Bourneville's Disease
Bourneville's Disease Definition
Bourneville's disease (also known as Tuberous sclerosis) is characterized by facial lesions with tuberous sclerosis, first reported as adenoma sebaceum, but now recognised as angiofibromas. It produces tuberous sclerosis occurring in association with adenoma sebaceum. It is syndrome of epilepsy, severe mental retardation associated with adenoma sebaceum (overgrowth of the sebaceous glands) of the face, hamartomatous tumours of the heart and kidney, and cerebral cortical tubers (hence the name "tuberous sclerosis"). It is heredofamilial and usually shows itself early in life. Females are more often affected by this disease than males. Incomplete forms of the syndrome can manifest. Bourneville's disease is transmitted as an autosomal dominant trait with variable expressivity.
Bourneville's Disease Epidemiology
Tuberous sclerosis can be found in all races and ethnic groups, and in both genders. The live-birth prevalence is approximated to be between 10 and 16 cases per 100,000. A study in 1998 estimated total population prevalence between about 7 and 12 cases per 100,000, with more than half of these cases going undetected. These estimates are dramatically higher than those produced by older studies, when tuberous sclerosis was regarded as an extremely rare disease. This is because the invention of CT and ultrasound scanning have enabled the diagnosis of many non-symptomatic cases. Before this, the diagnosis of tuberous sclerosis was largely restricted to severely affected individuals with Vogt's triad of learning disability, seizures and facial angiofibroma. The total population prevalence figures have steadily increased from 1:150,000 in 1956, to 1:100,000 in 1968, to 1:70,000 in 1971, to 1:34,200 in 1984, to the current figure of 1:12,500 in 1998. While still regarded as a rare disease, it is common when compared to many other genetic diseases.
Bourneville's Disease Prognosis
The prognosis for individuals with Bourneville's disease depends on the severity of symptoms, which range from mild skin abnormalities to varying degrees of learning disabilities and epilepsy to severe mental retardation, uncontrollable seizures, and kidney failure. Those individuals with mild symptoms typically do well and live long productive lives, while individuals with the more severe form may have serious disabilities. With appropriate medical care, however, most individuals with the disorder can look forward to normal life expectancy. Leading causes of death include brain tumour, renal disease, lymphangiomyomatosis of the lung, and status epilepticus or bronchopneumonia in those with severe mental handicap. Cardiac failure resulting from rhabdomyomas is a risk in the fetus or neonate, but is rarely a problem subsequently. Kidney complications such as angiomyolipoma (AML) and cysts are common, and more frequently found in females than males and in TSC2 than TSC1. Renal cell carcinoma is rare in association with the disease. Lymphangioleiomyomatosis (LAM) is only a risk for females affected with AMLs. In the brain, the subependymal nodules may occasionaly degenerate to subependymal giant cell astrocytomas (SEGA). These may hinder the circulation of cerebrospinal fluid around the brain, leading to hydrocephalus.
Bourneville's Disease Symptoms and Signs
The physical manifestations of tuberous sclerosis are the result of the formation of hamartomas (benign growths such as facial angiofibroma and subependymal nodules), hamartia (malformed tissue such as the cortical tubers), and, very rarely, cancerous hamartoblastomas. The effect of these on the brain causes the neurological symptoms such as seizures, developmental delay and behavioral problems.