Dillon was a bright, normally developing child with no apparent illnesses or language delay, but at about age 31/2, his nursery school teachers began to notice changes in his behavior. Hearing loss was suspected because he did not respond when called, but the results of an audiological evaluation were normal. His teachers continued to have concerns, but it was not until a full year later that Dillon experienced a severe regression in language functioning and was diagnosed with a rare epileptic disorder, Landau-Kleffner Syndrome (LKS). Because impaired language comprehension is often one of the first overt symptoms of LKS, audiologists and speech-language pathologists can play an important role in identifying the disorder and helping to prevent misdiagnosis. (See Dillon's case study, which includes a video.)

Diagnosis

LKS is an acquired epileptic disorder in children that presents as a sudden or gradual loss of language skills in typically developing children (Mikati & Shamseddine, 2005). It was first described in 1957 (Landau & Kleffner, 1957) and can be difficult to diagnose. Although 70%–75% of the children show overt clinical seizures (Stefanatos, Kinsbourne, & Wasserstein, 2002), the identifying symptom is the presence of subclinical seizure activity that is detected only on electroencephalograms (EEGs). If overt seizures do occur, they do not necessarily coincide with the language loss and may occur months before or after. Furthermore, medication to control the overt seizures does not necessarily result in improved language skills (Ballaban-Gil & Tuchman, 2000; Rapin, 1995).

Children must have an EEG during sleep for LKS to be diagnosed (Stefanatos et al., 2002). No typical pattern of abnormal epileptiform activity absolutely differentiates LKS syndrome from other epileptiform disorders. Typically, abnormalities are seen in the temporal or parietal areas and can be either bilateral or lateralized to either hemisphere (Stefanatos et al., 2002). The relationship between these subclinical seizures and language loss is not necessarily any clearer than the relationship to overt seizures. For example, even when EEGs are normalized following medication, language recovery does not always occur (Soprano, Garcia, Caraballo, & Fejerman, 1994). Other neurological findings such as computed tomography scans (CT) and magnetic resonance imaging (MRI) are usually normal (Ballaban-Gil, & Tuchman, 2000).

The etiology of the disorder is not known (Van Bogaert & Pacquier, 2009). Case reports relate LKS to a number of medical conditions but the relationships are inconclusive (Mikati & Shamseddine, 2005; Stefanatos et al., 2002). Beaumanoir (1985) reports that a familial history of epilepsy exists in 12% of the individuals who are questioned, and males are more frequently diagnosed than females (Camfield & Camfield, 2002; Mikati & Shamseddine, 2005). Incidence is difficult to calculate because some practitioners are unaware of LKS or the need for a sleep EEG for diagnosis.

Relationship to ASD 

Because both LKS and some forms of autism are characterized by apparently normal development followed by language deterioration, there is a great deal of discussion in the literature about the relationship between LKS and autism. Similarities include:

• The presence of abnormal epileptiform activity on EEG recordings in a significant number of children with autism spectrum disorders (ASD) who have a history of language regression (Tuchman & Rapin, 1997).
• Similar behavior patterns in ASD and LKS including resistance to change, echolalia, over-sensitivity to auditory stimuli, and social withdrawal (Stefanatos et al., 2002).

Although some researchers conclude that the shared features of LKS, ASD, and other forms of acquired aphasia suggest that these disorders be located on a "spectrum of common pathophysiology" (Stefanatos et al., 2002, p. 218), many researchers caution against this view. Tuchman (2009) points to several clinical differences between LKS and ASD:

• The mean age of regression is earlier in ASD than in LKS (21 months vs. 5–7 years). The language that is lost in ASD is at most single words, not fully developed language as in LKS.
• Children with ASD demonstrate more severe social deficits and repetitive behaviors than those with LKS.
• Although sleep EEG studies find epileptiform abnormalities in some children with ASD, the presence of these abnormalities does not necessarily differentiate ASD with and without regression.

Communication Function 

Language regression is usually first observed when children appear not to understand what is said. For this reason, hearing loss is suspected and audiologic assessment is carried out. Typically, children show a gradual regression in expressive language. The literature highlights a variety of expressive deficits, including reduced syntactic complexity, telegraphic speech, word-finding deficits, jargon, neologisms, paraphasias, perseveration, and mutism. Articulation deficits, apraxia, and voice disorders also have been reported (Harrison, 2000; Soprano et al., 1994; Stefanatos et al., 2002).

