Transient Ischemic Attacks

(Great Britain—The Practitioner, June 2001, p. 481.) Transient ischemic attacks (TIAs) affect approximately 40 per 100,000 persons per year but because symptoms are frequently brief and minor, the condition is significantly underdiagnosed. The symptoms depend on the affected area of the brain, but are generally “negative,” such as loss of movement or speech difficulty. Headaches, seizures, and loss of consciousness are highly unusual with TIAs. Diagnosis is based on clinical features, because only 25 to 50 percent of affected patients show abnormalities on brain imaging. Within the first year, patients with TIAs have approximately 12 times the risk of stroke compared with persons without TIAs, and remain at increased risk. The risk of myocardial infarction is also significantly increased. Patients should be carefully assessed for predisposing vascular and cardiac conditions for TIA, especially atrial fibrillation. Following a TIA, lifestyle modifications such as smoking cessation and normalization of blood pressure must be aggressively pursued to minimize subsequent occurrence of stroke or myocardial infarction. Aspirin in a dosage of 75 mg per day is effective preventive therapy in most patients. Dipyridamole is widely used as an alternative treatment. Carotid endarterectomy is indicated if arteries are 70 percent or more stenosed and should be performed soon after the TIA event in selected patients.

Management of Bee and Wasp Stings

(Canada—Canadian Family Physician, June 2001, p. 1185.) The two types of stinging insects (hymenoptera) are vespids (wasps, yellow jackets, hornets, and fire ants) and apids (honeybees and bumblebees). Vespids are attracted to bright colors and strong odors and can sting repeatedly without provocation. Bumblebees also are able to sting repeatedly, but apids tend to sting only in defense. The severity of any hymenoptera sting depends on the volume and toxicity of venom injected, the site of the sting and the allergic status of the patient. Initial mild swelling and erythema can be treated with cold compresses and analgesics plus careful removal of the stinger if from a honeybee. Large local reactions can develop over two days and last up to one week. These reactions have the appearance of cellulitis, but are much less tender. Most patients respond to treatment with elevation, cold compresses, and nonsteroidal anti-inflammatory drugs. Antihistamines may relieve itching, and very severe local reactions may benefit from oral steroid treatment for up to three days. Anaphylactic reactions occur in up to 3 percent of stings. These can include urticaria, flushing, angioedema, bronchospasm, and circulatory collapse. Symptoms may begin within 10 minutes of the sting or be delayed for up to five hours. A dangerous biphasic reaction occurs in up to one fifth of cases. In addition to aggressive treatment of anaphylactic reactions, patients who are allergic should be given preventive advice and the option of venom immunotherapy.

Wet Age-Related Macular Degeneration

(Canada—Canadian Family Physician, May 2001, p. 955.) The wet type of age-related macular degeneration may be caused by choroidal neovascularization or detachment of the pigment epithelium because of serous fluid or bleeding between the layers of the retina. Patients with this condition experience significant visual impairment and decreased quality of life. Retinal angiography should be performed to confirm the diagnosis and guide treatment decisions. Thermal laser photocoagulation can produce long-term benefits, but is limited by associated visual loss around the time of treatment. Photodynamic therapy uses a photosensitizing dye to target blood vessels for laser therapy, reducing the potential damage to healthy retinal tissue. Studies indicate that photodynamic therapy reduces long-term visual loss with approximately one patient benefiting for every three patients treated.

Chemical Injuries to the Eye

(Canada—Canadian Family Physician, July 2001, p. 1387.) Alkalis produce more devastating eye injuries than acids because the high pH of alkali solutions destroys corneal epithelial cells, allowing the chemicals to penetrate the eye tissues. Acids can cause denaturing of proteins in the superficial cornea, forming a barrier and limiting damage. Copious irrigation is essential in all chemical exposures to the eye. Irrigation with normal saline, Ringer's lactate, or balanced salt solution should continue for at least 30 minutes or until pH measurements of the conjunctival fornices are neutral. The need for subsequent medical or surgical management depends on the severity of each case. Topical steroids can reduce inflammation, while ascorbic acid may promote collagen synthesis following alkali exposure. Antibiotics may also be indicated. In some cases, tenoplasty or corneal transplantation may be required.