An Overview of Landau-Kleffner Syndrome

Dr. Frank Musiek
March 15, 2022

Alix M. Moody and Matthew S. Lee
Faculty Mentor:  Annette Hurley
LSU Health Sciences Center, Dept. of Communication Disorders

Landau Kleffner syndrome (LKS) is a rare childhood acquired aphasia of unknown etiology, characterized by a regression in language and abnormal electroencephalogram activity bilaterally in the speech cortex (Hungerford et al., 1998; Van Slyke, 2004). LKS is also accompanied by a seizure disorder in 75% of cases (Hungerford et al., 1998; Van Slyke, 2004; Vance et al., 1999). Other names for Landau-Kleffner syndrome, as described in the literature, can include acquired aphasia with convulsive disorder or acquired receptive aphasia (Vance et al., 1999). Onset of LKS varies and can occur at any time between two- and seven-years old (Hungerford et al., 1998; Van Slyke, 2004). Prior to onset, however, children with LKS will present with a period of normal speech and language development. Post-onset, these children experience a regression in both expressive and receptive language capabilities. Whether the regression in language abilities or the experience of seizures are typically the first symptom of the disorder to be recognized, this is not universally agreed upon (Cockerell et al., 2011). Although these characteristics of LKS indicate a seemingly well-defined abnormality, it is important to note that the associated symptomology varies widely.

The current literature describes deficits in their receptive language as an auditory verbal agnosia, or the inability to comprehend speech (Hungerford et al., 1998; Vance et al., 1999). On the contrary, children with LKS present with varying degrees of expressive language abilities, such as total muteness, articulation disorders, and word-finding difficulties. Such children might also present with paraphasia, perseverative jargon, and difficulties with morphosyntax. Their cognition remains normal, and they achieve all other appropriate developmental milestones (Hungerford et al., 1998). Despite their lack of response to speech, those with LKS have normal hearing as demonstrated by normal pure tone audiometry and auditory brainstem response results (Hungerford et al., 1998; Vance et al., 1999). However, even with evidence of normal hearing sensitivity in most cases, the literature has described the auditory deficits in children with LKS as “hearing loss with reduced response to speech and environmental sounds” (Vance et al., 1999).

Children with LKS often experience non-auditory symptoms as well. Several autism-like behaviors can be observed in children with Landau-Kleffner syndrome. These could include echolalia or perseverative play. Some children with LKS may also demand routine and exhibit impulsiveness and further demonstrate autism-like mannerisms (Hungerford et al., 1998). Other common behaviors, unrelated to speech deficits, observed in LKS can include aggression, depression, or hyperactivity. Despite these common characteristics observed in children with Landau-Kleffner syndrome, there is no universally accepted diagnostic criteria for a LKS diagnosis (Hungerford et al., 1998). Moreover, the lack of universal agreement coupled with the non-specific symptoms described often leads to misdiagnosis of Landau-Kleffner syndrome. These symptoms are common in many other childhood disorders, such as Autism Spectrum Disorder, Attention Deficit Hyperactivity Disorder, selective mutism, and deafness (Hungerford et al., 1998); thus, further contributing to misdiagnosis in children with Landau-Kleffner syndrome. Recently, there has been some consideration given to whether the variability in the clinical manifestations, differences in pathological mechanisms, and differences in responses to treatment may garner viewing the syndrome as a spectrum disorder, similar to the autism spectrum (Cockerell et al., 2011).

Moreover, there is no distinct site of lesion that has been observed in the current literature. Some research has posited a possible long-term metabolic disorder within the temporal lobe. Other investigations of electroencephalogram activity during sleep revealed an abnormal bilateral spike wave pattern in either the temporal or parietal lobe, primarily in the superior temporal gyri or the sylvian fissure, in children with LKS (Vance et al., 1999). Although, the site of lesion remains unclear (Vance et al., 1999). A variety of epileptic seizures, including partial and generalized seizures, occur in 70-80% of patients with this diagnosis (Fandiño et al., 2011). As a result, recorded electroencephalography during sleep is the gold standard for diagnosis of Landau-Kleffner syndrome. Evidence suggests that patients with the disorder may show abnormal activity of the temporal lobe during non-rapid eye movement sleep Fandiño et al., 2011). However, more research is necessary before a conclusive site of lesion can be determined.