The nature of expressive and receptive deficits suggests that the impairment is primarily in the area of auditory processing. Auditory processing deficits are reflected in reports of abnormal dichotic listening results and phonological short-term memory deficits, even in adults who demonstrate good language recovery (Metz-Lutz, 2009). In a follow-up study of some of the original patients described by Landau and Kleffner, many of the adults still had difficulty understanding speech in a noisy environment (Mantovani & Landau, 1980). Individuals who have recovered language later report that speech sounded like "blah, blah, blah" (Landau & Kleffner, 1957). One client followed by Montonvani and Kleffner recalled that the word "fly swatter" sounded like "glass of water." The success of many children with LKS in learning to communicate through sign language or written language lends further support to the view that the disorder is an impairment of auditory processing.

Nonverbal intelligence is generally thought to be preserved in LKS, but assessment of these children is difficult because most tests have some verbal component (Praline et al., 2003; Soprano et al., 1994; Stefanatos et al., 2002). In addition, behavioral problems sometimes associated with LKS—such as hyperactivity and attention deficit—can influence test results. Other reported behavioral issues include negativity, tantrums, nightmares, depression, and withdrawal (Harrison, 2000; Stefanatos et al., 2002).

Management 

Treatment options for LKS include medications, surgery, dietary modifications, speech-language treatment, and educational adaptations.

Pharmacology 

Many medications are described in the literature as successfully treating both language and epileptiform symptoms, and individual children respond differently to various medications. Antiepileptic drugs and corticosteroids have been successful in reducing seizures and improving language in a significant percentage of children with LKS (Mikati, Saab, Fayad, & Choueiri, 2002; Mikati & Shamseddine, 2005). Intravenous immunoglobulin treatment (IVIG) is recommended for children who have not responded to other antiepileptic medications or corticosteroids (Cavazzuti, 2003).

Surgery 

Some children who have not responded to medication have shown reduction in seizures and improved language through a surgical procedure called multiple subpial transection (Morrell et al., 1995; Van Slyke, 2002). The surgery effectively controls seizures without producing major motor deficits but is still considered experimental by many.

Diet

A ketogenic diet has been used successfully to reduce seizures but few studies support its usefulness in LKS (Lagae, 2009). This diet uses a 4:1 fat-to-nonfat ratio and is designed to produce a state of ketosis and acidosis that apparently acts as an antiepileptic (Epilepsy Foundation, 2010).

Interventions 

For most children, speech-language treatment and educational modifications continue to be required after medical treatment because subtle deficits often persist even when many language functions return to normal (Mikati & Shamseddine, 2002). Use of input modalities that bypass the auditory modality is a recurrent theme in intervention programs. Teaching sign language has been successful in a number of cases and, in fact, some children with LKS have been placed in educational programs for students with hearing loss or deafness (Deonna, Prelaz-Girod, Mayor-Dubois, & Roulet-Perez, 2009). The ability of some children with LKS to achieve age-appropriate language through the nonauditory modality suggests that they are not "aphasic" in the traditional sense because higher-order language areas are apparently preserved. Other intervention approaches used with children with hearing loss also have been suggested for LKS, including FM systems, cued speech, preferential seating, and auditory training. Some children have responded well to programs employing alternative and augmentative communication systems (Chapman, Stormont, & McCathren, 1998; Mikati & Shamseddine, 2002; Harrison, 2000; Vance, 1991; Van Slyke, 2002).

Although some children need only minimal curricular adaptations, others require one-on-one assistance or special education classes. Language loss is not the only issue requiring educational modifications; in many cases, attention deficits interfere with classroom success (Chapman et al., 1998; Harrison, 2000; Pedro & Leisman, 2005; Van Slyke, 2002).

Prognosis and Course 

Follow-up studies of individuals who had been diagnosed with LKS show a wide range of language outcomes ranging from poor—even with the elimination of epileptiform activity—to excellent in spite of continued impairment of phonological short-term memory and dichotic listening (Alpern, 2008). Mantovani and Landau (1980) followed nine patients for 10 to 28 years after the onset of their aphasia and found that four had recovered fully, one had mild language difficulty, and four had moderate language problems. All eventually attended mainstream schools and several had attended or were registered in college or technical school at the time of the study. At a recent conference on LKS, Landau showed a video of one of the original subjects, a 52-year-old woman who functioned well as a mother and had normal EEG and MRI results (Kleffner & Landau, 2009).         

It is important to be aware that if language regression is observed in a child, subclinical seizure activity could be the cause. SLPs, audiologists, and teachers have an important role to play in making appropriate referrals for these children, especially because earlier medical treatment is often associated with better outcomes (Deonna et al., 2009). Future research using more sophisticated forms of brain imaging may help to clarify why some children regain language so much more easily and which interventions, both behavioral and pharmacological, will result in the most positive outcomes for individual children.