The involved hemisphere is larger than normal. In addition to being large, it is also profoundly dysfunctional as the brain in that area has not developed properly. The unaffected side typically has normal cortical developement but is abnormally small, because the large abnormal side restricts the normal growth of the unaffected side. The exact cause of this developmental disease is unknown and is probably multifactorial. While it can occur as an isolated finding, it can also occur along with other developmental syndromes. The presence of the abnormal brain, along with the chronic damage done by frequent seizures, often results in developmental delay and if left untreated these patients often deteriorate significantly to severe mental retardation. In order to minimize seizures, to minimize further developmental delay and to allow the other side of the brain the best chance to preserve function and develop normally, surgery is often recommended. Although each case is different and must be considered separately, one of the most common surgical treatments is removal and/or disconnection of the affected hemisphere. This, so called, hemispherectomy is a dramatic surgical treatment but may be the best option to improve the outcome of these unfortunate children. While this procedure removes half the brain, it is brain that was abnormal to begin with. Additionally, if done in very young patients, the opposite side, assuming it is fairly normal, can gradually take over some of the function. These patients do typically have some degree of hemiparesis or hemiplegia, weakness or paralysis, of the other side of the body. This dramatic developmental disease is difficult to treat and is usually done at centers that specialize in complex pediatric diseases of the nervous system. Each patient is different so each patient and their family should consult their own treating physicians about the most appropriate treatment options in their unique case. Infantile spasms is the name for the type of seizure, but does not explain the underlying cause of the infant epilepsy. There are various underlying diseases which can be associated with these seizures including West Syndrome (characterized by infantile spasms, hypsarrhythmia and mental retardation), cortical dysplasia, hemimegalencephaly and cerebral palsy, to name a few. In some patients a focal brain lesion can be identified which is thought to be the source of the seizures. If these cases cannot be controlled with medication alone, some will be offered surgery to surgically remove the source of the epilepsy in the brain. If the seizures cannot be controlled or eliminated completely, many of these patients will develop other seizure types and epilepsy syndromes later in life. Each patient is different and there are multiple potential causes of this type of seizure. Each patient and their family should consult their own treating physicians regarding the recommended treatment options and prognosis.What Is It?
Hemimegalencephaly is a rare, severe congenital malformation of the brain which is usually associated with epilepsy. As the name implies, an entire hemisphere of cortex, half of the brain, is involved. Like other forms of cortical dysplasia, there is an abnormality during development of the nervous system which leads to abnormal formation of the cerebral cortex, the outer layer of the brain, a form of grey matter. Whereas in typical cortical dysplasia this malformation of the cortex is localized to a restricted area of the brain, in hemimegalencephaly an entire hemisphere is involved.What Types of Symptoms Are Typical?
The most common presenting symptom of this disease is seizures. The abnormally developed hemimegalencephalic brain is prone to seizures which occur frequently, usually starting at or shortly after birth, and often spread to involve the whole brain. In addition, the patient generally has abnormal function of the involved hemisphere and can have sensory and motor dysfunction on the opposite side of the body.How Is The Diagnosis Typically Made?
In a young patient, generally an infant, who presents with neurological symptoms and epilepsy, a thorough neurological examination and brain MRIusually reveal the presence of hemimegalencephaly. The appearance of this condition on MRI is quite characteristic and is usually not confused with other diagnoses. However, biopsy of the abnormal tissue at the time of surgery can help confirm the diagnosis.What Are Some Common Treatments?
As with other forms of epilepsy, hemimegalencephaly may be treated by both medical and surgical means. Generally, patients are initially treated with anti-seizure medications. In this disease, these medications are rarely sufficient to control seizures completely. Additionally, the presence of the large, abnormal hemisphere may put pressure on and limit the normal growth and development of the other side of the brain.Infantile Spasms
What Is It?
Infantile spasms are a specific type of seizure which can be associated with various forms of epilepsy. As the name implies, they typically occur in infants and very young children. Patients with these types of seizures usually stop having these seizures by around 5 years of age on average but are usually replaced by other seizure types.What Types of Symptoms Are Typical?
The typical spasms usually first present in the first year of life, most commonly between 3 to 6 months but can occur as early as birth. The seizure itself is usually characterized by sudden bending forward and stiffening of the body, arms and legs, sometimes followed by flacidity. The are more frequent after arousal from sleep. Each spasm is usually brief, only lasting seconds, but can occur in clusters of many spasms in a row. The frequency and severity of these seizures varies depending on the underlying cause and is different in each patient. In severe cases patients can have dozens of clusters and even hundreds of spasms a day.How Is The Diagnosis Typically Made?
These seizures are generally diagnosed in infancy by their clinical characteristics followed by a thorough neurological evaluation and anelectroencephalogram which demonstrates seizure activity. Further testing, including MRI and other neurological testing may be done to identify the underlying cause of the seizures.What Are Some Common Treatments?
Untreated infantile spasms, like any form of seizures in early life, can lead to developmental delay and mental retardation. Generally, the goal if possible is to reduce or eliminate the seizures as early in life as possible with a combination of treatments. Medical treatments can include medications to reduce the seizure frequency. These medications include both anti-seizure medications as well as ACTH (adrenocorticotropic hormone) and prednisone in some cases.
Wednesday, March 31, 2010
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