Magnetic field influence on central nervous system function

The effects of strong static magnetic fields on the excitability of striate cortex in adult cats was studied. The visual evoked response was used as a measure of cortical excitability. In all animals a 1200-G field was associated with a significant decrease in both amplitude and variability of the evoked response. This effect began more than 50 s after the field was turned on and persisted, even after the field was turned off, for several minutes. This phenomenon appears to be due to action of the magnetic field at the synapse rather than on axonal conduction.     

Peripheral and central nervous system alterations in hypothyroidism: electrophysiological findings

The purpose of this study is to evaluate objectively the functional changes in the nervous system in hypothyroidism by different electrophysiological parameters and to determine the frequencies of these changes in patients with hypothyroidism. We enrolled 23 patients (17-64 years old, mean 38.2) with biochemical evidence of hypothyroidism, with thyroxine less than 4 microg/dl and thyrotropin above 4.5 mU/ml, and 200 age- and sex-matched normal subjects. Detailed clinical examination and electrophysiological measurements included electromyography, motor conduction velocity, visual-evoked potentials (VEPs), brainstem auditory-evoked potentials (BAEPs) and event-related potentials. Determinations of P300, Wechsler Adult Intelligence Scale (IQ) and electroencephalography (EEG) were performed. Of the hypothyroid patients 52% had peripheral nervous system (PNS) involvement. Entrapment neuropathy was the commonest (35%). Axonal neuropathy was recorded in 9% and myopathy was recorded in another 9%. The central nervous system (CNS) was affected in 78% of the cases. Significant prolongations of P100 latency of VEP, latency and interpeak latency of BAEPs of different waves of hypothyroid patients were compared to the control group. 52% had abnormal VEPs and BAEPs above the mean +/- 2 SD of the normal control group. Six patients (26%) had prolonged P300 latency while 16 patients had an IQ below 90. Eight patients (35%) had EEG changes. Diffuse slowing of background activity was the commonest. No significant correlation was observed between hormonal levels and the different electrophysiological parameters. Thus, the CNS is more vulnerable to the effect of hypothyroidism than the PNS. Therefore, we suggest performing electrophysiological studies in hypothyroid patients, even in the asymptomatic ones, early in the course of disease in order to detect the nervous system involvement.     

Studies of the influence of biogenic amines on central nervous system ischemia

Several serotonin inhibitors have been shown to reduce neurologic deficits in experimental CNS ischemia. Using biochemical and histological methods we tested the effects of the serotonin inhibitors cyproheptadine and brom-LSD in a highly reproducible rabbit spinal cord ischemia model. Detailed mapping of regional spinal cord blood flow was used to guide sampling for the biochemical studies. We found that it is possible to study biochemical and morphological aspects of spinal cord ischemia in great detail using a combination of quite precise techniques. However, at this level of resolution there were no substantial changes in biogenic amine concentrations in severely ischemic or marginally perfused tissue after the durations of ischemia that cause the onset of irreversible tissue damage. Treatment with doses of serotonin inhibitors that produce preservation of neurological function did not cause significant alterations of tissue concentrations of biogenic amines or tissue morphology in treated versus untreated animals.     

Immunology of the central nervous system

Immunology of the central nervous system (CNS) is a growing field of study. Until recently the brain was considered an 'immunologically privileged' site. It is increasingly apparent that the CNS has a significant but tightly regulated capability to mount an inflammatory and immune response. This article serves as an introduction to the special section at the start of this issue on neuroimmunology. We also focus on several immunological concepts that are particularly relevant in the context of neuroimmunology-cross-reactivity, the immunological synapse and the nature of the immune response to transplantation in the CNS. We conclude that the fundamental concepts are common to all branches of immunology. Better understanding of the basic mechanisms will blur the borders between the different areas of immunology.     

Immunology of the central nervous system

Abstract

Immunology of the central nervous system (CNS) is a growing field of study. Until recently the brain was considered an 'immunologically privileged' site. It is increasingly apparent that the CNS has a significant but tightly regulated capability to mount an inflammatory and immune response. This article serves as an introduction to the special section at the start of this issue on neuroimmunology. We also focus on several immunological concepts that are particularly relevant in the context of neuroimmunology—cross-reactivity, the immunological synapse and the nature of the immune response to transplantation in the CNS. We conclude that the fundamental concepts are common to all branches of immunology. Better understanding of the basic mechanisms will blur the borders between the different areas of immunology.     

Aspergillosis of the central nervous system

Aspergillosis of the central nervous system is rare. The spread to the CNS is usually from the lungs and uncommonly from paranasal sinuses. Four cases of CNS aspergillosis with spread of infection from the paranasal sinuses are described. Two patients had meningitis, one intracranial granuloma and one presented with subarachnoid haemorrhage resulting from a fungal mycotic aneurysm. Difficulties in establishing the diagnosis are discussed.     

