Geraldo de Barros Ribeiro

Vitiligo na infância: características clínicas e epidemiológicas

BACKGROUND: vitiligo affects 0.5 to 4% of the world population. Twenty-five per cent of cases have their onset before the age of 10 years. Although the condition is prevalent in childhood, there are few epidemiological reports in children in the Brazilian literature. OBJECTIVE: to evaluate clinical and epidemiologic characteristics of vitiligo in childhood. METHODS: a descriptive study was performed in 73 children with vitiligo seen at the Pediatric Dermatology Outpatient Clinics of the Hospital das Clinicas- Universage Federal de Minas Gerais. The variables sex, age of onset of disease and treatment, affected body surface area, clinical type, site, autoimmune disease association, family history of vitiligo and initial treatment were evaluated. The statistical analysis was performed using simple frequency and means were compared through analysis of variance. RESULTS: Females accounted for 60.3% of the sample. The mean age at onset of disease was 5.7 years and the mean age at onset of treatment was 7 years. The body surface area affected was smaller than 1% in 71.8% and the localized type was detected in 76.7%. The most common site affected was the head. Family history of vitiligo was observed in 30.1% of patients. Hypothyroidism was found in one patient and 11% reported autoimmune diseases in their families. The initial treatment was topical steroids in the majority of patients. CONCLUSIONS: the findings of vitiligo in childhood in this study are basically similar to those reported in other countries.

Quality of life of patients with strabismus

PURPOSE To evaluate the impact of strabismus on quality of life. METHODS This cross-sectional study included 101 individuals aged 7-67 years with strabismus. They were interviewed and made to answer a questionnaire with 20 questions intended to assess the individuals interaction with their social and working environment, sensory perception, and limitations in their daily lives. There were five types of possible responses for each question: never, rarely or very few times, sometimes, frequently, and always. The questionnaire was based on the AS-20 and contained 11 questions assessing psychosocial aspects and 9 questions assessing functional aspects. Among those who were interviewed, 24.8% had undergone surgical correction of strabismus. RESULTS We observed a significant impact of strabismus on the quality of life of the interviewed individuals. Feelings of sadness and inferiority because of strabismus were reported by 74.2% and 58.4% respondents, respectively. In terms of functionality, 12.1% reported difficulty in reading, 14% said they had difficulty in depth perception (stereopsis), and 17.8% frequently or always associated pain or burning sensation in the eyes to strabismus. A significant difference was detected in the quality of life scores for the psychosocial aspect among patients who had and had not undergone surgery (Wilcoxon test, 158; p<0.001). Individuals who had undergone surgery had a better quality of life from the psychosocial perspective. CONCLUSIONS In this evaluation, we found a significant negative interference of strabismus on quality of life from both the functional and psychosocial perspectives. This demonstrated the importance of treatment for strabismus, regardless of age, because it can interfere with the functional well-being of the individual.

Study of crotoxin on the induction of paralysis in extraocular muscle in animal model

PURPOSE Crotoxin is the major toxin of the venom of the South American rattlesnake Crotalus durissus terrificus, capable of causing a blockade of the neurotransmitters at the neuromuscular junction. The objective of this study was to appraise the action and effectiveness of the crotoxin induced paralysis of the extraocular muscle and to compare its effects with the botulinum toxin type A (BT-A). METHODS The crotoxin, with LD50 of 1.5 µg, was injected into the superior rectus muscle in ten New Zealand rabbits. The concentration variance was 0.015 up to 150 µg. Two rabbits received 2 units of botulinum toxin type A for comparative analysis. The evaluation of the paralysis was performed using serial electromyography. After the functional recovery of the muscles, which occurred after two months, six rabbits were sacrificed for anatomopathology study. RESULTS The animals did not show any evidence of systemic toxicity. Transitory ptosis was observed in almost every animal and remained up to fourteen days. These toxins caused immediate blockade of the electrical potentials. The recovery was gradual in the average of one month with regeneration signs evident on the electromyography. The paralysis effect of the crotoxin on the muscle was proportional to its concentration. The changes with 1.5 µg crotoxin were similar to those produced by the botulinum toxin type A. The histopathology findings were localized to the site of the injection. No signs of muscle fibers necrosis were seen in any sample. The alterations induced by crotoxin were also proportional to the concentration and similar to botulinum toxin type A in concentration of 1.5 µg. CONCLUSION Crotoxin was able to induce transitory paralysis of the superior rectus muscle. This effect was characterized by reduction of action potentials and non-specific signs of fibrillation. Crotoxin, in concentration of 1.5 µg was able to induce similar effects as botulinum toxin type A.

