Neurogenic switching: a hypothesis for a mechanism for shifting the site of inflammation in allergy and chemical sensitivity.
(73/104)Neurogenic switching is proposed as a hypothesis for a mechanism by which a stimulus at one site can lead to inflammation at a distant site. Neurogenic inflammation occurs when substance P and other neuropeptides released from sensory neurons produce an inflammatory response, whereas immunogenic inflammation results from the binding of antigen to antibody or leukocyte receptors. There is a crossover mechanism between these two forms of inflammation. Neurogenic switching is proposed to result when a sensory impulse from a site of activation is rerouted via the central nervous system to a distant location to produce neurogenic inflammation at the second location. Neurogenic switching is a possible explanation for systemic anaphylaxis, in which inoculation of the skin or gut with antigen produces systemic symptoms involving the respiratory and circulatory systems, and an experimental model of anaphylaxis is consistent with this hypothesis. Food-allergy-iducing asthma, urticaria, arthritis, and fibromyalgia are other possible examples of neurogenic switching. Neurogenic switching provides a mechanism to explain how allergens, infectious agents, irritants, and possibly emotional stress can exacerbate conditions such as migraine, asthma, and arthritis. Because neurogenic inflammation is known to be triggered by chemical exposures, it may play a role in the sick building syndrome and the multiple chemical sensitivity syndrome. Thus neurogenic switching would explain how the respiratory irritants lead to symptoms at other sites in these disorders. (+info)
Measuring chemical sensitivity prevalence: a questionnaire for population studies.
(74/104)Because no information exists on the prevalence of chemical sensitivity syndromes such as multiple chemical sensitivities, a questionnaire for use in population studies was developed and tested to assess the presence or absence of chemical sensitivity. Seven hundred five individuals attending clinics answered a questionnaire asking whether each of 122 common substances caused symptoms. Results showed that patients with multiple chemical sensitivities and asthma had average total scores that were significantly different from each other and from those of each of the other diagnostic categories. Higher total scores were also reported by female patients. The instrument described here may facilitate meaningful prevalence studies of multiple chemical sensitivities. It will also allow study of chemically induced symptoms in other conditions such as asthma. (+info)
Illness as lifestyle.
(75/104)To appreciate what illness means to an individual, physicians must understand that person's attitudes, views, and style of life. People react uniquely and creatively to illness and disability. Some incorporate the illness into their lives and use it to help them achieve goals that might not be obvious to the doctor. A case study presents diagnostic and therapeutic problems familiar to family physicians. (+info)
The environment was right for Nova Scotia's new environmental health clinic.
(76/104)With a $1-million contribution from the Nova Scotia government, Dalhousie University medical school is establishing an environmental health clinic that will research and treat the controversial condition known as multiple-chemical sensitivity. Already several hundred Nova Scotians, including about 100 former employees of Halifax's Camp Hill Hospital, have been referred to a part-time clinic that addresses environmental illness and other unexplained conditions. Some physicians contend that the sensitivity is largely psychosomatic and treatments provide little more than a placebo effect, but proponents believe research will support environmental health's goal of becoming a new, recognized speciality. (+info)
Practical application of air-quality research incorporated in CMHC's research house.
(77/104)The Canada Mortgage and Housing Corporation has been looking at ways to improve indoor air quality since 1984 and now hopes to interest house designers and manufacturers in the results of its research. Its flagship project has been the construction of a proto-type research house for environmentally hypersensitive people. (+info)
Waiting list already 7 months long at Toronto's new Environmental Health Clinic.
(78/104)Following the head set by Nova Scotia, Ontario now has a clinic devoted to the treatment of patients with "environmental illness." It opened in Toronto last year, and patients must be referred by their family physician and complete a 16-page previsit questionnaire. They receive a 3-hour assessment in which their medical history is explored, plus a full physical examination and blood and urine tests. Dr. Frank Foley, who heads the Toronto clinic, says his patients have seen from 8 to 10 health care professionals in the 2 years before their visit and most have been told the problem is "in your head." He says they need to "have their symptoms validated and their distress acknowledged." (+info)
Chemical sensitivity: the scientific literature.
(79/104)This article provides an overview of the scientific literature in which chemically sensitive patients have been directly evaluated. For that purpose, consideration of various case definitions is offered along with summaries of subjects' demographic profiles, exposure characteristics, and symptom profiles across studies. Controlled investigations of chemically sensitive subjects without other organic illnesses are reviewed. To date, psychiatric, personality, cognitive/neurologic, immunologic, and olfactory studies have been conducted comparing subjects with primary chemical sensitivity to various control groups. Thus far, the most consistent finding is that chemically sensitive patients have a higher rate of psychiatric disorders across studies and relative to diverse comparison groups. However, since these studies are cross-sectional, causality cannot be implied. Demonstrating the role of low-level chemical exposure in a controlled environment has yet to be undertaken with this patient group and is crucial to the understanding of this phenomenon. (+info)
Profile of patients with chemical injury and sensitivity.
(80/104)Patients reporting sensitivity to multiple chemicals at levels usually tolerated by the healthy population were administered standardized questionnaires to evaluate their symptoms and the exposures that aggravated these symptoms. Many patients were referred for medical tests. It is thought that patients with chemical sensitivity have organ abnormalities involving the liver, nervous system (brain, including limbic, peripheral, autonomic), immune system, and porphyrin metabolism, probably reflecting chemical injury to these systems. Laboratory results are not consistent with a psychologic origin of chemical sensitivity. Substantial overlap between chemical sensitivity, fibromyalgia, and chronic fatigue syndrome exists: the latter two conditions often involve chemical sensitivity and may even be the same disorder. Other disorders commonly seen in chemical sensitivity patients include headache (often migraine), chronic fatigue, musculoskeletal aching, chronic respiratory inflammation (rhinitis, sinusitis, laryngitis, asthma), attention deficit, and hyperactivity (affected younger children). Less common disorders include tremor, seizures, and mitral valve prolapse. Patients with these overlapping disorders should be evaluated for chemical sensitivity and excluded from control groups in future research. Agents whose exposures are associated with symptoms and suspected of causing onset of chemical sensitivity with chronic illness include gasoline, kerosene, natural gas, pesticides (especially chlordane and chlorpyrifos), solvents, new carpet and other renovation materials, adhesives/glues, fiberglass, carbonless copy paper, fabric softener, formaldehyde and glutaraldehyde, carpet shampoos (lauryl sulfate) and other cleaning agents, isocyanates, combustion products (poorly vented gas heaters, overheated batteries), and medications (dinitrochlorobenzene for warts, intranasally packed neosynephrine, prolonged antibiotics, and general anesthesia with petrochemicals). Multiple mechanisms of chemical injury that magnify response to exposures in chemically sensitive patients can include neurogenic inflammation (respiratory, gastrointestinal, genitourinary), kindling and time-dependent sensitization (neurologic), impaired porphyrin metabolism (multiple organs), and immune activation. (+info)