Spider bites are usually too small to be easily seen, and often cause minor swelling ... tal Trauma Life Support (Mosby, 1999); Alcides Zambrano, et al., âSevere ...
Spider Bites
Language-based learning disabilities (one of which is dyslexia) cause difficulties in reading, spelling, and/ or writing. These disabilities, which seem hereditary, are linked with abnormalities in the brain structure. The prevalence is estimated in about 9 percent of 10year-old children. Spasmodic dysphonia (also called “laryngeal dystonia”) is a voice disorder characterized by involuntary spasms or movements of the vocal cords, which stiffen and slam together, giving origin to strained or strangled sounds, or remain open, producing weak and whispery sounds. Spasmodic dysphonia most often affects women between 30 and 50 years. Researchers estimate that 10,000 to 30,000 individuals are affected in the United States. In many of these disorders, effective treatments are provided by speech-language pathologists who work closely with the patients’ families, teachers, psychologists, audiologists, and physicians of various specialities (e.g.,����������������������������������������� pediatricians��������������������������� , neurologists, otoryngologists, physiatrists, etc.). These professionals can use different, individually tailored approaches, such as breathing techniques, relaxation strategies, oral-motor drills, and exercises. In severe cases, patients can communicate with their environment using formal or informal sign language, picture boards, and/or electronic communication devices. SEE ALSO: Autism; Head and Neck Cancer; Muscular
Dystrophy; Myasthenia Gravis; Neurologic Diseases; Voice Disorders.
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humans. A few species are capable of causing necrotic wounds and, occasionally, death. The only spiders of real medical importance to humans in the United States and in other countries are the Loxosceles and Latrodectus species, primarily the brown recluse and the black widow, respectively. These spiders bite humans only when trapped or crushed against the skin. Bite marks from most spiders are usually too small to be easily seen. Frequently, the patient will not recall being bitten. Spiders rarely bite more than once, so multiple bites are usually caused by insects such as fleas, bedbugs, ticks, mites, and biting flies. Spider bites often cause minor swelling, redness, pain, and itching. These mild reactions are common and may last from a few hours to a few days. Unfortunately, sometimes more severe reactions to bites or stings can be produced by spider bites. Babies and children may be more affected by bites or stings than adults. Taxonomically, spiders belong to class Arachnida which is composed by the orders Scorpionida, Acarina, Opiliones, Pseudoscorpiones, and Araneida. These arthropods belong specifically to the last order which is constituted for a large number of families. SEE ALSO: Immunology; Toxicology. BIBLIOGRAPHY. Harold Brown, Clinical Parasitology (Appleton-Century-Crofts, 1983); Gordon Cook and Alimuddin Zulma, Manson’s Tropical Diseases (Saunders, 2003);
BIBLIOGRAPHY. Dorothy V. M. Bishop and Lawrence
Leonard, eds., Speech and Language Impairments in Children (Psychology Press, 2000); Skye McDonald, et al., Communication Disorders Following Traumatic Brain Injury (Psychology Press, 1999).
Alessandra Padula, Ph.D. L’Aquila University
Spider Bites Spiders are dangerous to humans when the former accidentally bite the latter. About 20 species of spiders are known to cause dangerous envenoming of
Spider bites are usually too small to be easily seen, and often cause minor swelling, redness, pain, and itching.
1590 Spina Bifida James H. Diaz, “The Global Epidemiology, Syndromic Classification, Management, and Prevention of Spider Bites,” American Journal of Tropical Medicine and Hygiene (v.71/2, 2005); David Feliciano, Trauma (Appleton & Lange, 1996); Geoffrey K. Isbister, et al., “Spider Bites: Addressing Mythology and Poor Evidence,” American Journal of Tropical Medicine and Hygiene (v.72/4, 2005); NAEMT, Pre-Hospital Trauma Life Support (Mosby, 1999); Alcides Zambrano, et al., “Severe Loxoscelism with Lethal Outcome,” Revista Medica de Chile (v.133/2, 2005). Alfonso J. Rodriguez-Morales, M.D., M.Sc. Universidad de Los Andes Carlos Franco-Paredes, M.D., M.P.H. Emory University
Spina Bifida Spina bifida (SB) refers to protrusion of the spinal contents through a bony defect in the spine. The abnormality probably results from maldevelopment at the fourth week of gestation: the bony sheath surrounding the spinal cord does not form properly due to failure of the posterior vertebral arches to close. Although the spinal opening can be surgically repaired shortly after birth, the nerve damage is permanent, resulting in varying degrees of paralysis of the lower limbs. Even when there is no lesion present, there may be improperly formed or missing vertebrae and accompanying nerve damage. In addition to physical and mobility difficulties (such as congenital scoliosis, kyphosis, and hip deformities), most individuals have some form of learning disability. SB may also cause bowel and bladder complications, and many children with SB have hydrocephalus (excessive accumulation of cerebrospinal fluid in the brain). SB is one of the most common birth defects, with an average worldwide incidence of one to two cases per 1,000 births, but certain populations have a significantly greater risk. In the United States, the average incidence of SB is 0.7 per 1,000 live births. The incidence is higher on the East Coast than on the West Coast, and higher in Caucasians (one case per 1,000 live births) than in African Americans (0.1–0.4 case per 1,000 live births). Immigrants from Ireland have
a higher incidence of spina bifida than do nonimmigrants. This corresponds to the fact that the highest incidence rates worldwide are found in parts of the British Isles, mainly Ireland and Wales, where three to four cases of myelomeningocele per 1,000 population have been reported, along with more than six cases of anencephaly (both live births and stillbirths) per 1,000 population. The reported overall incidence of myelomeningocele in the British Isles is 2 to 3.5 cases per 1,000 births. The three most common types of SB are myelomeningocele, the severest form, in which the spinal cord and its protective covering (the meninges) protrude from an opening in the spine; meningocele in which the spinal cord develops normally but the meninges protrude from a spinal opening; and occulta, the mildest form, in which one or more vertebrae are malformed and covered by a layer of skin. Ten to 15 percent of spinal defects are closed by normal skin covering the bony defect. The remainder are open and most are detectable by maternal serum alphafetoprotein screening. Approximately 80 percent of lesions occur in the lumbar, thoracolumbar, or lumbosacral areas of the spine, with the remainder in the cervical and sacral areas. Prenatal Detection The diagnostic sensitivity of prenatal sonography for early detection of the site and extent of the spinal lesion is important because these features correlate with neurologic outcome; more severe neurologic dysfunction is associated with higher and larger lesions. Spina bifida can be detected before the 12th postmenstrual week by noting irregularities of the bony spine or a bulging within the posterior contour of the fetal back. After the 12th postmenstrual week, well-established additional sonographic findings (e.g., lemon sign, banana sign, and hydrocephaly) facilitate detection. A detailed scan of the spine in the sagittal and transverse planes is indicated if these cranial findings have been observed. Treatment There is no cure for SB because the nerve tissue cannot be replaced or repaired. Treatment for the variety of effects of SB may include surgery, medication, and physiotherapy. Many individuals with SB will need assistive devices such as braces, crutches, or
