The prognosis for children with LKS varies. Some affected children may have a permanent severe language disorder, while others may regain much of their language abilities (although it may take months or years). In some cases, remission and relapse may occur. The prognosis is improved when the onset of the disorder is after age 6 and when speech therapy is started early. Seizures generally disappear by adulthood. Short-term remissions are not uncommon in LKS but they create difficulties in evaluating a patient's response to various therapeutic modalities. The following table demonstrate the Long-Term Follow-up of Acquired Epileptic Aphasia across many different instrumental studies:. Study Number of Patients Mean Follow-up, y Number of Patients with Normal or Mild Language Problems Soprano et al. (1994) 12 8 3 Mantovani and<unk>  (1980) 9 22 6 Paquier (1992) 6 8.1 3 Rossi (1999) 11 9.7 2 Robinson et all (2001) 18 5.6 3 Duran et al. (2009) 7 9.5 1 Total 63 18 (28.6%) Lower rates of good outcomes have been reported, ranging between 14% to 50%. Duran et al. used 7 patients in his study (all males, aged 8–27 years of age) with LKS. On long-term followup, most of his patients did not demonstrate total epilepsy remission and language problems continued. Out of the seven patients, one reported a normal quality of life while the other six reported aphasia to be a substantial struggle. The Duran et al. study is one of few that features long-term follow up reports of LKS and utilizes EEG testing, MRIs, the Vineland Adaptive Behavior Scales, the Connor's Rating Scales-revised, and a Short-Form Health Survey to analyze its patients. Globally, more than 200 cases of acquired epileptic aphasia have been described in the literature. Between 1957 and 1980, 81 cases of acquired epileptic aphasia were reported, with 100 cases generally being diagnosed every 10 years.
Landau–Kleffner syndrome
Smith–Lemli–Opitz syndrome
Letterer–Siwe disease
Kapur–Toriello syndrome
Klüver–Bucy syndrome
Smith–Magenis syndrome
Pelger–Huët anomaly
Schinzel–Giedion syndrome