To begin with, the affected children exhibit normal development but eventually lose their language skills and their ability to understand what is being said to them. The condition is often mistaken for deafness, but hearing tests results are normal.
The symptoms of LKS vary widely between patients and, therefore, lack uniform diagnostic criteria. One of the first sign of trouble is when these children become unable to comprehend speech. This condition is also known as auditory verbal agnosia (AVA). In some children AVA is preceded by deafness although it may not be so in most. Children with AVA become unable to recognize or localize noises that were once familiar to them.
As this form of aphasia affects children during their crucial phase of development, it impairs their speech. The earlier AVA manifests, the poorer is the language skill. The condition worsens with time and many become totally mute.
Causes of this condition are believed to be multi factorial, yet are not well defined. Although familial clustering has been observed, most cases of LKS are spontaneous. Low-grade brain tumors, neurocysticercosis, closed-head injury, demyelinating disease and central nervous system (CNS) vasculitis have been associated with acquired epileptic aphasia.
The most prominent of the symptoms is speech impairment which worsens with time. And for this reason LKS can also be called as “secondary infantile aphasia”. Mutism is often preceded by night time epileptic seizures in these children, which eventually stop as the child enters teens.
Secondary impairments such as neuropsychological and behavioral problems comprising of low attention span, hyperactivity, anxiety, depression, rage, aggression and short- term memory are common in, approximately, 80% of children with LKS.
LKS can be misdiagnosed as autism, attention deficit problem, intellectual deficiency problem or even childhood schizophrenia. It is therefore important to confirm the diagnosis with the help of an overnight sleep electroencephalogram (EEG). Most patients with LKS report abnormal activity in both the left and the right hemispheres of the brain.
Magnetic resonance imaging (MRI), quantitative proton magnetic resonance spectroscopy (MRS) and cerebrospinal fluid analysis are some of the techniques used to diagnose LKS.
Various treatment modalities have been employed to treat LKS with variable success. They include anticonvulsant drugs, corticosteroids such as adrenocorticotropin hormone [ACTH]), surgical intervention with multiple subpial transections (MSTs) and ketogenic diet.
Valproic acid and diazepam are used as initial therapy. The calcium channel blocker nicardipine has been employed with variable success in the treatment of acquired epileptic aphasia.
Speech therapy and behavioral intervention can also be beneficial to the patient.
Long-term follow-up studies show that epilepsy and EEG abnormalities persist for life in many. Language problems too never go away. For all these reasons, the quality of life is rather poor in many. Patients in whom the language problems arose below the age of 5 years suffer poorer prognosis compared to those in whom it appeared later. Although short term remissions are common in many, the chances of language recovery are slim for those in whom the symptoms have persisted for over a year.