Listeriosis of the central nervous system

Listeriosis of the CNS is an inflammatory disease of the central nervous system that occurs mostly sporadically or occasionally as a limited epidemic. The pathogens are generally ingested with the food. Whether or not the infection becomes manifest in an exposed person depends on the number of pathogens ingested, on the virulence of the Listeria strain and on the individual disposition. It appears to be of decisive importance for an infection that the cellular immunodefense mediated by the T cells is disturbed; however, even persons without any previous disease worth mentioning may be affected. The characteristics of the various CNS manifestations are demonstrated via the case histories of 12 own patients (acute meningitis and meningoencephalitis, brain stem encephalitis, brain abscess, meningoencephalitis with infected cerebral infarct, chronic recidivating encephalitis). Early neurological focal signs and symptoms, combined with CSF findings atypical for bacterial CNS disease, should not be taken lightly and may point to listeriosis even though they are not specific for CNS listeriosis. The decisive criterion is the proof of the pathogen in the blood or CSF or the proof of antibody titre changes in the serum. Recent CSF diagnostic methods such as CSF lactate determination and the identification of IgG-positive B lymphocytes are useful in differentiating between viral and noninflammatory CNS disease; most important for follow-up are repeat CSF examinations. High-dosage ampicillin or amoxycillin treatment combined with gentamycin is the therapy of choice in CNS listeriosis. The bactericidal effect achieved thereby is desirable especially if immunodefense is disturbed. Prognosis of CNS listeriosis depends on the underlying disease in each case. The high mortality even among persons who had been healthy before the infection, is at least in part due to delayed diagnosis.     

Sarcoidosis of the central nervous system

Six patients with sarcoidosis of the central nervous system are described. Pathological confirmation was obtained by brain biopsy in two patients and at necropsy in two; in two patients the diagnosis was presumptive and was made on the evidence of multisystem involvement. The symptomatology, methods of diagnosis, and results of treatment are discussed.     

Tuberculoma of the central nervous system

Tuberculosis is among the oldest and most devastating infectious diseases worldwide. Nearly one third of the world’s population has active or latent disease, resulting in 1.5 million deaths annually. Central nervous system involvement, while rare, is the most severe form of tuberculosis. Manifestations include tuberculoma and tuberculous meningitis, with the majority of cases occurring in children and immunocompromised patients. Despite advancements in imaging and laboratory diagnostics, tuberculomas of the central nervous system remain a diagnostic challenge due to their insidious nature and nonspecific findings. On imaging studies tuberculous meningitis is characterized by diffuse basal enhancement, but tuberculomas may be indistinguishable from neoplasms. Early diagnosis is imperative, since clinical outcomes are largely dependent on timely treatment. Stereotactic biopsy with histopathological analysis can provide a definitive diagnosis, but is only recommended when non-invasive methods are inconclusive. Standard medical treatment includes rifampicin, isoniazid, pyrazinamide, and streptomycin or ethambutol. In cases of drug resistance, revision of the treatment regimen with second-line agents is recommended over the addition of a single drug to the first-line regimen. Advances in genomics have identified virulent strains of tuberculosis and are improving our understanding of host susceptibility. Neurosurgical referral is advised for patients with elevated intracranial pressure, seizures, or brain or spinal cord compression. This review synthesizes pertinent findings in the literature surrounding central nervous system tuberculoma in an effort to highlight recent advances in pathophysiology, diagnosis, and treatment.     

Angiolipoma of the central nervous system

Angiolipomas of the central nervous system are rare tumors (37 cases in the literature) and are mostly located in the spine (95%), rarely in the skull. When they are intraspinal, these masses are extradural in more than 90% of the cases. Angiolipomas are benign tumors containing vascular and mature adipose elements. The clinical symptomatology is non specific, but computed tomography and mostly MRI provide a precise diagnosis. With 2 additional cases and a review of the literature, we define the main characteristics of these tumors.     

Angioendotheliomatosis of the central nervous system

Summary A case of angioendotheliomatosis is described in which the neoplastic proliferation of the vascular endothelium was restricted to the central nervous system. Although the process resembled a malignant tumour, neoplastic growth did not occur outside the blood vessels. The process was accompanied by a chronic inflammatory reaction in and around the blood vessels.     

Vasculitis of the central nervous system

Central nervous system (CNS) involvement and management in primary vasculitis (giant cell arteritis, primary angiitis of the CNS, Takayasu’s disease, periarteritis nodosa, Kawasaki disease, Churg-Strauss syndrome, Wegener’s granulomatosis) and vasculitis secondary to collagen vascular diseases, Beçhet’s disease and other systemic conditions (excluding those secondary to infections) and the use of illicit drugs are reviewed. Vasculitis is an infrequent cause of stroke even in the young age groups, and routine screening of stroke patients for vasculitis is not cost-effective. CNS vasculitis may present with isolated CNS symptoms and signs (headaches, meningeal signs, encephalopathy, psychiatric syndromes, dementia, cranial nerve palsies, seizures, strokes), neuropathy or muscle damage, multiorgan involvement or non-specific systemic symptoms or a combination of the above. Magnetic resonance is the most sensitive ancillary procedure to detect CNS damage. Many of the angiographic features found in vasculitis are non-specific. Autoantibodies and tissue biopsy are also useful to the diagnosis. There are few controlled studies on the treatment of vasculitis. Usually a combination of steroids and cytotoxic drugs is used, but there is considerable variation between centres on current therapeutic regimens.