About Landau-Kleffner Syndrome (LKS)
Landau-Kleffner Syndrome (LKS) is a rare form of acquired childhood aphasia, characterized by abnormal electroencephalographic (EEG) findings in the speech cortex and language deterioration, possibly accompanied by overt seizures. Since the first report by Landau and Kleffner (1957) of this unusual type of acquired childhood aphasia, there have been only 170 cases reported in the literature through 1992. The abnormal epileptiform activity is characterized by bilateral continuous spike-wave pattern during slow wave sleep, usually in the posterior temporal regions of each hemisphere (Morrell et al., 1995). The onset is between 2 ½ and 6 years of age, after a period of normal cognitive and language development. Concomitant characteristics include severe auditory verbal agnosia, attention deficits and behavioral disturbances. Etiology is unknown at this time, although possible hypothesized causes include inflammatory process, possibly encephalitis, a slow type of virus, myelin defect, low erythrocyte zinc content, or Toxoplasma Gondii infection. The literature does not reflect that etiological issues have been resolved. In summary, since the original report by Landau and Kleffner (1957), there have been numerous articles written regarding the pathophysiology, the concomitant behavioral findings, and the course and prognosis of the disease, but few articles document the language disorder present in children with LKS (Bishop, 1985; Cooper and Ferry, 19978; Deonna, 1991; Gordon, 1990; Grote, C., Van Slyke, P., & Hoeppner, J. (1999); Marescaux, et al., 1990; Pacquier, Van Dongen & Loonen, 1992; Rapin, Mattis, Rowan, and Golden, 1977; Vance, 1991; Van de Sandt-Koenderman, Smit, Van Dongen, & Van Hest, 1984); Van Slyke (2002)
Although the language disorder is one of the hallmarks of the syndrome, there has been surprisingly little written in the literature regarding the pathophysiology of the language regression. Morrell et al (1995) hypothesized that the epileptiform activity develops during the critical time period of one to eight years of age when the “fundamental circuitry for speech” (p.1542) is being established. During typical development, synaptogenesis is the “circuit building process that establishes both the neural substrate for language and its hemispheric lateralization” (p. 1542). Highly abundant numbers of axonal processes (twice that found in adults) make contact with specified cells. Subsequently, synaptic formations not needed will be eliminated (cell death) and others will become permanent connections. Morrell and his colleagues (1995) hypothesized that during this normal process of speech circuitry connection, the abnormal epileptiform activity encroaches on the area, causing inappropriate connections, thus disrupting language acquisition during a crucial time of development.
The age of onset of LKS is one of the critical determinants of how these children lose language, if they become mute, or how language is impaired through a lesser degree of deterioration during the course of the disease. It is at some point during the critical language learning years that LKS affects a previously normal language developing child. Bishop’s (1985) landmark study concluded from 55 cases that the younger the child at the time of disease onset, the worse the prognosis for language recovery, which would be consistent with the idea that language loss is due to a higher level auditory processing disorder. It stands to reason then, when the processing system is damaged at an early age, the child’s brain would not have the same capacity to develop language as an older child whose processing system has already allowed them to develop language. Interestingly, a few children with late-onset LKS have not shown as severe a loss in language, either receptively or expressively (Bishop, 1985; Gordon, 1990; Lees, 1993).
Despite 50 years of research on LKS, the hallmark language characteristics have not been carefully documented. Most early reports in the literature address the characteristics of the language disorder associated with this syndrome in terms of “improved”, “normal” or “no change”, without documented results of standardized assessment to support these categories. One exception is a study by Grote, Van Slyke & Hoeppner (1999). Grote and his colleagues report on the speech and language outcome of 14 children who underwent multiple subpial transection (MST) surgical treatment of LKS. (Surgical treatment is described in detail further in this paper). Pre and post operative results from the Peabody Picture Vocabulary Test - Revised (PPVT-R) (Dunn and Dunn, 1984) and the Expressive One Word Picture Vocabulary Test - Revised (EOWPVT-R) (Gardener, 1990) were reported. Eleven children demonstrated significant postoperative improvement on measures of receptive or expressive vocabulary and the best predictor of postoperative gains in language function was length of time since the surgery.
