Neuropathological Findings in Ephedrone Encephalopathy.

BACKGROUND: A number of cases of severe parkinsonism-dystonia have been recognized and reported following the illicit use of ephedrone prepared from pseudoephedrine and potassium permanganate. The pathology associated with ephedrone neurotoxicity has not been described yet in the scientific literature. OBJECTIVES: To report the first neuropathological study of ephedrone toxicity. METHODS: The brain of a 33-year-old Ukrainian female ex-ephedrone addict with a long history of l-dopa-unresponsive parkinsonism with dysarthria, dystonia, profound postural instability, cock-gait, and frequent falls, and on antiretroviral treatment, was examined using routine stains and immunohistochemistry. RESULTS: Neuropathological findings included diffuse pallidal astrogliosis without neuronal depletion. There was also widespread vascular pathology with small vessels occluded by foreign material, associated with giant cell response without any evidence of consequent focal infarction and a cerebellar abscess. CONCLUSIONS: Clinical findings of l-dopa-unresponsive parkinsonism with dystonia, caused by illicit use of ephedrone, are fully consistent with neuropathological changes in the pallidum, lack of change in the SN, and preserved tyrosine hydroxylase activity. The findings in the basal ganglia are compatible with manganese toxicity. The vascular pathology is likely a joint effect of infection and the ephedrone toxicity on the vessels. © 2020 International Parkinson and Movement Disorder Society.

Ultrastructural changes in microvessels in familial hemiplegic migraine with CACNA1A mutation.

AIMS: Familial hemiplegic migraine type 1 (FHM1) due to mutations in the CACNA1A gene is known as functional vascular disorder with cerebellar atrophy. We describe a case of a FHM1 family in which pathological changes occurred in both brain neuroimaging and skin and muscle biopsy. MATERIALS AND METHODS: In 5 of 18 affected family members, brain MRI scans revealed hyperintense changes in the cerebral white matter. In 2 of these 5 patients, skin and muscle biopsies were performed at the interictal period of the disease and examined under light and transmission electron microscopy. RESULTS: Ultrastructural examination of the biopsy samples revealed abnormal appearance of microvessels resembling oncosis. In the affected vessels, endothelial cells and myocytes/pericytes showed clear cytoplasm, distended endoplasmic reticulum, enlarged mitochondria, and numerous intracytoplasmic vesicular structures. Swollen endothelial cells often significantly narrowed vessel lumen. CONCLUSION: The morphological changes described for the first time in FHM1 suggest that the disease may not only be a functional, but also a structural vascular disorder. We suggest that the presence of these vascular abnormalities can interfere with microcirculation causing damage to the cerebral white matter, visible in MRI scans as hyperintense changes.
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Nuclear abnormalities in vascular myocytes in cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a stroke and dementia syndrome with degeneration and loss of vascular smooth muscle cells (VSMCs). The disease is due to mutations in NOTCH3 playing an important role in VSMC differentiation, proliferation and apoptosis. Searching for a possible cause of VSMC dysfunction in CADASIL, we investigated morphology and proliferative activity the affected myocytes. In material from autopsy brains and skin-muscle biopsies of patients with CADASIL diagnosis, assessment of VSMCs in arterial vessels at the level of light and electron microscopy was performed. Proliferative activity of VSMCs was evaluated in immune reactions to proliferative markers: proliferating cell nuclear antigen, and cyclins B1 and D. In CADASIL, abnormal morphology of VSMC nuclei was observed in 18.1%, 11.5%, and 6.9% of the cerebral, skin, and skeletal muscle vessels, respectively. The affected myocytes showed variability in nuclear size, irregularity in nuclear shape, and abnormal chromatin appearance. Frequently, double nuclei of equal size or micronuclei were observed. Sometimes, even multinuclear myocytes were found. In some of the nuclei immune reactions to the examined proliferative markers were positive. Aberrant structure and number of VSCM nuclei, and their immunoreactivity to proliferative markers suggest mitotic instability of vascular myocytes in CADASIL. We speculate that mutant NOTCH3 which is unable to control properly VSMC proliferation, and may be responsible for their premature or inappropriate entry into mitosis, irreversible arrest of the cell cycle, senescence or degeneration and loss.

Cerebral amyloid angiopathy-related inflammation - A case report presenting diagnostic difficulties.

