Thursday, November 3, 2016

Anterior encephaloceles in children of Assamese tea workers

Dutta HK, Deori P. Anterior encephaloceles in children of Assamese tea workers. J Neurosurg Pediatr. 2010 Jan;5(1):80-4.

Anterior encephaloceles are rare congenital malformations. Most of the cases in the literature are reported from Southeast Asia. In India it is seen more frequently among manual laborers in the tea gardens of Assam. A brief background of the patients, clinical presentation, operative treatment, and outcome are discussed, with a review of the relevant literature. The causes and pathogenesis of anterior encephaloceles are discussed. The authors' surgical approach to repair of the defect, postoperative complications, and results are described.
Twenty-eight patients (mean age 38 months, range 1 month-12 years) with anterior encephaloceles who presented between 1998 and 2007 are included in the study. Patients were assessed for physical and psychological growth and development; any associated anomalies were noted. A detailed history of the patient's family, including the prenatal history, was obtained. Lesions were classified with the help of neuroimaging studies (skull x-ray, CT, ultrasonography, and MR imaging studies) and confirmed at surgery.
Sixteen patients had nasofrontal, 9 had nasoethmoidal, and 3 had nasoorbital encephaloceles, and 12 patients had associated hydrocephalus. The modes of presentation were nasofrontal swelling, watering from the eyes, CSF leakage, fever, and vomiting. Parents of all the patients were ethnic tea garden workers. The average parental age at the time of marriage was 24 years for men and 18 years for women. Consanguinity was present in 6 patients. Alcohol consumption and tobacco chewing were a common practice in both parents. A total of 42 surgical procedures were done in 16 patients, one of whom died of postoperative meningitis. The mean follow-up duration was 38 months (1-92 months).
Anterior encephaloceles are rare in Western countries and other states in India, but this defect is more commonly seen among the ethnic tea garden workers in Assam. Transcranial repair is the treatment of choice. Unlike encephaloceles in other locations, anterior encephaloceles have a better clinical outcome after surgery.

From the article

Experimental studies have shown that administration of the folic acid antagonist trypan blue along with large doses of vitamin A to pregnant rats in the early stages of gestation produced encephalocele defects. Maternal malnutrition and exposure to radiation also have the same effect. Rapport et al. postulated that this condition may have several etiological factors, because mesodermal abnormalities alone cannot account for the observed abnormalities. Lemire et al. believed that anterior encephalocele results not only from defective neurulation, as is seen in the case of myelomeningocele, but is also due to abnormal dedifferentiation. The fact that anterior encephalocele is covered by skin as well as by membrane gives credence to this theory. Some authors have also noted histological abnormality of the overlying skin, which suggests a neuroectodermal abnormality…

The special geographic distribution of this condition suggests some kind of yet unidentified environmental factors. In our series, all but 1 patient are from the same ethnic group, the tea tribes of Assam, who migrated from various states of India ~ 150 years ago. They are employed as manual laborers in tea gardens, and at present their population is ~ 7 million. Because the number of such cases is increasing among their children, a possible environmental factor is most likely. Moreover, chemical pesticides are commonly used in the gardens, and the mothers, who are used for plucking tea leaves, are exposed to these harmful chemicals during the early part of their pregnancy. Other factors that can contribute to the causation of this condition in our patients are multiparity, poor living conditions, malnutrition, indigenous medicines used for common ailments, young mothers (age < 20 years), prevalence of consanguineous marriage in their society, and so on.

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