This is the condition affecting the infants or the child presenting the unusually large brain that may be malfunctioning. The head enlargement can either be evident at the birth of the infant or can develop during the early years of their life. This condition is believed to develop as the result of a problem with the normal regulation of cell production in the brain. Among the affected individuals, the neuron proliferation is not regulated properly and as the result, excess cells are produced which can also be associated with various other condition such as leukodystrophies. Some of the common symptoms associated with megalencephaly include seizures, delayed development and corticospinal dysfunction. The three forms of megalencephaly include the primary megalencephaly or the familial megalencephaly, secondary megalencephaly that develops as the result of another condition or unilateral megalencephaly or hemimegalencephaly which is the enlargement of half of the brain. There are various disorders that can present megalencephaly such as Alexander’s disease, tuberous sclerosis, neurofibromatosis, Klinefelter’s syndrome and megalencephalic leukoencephalopathy with subcortical cysts.
Megalencephalic leukoencephalopathy with subcortical cysts
This is a very rare disorder affecting the white matter of the brain that causes the loss of physical and mental health. The typical symptom is the enlarged brain (megalencephaly) that is evident at the birth of the infant. They can also continue to develop cysts in the brain which can grow in size and numbers. This disorder can continue to deteriorate between the ages of two and ten presenting signs such as involuntary writhing movements, unsteadiness and stiffness of muscle tone. When the motor skills become affected they can present slurring of speech and incoordination of swallowing. Additional symptoms can include behavior problems, epileptic seizures and learning difficulties. The life expectancy can become greatly reduced among the most severe cases. There is no treatment to stop the progression of this condition although treatment can provide relief from the associated symptoms.
Alexander’s Disease
This is an extremely rare neurological condition that occurs when the myelin, the white matter is destroyed along with the abnormal protein deposits called Rosenthal fibers. The infantile form of this condition presents poor prognosis with the most of the affected child not surviving past the age of 6. The symptoms include the severe mental retardation that progressively deteriorates, abnormally large brain, fluid accumulation in the brain, failure to grow and gain weight, difficulty with feeding, walking and speech. There is no cure for this disease and the treatment focuses on providing supportive care.
Neurofibromatosis
This is a genetic condition causing the development of the tumors on the nerve tissue which can occur anywhere on the nervous system such as the brain, spinal cord and the nerves. This condition is generally diagnosed in childhood or early adulthood. The symptoms include café au lait spots, tiny bumps on the iris of the eye, soft bumps under the skin, tumor on the optic nerve, large head as the result of increased brain volume, short stature and learning disabilities. There is no cure for this condition but treatment can provide relief from the symptoms. Depending on the cases, the surgery may be required to remove the tumors and cochlear implants or auditory brainstem implants.
References
https://rarediseases.org/rare-diseases/alexander-disease/