We describe an 86-year-old woman with a history of hypertension who presented sudden disturbances of consciousness and left hemiparesis. Brain magnetic resonance imaging (MRI) revealed diffused hyperintensive changes on T2-weighted images localized subcortically in the white matter of both cerebral hemispheres, corresponding to acute vasogenic edema, causing moderate mass effect. Posterior reversible encephalopathy syndrome was initially diagnosed. After implementation of anti-edema intravenous steroid treatment and hypotensive therapy the symptoms began to retire, till the total regression. The successive hospitalizations took place two and eight months later due to the occurrence of seizures, motor deficits and the development of mild cognitive impairment. Brain MRI revealed progression of the white matter changes and diffused subcortical microhemorrhages. Each time pulse steroid therapy was implemented and the symptoms improved significantly after several days. Chronic oral steroid treatment resulted in the stabilization of neurological status. The long-term observation of clinical symptoms, remission after immunosuppressive therapy and white matter changes with subcortical microhemorrhages in brain MRI leaded to the diagnosis of cerebral amyloid angiopathy-related inflammation.

Identification of the first in Poland CACNA1A gene mutation in familial hemiplegic migraine. Case report.

INTRODUCTION: Migraine is a common neurological disorder characterized by a particular phenotype, complex pathophysiology and a heterogeneous genetic background. Among several heritable forms, familial hemiplegic migraine is the best described one. In the majority of cases it is caused by mutations in one of three different genes. CASE REPORT: Clinical symptoms of a 47 year old proband (and independently described in his 20 year old son) as well as differential diagnosis are discussed in the presented report. The most characteristic were recurrent attacks of blurred vision, paresthesias and hemiparesis often accompanied by speech disturbances and followed by severe headache with vomiting. Advanced morphological and genetic procedures were required to exclude MELAS, CADASIL and Call-Fleming syndrome. Finally, the definite diagnosis was possible after the application of the whole exome sequencing technique. It confirmed, for the first time in the Polish population, a heterozygous T666M mutation (c.1997C>T; p.Thr666Met) in the CACNA1A gene in the proband, the proband's son and in several other family members. CONCLUSION: The presented report provides clinical and genetic insight into familial hemiplegic migraine 1 resulting from a mutation in the CACNA1A gene.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) - literature review apropos an autopsy case.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a non-atherosclerotic, non-amyloid cerebral angiopathy involving small arteries and arterioles. This entity presents vascular changes in the form of smooth muscle degeneration with swollen myocytes and PAS-positive granular deposits, together with vascular fibrosis and hyalinization. In parallel, diffuse white matter destruction with infarcts, tissue rarefaction, spongiosis, lacunes and demyelination are characteristic. Ultrastructurally, vascular granular osmiophilic material (GOM) is pathognomonic for this hereditary disease caused by NOTCH3 mutation. We diagnosed CADASIL in the autopsy examination of a 53-year-old woman with a 9-year history of a progressive neurological disease with complex motor and cognitive deficits, accompanied by non-specific diffuse white matter changes on neuroimaging. Despite several multicentre hospitalizations, the precise diagnosis was not established until the post-mortem examination of the brain was made. CADASIL is a rare entity, but it should be considered by a pathologist in a differential diagnosis of vascular diseases of the brain, especially in cases with atypical clinical presentation and familial history. The prompt diagnosis depends on the quality of the brain autopsy and proper sampling. The post mortem examination, where "Morituri vivos docent", is still significant.

Paraneoplastic brainstem encephalomyelitis and atypical form of chronic inflammatory demyelinating polyneuropathy in patient with testicular germinal tumor-is this an overlap syndrome? a case report.