Treatment for LKS is either pharmacological (anticonvulsants or corticosteroids) or surgical intervention to control the epileptiform activity. Pharmacological treatment is always the initial form of treatment. If the abnormal epileptiform activity is not controlled by medication and continues unabated, the child could be a surgical candidate, providing the appropriate criteria for surgery is met. The surgical procedure, multiple subpial transection (MST), was developed due to the location of the epileptiform activity in the speech cortex, which involves speech, memory, and primary motor and sensory function. This procedure severs the horizontal intracortical fibers, while preserving the vertical fiber connection of both incoming and outgoing nerve pathways and the penetrating blood vessels (Morrell, Whisler, and Bleck, 1989). The results of this procedure were reported in Brain by Morrell et al., 1995.
Auditory Verbal Agnosia
One of the primary characteristics of LKS is auditory verbal agnosia (Rapin, et al., 1977), which significantly affects the child’s ability to process the oral input of language. Rapin and her colleagues (1977) described this phenomena as a severe comprehension disorder due to the disruption of the auditory input system. This implies that the severe disturbance of the pathway taking language information into the cerebral area, not a disruption in the cortical structure, is responsible for the difficulty in processing the verbal language input. Classically, the child with LKS demonstrates a progressive deterioration of his auditory response to oral language, and may not even head turn to the calling of his name. Some children do not respond to environmental noises, such as the telephone ringing, doorbell, or the dog barking. Often, children with LKS initially have been misdiagnosed as suddenly becoming deaf, and in some cases these children were subsequently fit with hearing aids.
Even after either the pharmacological treatment and/or the surgical intervention, these children display continued deficits in the processing of oral language for some time (Grote et al.1999). Therapists and classroom teachers often may believe that treatment of any type will eliminate the processing deficits and the child will return to the school environment ‘cured’. Given the heavy demands of language in any classroom, the need for children to be able to understand verbal directions and to process what is being said in the classroom in order to learn and achieve academic success, it is understandable how significantly the auditory verbal agnosia will impact the educational progress of children with LKS. Thus, it is critical to maximize language recovery and academic learning in the classroom for these children, before and during the recovery period.
There are a few case study reports in the literature regarding classroom methodology for these children with LKS. Vance (1991) discussed numerous classroom interventions to assist a five year old boy with his severely deteriorated communication skills due to the onset of LKS at age 3; 6. Sign language, a daily diary of sequenced pictures for the classroom routine of the day, and auditory training beginning at the level of environmental sounds were successfully used with this child. Further more, Vance (1991) reported that Cued Articulation (Passy, 1990), a system providing visual cues for consonant sounds, was helpful in increasing the child’s speech intelligibility over time. Vance suggested that these methods were most successful when reinforced within the classroom and in the speech language therapy sessions.
Lea (1979) described a Color-Pattern Scheme that uses systematic color coding of various classes of words (nouns, verbs, articles, etc.) to visually reinforce syntax and aid in comprehension questions. Vance (1991) reported that Lea’s color coded system for words was utilized in conjunction with the printed word from the ‘daily diary’ and signing of the word to introduce and develop literacy skills in her case study. In addition, Vance (1991) discussed the technique of ‘graphic conversation’, using written word of literal conversation placed on ‘speech balloons’, to further the child’s literacy development into sequencing of stories, incorporating comprehension and vocabulary.
Worster-Drought (1971) also supported the use of reading to teach language, especially for those children whose receptive language comprehension remained severely impaired. Suzuki & Notoya (1980) determined from their case study that written language was of benefit to those children who presented with auditory verbal agnosia. Finally, Van Slyke (2004; 2002) discusses multiple ways to adapt the regular classroom curriculum to assist children with LKS reach their maximum potential in academic achievement.