LKS is a life-long condition, and there is no cure for this disorder. However, treatment for LKS can include medical, surgical, and pharmacological management. Anticonvulsants will be prescribed to help manage the accompanying seizure disorder and are an essential part of treatment. There has been some success with corticosteroids to treat both the seizures and language disorder (Hungerford et al., 1998). As a third line of pharmacological treatment, an older anti-epileptic drug, Sultiame, has shown some efficacy in controlling both the seizures and the spike frequency within the temporal lobe (Fandiño et al., 2011). In some cases, surgical management may be required to control the seizures and epileptiform activity. One surgical approach is multiple subpial transection, a surgical procedure in which the surgeon severs the horizontal intracortical fibers while taking care to preserve the vertical intracortical fiber connections (Vance et al., 1999). Although this surgical intervention is often successful in controlling seizures, children with LKS are likely to continue to experience deficits in speech processing post-surgery. Despite attaining clinical control of the seizures and improving secondary behaviors, continued deficits in the processing of language may continue for some time. Information about the long-term success of this procedure is limited. Although, some improvement of the language impairment has been recorded (Stefanatos et al. 2002). As such, a referral to a speech language pathologist and other educational professionals to assist in management of the disorder may be made in order to achieve optimal communicative and functional abilities (Fandiño et al., 2011).

Because the ability for the brain to process visual information remains intact, taking advantage of visual cues is important for the long-term success of those with LKS (Stefanatos et al., 2002). The visual modality can be used to compensate for the problems with auditory processing of information. Utilizing alternative modes of communication, like sign language, cued speech, or other modes of visual communication, coupled with speech therapy and auditory training, can facilitate some recovery of oral communication due to the involved stimulation of still-functional communication networks within the brain (Fandiño et al., 2011). By allowing the individual to maintain some form of communication, typical behavioral problems associated with LKS may be addressed since they are typically born out of the frustration experienced with spoken language difficulties (Fandiño et al., 2011).

LKS is a rare disorder that is not commonly seen or well known amongst professionals in the fields of otolaryngology, audiology, and speech language pathology. Because of its rarity, there exists a lack of familiarity about the disorder and its diagnosis. Despite this, prognostic data indicates that, with proper and timely care, 50% of patients with LKS may go on to lead a mostly normal life, with 10-20% achieving complete normalcy (Fandiño et al., 2011). Patients with a later onset of the disorder do have a better prognosis. One reason for this may be that these patients were exposed to oral communication for a longer period and would have acquired more language by the time of onset of the disorder. Although the abnormalities of EEG results have been shown to be mostly age dependent, frequently normalizing by the age of 15, the difficulties associated with speech and language tend to be lasting (Fandiño et al., 2011).

It is crucial that a team of professionals from related fields be involved in the providing of an accurate diagnosis and appropriate management for children with Landau-Kleffner syndrome.

Previous reports of auditory processing deficits in LKS patients have cited difficulty listening in background noise and other degraded listening environments, challenges with auditory discrimination, and problems with dichotic listening tasks (Bamiou, Musiek, & Luxon, 2001). An assistive listening device such as an FM system may be useful to improve the signal-to-noise ratio. Additionally, auditory training to include speech-noise training or dichotic listening training may be appropriate treatments to improve listening difficulties.



Bamioue, d.E., Musiek, F.E., Luxon, L.M. (2001) Aetiology and clinical presentations of auditory processing disorders- a review. Arch Dis Child: 85: 361-365.

Fandiño, M., Connolly, M., Usher, L., Palm, S., & Kozak, F. K. (2011). Landau-Kleffner syndrome: a rare auditory processing disorder series of cases and review of the literature. International Journal of Pediatric Otorhinolaryngology, 75(1), 33–38.

Hungerford, S., Coppens, P., & Clarke, N. (1998). Computer-based treatment in a case of Landau-Kleffner Syndrome. Neurophysiology and Neurogenic Speech and Language Disorders, 12-17.

Stefanatos, G. A., Kinsbourne, M., & Wasserstein, J. (2002). Acquired Epileptiform Aphasia: A Dimensional View of LKS and the Relation to Regressive Autistic Spectrum Disorders. Child Neuropsychology, 8(3), 195.

Van Slyke, P. A. (2004). Modifications for classroom instruction for children with Landau-Kleffner Syndrome. School Based Issues, 22-26.

Vance, M., Dry, S., & Rosen, S. (1999). Auditory processing deficits in a teenager with Landau-Kleffner Syndrome. Neurocase, 5, 545-554.

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