Paraneoplastic neurologic syndromes are diagnosed when neurologic symptoms are associated with neoplasm and other causative factors are excluded. They may precede or be simultaneous to various types of neoplasms, mainly malignant. In men up to 45-50 years old the most common cancer causing the paraneoplastic syndrome is testicle tumor, manifesting usually as limbic/brain stem encephalitis and myelitis. Usually effective treatment of underlying neoplasm brings resolution of neurologic symptoms. But corticosteroids and intravenuous immunoglobulins are also used. In the presented case a 37-year-old man was primarily diagnosed and treated for progressive tetraparesis with signs of both upper and lower motor neuron dysfunction, associated with bulbar symptoms. Having various diagnostic procedures performed an atypical form of chronic inflammatory demyelinating polyradiculoneuronopathy was primarily suspected, but eventually a discovery of endodermal sinus tumor in the testicle enabled to state the diagnosis of possible paraneoplastic syndrome. In spite of chemotherapy the patient died shortly after the diagnosis because of infectious complications. Histopathology displayed intense inflammatory changes in the brain stem as well as in cranial nerves and cervical spinal cord. The same immunological process evoked by various pathogenetic factors (infection vs. neoplasm) may cause similar clinical picture and hinder the diagnosis. Most importantly it may delay the proper way of treatment.

Dynactin Deficiency in the CNS of Humans with Sporadic ALS and Mice with Genetically Determined Motor Neuron Degeneration.

Dynactin is a complex motor protein involved in the retrograde axonal transport disturbances of which may lead to amyotrophic lateral sclerosis (ALS). Mice with hSOD1G93A mutation develop ALS-like symptoms and are used as a model for the disease studies. Similar symptoms demonstrate Cra1 mice, with Dync1h1 mutation. Dynactin heavy (DCTN1) and light (DCTN3) subunits were studied in the CNS of humans with sporadic ALS (SALS), mice with hSOD1G93A (SOD1/+), Dync1h1 (Cra1/+), and double (Cra1/SOD1) mutation at presymptomatic and symptomatic stages. In SALS subjects, in contrast to control cases, expression of DCTN1-mRNA but not DCTN3-mRNA in the motor cortex was higher than in the sensory cortex. However, the mean levels of DCTN1-mRNA and protein were lower in both SALS cortexes and in the spinal cord than in control structures. DCTN3 was unchanged in brain cortexes but decreased in the spinal cord on both mRNA and protein levels. In all SALS tissues immunohistochemical analyses revealed degeneration and loss of neuronal cells, and poor expression of dynactin subunits. In SOD1/+ mice both subunits expression was significantly lower in the frontal cortex, spinal cord and hippocampus than in wild-type controls, especially at presymptomatic stage. Fewer changes occurred in Cra1/SOD1 and Cra1/+ mice.It can be concluded that in sporadic and SOD1-related ALS the impairment of axonal retrograde transport may be due to dynactin subunits deficiency and subsequent disturbances of the whole dynein/dynactin complex structure and function. The Dync1h1 mutation itself has slight negative effect on dynactin expression and it alleviates the changes caused by SOD1G93A mutation.

Enlargement of the Nissl substance as a manifestation of early damage to spinal cord motoneurons in amyotrophic lateral sclerosis.

AIMS: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease of motoneurons. Recent studies indicate that in ALS, degeneration of motoneuron body is late in comparison to degeneration of axons. The morphological consequence of the axonal damage is chromatolysis. Therefore, loss of tigroid in motoneurons as a morphological manifestation of chromatolysis should be a prominent feature seen in an early stage of the disease. To verify that assumption we examined morphologically spinal cord motoneurons in patients with sporadic ALS. MATERIAL AND METHODS: In anterior horn motoneurons of 33 patients tigroid were assessed at light microscopy and morphometrically analyzed. Material was divided into an "acute" ALS group with a duration of the disease of up to 1 year, and a "chronic" ALS group with a clinical course lasting for 4 - 9 years. RESULTS: In the "acute" ALS group, loss of motoneurons was slight, and only a part of them showed central chromatolysis. Instead of chromatolysis the enlargement of the tigroid was found. This phenomenon was observed only in "acute" ALS and confirmed by morphometric analysis. CONCLUSIONS: In ALS, enlargement of the tigroid seems to be an early morphological feature - occuring earlier than central chromatolysis. Its presence may be connected with endoplasmic reticulum stress, disturbed axonal transport or functional compensation of the neuronal deficit.

