple choice vocabulary test (MWT = Mehrfachwahl-Wortschatz-Test). At present only German versions are available. They are presented in some detail because of their advantages. Construction of the MWT is simple, and it can be easily administered in about five minutes. The results correlate fairly well with global IQ in healthy adults (median of r = 0.72 in 22 samples) and are more insensitive to current disturbances than such tests as the WAIS vocabulary test. The limitations of premorbid tests with respect to diagnostic validity are discussed. It is concluded, that studies which do not control premorbid intelligence have to be considered as a "malpractice" and should not be accepted by scientists.

Congenital brain damage spares the basic patterns of parental behavior in affected mice

Pregnant albino mice were treated with 5-azacytidine so that the embryonic brains were affected late in their morphological ontogeny. The offspring showed retarded body growth and a conspicuous reduction in the size of the cerebral hemispheres as measured at the end of development. Histological alterations were found in the hippocampus and the cingulate cortex. No behavioral alterations were detected during development, with the exception of the hyperactivity which probably caused the better performance of treated offspring observed in a self-feeding test. This functional abnormality, attributed by previous authors to retardation in telencephalic development, persisted into adulthood. The parental behavior of virgin females towards a weak stimulus-object was robust. Treated subjects were non-neophobic, seldom aggressive and showed clearcut parental responses. In addition, although the frequency of overall parental tendency was lower in the treated subjects, it gradually approached that of the controls across repeated trials. The brain structures affected by this treatment seem influential on behavioral organization and habituation to novelty, not on basic patterns of behavior, which are probably rooted in phylogenetically more ancient structures.

MR of toxic effects of accelerated fractionation radiation therapy and carboplatin chemotherapy for malignant gliomas

PURPOSE

To present MR findings of parenchymal brain injury after accelerated fractionation radiation therapy combined with carboplatin chemotherapy in the treatment of malignant brain gliomas.

METHODS

Eighty-one evaluable subjects in an ongoing treatment protocol for malignant gliomas form the patient base for this report. After surgical resection of tumors, patients underwent a course of accelerated fractionation radiation therapy to a total dose of 60 Gy. Carboplatin was infused intravenously before each radiation treatment. Precontrast and postcontrast MR scans were obtained before treatment and at 4-week intervals afterward and were analyzed retrospectively.

RESULTS

Posttreatment MR imaging in 20 of the 81 patients showed development of unusual parenchymal lesions or enlarging masses needing debulking, and these patients underwent second operations. Two groups emerged: those with tumor and necrotic brain (n = 11) and those with necrosis and reactive gliosis but no definitive tumor (n = 9). Enhancing lesions in the tumor-negative group appeared later than those in the tumor-positive group, were often multiple, and were usually located several centimeters away from the tumor resection site or even contralaterally. Common locations were the corpus callosum and corticomedullary junctions. Lesions in the tumor-positive group were more often solitary and located immediately adjacent to the surgical site. Positive and negative results of positron emission tomography with fludeoxyglucose F 18 were obtained in both groups. The incidence of brain necrosis without associated tumor was 11%.

CONCLUSIONS

A pattern of unusual enhancing parenchymal brain lesions was seen on MR imaging after accelerated fractionation radiation therapy and concomitant carboplatin chemotherapy. The abnormalities seem more extensive than focal necrotic lesions on enhanced CT or MR imaging after conventional radiation therapy, and they may mimic recurrent tumor.

The residual neuropsychological effects of cannabis: the current status of research

Evidence for the residual neuropsychological effects of cannabis must first be separated from evidence regarding (i) the acute effects of the drug, (ii) attributes of heavy cannabis users, and (iii) actual psychiatric disorders caused or exacerbated by cannabis. The remaining evidence must then be subdivided into (a) data supporting a 'drug residue' effect during the 12-24 h period immediately after acute intoxication and (b) data suggesting a more lasting toxic effect on the central nervous system which persists even after all drug residue has left the system. We reviewed the literature, comparing both 'drug-administration' studies in which known amounts of cannabis were administered to volunteers, and 'naturalistic studies' in which heavy marijuana users were tested after some period of abstinence. The data support a 'drug residue' effect on attention, psychomotor tasks, and short-term memory during the 12-24 h period immediately after cannabis use, but evidence is as yet insufficient to support or refute either a more prolonged 'drug residue' effect, or a toxic effect on the central nervous system that persists even after drug residues have left the body. We describe possible study designs to address these latter questions.

MR and cognitive testing of patients undergoing osmotic blood-brain barrier disruption with intraarterial chemotherapy

PURPOSE

To determine whether osmotic blood-brain barrier disruption is associated with MR abnormalities or cognitive deterioration and, if so, whether the MR findings correlate with cognitive test results.

METHODS

Fifteen brain tumor patients who had a complete tumor response (nine central nervous system lymphoma, three germ cell and two astrocytoma, and one primitive neuroectodermal tumor) treated with blood-brain barrier disruption procedures (318 total procedures) with intraarterial chemotherapy were included. MR images were evaluated for the development of white matter hyperintensity, vascular lesions, or atrophy. Cognitive testing was performed to assess deterioration caused by this therapy.

RESULTS

In two patients white matter hyperintensity developed, in two small vascular lesions developed, and in one mild atrophy developed. One infarct was asymptomatic and the second one resulted in mild dysesthesia in one upper extremity. No patient showed diminished cognitive function on the posttherapy evaluation.

CONCLUSION

In patients undergoing blood-brain barrier disruption with intraarterial chemotherapy, new abnormalities on MR imaging may develop. These patients maintain the same level of cognitive and neurologic function and MR findings do not correlate with the results of cognitive testing.

Lack of involvement of nitric oxide in the mechanisms of seizures and hippocampal damage produced by kainate and ouabain in rats

The gross behavioural, electrocortical and neuropathological effects of kainate (10 mg/kg i.p,) and ouabain (1 micrograms, given into one dorsal hippocampus) were studied in rats. The effects of these treatments on nitric oxide synthase (NOS) activity in homogenates of hippocampus and cortex were also studied. Administration of kainate or ouabain produced motor and electrocortical seizures similar for latency to onset (approximately 15 min) and intensity (in all instances 80-100% of the treated rats showed behavioural and electrographic seizures). These effects were accompanied at 24 h by severe damage to all subsectors of the hippocampal formation and this concerned a similar proportion of the treated rats (n = 4-8 per treatment). No significant changes in nitric oxide synthase (NOS) activity were noted in the cerebral cortex and hippocampus of rats receiving injections of kainate and ouabain. In addition, pretreatment with N omega-Nitro-L-arginine methyl ester (300 micrograms, given into one lateral cerebral ventricle 15 min previously) was ineffective in preventing the effects of kainate and ouabain. In conclusion, present data suggest that excessive production of NO is not involved in the mechanisms triggering seizures and neurodegeneration produced by kainate or ouabain.