Crotoxin in humans: analysis of the effects on extraocular and facial muscles

PURPOSE Crotoxin is the main neurotoxin of South American rattlesnake Crotalus durissus terrificus. The neurotoxic action is characterized by a presynaptic blockade. The purpose of this research is to assess the ability of crotoxin to induce temporary paralysis of extraocular and facial muscles in humans. METHODS Doses of crotoxin used ranged from 2 to 5 units (U), each unit corresponding to one LD50. We first applied 2U of crotoxin in one of the extraocular muscles of 3 amaurotic individuals to be submitted to ocular evisceration. In the second stage, we applied crotoxin in 12 extraocular muscles of 9 patients with strabismic amblyopia. In the last stage, crotoxin was used in the treatment of blepharospasm in another 3 patients. RESULTS No patient showed any systemic side effect or change in vision or any eye structure problem after the procedure. The only local side effects observed were slight conjunctival hyperemia, which recovered spontaneously. In 2 patients there was no change in ocular deviation after 2U crotoxin application. Limitation of the muscle action was observed in 8 of the 12 applications. The change in ocular deviation after application of 2U of crotoxin (9 injections) was in average 15.7 prism diopters (PD). When the dose was 4U (2 applications) the change was in average 37.5 PD and a single application of 5U produced a change of 16 PD in ocular deviation. This effect lasted from 1 to 3 months. Two of the 3 patients with blepharospasm had the hemifacial spasm improved with crotoxin, which returned after 2 months. CONCLUSIONS This study provides data suggesting that crotoxin may be a useful new therapeutic option for the treatment of strabismus and blepharospasm. We expect that with further studies crotoxin could be an option for many other medical areas.

Estudo comparativo da ação da toxina botulínica tipo A e da crotoxina sobre as células satélites da musculatura extrínseca ocular em modelo animal

OBJETIVOS: Avaliar o efeito da toxina botulinica do tipo A e da crotoxina na ativacao de celulas satelites das fibras musculares de retos superiores de coelhos. METODOS: Os musculos retos superiores do olho direito de 29 coelhos machos albinos neozelandeses foram inoculados com toxina botulinica do tipo A ou com crotoxina, em diferentes doses. Os musculos retos superiores contralaterais de cada animal foram inoculados com solucao salina em volume igual ao das toxinas. Os animais foram sacrificados 12, 18 ou 25 dias apos as aplicacoes. Os olhos foram enucleados e cada musculo foi preparado para analise imunoistoquimica, com marcadores de celulas satelites. Foi realizada contagem dos nucleos corados pelos marcadores a cada cem miofibras. RESULTADOS: A aplicacao de toxina botulinica e de crotoxina provocou um aumento no numero de celulas satelites ativadas e em proliferacao nos musculos retos superiores. Uma maior ativacao foi observada apos a aplicacao de crotoxina, embora, estatisticamente, a diferenca do efeito de ativacao entre os grupos botoxina e crotoxina nao tenha sido significativa. Nos grupos botoxina e crotoxina, nao houve correlacao estatisticamente significativa entre a dose e o volume aplicados e o aumento na ativacao das celulas. O tempo de vida apos a aplicacao contribuiu para o aumento das celulas ativadas nos grupos. CONCLUSAO: A observacao de maior desorganizacao na estrutura muscular e de sinais de regeneracao mais evidentes no grupo crotoxina parece estar correlacionada ao aumento de celulas satelites ativadas.

Nova abordagem cirúrgica no tratamento de estrabismos incomitantes: relato de caso

The authors report the utilization of the surgical technique proposed by Scott, in 1994, of recess and resection of the same extraocular muscle in the treatment of incomitant horizontal strabismus. A 22-year-old female presented with incomitant strabismus, with an esotropia of 9D for distant and 30D for near. She was submitted to a recess and resection of the right medial rectus. She presented satisfactory results in the long-term, showing that this technique could be part of the therapeutic arsenal for correction of incomitant strabismus.