Kinesin expression in the central nervous system of humans and transgenic hSOD1G93A mice with amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis is a fatal motor neuron degenerative disease. Most cases are sporadic (SALS), and approximately 10% are familial (FALS) among which over 20% are linked to the SOD1 mutation. Both SALS and FALS have been associated with retrograde axonal transport defects. Kinesins (KIFs) are motor proteins involved mainly in anterograde transport; however, some also participate in retrograde transport. OBJECTIVE: The purpose of the study was to investigate and compare the expression of kinesins involved in anterograde (KIF5A, 5C) and retrograde (KIFC3/C2) axonal transport in SALS in humans and FALS in mice with the hSOD1G93A mutation. METHODS: The studies were conducted on various parts of the CNS from autopsy specimens of SALS patients, and transgenic mice at presymptomatic and symptomatic stages using real-time quantitative PCR and reverse-transcription PCR. RESULTS: All KIF expression in the motor cortex of individual SALS subjects was higher than in the adjacent sensory cortex, in contrast to the expression in control brains. It was also significantly higher in the frontal cortex of symptomatic but not presymptomatic mice compared to wild-type controls. However, the mean KIF expression in the SALS motor and sensory cortexes was lower than in control cortexes. To a lesser extent the decrease in KIF mean expression also occurred in human but not in mouse ALS spinal cords and in both human and mouse cerebella. CONCLUSION: Disturbances in kinesin expression in the CNS may dysregulate both anterograde and retrograde axonal transports leading to motor neuron degeneration.

Pericytes as a new target for pathological processes in CADASIL.

CADASIL is a generalized angiopathy caused by mutations in NOTCH 3 gene leading to degeneration and loss of vascular smooth muscle cells (VSMC) in small arteries and arterioles. Since the receptor protein encoded by NOTCH 3 gene is expressed not only on VSMC but also on pericytes, pericytes and capillary vessels can be damaged by CADASIL. To check this hypothesis we examined microvessels in autopsy brains and skin-muscle biopsies of CADASIL patients. We found degeneration and loss of pericytes in capillary vessels. Pericytes were shrunken and their cytoplasm contained numerous vacuoles, big vesicular structures and complexes of enlarged pathological mitochondria. Degenerative changes were also observed within endothelial-pericytic connections, especially within peg-and-socket junctions. Nearby pericyte cell membranes or inside infoldings, deposits of granular osmiophilic material (GOM) were usually seen. In the affected capillaries endothelial cells revealed features of degeneration, selective death or swelling, leading to narrowing or occlusion of the capillary lumen. Our findings indicate that in CADASIL not only VSMC but also pericytes are severely damaged. Pericyte involvement in CADASIL can result in increased permeability of capillary vessels and disturbances in cerebral microcirculation, leading to white matter injury. Since in capillaries pericytes regulate vessel contractility, their degeneration can also cause defective vasomotor reactivity, the phenomenon observed very early in CADASIL, before development of histopathological changes in vessel walls.

[Psychotic symptoms and cognitive impairment in neurosarcoidosis. Case report and review of literature]. / Objawy psychotyczne i zaburzenia poznawcze w przebiegu neurosarkoidozy--opis przypadku i przeglad pismiennictwa.

Clinical involvement of the nervous system occurs in about 5% of patients with sarcoidosis. We describe a fatal case of a young patient with neurosarcoidosis with a relatively rare psychotic syndrome in the course of neurosarcoidosis, presenting itself as a depressive syndrome with delusions. The neurological manifestations consisted of cerebellar symptoms, peripheral neuropathy and general epileptic seizures. Cerebrospinal fluid examination, serum angiotensin-converting enzyme level, magnetic resonance imaging, chest radiography, gallium isotope scanning and other tests were used as diagnostic tools. He was treated with steroids, methotrexate and neuroleptics ineffectively. The patient died because of complications related to neurosarcoidosis. The diagnosis of neurosarcoidosis was confirmed by autopsy.

Technical aspects and current clinical applications of the skin and skeletal muscle biopsy in neurological diagnostics: an overview.

This short overview recalls the basic principles and technical aspects of skin and skeletal muscle biopsies in humans with paying special attention to the stages of these procedures essential for further correct morphological diagnosis. Some of these principles may also be useful in animal experimental studies. The authors emphasize the important role of proper thickness of the skin fragment, proper orientation of muscle fibres and a scalpel during skin biopsy, and proper concentration of fixatives. They recommend avoiding anaesthesia of the skeletal muscle itself and using forceps carefully so as not to crush the epidermis.

The spectrum of microvascular ultrastructural changes in the subpopulation of patients with migraine and cerebral white matter hyperintensities on MRI.

INTRODUCTION: Migraine is considered not only as a separate clinical entity but also as a symptom of various brain disorders, including cerebral small vessel diseases. Since cerebral small vessel diseases are usually general angiopathies, evaluation of biopsy material other than brain tissue may help in their diagnosis in vivo. In patients with migraine, brain magnetic resonance imaging (MRI) often shows hyperintense changes in the cerebral white matter. Such changes may indicate the symptomatic nature of migraine and coexisting structural or biochemical vascular abnormalities. MATERIAL AND METHODS: To verify the hypothesis of the symptomatic nature of migraine in patients with abnormal brain neuroimaging, we performed an ultrastructural examination of skin and skeletal muscle vessels in biopsy material from 40 patients with clinically diagnosed migraine and hyperintense white matter lesions on MRI. RESULTS: In 80% of the examined patients, ultrastructural examination showed various pathological changes in the microvessels including abnormalities characteristic of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and elastin disorders, as well as less specific changes such as thickening of the basal lamina, narrowing of the vessel lumen, degeneration of the vessel wall cells, endothelial activation, oncosis-like changes, and the presence of various types of deposits in the vessel wall. In 20% of the examined cases, ultrastructural examination of the vessels was normal. CONCLUSIONS: Patients with migraine and hyperintense cerebral white matter changes on MRI have an increased risk of concomitant microangiopathy. In this group of patients, skin-muscle biopsy allows the identification of cases with coexisting vessel abnormalities.

Diplomyelia in a patient with a clinical suspicion of autosomal recessive spastic ataxia of Charlevoix-Saguenay type (ARSACS).

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a form of cerebellar ataxia related to mutations in the SACS gene on chromosome 13q12.12 encoding sacsin protein. Characteristic clinical features are ataxia, spasticity, distal muscle wasting, neuropathy, dysarthria, nystagmus, and finger or feet deformities. The presented case concerns a 32-year-old man with clinical diagnosis of ARSACS. Magnetic resonance imaging (MRI) scans of the brain revealed cerebellar atrophy typical of the disease while neuroimaging of the C1-C3 and C6-Th12 segments showed only the thin thoracic spinal cord. The patient died suddenly and a gross examination of the spinal cord revealed extraspinal tumour at the C4-C5 levels, which turned out to be an additional spinal cord. Microscopic examination showed an extensive ischemic necrosis involving C6-Th5 segments of the proper spinal cord, and disturbed intrinsic structure containing many pathological vessels of the extra spinal cord. Lack of visualization of C4-C5 spinal cord segments on MRI scans made diagnosis of diplomyelia in vivo impossible. However, diplomyelia does not exclude coexistence of ARSACS because of the occurrence of such clinical symptoms as dysarthria or nystagmus which cannot be explained by the presence of the spinal cord defect. The possibility of congenital malformations of the spinal cord in adults should be remembered as their early identification and surgical correction can improve neurological symptoms.

The prevalence and types of oral- and pharyngeal-stage dysphagia in patients with demyelinating diseases based on subjective assessment by the study subjects.

BACKGROUND: Studies show that dysphagia is a common problem in patients with demyelinating diseases. However, there are no published studies on dysphagia in this group of patients, which would include the individual phases or the safety and effectiveness of the swallowing process. OBJECTIVE: The main objective of this study was to assess the prevalence of swallowing disorders and to characterize them based on subjective assessment by the study subjects with multiple sclerosis and Devic's syndrome. METHOD: The study included 72 patients (47 F, 25 M). Patients at risk of dysphagia were identified using the DYMUS, EAT-10 and SDQ questionnaires. To assess the type of oral- and pharyngeal-stage dysphagia, questions in the questionnaires were classified into groups according to symptoms typical of each stage. RESULTS: The risk of dysphagia and the need for instrumental examination were identified in 37.5% of the study subjects. Pharyngeal-stage dysphagia (repeated swallowing, increased effort of swallowing, cough, a feeling of food sticking in the throat) was reported to occur at a significantly higher frequency. However, no differences were found between difficulty in swallowing liquids and difficulty in swallowing solid food. CONCLUSION: There is a need for further research, which should include a detailed dysphagia-oriented diagnosis, with a view to gaining a detailed insight into the pathophysiology of deglutition in this group of patients.

Clinical presentation of Y189C mutation of the NOTCH3 gene in the Polish family with CADASIL.

INTRODUCTION: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary, progressive ischemic disease of small vessels of the brain characterized by migraine with aura (MA), recurrent subcortical ischemic episodes, cognitive decline and psychiatric disorders. CADASIL is caused by mutations in the NOTCH3 gene. We identified the NOTCH3 Y189C mutation as a genetic cause of CADASIL in a Polish family and provided its first clinical manifestation. MATERIAL AND METHODS: The study included twelve subjects from one family. The NOTCH3 mutation, APOE and MTHFR polymorphisms were determined by high-resolution melting analyses (HRMA) and Sanger sequencing. Neuroimaging included CT and MRI. Ultrastructural examination of skin-muscle biopsy material of the proband was performed. RESULTS: The NOTCH3 Y189C mutation was present in a 36-year-old woman and her two sisters (aged 40 and 27) from 6 siblings. The MA was found in all of them, and started or became more severe after childbirth. The numerous T2/FLAIR hyperintense lesions were shown in the brain MRI. The deposition of granular osmiophilic material in the wall of small vessels of the proband observed in histopathological analysis confirmed the high degree of CADASIL severity. CONCLUSIONS: Patients with the Y189C mutation of NOTCH3 from the same family display a similar phenotype of CADASIL.

Mysteries of CADASIL - the contribution of neuropathology to understanding of the disease.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a systemic vascular disease characterized by impairment of vascular smooth muscle cell (VSMC) structure and function related to NOTCH 3 mutations. Clinically the syndrome is manifested as recurrent ischaemic strokes, migraine with aura, dementia and psychiatric symptoms. In spite of intensive investigations, there is relatively little insight into the underlying pathomechanisms that link VSMC with the Notch 3 signalling pathway, morphological changes and clinical symptoms. The introduction into neuropathology of novel immunohistochemical and molecular techniques opened new research and diagnostic perspectives in CADASIL studies. We present a review of current concepts regarding CADASIL pathogenesis, clinical picture and diagnosis in which neuropathological examinations played a key role.

Unexpected morphological changes within hippocampal structures in a photochemical ring model of cerebral ischaemia.

A photochemical ring model of ischaemia was introduced in the middle of the nineteen eighties. Irradiation by a laser or arc lamp followed by intravenous injection of rose bengal resulted in thrombosis of pial and superficial cortical vessels. This ring model imitated focal ischaemic damage in humans. In our experiment twenty-seven Wistar rats of both sexes weighing 250-300 grams were examined. A photochemical ring model based on irradiation of the area of parietal bone 4 mm posteriorly to the bregma and 4 mm laterally from the sagittal suture was applied. A ring-shaped light beam with a wavelength of 510-540 nm with 5 mm diameter was generated by a high pressure discharge lamp at a power of 400 W. Two groups of rats treated and untreated with MK-801 and two rings of the thickness of 0.35 mm and 0.5 mm were used in the experiment. Morphological examination was performed in animals sacrificed 1 and 4 days after the irradiation. On formalin-fixed and paraffin-embedded slices HE staining method and immunoreaction with antibodies to ubiquitin were applied. Our material confirmed well known information about the dynamics of infarct breakdown, ischaemic-induced angiogenesis, glial reaction and other typical changes described previously in handbooks and numerous papers. In the experiment, morphological changes were more intensive after the irradiation by 0.5 mm than 0.35 mm irradiating rings and 4 days than one day after the irradiation. A surprising finding observed in some of the examined animals was more intensive neuronal damage after treatment with MK-801. Another unpredicted discovery was intensive morphological alterations found in CA4 and CA3 hippocampal sectors. Moreover, these alterations were not limited to the damaged hemisphere, but were also observed contralaterally. In some of the rats, ischaemic and necrotic cells were additionally found within both parasagittal areas. We connect this atypical localization of the ischaemic changes with dispersion of light emitted by the used lamp. Dispersed light also leads to thrombotic occlusion of the meningeal arteries in the parasagittal area. Among these arteries, thrombosis in pericallosal and penetrating arteries was present. Our experiment demonstrated that if a non-laser lamp is used, brain areas distant from the necrotic ring must be carefully investigated.